Supplementary Notes On Microbiology And Parasitology

Chapter 1 Microbiology—The Science Terms Introduced in This Chapter After reading Chapter 1, you should be familiar with the following terms. These terms are defined in Chapter 1 and in the Glossary. Abiogenesis Antibiotic Bacteriologist Bacteriology Biogenesis Biology Bioremediation Biotechnology Decomposers Etiologic agent Etiology Fastidious microorganisms Genetic engineering In vitro In vivo Indigenous microflora Infectious diseases Koch's Postulates Microbial ecology Microbial intoxications Microbiologist Microbiology Microorganisms Microscope Mycologist Mycology Nonpathogens Obligate intracellular pathogens Opportunistic pathogens Paleomicrobiology Parasites Parasitologist Parasitology Pasteurization Pathogens Petri dish

Phycologist Phycology Phytoplankton Plankton Protozoologist Protozoology Pure culture Saprophyte Toxin Ubiquitous Virologist Virology Zoonoses (sing., zoonosis) Zooplankton

Insight Additional Careers in Microbiology

Agricultural Microbiology

Agricultural microbiology is an excellent career field for individuals with interests in agriculture and microbiology. Included in the field of agricultural microbiology are studies of the beneficial and harmful roles of microbes in soil formation and fertility; in carbon, nitrogen, phosphorus, and sulfur cycles; in diseases of plants; in the digestive processes of cows and other ruminants; and in the production of crops and foods. Many different viruses, bacteria, and fungi cause plant diseases. A food microbiologist is concerned with the production, processing, storage, cooking, and serving of food, as well as the prevention of food spoilage, food poisoning, and food toxicity. A dairy microbiologist oversees the grading, pasteurization, and processing of milk and cheeses to prevent contamination, spoilage, and transmission of diseases from environmental, animal, and human sources. Certain aspects of agricultural microbiology are discussed in Chapter 10.

Biotechnology (Industrial Microbiology)

Biotechnology (Industrial Microbiology)—the use of microorganisms in industry—is an excellent career field for individuals with interests in industry and microbiology. Many businesses and industries depend on the proper growth and maintenance of certain microbes to produce beer, wine, alcohol, and organic materials such as enzymes, vitamins, and antibiotics. Industrial microbiologists monitor and maintain the microorganisms that are essential for these commercial enterprises. Applied microbiologists conduct research aimed at producing new products and more effective antibiotics. Biotechnology is discussed more fully in Chapter 10.

Environmental Microbiology and Bioremediation

The field of environmental microbiology, or microbial ecology, has become increasingly important in recent years because of heightened awareness and concern about dangers to the environment. Environmental microbiologists are concerned about water and sewage treatment. The purification of waste water is partially accomplished by bacteria in the holding tanks of sewage disposal plants, in which feces, garbage, and other organic materials are collected and reduced to harmless waste (discussed in Chapter 11). Some microorganisms, such as the iron- and sulfur-utilizing bacteria even break down metals and minerals. Bioremediation involves the use of microorganisms to clean up after ourselves—that is, to clean up landfills and industrial and toxic wastes. The beneficial activities of microbes affect every part of our environment, including soil, water, and air. Environmental microbiology and bioremediation are excellent career fields for individuals with interests in ecology and microbiology.

Microbial Genetics and Genetic Engineering

Microbial genetics involves the study of microbial DNA, chromosomes, plasmids, and genes. (Plasmids are small, circular molecules of extrachromosomal DNA; they are discussed in Chapter 3.) Genetic engineering involves the insertion of foreign genes into microorganisms (usually into bacteria or yeasts). These foreign genes may come from any other organism (e.g., another microorganism, an animal, or even a plant). The primary purpose of inserting a foreign gene into a microorganism is to create a microbe that is capable of either producing a product of importance to us or accomplishing some task of importance to us. Genetic engineering has applications in agricultural, environmental, industrial, and medical microbiology. The intestinal bacterium, Escherichia coli, has been used

extensively in microbial genetics, genetic engineering, and microbial physiology. Microbial genetics and genetic engineering are excellent career fields for individuals with interests in genetics and microbiology. Microbial physiology and genetics are discussed in Chapter 7.

Microbial Physiology

Research in microbial physiology has contributed immensely to our understanding of the structure and functions of microbial cells. What microbiologists learn about microbial cells quite often applies to cells, in general. Microbial physiology is an excellent career field for individuals with interests in biochemistry and microbiology.

Paleomicrobiology The field of paleomicrobiology involves the study of ancient microbes. Although life is thought to have originated between 3.7 and 4 billion years ago, there are no cellular fossils available from that time period. But there are molecular fossils—molecules (usually lipids) known to be made only by organisms or, in some cases, only by particular organisms. Finding such molecular fossils in ancient rocks serves as evidence that life existed at that time. The earliest molecular fossils date back to between 3.7 and 4 billion years ago. Some paleomicrobiologists examine and study skeletons and mummified human remains to determine the infectious diseases that occurred in ancient civilizations. Such studies often involve the recovery of microbial DNA from bone and mummified tissue samples. For example, finding Mycobacterium tuberculosis DNA in Egyptian mummies has revealed that tuberculosis existed as far back as 3000 BC. Paleomicrobiology is an excellent career field for individuals with interests in anthropology, archaeology, and microbiology.

Parasitology

Technically, any organism that lives on or in another living organism is called a parasite. It would seem, then, that the term parasite would apply to all of the microorganisms of our indigenous microflora—the viruses and bacteria that live on or in the human body. However, the field of parasitology involves only the following three categories of parasites: parasitic protozoa, helminths (parasitic worms), and arthropods (specifically, certain insects and

arachnids). A parasitologist studies these organisms and their life cycles in an attempt to discover the best ways to control and treat the diseases that they cause. Chapter 18 contains a wealth of information about medical parasitology.

Sanitary Microbiology

The field of sanitary microbiology includes the processing and disposal of garbage and sewage wastes, as well as the purification and processing of water supplies to ensure that no pathogens are carried to the consumer by drinking water. These topics are discussed in Chapter 11. Sanitary microbiologists also inspect food processing installations and eating establishments to ensure that proper food handling procedures are being enforced.

Veterinary Microbiology

A wide variety of microbes—including viruses, bacteria, fungi, and protozoa—cause infectious diseases in animals. Control of such diseases is the concern of veterinary microbiologists. The production of food from livestock, the raising of other agriculturally important animals, the care of pets, and the transmission of diseases from animals to humans are areas of major importance in this field. Infectious diseases of humans that are acquired from animal sources are called zoonoses or zoonotic diseases. Zoonoses are discussed in Chapter 11. Veterinary microbiology is an excellent career field for a person who is fond of animals and microbiology.

Increase Your Knowledge 1.

For additional information about careers in microbiology, visit the American Society for Microbiology (ASM) web site (www.asm.org), and read the book, Many Faces, Many Microbes: Personal Reflections in Microbiology, edited by Ronald M. Atlas (ASM Press, Washington, D.C., 2000). The ASM web site also contains information about colleges and universities offering undergraduate and graduate degrees in microbiology.

2.

Students wishing to learn more about the history of microbiology should read any of the following books: Microbe Hunters, by Paul de Kruif (Harcourt, Brace, 1926), Milestones in Microbiology, edited by Thomas Brock (ASM Press, Washington, D.C., 1961),

Microbe Hunters Then and Now, edited by Hilary Koprowski and Michael B.A. Oldstone (Medi-Ed Press, Bloomington, IL, 1996), and A Chronology of Microbiology in Historical Context, by Raymond W. Beck (ASM Press, Washington, D.C., 2000). 3.

For in-depth information about Louis Pasteur and Robert Koch, you might want to read the following books (information about these books can be found at http://estore.asm.org): Pasteur and Modern Science, by Rene Dubos and Thomas D. Brock. ASM Press, Washington, D.C., 1998. Robert Koch: A Life in Medicine and Bacteriology, by Thomas D. Brock. ASM Press, Washington, D.C., 1998.

Microbiology—Hollywood Style Students wishing to gain a better understanding of Louis Pasteur and the 19th-century problems he faced should rent the thoroughly enjoyable video entitled The Story of Louis Pasteur. This 1936 black-and-white movie starred Paul Muni, who won an Academy Award for his portrayal of Louis Pasteur.

Critical Thinking 1.

Microorganisms are said to be ubiquitous. Can you think of any locations that would be devoid of microorganisms?

2.

Of all the various areas of microbiology mentioned in this chapter, which appeal to you the most as a possible career field? Why?

3.

Assume that you are entering a health-related profession. Of what value will knowledge of microbiology be to you?

4.

Many people consider Louis Pasteur’s contributions to be the foundation of the science of microbiology and a cornerstone of modern medicine. What contributions did he make that would cause people to believe that?

5.

You have isolated a bacterium from the blood of a patient with a newly described disease. What steps would you take to prove that the organism that you’ve isolated is the cause of the patient’s disease? (Hint: Remember Koch’s Postulates.)

Answers to the Chapter 1 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

A B D D B B D B B B

Additional Chapter 1 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

A. B. C. D. E.

Anton van Leeuwenhoek Robert Koch Louis Pasteur Rudolf Virchow Alexandre Emil Jean Yersin

pathogens nonpathogens opportunistic pathogens indigenous microflora saprophytes

_____

1. Developed vaccines for anthrax and rabies.

_____ 2.

Proposed the theory of biogenesis.

_____ 3.

Discovered the causative agent of plague.

_____ 4.

The first person to observe live bacteria and protozoa.

_____ 5.

Developed an experimental procedure that could be used to prove that a specific microorganism is the cause of a specific infectious disease.

_____

6. Organisms that live on dead or decaying organic matter.

_____ 7.

Microorganisms that do not cause disease.

_____ 8.

Microorganisms that usually do not cause disease, but can cause disease under certain circumstances.

_____ 9.

The microorganisms that live on us and in us.

_____ 10.

The most common causes of infectious diseases or microbial intoxications.

True/False Questions _____ 1.

All infectious diseases are caused by pathogens.

_____ 2.

Pathogens greatly outnumber nonpathogens.

_____ 3.

Using microorganisms to clean up the environment is known as bioremediation.

_____ 4.

Microorganisms are essential in the field of genetic engineering.

_____ 5.

Microorganisms probably appeared on earth about 3.5 million years ago.

_____ 6.

Anton van Leeuwenhoek’s experiments helped to prove that microorganisms cause disease.

_____ 7.

Louis Pasteur and Robert Koch made significant contributions to the “Germ Theory of Disease.”

_____ 8.

Pasteurization is a process that kills all microorganisms present in the liquid being pasteurized.

_____ 9.

Microorganisms contribute more oxygen to our atmosphere than plants do.

_____ 10.

Infectious diseases that are transmitted from animals to humans are known as zoonoses.

Answers to the Additional Chapter 1 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9.

C D E A B E B C D

10.

A

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (the reverse is true) True True False (3.5 billion years ago) False (Leeuwenhoek did not make the link between diseases and the microorganisms he observed; scientists like Pasteur and Koch made such connections) True False (pasteurization is a process designed to kill pathogens; it does not kill all of the microorganisms that might be present in the liquid being pasteurized) True True

Chapter 2 Microscopy Terms Introduced in This Chapter After reading Chapter 2, you should be familiar with the following terms. These terms are defined in Chapter 2 and in the Glossary. Bacillus (pl., bacilli) Brightfield microscope Centimeter Coccus (pl., cocci) Compound light microscope Darkfield microscope Decimeter Electron micrograph Electron microscope Empty magnification Fluorescence microscope Micrometer Microscopic Millimeter Nanometer Phase-contrast microscope Photomicrograph Resolving power (resolution) Scanning electron micrograph Scanning electron microscope Simple microscope Transmission electron micrograph Transmission electron microscope

Critical Thinking You are planning to create a better compound light microscope—one that will enable you to see objects smaller in diameter than 0.2 µm. You gather together the best lens grinders in the world and put them to work in a lens-grinding laboratory having unlimited resources. You instruct them to grind marvelous magnifying lenses and add them to an existing compound light microscope. What’s wrong with this plan?

Answers to the Chapter 2 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

D B A D D B A D B B

Additional Chapter 2 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

10 100 1,000 1,000,000 1,000,000,000

_____

1. The number of nanometers in a micrometer.

_____ 2.

The resolving power of the compound light microscope is __________ times better than the resolving power of the unaided eye.

_____ 3.

The number of micrometers in a millimeter.

_____ 4.

The resolving power of the transmission electron microscope is __________ times better than the resolving power of the scanning electron microscope.

_____ 5.

The resolving power of the transmission electron microscope is __________ times better than the resolving power of the unaided eye.

A. B. C. D. E.

0.2 nm 20 nm 0.2 µm 1 µm 0.2 mm

_____

6.

The width of a typical coccus.

_____ 7.

The resolving power of the unaided eye.

_____ 8.

The resolving power of the scanning electron microscope.

_____ 9.

The resolving power of the transmission electron microscope.

_____ 10.

The resolving power of the compound light microscope.

True/False Questions _____ 1.

Anton van Leeuwenhoek is given credit for developing the first compound light microscope.

_____ 2.

The wavelength of visible light limits the size of objects that can be seen with the compound light microscope.

_____ 3.

The resolving power of compound light microscopes can be improved by adding additional magnifying lenses.

_____ 4.

A brightfield microscope can be converted to a darkfield microscope by replacing the condenser on a brightfield microscope with a darkfield condenser.

_____ 5.

Transmission electron microscopes are used to study surface features.

_____ 6.

Primary syphilis is usually diagnosed in the clinical microbiology laboratory by the use of a scanning electron microscope.

_____ 7.

A magnifying glass could be considered a simple microscope.

_____ 8.

The total magnification achieved when the oil immersion lens is used is ×1,000.

_____ 9.

Fluorescence microscopy is often used in immunology laboratories.

_____ 10.

The resolving power of electron microscopes is much better than that of compound light microscopes because the wavelength of electrons is much longer than that of visible light.

Answers to the Additional Chapter 2 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7.

C C C B D D E

8. 9. 10.

B A C

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

False (Leeuwenhoek made simple microscopes, not compound microscopes) True False (adding additional magnifying lenses to existing compound light microscopes would not improve resolving power; it is referred to as “empty magnification”) True False (transmission electron microscopes are used to observe internal structures; scanning electron microscopes are used to study surface features) False (primary syphilis is usually diagnosed using darkfield microscopy) True True True False (it is because the wavelength of electrons is much shorter than that of visible light)

Chapter 3 Cell Structure and Taxonomy Terms Introduced in This Chapter After reading Chapter 3, you should be familiar with the following terms. These terms are defined in Chapter 3 and in the Glossary. Amphitrichous bacterium Archaea Archaeans Asexual reproduction Autolysis Axial filaments Bacteria Bacteria Binary fission Capsule Cell Cell membrane Cell theory Cell wall Cellulose Chitin Chloroplast Chromosomes Cilium (pl., cilia) Conjugation Cytokinesis Cytology Cytoplasm Cytoskeleton Deoxyribonucleic acid (DNA) Diploid cells Endoplasmic reticulum (ER) Endospore Eucarya Eucaryotic cells Fimbriae (sing., fimbria) Flagella (sing., flagellum) Flagellin Gene Gene product Generation time

Genotype (Genome) Genus (pl., genera) Glycocalyx Golgi complex Haploid cells Life cycle Lophotrichous bacterium Lysosome Meiosis Metabolism Microtubules Mitochondria (sing., mitochondrion) Mitosis Monotrichous bacterium Negative stain Nuclear membrane Nucleolus Nucleoplasm Nucleus (pl., nuclei) Organelles Peptidoglycan Peritrichous bacterium Peroxisome Phagocyte Phagocytosis Photosynthesis Pili (sing., pilus) Plasmid Plastid Polyribosomes Procaryotic cells Protists Protoplasm Ribonucleic acid (RNA) Ribosomes Rough endoplasmic reticulum (RER) Selective permeability Sex pilus Sexual reproduction Slime layer Smooth endoplasmic reticulum (SER) Species (pl., species) Specific epithet Spirochetes Sporulation Taxa (sing., taxon)

Taxonomy Tyndallization

Insight Asexual Versus Sexual Reproduction In asexual reproduction, a single organism is the sole parent. It passes copies of all of its genes (i.e., its entire genome) to its offspring. Some single-celled eucaryotic organisms can reproduce asexually by mitotic cell division (mitosis; described later), a process by which their chromosomes are copied and allocated equally to two daughter cells. The genomes of the offspring are identical to the parent’s genome. Procaryotic organisms reproduce asexually by a process known as binary fission (described later). In sexual reproduction, two parents give rise to offspring that have unique combinations of genes inherited from both parents. The alternation of meiosis (described later) and fertilization is common to all organisms that reproduce sexually. In sexual reproduction, a zygote (fertilized egg) is formed by the fusion of gametes. Most protists can reproduce asexually. Some protists are exclusively asexual, whereas others can also reproduce sexually (involving meiosis and the fusion of gametes). Fungi (other than yeasts) reproduce by releasing spores, which are produced either sexually or asexually. Most yeasts reproduce asexually, either by simple cell division or by the process of budding. Budding, a type of mitosis, involves the formation of a small cell (called a bud), which then pinches off the parent cell. Some yeasts reproduce sexually. Life Cycles A life cycle can be defined as the generation-to-generation sequence of stages that occur in the reproductive history of an organism. The human life cycle (which is also the life cycle of most animals and some protists) involves production of haploid gametes by meiosis, fusion of gametes to produce a diploid zygote, and mitotic division of the zygote to produce a multicellular organism, composed of diploid cells. (Haploid cells contain only one set of chromosomes, whereas diploid cells contain two sets of chromosomes.) Another type of life cycle that occurs in most fungi and some protists, including some algae, involves fusion of haploid gametes to form a diploid zygote, meiosis to produce haploid cells, and then division of the haploid cells by mitosis to give rise to a multicellular adult organism that is composed of haploid cells. Gametes are then produced from the haploid organism by mitosis (rather than by meiosis). Thus, the only diploid stage is the zygote. A third type of life cycle that occurs in plants and some species of algae is called alternation of generations. In this type of life cycle, there are both diploid and haploid multicellular stages. The multicellular diploid stage is called the sporophyte. Meiosis in the sporophyte produces haploid cells called spores. Unlike a gamete, a spore gives rise to a multicellular organism without fusing with another cell. A spore divides mitotically to generate a multicellular haploid stage called the gametophyte. The gametophyte makes gametes by mitosis. Fertilization results in a diploid zygote, which develops into the next sporophyte generation. Thus, the sporophyte and gametophyte generations take turns reproducing each other.

Eucaryotic Cell Reproduction Eucaryotic cells may reproduce either by mitosis or meiosis. Mitosis results in two cells (called daughter cells), which are identical to the original cell (the parent cell). Meiosis results in four cells, each of which contains half the number of chromosomes as the parent cell. Mitosis The word mitosis comes from the Greek word mito, meaning “thread.” When cells are observed microscopically, threadlike structures can be seen during mitosis. Technically speaking, mitosis refers to nuclear division—the equal division of one nucleus into two genetically identical nuclei. Mitosis is preceded by replication of chromosomes, which occurs during a part of the cell life cycle known as interphase. During mitosis, the nuclear material of the parent cell shifts, reorganizes, and moves around, leading some people to refer to mitosis as “the dance of the chromosomes.” After mitosis occurs, the cytoplasm divides (a process known as cytokinesis), resulting in two daughter cells. Either haploid or diploid cells can divide by mitosis. Meiosis Only diploid cells can undergo meiosis. As with mitosis, meiosis is preceded by replication of chromosomes. In

meiosis, diploid cells are changed into haploid cells. Human diploid cells, for example, contain 46 chromosomes, whereas human haploid cells (sperm cells and ova) contain 23. Meiosis is the process by which gametes are produced. Many steps are involved in meiosis—too many to discuss in detail here. Suffice it to say that meiosis involves two divisions (called meiosis I and meiosis II). The end result is four daughter cells, each of which contains only half as many chromosomes as the parent cell. Recall that mitosis produces two daughter cells that are genetically identical to the parent cell. The Origin of Mitochondria and Chloroplasts Symbiosis is the living together or close association of two dissimilar organisms, usually two different species. In such a relationship, each party is referred to as a symbiont. Endosymbionts are organisms that live inside of other organisms, the latter of which are referred to as hosts. Many scientists believe that the mitochondria and chloroplasts of eucaryotic cells were originally derived from bacterial endosymbionts—bacteria that once led a free-living, independent existence. The theory known as the serial endosymbiosis hypothesis proposes that, at some point in time—perhaps 1.5 billion years ago—certain bacteria were engulfed (phagocytized) by other procaryotic cells. At first, the engulfed bacteria continued to live an independent existence within the host cells. But, in time, an interdependence developed between the two organisms, and the endosymbionts developed into the organelles known as mitochondria and chloroplasts. Most of the evidence for the serial endosymbiosis theory is based on similarities between these organelles and bacteria. Mitochondria possess a circular chromosome, a specific type of RNA, and ribosomes (which are very much like those of bacteria), and similar to bacteria, mitochondria arise only from preexisting mitochondria. Chloroplasts are very much like photosynthetic bacteria. They contain DNA and ribosomes quite similar to those found in bacteria, and they too arise independently of other organelles. This theory becomes even more plausible when one considers that many simple marine animals and protists existing today contain photosynthetic endosymbionts. Based on 16S rRNA sequence data, the most likely candidates to have evolved into mitochondria and chloroplasts are alpha purple bacteria and

cyanobacteria, respectively. (See text for information on 16S sequences.) Not all scientists agree with the serial endosymbiosis theory, however. Another theory— the autogenous hypothesis—states that mitochondria and chloroplasts, as well as other membranous structures found within eucaryotic cells, were derived from the cytoplasmic membrane. Undoubtedly, additional research will determine which of these hypotheses is correct.

Increase Your Knowledge Technical information about the bacterial genomes that have been sequenced to date can be found at the web site of The Institute for Genomic Research—www.tigr.org. TIGR published the first complete microbial genomic sequence—that of Haemophilus influenzae—in 1995.

Critical Thinking 1.

Draw a picture of a eucaryotic cell from memory, labeling as many structures as possible. Use the outline below to represent the cell membrane. When you are finished, compare your drawing to Figure 3-2 in the book.

2.

Draw a picture of a procaryotic cell from memory, labeling as many structures as possible. Use the outline below to represent the cell membrane. When you are finished, compare your drawing to Figure 3-6 in the book.

Answers to the Chapter 3 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

C C B C C C B C A C

Additional Chapter 3 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C.

plastids mitochondria ribosomes

D. E.

endoplasmic reticulum Golgi complex

_____

1. Membrane-bound organelles where photosynthesis occurs.

_____ 2.

The sites of protein synthesis in procaryotic cells.

_____ 3.

Considered a “packaging plant,” where proteins are packaged into membranebound vesicles.

_____ 4.

Membrane-bound organelles where energy is produced by the Krebs cycle and electron transport chain.

_____ 5.

Found in procaryotic cells as well as eucaryotic cells. 6. Short, hairlike projections used as organelles of locomotion by some eucaryotic cells.

_____ A. B. C. D. E.

pili cilia eucaryotic flagella capsules procaryotic flagella

_____ 7.

Found on some bacteria; they serve an antiphagocytic function.

_____ 8.

Found on some bacteria; they enable the bacteria to adhere to surfaces.

_____ 9.

Composed of a protein called flagellin.

_____ 10.

Long, whiplike structures having an internal organization that is described as a “9+2” arrangement of microtubules.

True/False Questions _____ 1.

The internal structure of procaryotic flagella is the same as the internal structure of eucaryotic flagella.

_____ 2.

The internal structure of eucaryotic cilia is the same as the internal structure of eucaryotic flagella.

_____ 3.

The production of endospores by bacteria is a reproductive mechanism.

_____ 4.

Bacteria never have cilia and eucaryotic cells never have pili.

_____ 5.

The 3-Domain System of classification is based on differences in the structure of transfer RNA (tRNA) molecules.

_____ 6.

One way that archaeans differ from bacteria is that archaeans possess more peptidoglycan in their cell walls.

_____ 7.

Chitin is found in the cell walls of algae, but is not found in the cell walls of any other types of microorganisms.

_____ 8.

Tyndallization is a process that kills spores as well as vegetative cells.

_____ 9.

Procaryotic cells do not contain endoplasmic reticulum, Golgi bodies, mitochondria, plastids, or membrane-bound vesicles.

_____ 10.

In eucaryotic cells, ribosomal RNA (rRNA) molecules are manufactured in the nucleolus.

Answers to the Additional Chapter 3 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8.

A C E B C B D A

9. 10.

E C

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

False (eucaryotic flagella contain microtubules, whereas procaryotic flagella do not) True False (production of endospores is a survival mechanism) True False (the 3-Domain System is based on differences in the structure of ribosomal RNA [rRNA]) False (archaean cell walls do not contain peptidoglycan) False (chitin is found in the cell walls of fungi) True True True

Chapter 4 Diversity of Microorganisms Part 1: Acellular and Procaryotic Microbes Terms Introduced in This Chapter After reading Chapter 4, you should be familiar with the following terms. These terms are defined in Chapter 4 and in the Glossary. Acid-fast stain Aerotolerant anaerobe Anaerobe Anoxygenic photosynthesis Bacteriophage Capnophile Capsid Capsomeres Coccobacillus Differential staining procedures Diplobacilli Diplococci Facultative anaerobe Gram stain Inclusion bodies L-forms Lytic cycle Microaerophiles Nanobacteria Nitrogen fixation Obligate aerobe Obligate anaerobe Octad Oncogenic viruses Oxygenic photosynthesis Pleomorphism Prions Simple stain Staphylococci Streptobacilli Streptococci Structural staining procedures Temperate bacteriophage Tetrad

Vectors Virions Viroid Virulent bacteriophage

Insight Microbes in the News—“Mad Cow Disease” The disease known to most people as “mad cow disease” has received a great deal of publicity during recent years and has led to the slaughter of millions of cows, primarily in the United Kingdom. The scientific name for what the press calls “mad cow disease” is bovine spongiform encephalopathy (BSE). It is a progressive neurologic disorder of cattle that results from infection by an unconventional transmissible agent. The most accepted theory is that the agent is a modified form of an abnormal cell surface component known as a prion protein. As of November, 2005, only two BSE cases in cows have been diagnosed in the United States. There is strong epidemiologic and laboratory evidence for a causal association between BSE and variant Creutzfeldt-Jakob disease (vCJD) of humans. In contrast to the classic form of CJD, the new variant form in the United Kingdom predominantly affects younger persons. It has atypical clinical features, with prominent psychiatric or sensory symptoms at the time of clinical presentation and delayed onset of neurologic abnormalities. These include ataxia (an inability to coordinate the muscles in the execution of voluntary movement) within weeks or months, dementia and myoclonus (clonic spasm or twitching of a muscle or group of muscles) late in the illness, a duration of illness of at least 6 months, and a diffusely abnormal nondiagnostic electroencephalogram. The characteristic neuropathologic profile of vCJD includes, in both the cerebellum and cerebrum, numerous kuru-type amyloid plaques surrounded by vacuoles and prion protein accumulation at high concentration indicated by immunohistochemical analysis. (Kuru is described in Chapter 4 in the text.) Variant CJD was first reported in 1996, in the United Kingdom. As of November 2005, a total of 185 cases of vCJD have been reported. The majority of the cases (85%) were reported from the United Kingdom. Although 2 cases have been reported from the United States, the CDC suspects that both patients were exposed to the BSE agent while they resided in the United Kingdom. Life in the Absence of Oxygen Someday, you may overhear someone erroneously state that “Life is impossible there (perhaps referring to one of the planets) because there isn’t any oxygen.” But, you’ll know differently! You’ll be able to point out that life is indeed possible in the absence of oxygen. Furthermore, you’ll be able to explain that organisms capable of life in the absence of oxygen are called anaerobes. But, who discovered anaerobes? The credit for discovering anaerobes can be given to three scientists: a 17th-century scientist, an 18th-century scientist, and a 19th-century scientist. Each of them made scientific observations that contributed to our present knowledge and understanding of anaerobes.

In 1680, Anton van Leeuwenhoek performed an experiment using pepper and sealed glass tubes. In a letter to the Royal Society of London, he wrote that “animalcules developed although the contained air must have been in minimal quantity.” [Leeuwenhoek used the term “animalcules” to refer to the tiny organisms that he observed, using the simple, single lens microscopes, which he made.] Lazzaro Spallanzani, an Italian scientist, performed similar experiments in the latter half of the 18th century. He drew the air from microbe-containing glass tubes, fully expecting the microbes to die—but some did not. He wrote in a letter to a friend, “The nature of some of these animalcules is astonishing! They are able to exercise in a vacuum the functions they use in free air.…How wonderful this is! For we have always believed there is no living being that can live without the advantages air offers it.” It was Louis Pasteur who actually introduced the terms “aerobe” and “anaerobe.” In an 1861 paper, he wrote “these infusorial animals are able to live and multiply indefinitely in the complete absence of air or free oxygen.…These infusoria can not only live in the absence of air, but air actually kills them.…I believe this is…the first example of an animal living in the absence of free oxygen.” [The term “infusoria” was used by early microbiologists to refer to microorganisms. Infusoria was later used to specifically refer to ciliated protozoa, but the term is now obsolete.] We know now that anaerobes are quite common and that they live in specific ecologic niches. They can be found in soil, in freshwater and saltwater sediments (mud), and in the bodies of animals and humans. The indigenous microflora of humans contains many species of anaerobes, some of which are opportunistic pathogens. Anaerobes cause a wide variety of human diseases, including botulism, tetanus, gas gangrene, pulmonary infections, brain abscesses, and oral diseases. It was Louis Pasteur who, in 1877, discovered the first pathogenic anaerobe—the bacterium that today is known as Clostridium septicum. The Oxygen Holocaust In the beginning, all the world was anaerobic—there was no oxygen. Scientists tell us that the first organisms were anaerobic microorganisms that evolved some 3 to 4 billion years ago. Life on earth then remained anaerobic for hundreds of millions of years. Then, about 2 billion years ago, the first worldwide pollution crisis occurred. “The oxygen holocaust” (as described by Margulis and Sagan) came about as the result of the evolution of the purple and green photosynthetic microbes. These organisms were able to make use of the hydrogen in water, by photosynthesis, leaving a waste product called oxygen. Yes, the oxygen that we humans consider so precious was originally a gaseous poison dumped into the atmosphere. As oxygen gains electrons (becomes reduced), highly reactive, short-lived chemicals (called free radicals) are produced. These free radicals wreak havoc with the organic compounds that are the very basis of life. They destroy membranes and enzymes and are lethal to cells. As stated by Lovelock, “the first appearance of oxygen in the air heralded an almost fatal catastrophe for early life.” Many anaerobic microbes were immediately destroyed. The microbes able to survive were those that responded to the crisis by developing ways to detoxify and eventually exploit the dangerous pollutant. These were the organisms that developed the ability to produce enzymes—like catalase, peroxidase, and superoxide dismutase—that break down and neutralize the various toxic reduction products of oxygen. Those organisms lacking such enzymes either died or were forced to retreat to ecologic

niches devoid of oxygen, such as soil and mud and deep within the bodies of animals. Those anaerobes that constitute part of our own indigenous microflora, for example, lead a rather pampered existence. We provide them with warmth and nutrients and a safe haven from their worst enemy—oxygen. (To learn more about this subject, refer to Microcosmos: Four Billion Years of Microbial Evolution, by Lynn Margulis and Dorion Sagan [Summit Books, 1986] and Gaia: a New Look at Life on Earth, by J.E. Lovelock [Oxford University Press, 1979]).

Increase Your Knowledge Information about Bergey's Manual of Systematic Bacteriology and the Bergey’s Manual Trust (the organization responsible for publishing the manual) can be found at www.cme.msu.edu/bergeys

Microbiology—Hollywood Style The German chemist, Paul Ehrlich (1854–1915), made significant contributions to microbiology. In 1882, he developed a method of staining the causative agent of tuberculosis (Mycobacterium tuberculosis). His method was subsequently modified, and is today referred to as the acid-fast staining procedure. Ehrlich was also the first person to use chemicals to treat infectious diseases (discussed in Chapter 9). Students wishing to gain a better understanding of Paul Ehrlich and his contributions to microbiology should rent the thoroughly enjoyable video entitled Dr. Ehrlich’s Magic Bullet. This 1940 blackand-white movie starred Edward G. Robinson as Dr. Ehrlich.

Critical Thinking 1.

Be prepared to discuss key differences between viruses and bacteria.

2.

Be prepared to explain why rickettsias, chlamydias, and mycoplasmas are described as unique bacteria.

3.

Be prepared to discuss key differences between bacteria and archaeans.

Answers to the Chapter 4 Self-Assessment Exercises in the Text

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

D A A C A B C A D A

Additional Chapter 4 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

A. B. C. D. E.

diplococci diplobacilli staphylococci streptobacilli streptococci

chlamydias cyanobacteria mycoplasmas rickettsias spirochetes

_____

1. Spherical bacteria arranged in pairs are called _______________.

_____ 2.

Rod-shaped bacteria arranged in chains are called _______________.

_____ 3.

Spherical bacteria arranged in clusters are called _______________.

_____ 4.

Rod-shaped bacteria arranged in pairs are called _______________.

_____ 5.

Spherical bacteria arranged in chains are called _______________.

_____

6. The bacteria that cause syphilis and Lyme disease are _______________.

_____ 7.

_______________ are obligate intracellular pathogens that cause diseases such as trachoma, inclusion conjunctivitis, and urethritis.

_____ 8.

_______________ are photosynthetic.

_____ 9.

_______________ have no cell walls.

_____ 10.

_______________ are obligate intracellular pathogens that cause diseases such as typhus and Rocky Mountain spotted fever.

True/False Questions _____ 1.

All diseases caused by Rickettsia spp. are arthropodborne.

_____ 2.

Viruses contain both DNA and RNA.

_____ 3.

The cell walls of archaeans contain a thicker layer of peptidoglycan than bacterial cell walls.

_____ 4.

On entering a bacterial cell, all bacteriophages immediately initiate the lytic cycle.

_____ 5.

Mycoplasmas cannot grow on artificial media.

_____ 6.

Viruses are the smallest infectious agents.

_____ 7.

Rickettsia spp. and Chlamydia spp. cannot be grown on artificial media.

_____ 8.

Prions are infectious RNA molecules.

_____ 9.

HIV is an enveloped, double-stranded RNA virus.

_____ 10.

Organisms in the genus Vibrio are curved bacilli.

Answers to the Additional Chapter 4 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

A D C B E E A B C D

True/False Questions

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (they contain either DNA or RNA) False (archaean cell walls do not contain peptidoglycan) False (temperate bacteriophages cause lysogeny) False (yes they can) False (viroids and prions are infectious agents that are smaller than viruses) True False (prions are infectious proteins; viroids are infectious RNA molecules) True True

Chapter 5 Diversity of Microorganisms Part 2: Eucaryotic Microbes Terms Introduced in This Chapter After reading Chapter 5, you should be familiar with the following terms. These terms are defined in Chapter 5 and in the Glossary. Aerial hyphae Algae (sing., alga) Ameba (pl., amebae) Aseptate hyphae Ciliates (sing., ciliate) Ciliophora Conidium (pl., conidia) Contractile vacuole Cyst Cytostome Dimorphism Flagellates (sing., flagellate) Hyphae (sing., hypha) Lichen Mastigophora Mycelium (pl., mycelia) Mycosis (pl., mycoses) Mycotoxicosis (pl., mycotoxicoses) Mycotoxins Pellicle Phycotoxicosis (pl., phycotoxicoses) Phycotoxins Pinocytosis Protozoa (sing., protozoan) Pseudohypha (pl., pseudohyphae) Pseudopodium (pl., pseudopodia) Sarcodina Sarcomastigophora Septate hyphae Slime mold Sporozoea Stigma (eyespot) Trophozoite Vegetative hyphae

Insight Microbes in the News—“Sick Building Syndrome” (Black Mold in Buildings) During the past few years, there has been quite a bit of publicity about black molds and the socalled sick building syndrome. The following information on these subjects is from the Centers for Disease Control and Prevention (CDC): “Stachybotrys chartarum (also known as S. atra) is a greenish-black mold. It can grow on material with a high cellulose and low nitrogen content, such as fiberboard, gypsum board, paper, dust, and lint. Growth occurs when there is moisture from water damage, excessive humidity, water leaks, condensation, water infiltration, or flooding. Constant moisture is required for its growth.” S. chartarum is one of a series of fungi that produces trichothecenes mycotoxins. Although S. chartarum is less common in buildings and homes than Cladosporium, Penicillium, Aspergillus, and Alternaria, it is not rare. “It is not necessary to determine what type of mold you may have [in your home or office]. All molds should be treated the same with respect to potential health risks and removal.” Health Risks. “The hazards presented by molds that may contain mycotoxins should be considered the same as other common molds which can grow in your house…There are very few case reports that toxic molds (those producing certain mycotoxins) inside homes can cause unique or rare health conditions such as pulmonary hemorrhage [see below] or memory loss. These case reports are rare, and a causal link between the presence of the toxic mold and these conditions has not been proven. A common-sense approach should be used for any mold contamination existing inside buildings and homes. The common health concerns from molds include hay-fever like allergic symptoms. Certain individuals with chronic respiratory disease (e.g., chronic obstructive pulmonary disorder, asthma) may experience difficulty breathing. Individuals with immune suppression may be at increased risk for infection from molds…For the most part, one should take routine measures to prevent mold growth in the home.” Although there has been some speculation about a possible link between Stachybotrys and acute idiopathic pulmonary hemorrhage (pulmonary hemosiderosis) in infants, the CDC is currently stating that such an association has not been proven. Pulmonary hemosiderosis is bleeding in the lungs. Severe bleeding can cause the coughing up of blood or nose bleeds. Chronic, low-grade bleeding can cause chronic cough and congestion with anemia. Mold Prevention. “(1) Keep humidity level in the house below 50%. (2) Use an air conditioner or a dehumidifier during humid months. (3) Be sure the home has adequate ventilation, including exhaust fans in kitchens and bathrooms. (4) Use mold inhibitors, which can be added to paint. (5) Clean bathrooms with mold killing products. (6) Do not carpet bathrooms. (7) Remove and replace flooded carpets.” Mold Removal. “Mold growing in homes and buildings, whether it is S. chartarum or other molds, indicates that there is a problem with water or moisture. This is the first problem to be addressed. Mold can be cleaned off surfaces with a weak bleach solution. Mold under carpets

typically requires that the carpets be removed. Once mold starts to grow in insulation or wallboard, the only way to deal with the problem is by removal and replacement. [The CDC does] not believe that one needs to take any different precautions with S. chartarum than with other molds. In areas where flooding has occurred, prompt cleaning of walls and other flooddamaged items with water mixed with chlorine bleach, diluted 10 parts water to 1 part bleach, is necessary to remove mold growth. Never mix bleach with ammonia. Moldy items should be discarded.”

Increase Your Knowledge 1. To learn more about medical, veterinary, and agricultural aspects of fungi, visit the web site, www.doctorfungus.org. 2.

To learn more about parasitic protozoa, visit the parasitology web site that is operated by the Centers for Disease Control and Prevention: www.dpd.cdc.gov/dpdx

Critical Thinking 1.

In the 5-Kingdom System of classification, algae and protozoa are combined in the Kingdom Protista. However, many taxonomists argue that algae and protozoa are so different from each other that they should not be classified together in the same kingdom. Pick one side of this argument and be prepared to defend your position.

2.

Certain microscopic pond water organisms (e.g., Euglena and Volvox) are considered by some taxonomists to be algae and by others to be protozoa. Take a position and be prepared to defend it.

3.

Be prepared to explain the differences between algal and fungal cells.

Answers to the Chapter 5 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7.

D D B C D C D

8. 9. 10.

A D D

Additional Chapter 5 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

algae fungi lichens protozoa slime molds

_____

1. Yeasts and molds are examples of _______________.

_____ 2.

All _______________ are photosynthetic.

_____ 3.

_______________ are classified by their means of locomotion.

_____ 4.

The cell walls of _______________ contain chitin.

_____ 5.

The cell walls of _______________ contain cellulose.

_____ 6.

_______________ rarely cause infectious diseases, but cause a variety of microbial intoxications.

_____ 7.

_______________ are examples of a symbiotic relationship known as mutualism.

_____ 8.

_______________ cause diseases such as African sleeping sickness, babesiosis, cryptosporidiosis, malaria, and toxoplasmosis.

_____ 9.

Diseases caused by _______________ are called mycoses.

_____ 10.

Toxins produced by _______________ are called phycotoxins.

True/False Questions _____ 1.

Slime molds possess characteristics of both fungi and protozoa.

_____ 2.

Protozoa in the category known as Mastigophora move by means of cilia.

_____ 3.

A dimorphic fungus would exist as a mold inside the human body.

_____ 4.

The organism that causes a “red tide” is an alga.

_____ 5.

Volvox is a multicellular alga.

_____ 6.

A stigma is an organelle that pumps water out of the cell.

_____ 7.

Sexual spores are also known as conidia.

_____ 8.

Classification of fungi is based on the type of conidia that they produce.

_____ 9.

Protozoa that move by means of pseudopodia are in a category known as Sarcodina.

_____ 10.

Fungi can cause both infectious diseases and microbial intoxications.

Answers to the Additional Chapter 5 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

B A (C is also an acceptable answer, because lichens contain algae) D B A A C D B A

True/False Questions

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (they move by means of flagella) False (a dimorphic fungus would exist as a yeast inside the human body) True True False (a stigma or “eyespot” is a photosensing organelle) False (asexual spores are also known as conidia) False (classification of fungi is based on the type of sexual spores that they produce) True True

Chapter 6 Biochemistry: The Chemistry of Life Terms Introduced in This Chapter After reading Chapter 6, you should be familiar with the following terms. These terms are defined in Chapter 6 and in the Glossary. Amino acids Anticodon Apoenzyme Biochemistry Biologic catalysts Carbohydrates Catalyst Catalyze Central Dogma Codon Coenzyme Cofactor Constitutive genes Covalent bond Dehydration synthesis reaction Dipeptide Disaccharide DNA nucleotides DNA polymerase DNA replication Double bond Enzyme Essential amino acids Essential fatty acids Fatty acid Genetic code Glucose Glycosidic bond Glycogen Heptose Hexose Holoenzyme Hydrocarbon Hydrolysis reaction Inducible genes Inorganic chemistry

Lipids Messenger RNA (mRNA) Monosaccharides Monounsaturated fatty acid Nucleic acids Nucleotides Organic chemistry Organic compounds Pentose Peptide bond Phospholipid Polymer Polypeptide Polysaccharide Polyunsaturated fatty acid Proteins Purine Pyrimidine Ribosomal RNA (rRNA) RNA nucleotides RNA polymerase Saturated fatty acid Single bond Starch Substrate Tetrose Transcription Transfer RNA (tRNA) Translation Triglyceride Triose Tripeptide Triple bond Waxes

Increase Your Knowledge Students interested in learning more about the discovery of the structure of DNA should read The Double Helix, by James D. Watson (Mentor, Penguin Books USA, New York, 1969).

Microbiology—Hollywood Style

Although difficult to find, the 1987 made-for-TV movie, The Race for the Double Helix, details the events leading up to the discovery of the structure of DNA by James Watson and Francis Crick. Also portrayed in the film are Maurice Wilkins and Rosalind Franklin. The role of James Watson was played by Jeff Goldblum.

Critical Thinking Assume that you are taking an organic chemistry class. Your teacher has given you four organic compounds to analyze. She tells you that one is a carbohydrate, one is a hydrocarbon, one is a nucleic acid, and one is a protein. a.

Compound A contains only carbon and hydrogen. Of the four types of compounds which were given to you to analyze, which one best describes Compound A? Compound A is a _______________

b.

You discover that Compound B contains only carbon, hydrogen, and oxygen. Of the four types of compounds which were given to you to analyze, which one best describes Compound B? Compound B is a _______________

c.

You discover that Compound C contains only carbon, hydrogen, oxygen, and nitrogen. Of the four types of compounds which were given to you to analyze, which one best describes Compound C? Compound C is a _______________

d.

You discover that Compound D contains only carbon, hydrogen, oxygen, nitrogen, and phosphorous. Of the four types of compounds which were given to you to analyze, which one best describes Compound D? Compound D is a _______________

Answers to the Chapter 6 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5.

A A C A A

6. 7. 8. 9. 10.

D D D D C

Answers to the Critical Thinking Questions A. B. C. D.

Hydrocarbon Carbohydrate Protein Nucleic acid

Additional Chapter 6 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

amino acids disaccharides fatty acids monosaccharides nucleotides

_____

1. _______________ are the building blocks of proteins.

_____ 2.

_______________ consist of a nitrogenous base, a pentose, and a phosphate group.

_____ 3.

_______________ are the building blocks of polysaccharides.

_____ 4.

Sucrose, lactose, and maltose are examples of _______________.

_____ 5.

Fructose, galactose, and glucose are examples of _______________.

A. B. C. D. E.

a dehydration synthesis reaction DNA replication a hydrolysis reaction transcription translation

_____

6. The end product of _______________ is a messenger RNA molecule.

_____ 7.

Combining two monosaccharides to form a disaccharide is an example of _______________.

_____ 8.

James Watson and Francis Crick were the first to publish an article describing _______________.

_____ 9.

The end product of _______________ is a protein.

_____ 10.

Breaking the bond in a disaccharide to produce two monosaccharides is an example of _______________.

True/False Questions _____ 1.

The covalent bonds that hold monosaccharides together in a polysaccharide are called glycosidic bonds.

_____ 2.

A DNA nucleotide consists of the following three parts: a nitrogenous base, ribose, and a phosphate group.

_____ 3.

The waxes in the cell walls of Mycobacterium tuberculosis cause this organism to be acid-fast.

_____ 4.

The basic structure of a cell membrane is a lipid bilayer.

_____ 5.

DNA polymerase is the only enzyme required for DNA replication.

_____ 6.

Genes that are expressed only when needed are called constitutive genes.

_____ 7.

Polysaccharides, polypeptides, and nucleic acids are all examples of polymers.

_____ 8.

During translation, amino acids are “activated” by attaching to an appropriate rRNA molecule.

_____ 9.

The peptide bonds that hold amino acids together in protein molecules are examples of covalent bonds.

_____10.

In double-stranded DNA molecules, the two strands are held together by hydrogen bonds.

Answers to the Additional Chapter 6 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

A E D B D D A B E C

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (a DNA nucleotide consists of a nitrogenous base, deoxyribose, and a phosphate group) True True False (DNA polymerase is the most important enzyme involved in DNA replication, but other enzymes are also involved) False (genes that are expressed only when needed are called inducible genes; genes that are expressed all of the time are called constitutive genes) True False (amino acids are “activated” by attaching to an appropriate tRNA molecule) True True

Chapter 7 Microbial Physiology and Genetics Terms Introduced in This Chapter After reading Chapter 7, you should be familiar with the following terms. These terms are defined in Chapter 7 and in the Glossary. Adenosine triphosphate (ATP) Ames test Anabolic reactions Anabolism Autotroph Beneficial mutation Catabolic reactions Catabolism Chemoautotroph Chemoheterotroph Chemolithotroph Chemoorganotroph Chemosynthesis Chemotroph Competence Competent bacteria Dehydrogenation reactions Ecology Ecosystem Electron transport chain Endoenzyme Episome Essential nutrients Exoenzyme Fermentation Gene therapy Genetics Glycolysis Harmful mutation Heterotroph Krebs cycle Lethal mutation Lysogenic bacterium Lysogenic conversion Lysogeny Metabolic reactions

Metabolite Microbial physiology Mutagen Mutant Mutation Oxidation Oxidation–reduction reactions Phenotype Photoautotroph Photoheterotroph Phototroph Prophage R-factor Reduction Silent mutation Transduction Transformation

Insight Why Anaerobes Die in the Presence of Oxygen When molecular oxygen (O2) is reduced (i.e., when O2 gains electrons; as in certain oxidation– reduction reactions), extremely reactive substances are produced (as shown in the following equations). O2 + e–  –O2 (superoxide anion) O2 + 2e–  H2O2 (hydrogen peroxide) O2 + 3e–  H2O + OH– (hydroxyl radical) These reduction products (superoxide anion, hydrogen peroxide, and hydroxyl radicals) are capable of causing severe damage to enzymes and cell membranes; they are potentially lethal to cells. To survive in the presence of oxygen, organisms must possess enzymes (e.g., superoxide dismutase and catalase) that can neutralize these toxic substances. Obligate anaerobes are killed in the presence of oxygen because they lack one or more of these enzymes. Aerotolerant anaerobes produce these enzymes, but not in high enough concentrations to enable the organisms to survive in high concentrations of oxygen. Genetically Engineered Bacteria and Yeasts The term genetic engineering refers to the manufacture and manipulation of genetic material in vitro (in the laboratory). Genetic engineering has been possible only since the late 1960s, when a scientist named Paul Berg demonstrated that fragments of human or animal DNA can be attached to bacterial DNA. Such a hybrid DNA molecule is referred to as recombinant DNA. When a

molecule of recombinant DNA is inserted into a bacterial cell, the bacterium is able to produce the gene product, usually a protein. Thus, microorganisms (primarily bacteria) can be genetically engineered to produce substances (gene products) that they would not normally manufacture. Paul Berg won a Nobel Prize in 1980 for his pioneering genetic engineering experiments. Molecules of self-replicating, extrachromosomal DNA, called plasmids, are frequently used in genetic engineering and are referred to as vectors. A particular gene of interest is first inserted into the vector DNA, forming a molecule of recombinant DNA. The recombinant DNA is then inserted into or taken up by a bacterial cell. The cell is next allowed to multiply, creating many genetically identical bacteria (clones), each of which is capable of producing the gene product. From the clone culture, a genetic engineer may then remove (“harvest”) the gene product. The Gram-negative bacillus, Escherichia coli, has often been used because it can be easily grown in the laboratory, has a relatively short generation time (about 20 minutes under ideal conditions), and its genetics are well understood by researchers. A Gram-positive bacterium (Bacillus subtilis), a yeast (Saccharomyces cerevisiae), and cultured plant and mammalian cells have also been used by genetic engineers to produce desired gene products. An example of a product produced by genetic engineering is insulin, a hormone produced in E. coli cells and used to treat diabetic patients. Human growth hormone (somatotropin), bovine growth hormone (BGH), porcine growth hormone (PGH), somatostatin (a hormone used to limit growth), tissue growth factors, clotting factors, and interferon are also produced by genetically engineered E. coli. Genetically engineered bacteria are being used to produce industrial enzymes, citric acid, and ethanol, and to degrade pollutants and toxic wastes. The hepatitis B vaccine that is administered to healthcare workers is produced by a genetically engineered yeast, called Saccharomyces cerevisiae. New uses for recombinant DNA and genetic engineering are being discovered every day, causing profound changes in medicine, agriculture, and other areas of science.

Increase Your Knowledge 1.

A Closer Look at Transduction. There are actually two types of transduction: specialized and generalized. The explanation in Chapter 7 describes specialized transduction, in which the infecting phage integrates into the bacterial chromosome or a plasmid. As the virus genome breaks away to replicate and produce more viruses, it carries one or more bacterial genes with it to the newly infected cell. In this way, genetic capabilities involving the fermentation of certain sugars, antibiotic resistance, and other phenotypic characteristics can be transduced to other bacteria. This process has been shown in the laboratory (in vitro) to occur in species of Bacillus, Pseudomonas, Haemophilus, Salmonella, and Escherichia, and it is assumed to occur in nature. In generalized transduction, the bacteriophage is a virulent lytic phage that does not incorporate into the bacterial genome or plasmid. Rather, it picks up fragments of bacterial DNA during the assembly of new virus particles and carries these bacterial genes to other cells that the new viruses infect. Generalized transduction has been observed in species of Streptococcus, Staphylococcus, and Salmonella, and in Vibrio

cholerae. 2.

A Closer Look at Fertility Factors. Bacteria possessing F+ or Hfr+ genes have the ability to produce sex pili and become donor cells. If the fertility factor is on a plasmid, it is called an F+ gene, whereas if it is incorporated into the chromosome, it is referred to as an HFr+ gene. A complete copy of the F plasmid (the plasmid containing the F+ gene) usually moves to the recipient (F-) cell; therefore, the recipient cell usually becomes F+ (i.e., the recipient cell becomes capable of producing a sex pilus and becoming a donor cell). On the other hand, the recipient cell usually receives only a portion of the chromosome from an HFr+ cell, and that portion does not include the HFr+ gene; therefore, in this case, the recipient cell remains Hfr–, does not produce a sex pilus, and cannot become a donor cell.

Critical Thinking 1.

What are some possible reasons why an obligate anaerobe is unable to live in the presence of oxygen?

2.

Assume that you are a microbiologist who has been doing research on a penicillinsensitive strain of Staphylococcus aureus for many months. One day you discover that the organism is now resistant to penicillin. You know that it has not come in contact with any other species of bacteria, nor has it come in contact with the DNA from any other species of bacteria. What are two possible explanations for its sudden change from penicillin susceptibility to penicillin resistance?

3.

Several products were mentioned in this chapter that are being produced by genetically engineered bacteria and yeasts. Using the Internet, can you find others?

Answers to the Chapter 7 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

C A D A C D D B C A

Additional Chapter 7 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

A. B. C. D. E.

autotrophs heterotrophs lithotrophs organotrophs phototrophs

conjugation lysogenic conversion mutation transduction transformation

_____

1. _______________ are chemotrophs that use inorganic chemicals as their energy source.

_____ 2.

Organisms that use organic compounds as their source of carbon are called _______________.

_____ 3.

Organisms that use organic compounds as their energy source are called _______________.

_____ 4.

Organisms that use carbon dioxide as their source of carbon are called _______________.

_____ 5.

Organisms that use light as their energy source are called _______________.

_____

6. In _______________, bacteria acquire new genetic information in the form of viral genes.

_____ 7.

Oswald Avery and his colleagues discovered that DNA is the hereditary molecule while performing _______________ experiments with Streptococcus pneumoniae.

_____ 8.

In _______________, bacteria acquire new genetic information as a result of absorbing pieces of naked DNA from their environment.

_____ 9.

In _______________, genetic information is passed from one bacterial cell to another via a hollow sex pilus.

_____ 10.

In _______________, bacteria acquire new genetic information when bacteriophages inject bacterial genes.

True/False Questions _____ 1.

Dehydration synthesis reactions always involve the removal of a molecule of water.

_____ 2.

The biosynthesis of polysaccharides, polypeptides, and nucleic acids are examples of catabolic reactions.

_____ 3.

Oxidation–reduction reactions are paired reactions that involve the transfer of electrons.

_____ 4.

Breaking a disaccharide down into its two monosaccharide components is an example of a hydrolysis reaction.

_____ 5.

Anabolic reactions are a cell’s major source of energy.

_____ 6.

The majority of energy produced in aerobic respiration is produced by the Krebs cycle.

_____ 7.

In glycolysis, a 6-carbon glucose molecule is broken down into two 3-carbon molecules of pyruvic acid.

_____ 8.

Aerobic respiration is a more efficient method of breaking down glucose than is fermentation.

_____ 9.

Virulent bacteriophages are responsible for lysogenic conversion.

_____ 10.

Mutations are always harmful.

Answers to the Additional Chapter 7 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7.

C B D A E B E

8. 9. 10.

E A D

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (these are examples of anabolic reactions) True True False (catabolic reactions are a cell’s major source of energy) False (the majority of the energy is produced by the electron transport chain) True True False (temperate bacteriophages are responsible for lysogenic conversion) False (mutations may be harmful, beneficial, or “silent”)

Chapter 8 Controlling Microbial Growth In Vitro Terms Introduced in This Chapter After reading Chapter 8, you should be familiar with the following terms. These terms are defined in Chapter 8 and in the Glossary. Acidophile Algicidal agent Alkaliphile Antisepsis Antiseptic Antiseptic technique Artificial media Asepsis Autoclave Bactericidal agent Bacteriostatic agent Barophile Biocidal agent Chemically defined media Complex media Contamination Crenated Crenation Death phase Desiccation Differential media Disinfectant Disinfection Enriched media Fungicidal agent Germicidal agent Haloduric organisms Halophiles Hemolysis Hypertonic solution Hypotonic solution Incubation Incubator Inoculation Isotonic solution Lag phase

Logarithmic growth phase Lyophilization Mesophile Microbicidal agent Microbistatic agent Osmosis Osmotic pressure Plasmolysis Plasmoptysis Population growth curve Pseudomonicidal Psychroduric organisms Psychrophile Psychrotroph Sanitization Selective medium Sepsis Sporicidal agent Stationary phase Sterile techniques Sterilization Thermal death point (TDP) Thermal death time (TDT) Thermophile Tuberculocidal agent Viable plate count Viricidal agent

Insight Microbes in Our Food Are there bacteria in the milk you drink? Pasteurization is designed to kill pathogens. The process does not kill all bacteria. According to accepted standards, raw milk may not have more than 75,000 bacteria per milliliter before pasteurization and must have less than 15,000 per milliliter after pasteurization. Let's say that the milk you are drinking contains 10,000 bacteria per milliliter. One fluid ounce equals approximately 29.6 mL. Therefore, an 8-ounce glass of that milk contains 2,368,000 bacteria. You will be chug-a-lugging over two million bacteria, assumed to be nonpathogens. Are there bacteria in the food you eat? Bacteria and fungi occur in most foods, but vary in quantity from one type of food to another. Assuming the food has been stored correctly (refrigeration, for example), there are usually fewer than 100,000 per gram or milliliter, depending on the type of food. The number may be much higher if the food has not been stored properly. Also, the way the food is prepared will influence the number of live organisms that are

present. For example, a thoroughly cooked (well done) hamburger may not contain any live bacteria. A rare or medium-rare hamburger, on the other hand, will contain many live bacteria. If some of those bacteria are pathogens (such as E. coli 0157:H7), you could develop severe gastrointestinal disease. Are there bacteria in your drinking water? There are many types of bacteria in the water you drink, but hopefully not too many pathogens. Ideally, drinking water should not contain any coliforms (Gram-negative bacilli, like E. coli, that live in the gastrointestinal tract and are present in feces). The presence of coliforms in drinking water represents contamination of the water with human or animal feces. The extent of fecal contamination of water can be determined by performing a coliform count. A “satisfactory” coliform count is one colony (a colony is derived from one organism) or less per 100 mL of water. If the coliform count is satisfactory, the water is considered potable (drinkable). It usually takes many coliforms per milliliter to cause disease in humans.

Increase Your Knowledge 1.

A Closer Look at Hydrothermal Vents. Organisms that prefer to live at high temperatures are called thermophiles, and those that prefer extremely high temperatures are called hyperthermophiles (or extreme thermophiles). The hottest places on earth where living organisms have been found are the hydrothermal vents at the bottom of the ocean. Hydrothermal vents are plumes of hot water that spew from cracks along the ocean floor, thousands of feet below the ocean surface. As the hot, mineral-rich water comes into contact with the cold ocean bottom water, the minerals precipitate, forming deposits on the surrounding rocks. Some of these deposits form tall (up to 18 stories tall) chimneyshaped structures, from which rise dark streams of hot black particles. The streams of particles are referred to as “smoke,” and the chimney-shaped structures are referred to as “black smokers.” Black smokers emit particles that are rich in sulfides, lead, cobalt, zinc, copper, and silver. There are also “white smokers,” which emit streams of gypsum and zinc, rather than sulfides, and they emit smaller amounts of iron and copper. Living in and around the black smokers are chemoautotrophic archaeans, which obtain their energy from inorganic chemicals, and then use that energy to synthesize the organic compounds that they require for growth and reproduction. They use carbon dioxide as their source of carbon. Some of the chemoautotrophic bacteria (called sulfur-oxidizing bacteria) are able to oxidize (remove electrons from) sulfur-containing compounds, such as hydrogen sulfide. Eucaryotic organisms living around the black smokers make use of the organic compounds produced by the bacteria, and often live in a symbiotic relationship with the bacteria (i.e., the bacteria actually live within the eucaryotic organisms, producing organic compounds that the eucaryotes utilize).

(Students having an interest in science fiction might enjoy reading Gravity, by Tess Gerritsen [Pocket Books, Simon & Schuster, Inc., New York, 1999]. When deep-sea archaeans are brought aboard an international space station, things go horribly wrong.) 2.

A Closer Look at Barometric Pressure. The barometric pressure at sea level is equal to one atmosphere (approximately 14.7 psi). Barometric pressure decreases with increases in altitude (e.g., the barometric pressure at the top of a mountain is less than one atmosphere). In the ocean, pressure (referred to as water pressure) increases with depth, as a result of the increasing mass of the overlying water. Pressure in the ocean increases one atmosphere for each additional 10 m (approximately 32.8 feet) of water depth. In the deepest parts of the ocean (approximately 11,000 m or 36,000 feet), the pressure is 1,100 atmospheres (more than 8 tons psi). A hyperbaric chamber contains a pressure that is greater than one atmosphere. Hyperbaric chambers are used to treat decompression sickness in divers and to provide hyperbaric oxygenation for patients with gas gangrene.

3.

A Closer Look at Contact Time. It would seem that some people think that disinfectants are magic. Squirt it on, wipe it off, and poof, the microbes are dead! But, it doesn’t work that way. It takes time for disinfectants to kill organisms (i.e., a disinfectant must remain in contact with the microbes long enough to kill them). This is true for all types of disinfectants, including those used in hospitals, antibacterial kitchen sprays, and antibacterial soaps. The amount of contact time necessary varies from one type of disinfectant to another. Read the instructions on the label. For example, the label on Lysol Antibacterial Kitchen Spray states that the spray must remain in contact with surfaces for 10 minutes before it is wiped off. Likewise, to be effective as a disinfectant, after lathering, antibacterial soaps must remain in contact with skin for at least 15 seconds before rinsing them off.

4.

For recommendations regarding the selection of hygienic procedures for use in the home, visit the web site of the International Scientific Forum on Home Hygiene (www.ifhhomehygiene.org).

Critical Thinking 1.

Assume that you must culture a particular bacterium in the laboratory for research purposes. To get the organism to grow in the laboratory, what are some of the factors you must take into consideration?

2.

Draw a population growth curve, label the four phases, and be prepared to explain what is happening to the bacteria in each phase.

3.

You obtained 300 colonies after plating 0.1 mL of a 1:10,000 dilution of a bacterial cell suspension. What was the bacterial concentration in the original, undiluted suspension?

The answer is 30 million bacteria/mL (or 3 × 107 bacteria/mL), but how did you obtain that answer?

Answers to the Chapter 8 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

B B B D C C A D B A

Additional Chapter 8 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

capnophiles fastidious organisms halophiles microaerophiles psychrotrophs

_____

1. Organisms that prefer salty environments are called _______________.

_____ 2.

Organisms that have especially demanding nutritional requirements are called _______________.

_____ 3.

Organisms that prefer environments having decreased concentrations of oxygen are called _______________.

_____ 4.

Organisms that prefer refrigerator temperature are called _______________.

_____ 5.

Organisms that grow best in environments containing increased concentrations of carbon dioxide are called _______________.

A. B. C. D. E.

Blood agar Chocolate agar MacConkey agar Phenylethyl alcohol agar Thayer-Martin agar

_____

6. Although Neisseria gonorrhoeae and Haemophilus influenzae will not grow on blood agar, they will grow on _______________.

_____ 7.

_______________ is a highly enriched and highly selective medium, used to isolate Neisseria gonorrhoeae from clinical specimens.

_____ 8.

_______________ is an example of a medium that is both enriched and differential.

_____ 9.

_______________ is selective for Grampositive bacteria.

_____ 10.

_______________ is an example of a medium that is selective and differential.

True/False Questions _____ 1.

A bacterial cell would swell and burst if placed in an extremely hypertonic solution.

_____ 2.

Pasteurization is a method of sterilizing liquids.

_____ 3.

Archaeans that live in or near hydrothermal vents at the bottom of the ocean are halophilic, barophilic, and thermophilic.

_____ 4.

Lyophilization is an excellent method of killing microorganisms.

_____ 5.

Antiseptic technique is a type of aseptic technique.

_____ 6.

In an autoclave, microorganisms are killed by ethylene oxide.

_____ 7.

The goal of disinfection is to kill all microorganisms.

_____ 8.

It is not possible to culture protozoa in the laboratory.

_____ 9.

Rapid freezing, using liquid nitrogen, is an excellent method of killing microorganisms.

_____ 10.

Microorganisms can be killed by direct exposure to ultraviolet light.

Answers to the Additional Chapter 8 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

C B D E A B E A D C

True/False Questions

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

False (a bacterial cell would shrink if placed in an extremely hypertonic solution) False (pasteurization is a disinfection technique; a technique designed to kill pathogens) True False (lyophilization is one of the major ways of preserving microorganisms) True False (in an autoclave, microorganisms are killed by steam under pressure) False (the goal of disinfection is to kill pathogens) False (it is possible to culture protozoa in the laboratory) False (rapid freezing is one of the major ways of preserving microorganisms) True

Chapter 9 Using Antimicrobial Agents to Control Microbial Growth In Vivo Terms Introduced in This Chapter After reading Chapter 9, you should be familiar with the following terms. These terms are defined in Chapter 9 and in the Glossary. Acquired resistance Antagonism Antibacterial agents Antifungal agents Antimicrobial agents Antiprotozoal agents Antiviral agents β-Lactam ring β-Lactamases Broad-spectrum antibiotics Cephalosporinase Chemotherapeutic agent Chemotherapy Drug binding site Empiric therapy Intrinsic resistance Narrow-spectrum antibiotics Penicillinase Semisynthetic antibiotics Superinfection Synergism

Critical Thinking 1.

Louis Pasteur once stated that “chance favors the prepared mind.” What did he mean by that? What discovery, mentioned in this chapter, clearly illustrates Pasteur’s statement?

2.

It has been stated that “when science builds a better mousetrap, nature builds a better mouse.” How does that statement relate to drug-resistant bacteria?

3.

A friend of yours is planning a trip to a country where diarrhea is commonly experienced by visitors to that country. She asked her physician to prescribe an antibiotic to prevent

traveler’s diarrhea, and the physician complied. She has already started taking the drug, and plans to take it throughout her trip. How would you explain to your friend that taking the drug in this manner (i.e., prophylactically) is not a good idea? 4.

A good friend of yours is a dairy farmer. He routinely uses antibiotic-containing cattle feed to keep his cows from getting sick. How would you tactfully explain to him how this practice is contributing to the problem of multidrug-resistant bacteria?

Answers to the Chapter 9 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

C D B D B C A B B C

Additional Chapter 9 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

Bactrim and Septra chloramphenicol, erythromycin, and tetracycline isoniazid, rifampin, pyrazinamide, ethambutol, and streptomycin methicillin, nafcillin, oxacillin, and cloxacillin penicillin and cephalosporin

_____

1. _______________ are examples of antibiotics that are produced by fungi.

_____ 2.

_______________ are in a class of drugs known as penicillinase-resistant penicillins.

_____ 3.

_______________ are examples of drugs that are used to treat tuberculosis.

_____ 4.

_______________ are examples of drugs that inhibit protein synthesis.

_____ 5.

_______________ are examples of

destroyed by β-lactamases.

drugs that could be

A. B. C. D. E.

a chemotherapeutic agent an antibiotic an antifungal agent an antiviral agent an antimicrobial agent

_____

6. Acyclovir is specifically used as _______________.

_____ 7.

_______________ is any chemical or drug that is used to treat any disease or medical condition.

_____ 8.

_______________ is a substance produced by a microorganism that is effective in killing or inhibiting the growth of another species of microorganism.

_____ 9.

Any drug used to treat an infectious disease is called _______________.

_____ 10.

Amphotericin B is specifically used as _______________.

True/False Questions _____ 1.

Strains of Staphylococcus aureus known as MRSA are resistant to methicillin but are susceptible to most other antibacterial agents.

_____ 2.

Bacteria can develop resistance to a particular antimicrobial agent as a result of a chromosomal mutation or the acquisition of a new gene.

_____ 3.

A bacterial cell that receives an R-factor becomes multidrug resistant.

_____ 4.

A “superinfection” is an infection that cannot be cured.

_____ 5.

Using two different antimicrobial agents to treat a patient’s infection is referred to as antagonism if the result that is achieved is much better than that which could have been achieved using only one of the drugs.

_____ 6.

Because he discovered penicillin, Alexander Fleming is often referred to as the “Father of Chemotherapy.”

_____ 7.

Bacteria can become drug resistant as a result of transduction, transformation, or conjugation.

_____ 8.

All antimicrobial agents are antibiotics.

_____ 9.

Administering an antibiotic to a patient to treat one type of infectious disease could actually cause other types of infectious diseases in that patient.

_____ 10.

Bacteria that acquire the genes that code for an MDR pump become multidrug resistant.

Answers to the Additional Chapter 9 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6.

E D C B E D

7. 8. 9. 10.

A B E C

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

False (MRSA strains are resistant to most antimicrobial agents) True True False (a superinfection is not a disease; it is an overgrowth of organisms that are usually present only in small numbers) False (this is known as synergism, not antagonism) False (Paul Ehrlich is often referred to as the “Father of Chemotherapy”) True False (some antimicrobial agents are antibiotics, but not all of them) True True

Chapter 10 Microbial Ecology Terms Introduced in This Chapter After reading Chapter 10, you should be familiar with the following terms. These terms are defined in Chapter 10 and in the Glossary. Ammonification Bacteriocins Biofilms Biotherapeutic agents Candidiasis Carrier Colicin Commensalism Denitrifying bacteria Endosymbiont Enteric bacilli Host Microbial antagonism Microcolonies Mutualism Neutralism Nitrifying bacteria Nitrogen-fixing bacteria Parasitism Symbionts Symbiosis Synergistic infection Synergistic relationship Vaginitis Vaginosis

Critical Thinking 1.

A friend of yours has been taking an antibacterial agent to cure an ear infection. Suddenly, she develops yeast vaginitis. Explain to her why this has occurred. Use the library or Internet to research additional factors that can alter vaginal pH or the microbial composition of vaginal flora, leading to conditions such as bacterial vaginosis (BV) and yeast vaginitis. Be prepared to discuss your findings.

2.

You’ve probably heard that farmers “rotate their crops.” One year they will plant a “cash crop” (e.g., corn), and the next year they will plant alfalfa or clover in that field. Why do they do that? Include the role of microorganisms in your answer.

Answers to the Chapter 10 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

D A D A A B C A D C

Additional Chapter 10 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

commensalism mutualism neutralism parasitism synergism

_____

1. When two microorganisms occupying the same environmental niche have absolutely no effect on each other, it is known as _______________.

_____ 2.

Bacterial vaginosis is an example of _______________.

_____ 3.

_______________ is a symbiotic relationship of benefit to one of the symbionts, but neither beneficial nor harmful to the other.

_____ 4.

_______________ is a symbiotic relationship of benefit to one of the symbionts, and detrimental to the

other.

A. B. C. D. E.

cyanobacteria denitrifying bacteria nitrifying bacteria nitrogen-fixing bacteria saprophytes

____

5.

A lichen is a classic example of _______________.

_____

6. In the nitrogen cycle, bacteria called _______________ convert atmospheric nitrogen gas into ammonia in the soil.

_____ 7.

_______________ live in the root nodules of legumes such as alfalfa and clover.

_____ 8.

_______________ are capable of converting the nitrogen within a dead plant or animal into ammonia in the soil.

_____ 9.

In the nitrogen cycle, soil organisms called _______________ convert ammonia into nitrites, and nitrites into nitrates.

_____ 10.

In the nitrogen cycle, soil organisms called _______________ convert the nitrogen in nitrates to nitrogen gas in the atmosphere.

True/False Questions _____ 1.

No microorganisms are able to live in the stomach, owing to the extremely low pH of the stomach contents.

_____ 2.

Microbial communities known as biofilms are interesting, but they have no medical significance.

_____ 3.

Microorganisms are unable to live in the colon because of the lack of oxygen there.

_____ 4.

Some of the bacteria used in bioremediation are naturally occurring, but others have been genetically engineered.

_____ 5.

Many of the members of our indigenous microflora have the potential to cause disease.

_____ 6.

There could be as many as 100 trillion microorganisms that live on us and in us.

_____ 7.

The most common organisms in the indigenous microflora of the mouth are various species of β-hemolytic streptococci.

_____ 8.

Microbes cause thousands of different types of plant diseases.

_____ 9.

Most relationships between humans and microbes are beneficial rather than harmful.

_____ 10.

Beneficial microorganisms far outnumber harmful ones.

Answers to the Additional Chapter 10 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7.

C E A D B D D

8. 9. 10.

E C B

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

False (the bacterium, Helicobacter pylori, is able to live in the stomach) False (certain types of biofilms do have medical significance) False (many different types of microorganisms live in the colon) True True True False (α-hemolytic streptococci, not β-hemolytic streptococci) True True True

Chapter 11 Epidemiology and Public Health Terms Introduced in This Chapter After reading Chapter 11, you should be familiar with the following terms. These terms are defined in Chapter 11 and in the Glossary. Active carrier Biologic warfare (bw) agents Bioterrorist agents Coliforms Communicable disease Contagious disease Convalescent carrier Endemic disease Epidemic disease Epidemiology Fomites Incidence Incubatory carrier Morbidity rate Mortality rate Pandemic disease Parenteral injection Passive carrier Prevalence Reservoirs of infection (reservoirs) Sporadic disease

Insight Epidemiologists Epidemiologists are scientists who specialize in the study of disease and injury patterns (incidence and distribution patterns) in populations, and ways to prevent or control diseases and injuries. Epidemiologists study virtually all types of diseases, including heart, hereditary, communicable, and zoonotic diseases and cancer. In some ways, epidemiologists are like disease detectives, gathering and piecing together clues to determine what causes a particular disease, why it occurs only at certain times, and why certain people in a population get the disease while others do not. Quite often, epidemiologists are called on to track down the cause of epidemics, and figure out how to stop them. Data collection and statistical analysis of data are among the

many duties of epidemiologists. Epidemiologists have a variety of educational backgrounds. Some are physicians, with specialization in epidemiology or public health. Others have a doctoral degree (PhD or DrPH), a master’s degree (MS or MPH), or a bachelor’s degree (e.g., an RN degree) plus specialized training in epidemiology. Many epidemiologists are employed at public health agencies and healthcare institutions. The Centers for Disease Control and Prevention (CDC) employs many epidemiologists, and offers a 2-year, postgraduate course to train health professionals as Epidemic Intelligence Service (EIS) Officers. EIS Officers, many of whom are employed at state health departments, conduct epidemiologic investigations, research, and public health surveillance. To learn more about the EIS, visit this CDC web site: www.cdc.gov/eis. Preparing for a Bioterorrist Attack Perhaps you’ve wondered what you can do as an individual to prepare yourself and your family for a bioterrorist attack. The best thing you can do is to be aware of what’s going on around you and throughout the nation. Remain vigilant and cautious, but not scared. Stay healthy by eating well and by boosting your immune system. A fully competent immune system is your best defense against pathogens of all types. Authorities (such as the CDC) advise against purchasing gas masks and taking or stockpiling antibiotics. Prepare your home and family as you would for any natural disaster (e.g., a hurricane or tornado), by ensuring that you have emergency supplies on hand, such as a flashlight, radio, extra batteries, and plenty of food and water. Should a bioterrorist attack occur, state and federal public health authorities will advise you of what actions to take. Be sure to comply with their recommendations regarding vaccination, including the anthrax and smallpox vaccines. With respect to the mail, be on the lookout for suspicious packages and envelopes. Check the CDC web site (www.cdc.gov) for the characteristics of suspicious pieces of mail. Be sure to follow the United States Postal Service and CDC recommendations regarding actions to take should you receive any suspicious pieces of mail.

Increase Your Knowledge 1.

Students interested in learning more about the World Health Organization (WHO), including updated information on epidemics, should visit their web site (www.who.int/en). If you click on “Health Topics,” you can find information about many different diseases (such as AIDS, anthrax, Ebola hemorrhagic fever, malaria, tuberculosis).

2.

For additional information about the Centers for Disease Control and Prevention (CDC), including information about various infectious diseases, visit their web site (www.cdc.gov). If you click on “A–Z Index,” you can find information about many different diseases. The National Center for Infectious Diseases (NCID) web site is www.cdc.gov/ncidod/ncid.htm.

3.

In the winter of 1989, an Ebola virus epidemic occurred among monkeys at an Army

research facility in Reston, VA, near Washington, D.C. A SWAT team of soldiers and scientists worked feverishly for 18 days to end the outbreak, not knowing at the time whether the virus could infect humans. To learn more about this exciting epidemic, read The Hot Zone, by Richard Preston (Random House, New York, 1994). 4.

To learn more about a variety of exotic and emerging pathogens that have the potential to cause widespread epidemics, read The Coming Plague, by Laurie Garrett (Penguin Books, New York, 1994).

5.

To learn more about biologic weapons, biowarfare, and bioterrorism, read Germs: Biological Weapons and America’s Secret War, by Judith Miller, Stephen Engelberg, and William Broad (Simon & Schuster, New York, 2001).

Microbiology—Hollywood Style •

Epidemics are very serious, and should never be taken lightly. Nonetheless, Hollywood has produced several excellent movies about them. In the 1971 movie, The Andromeda Strain, a team of scientists attempts to isolate a deadly strain of virus from outer space. The 1993 movie, And the Band Played On, tells the powerful and moving story of the initial years of the AIDS epidemic in the United States. In the 1995 movie, Outbreak, U.S. Army and CDC epidemiologists attempt to contain an epidemic in California, caused by a deadly virus (similar to Ebola virus) that was transported from the jungles of Zaire, Africa, to the United States by a monkey.

•

Likewise, bioterrorist attacks are very serious, and should never be taken lightly. However, if you’d like to watch a movie about bioterrorism in the United States, you might want to rent the 1998 movie, The Patriot, starring Steven Seagal. A violent extremist group unleashes a rapidly spreading lethal biologic agent in a small community and then takes over the town.

Critical Thinking 1.

The Centers for Disease Control and Prevention (CDC) is an agency of the Federal Government of the United States, and yet CDC epidemiologists travel to foreign countries to investigate epidemics. A friend of yours thinks that this is a waste of taxpayers’ dollars. Explain to her why it isn’t.

2.

Visit the CDC web site to learn what actions have been or are being taken to protect the public from bioterrorism. Can you think of any additional actions that could be taken?

3.

The cryptosporidiosis epidemic in Milwaukee, WI, in the spring of 1993 was the largest waterborne epidemic that has ever occurred in the United States. Search the Internet to learn more details about this epidemic.

Answers to the Chapter 11 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

B D A D A B A C C D

Additional Chapter 11 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

communicable diseases endemic diseases epidemic diseases pandemic diseases sporadic diseases

_____

1. Diseases that are always present in a population are known as _______________.

_____ 2.

Diseases that are transmissible from person to person are known as _______________.

_____ 3.

Diseases that occur only occasionally in a particular population are known as _______________.

_____ 4.

Because large numbers of cases of AIDS, malaria, and tuberculosis are presently occurring in many different countries, they are known as _______________.

_____ 5.

Diseases with unusually high numbers of cases that often occur in one particular

geographic location A. B. C. D. E.

biting flies bugs lice mosquitos ticks

are known as _______________. _____

6. The causative agents of dengue fever, filariasis, malaria, West Nile encephalitis, and yellow fever are all transmitted by _______________.

_____ 7.

_______________ transmit the causative agents of babesiosis, ehrlichiosis, Lyme disease, relapsing fever, and Rocky Mountain spotted fever.

_____ 8.

The causative agent of American trypanosomiasis (Chagas’ disease) is transmitted by arthropods in a class of insects known as _______________.

_____ 9.

_______________ transmit the causative agents of epidemic typhus and trench fever.

_____ 10.

African sleeping sickness, leishmaniasis, and onchocerciasis are transmitted by various types of _______________.

True/False Questions _____ 1.

Influenza is an example of a contagious disease.

_____ 2.

Zoonotic diseases are diseases that humans acquire from zoo animals.

_____ 3.

The largest waterborne outbreak ever to occur in the United States was caused by Giardia lamblia.

_____ 4.

Water containing 1 coliform per 100 mL would be considered potable.

_____ 5.

The most common zoonotic infection in the United States is Rocky Mountain spotted fever.

_____ 6.

Soil can contain the spores that cause botulism, gas gangrene, and tetanus.

_____ 7.

Chlamydial genital infections and gonorrhea are the two most common nationally notifiable infectious diseases in the United States.

_____ 8.

The levels of chlorine routinely used for water treatment are sufficient to kill Giardia cysts and Cryptosporidium oocysts.

_____ 9.

Yersinia pestis, the bacterium that causes plague, is one of the pathogens most often discussed as a potential biologic weapon.

_____ 10.

Gonorrhea is considered to be a communicable disease, but not a contagious disease.

Answers to the Additional Chapter 11 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8.

B A E D C D E B

9. 10.

C A

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (zoonotic diseases can be acquired from many types of animals, not just zoo animals) False (it was caused by Cryptosporidium parvum) True False (Lyme disease is the most common zoonotic disease in the United States) True True False (the levels of chlorine routinely used for water treatment will not kill Giardia cysts or Cryptosporidium oocysts) True True

Chapter 12 Healthcare Epidemiology: Nosocomial infections and Infection Control Terms Introduced in This Chapter After reading Chapter 12, you should be familiar with the following terms. These terms are defined in Chapter 12 and in the Glossary. Airborne precautions Antibiogram Biotype Community-acquired infection Contact precautions Droplet precautions Hospital-acquired infection Iatrogenic infection Medical asepsis Medical aseptic techniques Molecular epidemiology Nosocomial infection Protective isolation Source isolation Standard precautions Surgical asepsis Surgical aseptic techniques Transmission-based precautions

Insight

Nosocomial Zoonoses Literally hundreds of diseases are transmissible from animals to humans; these are collectively known as zoonoses or zoonotic diseases (see Table 11-2 in Chapter 11 in the text). Transmission from animals to humans occurs by many routes, including direct contact, scratch, bite, inhalation, contact with urine or feces, and ingestion. Fortunately, most zoonoses have no association with hospitals or hospitalized patients. There have been some reports, however, of nosocomial zoonoses—nosocomial infections transmitted directly or indirectly from live animals. How does this happen?

Wild rodents such as rats and mice might enter hospitals where they can transmit diseases such as leptospirosis, rat-bite fever, and rickettsial pox. Droppings from wild birds can enter air vents and air-conditioning systems, causing diseases such as histoplasmosis and cryptococcosis. Pathogens from laboratory animals could enter air ventilation systems and be conveyed to patient care facilities. Pet therapy is becoming increasingly popular in nursing homes, where pets provide companionship for the residents. Such pets can be the source of pathogens. If animal tissues and organs are used for transplantation, there is always the danger of undetected microorganisms and other infectious agents (e.g., viruses and prions) being present in the transplanted material. Healthcare professionals can also be the source of zoonotic pathogens, especially those who have domestic pets or farm animals where they live. Should these workers wear their uniforms while playing with or caring for their animals, the uniforms could be contaminated with zoonotic pathogens. Or, if they should fail to wash their hands after touching their animals, pathogens could be carried from home to hospital on their hands. Pathogens that could potentially cause nosocomial zoonoses include cutaneous fungi (such as Microsporum canis and others that cause ringworm infections); bacteria such as staphylococci, streptococci, Pseudomonas, Salmonella, and Campylobacter; yeasts; and parasites such as Cryptosporidium. Several outbreaks in intensive care nurseries have resulted from Malassezia furfur and Malassezia pachydermatis, fungi that were transmitted from pets to lowbirth-weight neonates via the hands and clothing of healthcare professionals. Prevention of nosocomial zoonoses involves keeping medical facilities free of rodents, preventing birds from nesting near air-conditioners and air vents, and ensuring that laboratory animal ventilation systems are not linked to ventilation systems in patient care areas. In addition, laboratory coats worn in animal facilities should never be worn in patient care areas, and hospital uniforms should not be worn to and from work. Animals used in pet therapy should be vaccinated and in good health. And the most important way to prevent nosocomial infections of any kind is frequent and proper handwashing. Healthcare professionals must always wash their hands after handling animals and before providing patient care.

Infection Control Professionals Individuals wishing to combine their interest in detective work with a career in medicine might consider a career as an infection control professional (ICP). ICPs include physicians (infectious disease specialists or epidemiologists), nurses, clinical laboratory scientists (medical technologists), and microbiologists. Most ICPs are nurses, many having baccalaureate degrees and some with master’s degrees. In addition to having strong clinical skills, ICPs require knowledge and expertise in such areas as epidemiology, microbiology, infectious disease processes, statistics, and computers. To be effective, they must be part detective, part diplomat, part administrator, and part educator. In addition, ICPs function as role models, patient advocates, and consultants. Within the hospital, ICPs provide valuable services that minimize the risks of infection and spread of disease, thereby aiding patients, healthcare professionals, and visitors. The ICP is the key person in implementing and facilitating the institution’s infection control program. The ICP is often the head of the hospital’s Infection Control Committee (ICC) and, as such, is responsible for scheduling, organizing, and conducting ICC meetings. At these meetings, medical

records are reviewed of all patients suspected of having incurred a nosocomial infection since the previous meeting. The committee discusses possible or known causes of such infections and ways to prevent them from occurring in the future. The ICP receives timely information from the clinical microbiology laboratory concerning possible outbreaks of infection within the hospital, and is responsible for rapidly organizing a team to investigate these outbreaks. ICPs are also responsible for educating healthcare personnel about infection risk, prevention, and control.

Increase Your Knowledge 1.

Information about the Society for Healthcare Epidemiology of American (SHEA) can be found at their web site: www.shea-online.org

2.

Information about Infection Control Professionals/Practitioners can be found at www.apic.org, the web site for the Association for Professionals in Infection Control and Epidemiology.

3.

Additional information about handwashing (or the lack thereof) can be found at www.washup.org

Critical Thinking 1.

As a clinical laboratory scientist, you have been processing environmental specimens that were collected as part of an investigation into a Pseudomonas aeruginosa outbreak that is occurring on the pediatric ward. You’ve isolated P. aeruginosa from a sample of water from a mop bucket on the pediatric ward. How would you go about proving that the P. aeruginosa from the mop bucket is the same strain of P. aeruginosa that caused the outbreak, and, therefore, that the contaminated mop bucket water is the probable source of the epidemic?

2.

A patient who has been hospitalized for several weeks as a result of pneumonia has just developed pseudomembranous colitis (PMC). What do you think caused this condition? Do you think that her PMC should be considered a nosocomial infection? Do you think that her PMC should be considered an iatrogenic infection?

Answers to the Chapter 12 Self-Assessment Exercises in the Text 1. 2.

A D

3. 4. 5. 6. 7. 8. 9. 10.

B B B B A D A D

Additional Chapter 12 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

arthropodborne infections community-acquired infections iatrogenic infections nosocomial infections nosocomial zoonoses

_____

1. Infections that patients develop while hospitalized or within 14 days of hospital discharge are considered to be _______________.

_____ 2.

Infections that patients have on hospital admission are considered to be _______________.

_____ 3.

_______________ may result if healthcare workers fail to wash their hands after handling laboratory animals or pets being used for pet therapy.

_____ 4.

Infections that are actually caused by healthcare workers are specifically known as _______________.

_____ 5.

Each year, in the United States, approximately 2 million hospitalized patients develop _______________.

A. B. C. D. E.

Airborne precautions Contact precautions Droplet precautions Medical aseptic technique Surgical aseptic technique

_____

6. In addition to Standard precautions, _______________ must be used when managing a patient with streptococcal pneumonia.

_____ 7.

The goal of _______________ is to render and keep objects and areas sterile.

_____ 8.

In addition to Standard precautions, _______________ must be used when managing a tuberculosis patient.

_____ 9.

The goal of _______________ is to reduce the number and transmission of pathogens.

_____ 10.

In addition to Standard precautions, _______________ must be used when managing a patient with a Clostridium difficile–associated disease.

True/False Questions _____ 1.

Most of the pathogens involved in nosocomial infections come from the patients themselves.

_____ 2.

An infection that results from urinary catheterization would be considered an iatrogenic infection.

_____ 3.

Bacteria are the only pathogens that have become drug resistant.

_____ 4.

A patient with tuberculosis should be placed in protective isolation.

_____ 5.

A superinfection with Clostridium difficile could lead to diseases such as antibiotic-associated diarrhea and pseudomembranous colitis.

_____ 6.

One of the major factors contributing to nosocomial infections is the failure of healthcare personnel to follow infection control guidelines.

_____ 7.

Joseph Lister is considered the “Father of Handwashing.”

_____ 8.

A leukopenic patient should be placed in a patient room having positive air pressure.

_____ 9.

Members of a hospital’s Infection Control Committee would investigate outbreaks and epidemics that occur within that hospital.

_____ 10.

By practicing Standard precautions, healthcare workers will be protected from becoming infected, regardless of the type of infectious disease that the patient has.

Answers to the Additional Chapter 12 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7.

D B E C D C E

8. 9. 10.

A D B

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True True False (certain viruses, fungi, and parasitic protozoa have also become drug resistant) False (a patient with tuberculosis should be placed in source isolation) True True False (Ignaz Semmelweis is considered the “Father of Handwashing”) True True False (for certain types of diseases, transmission-based precautions must also be practiced)

Chapter 13 Diagnosing Infectious Diseases Terms Introduced in This Chapter After reading Chapter 13, you should be familiar with the following terms. These terms are defined in Chapter 13 and in the Glossary. Bacteremia Bacteriuria Calibrated loop Cerebrospinal fluid (CSF) Clean-catch, midstream urine (CCMS urine) Clinical laboratory scientists Clinical laboratory technicians Clinical specimens Clinically relevant laboratory results Encephalitis Fungemia Gonococcus (pl., gonococci) Immunohematology Laboratory Leukemia Leukocytes Meningitis Meningococcemia Meningococcus (pl., meningococci) Meningoencephalitis Parasitemia Pathologist Pathology Preliminary report Septicemia Sputum Toxemia Viremia

Insight Specimen Quality and Clinical Relevance

Microbiology laboratory results are clinically relevant if they reveal information about the patient’s infectious disease and provide the physician with useful information that can be used to diagnose infectious diseases, monitor their progress, and guide therapy. To provide clinically relevant information, the microbiology laboratory must receive high-quality clinical specimens. The quality of the results can be no better than the quality of the specimen. If a poor-quality specimen is submitted to the laboratory, in all likelihood, the results obtained using that specimen will not be clinically relevant. In fact, results obtained from poor-quality specimens might very well be harmful to the patient. What constitutes a high-quality clinical specimen? The best quality specimen is one that has been selected, collected, and transported properly. First, it must be an appropriate specimen —the correct type of specimen required to diagnose the suspected disease. Next, the specimen must be collected in a manner that will minimize its contamination with indigenous microflora. And finally, it must be transported to the laboratory in the proper manner—rapidly, if necessary; on ice, if necessary; anaerobically, if necessary; with the proper preservative, if necessary; and so forth. A specimen labeled “sputum,” for example, must contain sputum—not merely saliva. A urine specimen submitted for culture must be a clean-catch, midstream specimen. Adequate care must be taken to adequately disinfect the phlebotomy site when blood is drawn for culture to minimize the chance of contamination of the specimen with indigenous skin flora. Those people who are responsible for submitting specimens to the laboratory are responsible for the quality of the specimens they submit. But, how do these people know which specimen to submit, or how to collect it, or the proper way to transport it to the laboratory? If they have not been taught such procedures in their course of study, they should consult the “floor manual,” which contains such information. A copy of the floor manual, which may be called the laboratory procedures manual or some other name, should be present on each ward or clinic and readily available for reference. It is the laboratory's responsibility to publish and distribute such a manual. If the laboratory demands high-quality specimens, as it should, then it must take the time to educate healthcare professionals as to what constitutes an appropriate specimen for the diagnosis of each infectious disease. Only in this way will the highest quality of service be assured, and only then will the microbiology laboratory’s results be clinically relevant.

The Medical Laboratory Professions Have you ever wondered what happens to your blood sample or throat swab after it leaves the doctor’s office? Or, have you ever wondered how doctors diagnose diseases? Medical laboratory professionals are an important part of the answer to these questions. They are members of the highly skilled medical team who work together to collect clinical data and diagnose disease. Medical laboratory professionals include pathologists, clinical laboratory scientists (CLSs; also known as medical technologists, MTs), clinical laboratory technicians (CLTs; also known as medical laboratory technicians, MLTs), histologic technicians, cytotechnologists, blood bank technologists, phlebotomy technicians, pathologist assistants, and cytogeneticists. More than a quarter of a million people work in the medical laboratory professions. Practice settings for these professionals include hospital laboratories; clinics; nursing homes; city, state, and federal public health facilities (e.g, the CDC); molecular diagnostic and biotechnology laboratories; research laboratories; educational institutions; and commercial companies (e.g., pharmaceutical

companies and food service industries). Clinical laboratory scientists (CLSs or MTs) and clinical laboratory technicians (CLTs or MLTs) constitute the majority of medical laboratory professionals. In conjunction with pathologists and physicians, these skilled professionals work in all areas of the clinical laboratory, including blood bank, chemistry, hematology, immunology, urinalysis, and microbiology. They perform a wide variety of laboratory tests used in the detection, diagnosis, and treatment of many diseases. CLSs have many responsibilities and are held accountable for accurate and reliable test results. They may hold a patient’s life in their hands! Education and training in Clinical Laboratory Science not only prepares the individual for a rewarding career in the profession, but also serves as a foundation for jobs in other fields (e.g., medicine, research, forensics). Individuals interested in pursuing a career in Clinical Laboratory Science should have a strong background in the high school and college sciences (i.e., biology and chemistry), as well as math and computer science. There are two levels of Clinical Laboratory Science training available. The minimum formal education requirements for a CLT are a 2-year associate degree in completion of an accredited CLT program. CLTs perform routine tests in all areas of the laboratory under the supervision of a CLS. The CLS requires formal education, which includes a baccalaureate degree and clinical experience in an accredited Clinical Laboratory Science program. CLSs are able to correlate results with disease states, establish and monitor quality control, and operate complex electronic equipment and computers. CLSs must be able to work in stressful situations and they must be reliable, self-sufficient, precise, and thorough. Clinical education programs for CLSs may be located in hospitals or university settings and include instruction in microbiology, chemistry, hematology, immunology, blood banking, virology, phlebotomy, urinalysis, management, and education. To ensure competency, graduates of both CLS and CLT clinical education programs must be certified by one or both of the two national credentialing agencies: the American Society for Clinical Pathology (ASCP), or the National Credentialing Agency (NCA). Careers in the medical laboratory professions, particularly as a CLS or CLT, offer a great opportunity for students interested in microbiology! Jobs are plentiful across the nation and offer competitive salaries. The Bureau of Labor Statistics of the U.S. Department of Labor projects that the employment of CLTs and CLSs will increase by 10 to 20% through the year 2008. According to Jobs Rated Almanac: The Best and Worst Jobs, by Les Krantz (2002), clinical laboratory science had 25% job growth and good job security. Among health-related professions, it ranked number 3. In 2004, the average starting salary for CLTs was about $26,000 to $30,000, and $38,000 to $43,000 annually for CLSs, based on geographic location. Currently, there is a shortage of laboratory scientists in many parts of the country, guaranteeing employment and higher salaries for graduates. For more information regarding the medical laboratory professions, see the “Increase Your Knowledge” section that follows.

Increase Your Knowledge 1.

For more detailed information about specimen collection, refer to A Guide to Specimen Management in Clinical Microbiology, 2nd ed., published by ASM Press, Washington, D.C., 1999.

2.

For more information regarding the medical laboratory professions, visit the following web sites: National Accrediting Agency for Clinical Laboratory Sciences (www.naacls.org) National Credentialing Agency (www.nca-info.org) American Society for Clinical Laboratory Science (www.ascls.org) American Society for Clinical Pathology (www.ascp.org)

3.

A Closer Look at the Polymerase Chain Reaction. The polymerase chain reaction (PCR) is used to make a huge number of copies of a particular gene of interest in just a few hours; it is referred to as an amplification procedure. There are three steps in a PCR, which are repeated over and over for 30 to 40 cycles. The three steps are: (1) denaturation, (2) annealing, and (3) extension. During a PCR, there is an exponential increase in the number of copies of the gene. If there was only one copy of the desired gene to begin with, there will be two copies after one cycle, four copies after two cycles, eight copies after three cycles, and so on. There would be over 1 billion copies after 30 cycles and over 1 trillion copies after 40 cycles. The PCR was originally described by Kary B. Mullis in 1990. The patent rights to the PCR were reportedly sold for $300 million in 1992. For their contributions to the development of DNA-based chemistry methods, Mullis and Michael Smith were awarded the 1993 Nobel Prize in Chemistry. After only a little more than a decade of use, the PCR has revolutionized the Clinical Microbiology Laboratory. At some time in the near future, traditional microbiologic procedures, such as culturing and biochemical testing of isolates, might be completely replaced by PCR technology. As Mark Terry (ADVANCE for Medical Laboratory Professionals 14: 8, 2002) has stated, “It wouldn’t seem farfetched at all to imagine sputum, blood, or urine being placed in a test tube that contained a DNA chip or real-time PCR machine capable of analyzing—in a very short period of time—for every known bacterium and virus.”

4.

The Clinical and Laboratory Standards Institute (CLSI; formerly the National Committee for Clinical Laboratory Standards [NCCLS]) is a global, interdisciplinary, nonprofit organization that enhances the value of medical testing and healthcare services by developing and disseminating consensus standards. These standards, in the form of published documents, contain step-by-step instructions for how to perform laboratory tests. Laboratories are expected to purchase these documents and perform laboratory testing in the exact manner described in the documents. Students interested in learning more about the CLSI should visit their web site (www.clsi.org).

5.

For a more in-depth discussion of laboratory safety, consult Essential Procedures for Clinical Microbiology (1998, with subsequent updates) and the 7th edition of the Manual of Clinical Microbiology (1999), both published by ASM Press, Washington, D.C.

6.

To learn more about the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) at Fort Detrick, MD, visit their web site: www.usamriid.army.mil.

Critical Thinking 1.

If you were a clinical laboratory scientist (medical technologist) working in a CML, what are some of the actions you would take to protect yourself from becoming infected?

2.

You are a nurse and are accompanying a physician who is conducting ward rounds. After examining a patient, the physician turns to you and says, “I think this patient has Lyme disease. Get a specimen down to the lab, right away.” The physician then leaves the room. Assuming that you don’t recall what the appropriate specimen is to diagnose Lyme disease, where would you turn for assistance?

3.

The organism most commonly isolated from positive blood cultures is Staphylococcus epidermidis, and yet S. epidermidis is not the most common cause of either bacteremia or septicemia. Can you explain this apparent contradiction?

4.

A female patient has submitted a urine specimen as part of her prenatal screening appointment. Her urine culture yielded greater than 100,000 CFU/mL of mixed bacterial species, even though she does not have a urinary tract infection. Can you offer a possible explanation for her urine culture results?

Answers to the Chapter 13 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

D C C D A D C D D D

Additional Chapter 13 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.)

Matching Questions (Read CD-ROM Appendix 4 before attempting to answer these questions.) A. B. C. D.

agar dilution method disk diffusion method macro broth dilution method micro broth dilution method

_____

1. Because the _______________ of antimicrobial susceptibility testing uses large numbers of test tubes, this method is impractical for use in the Clinical Microbiology Laboratory.

_____ 2.

The _______________ of antimicrobial susceptibility testing is also known as the “Kirby Bauer method.”

_____ 3.

The _______________ of antimicrobial susceptibility testing is considered to be the “gold standard.”

_____ 4.

In the United States, the _______________ is currently the most popular method for performing antimicrobial susceptibility testing.

_____ 5.

Agar plates are used in both the agar dilution method and the _______________ of antimicrobial susceptibility testing.

A. B. C. D. E.

Bacteriology Section Mycology Section Mycobacteriology Section Parasitology Section Virology Section

_____

6. Mycoses are diagnosed in the _______________ of the Clinical Microbiology Laboratory.

_____ 7.

Tuberculosis is diagnosed in the _______________ of the Clinical Microbiology Laboratory.

_____ 8.

Hair clippings, nail clippings, and skin scrapings are most often processed in the _______________ of the Clinical Microbiology Laboratory.

_____ 9.

Susceptibility testing is routinely performed only in the Bacteriology Section and the _______________ of the Clinical Microbiology Laboratory.

_____ 10.

Miniaturized biochemical test systems— known as minisystems—are most often used in the _______________ of the Clinical Microbiology Laboratory.

True/False Questions _____ 1.

Poor-quality clinical specimens are unlikely to produce clinically relevant results.

_____ 2.

The director of the Clinical Microbiology Laboratory (CML) is ultimately responsible for the quality of clinical specimens submitted to the CML.

_____ 3.

Special disinfection procedures are required to prevent indigenous microflora of the skin from contaminating blood cultures.

_____ 4.

Bacteriuria is a sure sign of urinary tract infection.

_____ 5.

CSF specimens are treated as “stat” specimens in the Clinical Microbiology Laboratory.

_____ 6.

CSF specimens should be refrigerated en route to the Clinical Microbiology Laboratory.

_____ 7.

There is no need to refrigerate urine specimens for culture if they are clean-catch midstream specimens.

_____ 8.

Many clinical specimens labeled “sputum” are actually saliva specimens.

_____ 9.

The Clinical Microbiology Laboratory is part of the Clinical Pathology Division of the Pathology Department.

_____ 10.

β-Lactamase testing is always performed on isolates of Neisseria gonorrhoeae and Haemophilus influenzae.

Answers to the Additional Chapter 13 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7.

C B A D B B C

8. 9. 10.

B C A

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (the people who collect clinical specimens are responsible for the quality of those specimens) True False (very often, the bacteria causing bacteriuria are contaminants; thus, bacteriuria does not necessarily mean that the patient has a urinary tract infection) True False (CSF specimens should not be refrigerated; refrigeration might kill pathogens that are present in the specimens) False (even clean-catch, midstream urine specimens will contain contaminants, so they must be refrigerated if there will be a delay between collection and processing) True True True

Chapter 14 Pathogenesis of Infectious Diseases Terms Introduced in This Chapter After reading Chapter 14, you should be familiar with the following terms. These terms are defined in Chapter 14 and in the Glossary. Acute disease Adhesin Asymptomatic disease Asymptomatic infection Avirulent strains Botulinal toxin Chronic disease Coagulase Collagenase Endotoxin Enterotoxin Erythrogenic toxin Exfoliative toxin Exotoxin Facultative intracellular pathogen Hemolysin Hyaluronic acid Hyaluronidase Intraerythrocytic pathogen Intraleukocytic pathogen Kinase Latent infection Lecithin Lecithinase Leukocidin Localized infection Neurotoxin Pathogenesis Pathogenicity Primary disease Pyrogen Receptor Secondary disease Septic shock Shock Signs of a disease

Staphylokinase Streptokinase Symptomatic disease Symptoms of a disease Systemic infection Tetanospasmin Virulence Virulence factors Virulent strains

Increase Your Knowledge A Closer Look at Botulinal Toxin. The neurotoxin produced by Clostridium botulinum has various names, including botulin, botulinal toxin, botulinus toxin, botulinum toxin, botulism toxin, and botulismotoxin. The clinical effects of this potent neurotoxin—the disease botulism and its characteristic flaccid paralysis—have been known since 1897. Botulinal toxin acts presynaptically at nerve terminals to prevent the release of acetylcholine, which causes a chemical denervation. There are seven known, serologically distinct types of botulinal toxin, designated type A through type G. Although botulinal toxin is one of the most potent and dangerous toxins known to science, a purified form of type A, called Botox (Allergan, Inc.), has been used successfully to reduce muscle hyperactivity and spasm, and the pain associated with such conditions. Among its many applications, Botox has been used in the treatment of facial, vocal cord, and neck spasms; lazy eye; muscle spasticity caused by cerebral palsy, stroke, and multiple sclerosis; migraine headaches; excessive sweating; low back pain; and cosmetic problems such as crow’s feet, frown lines, and brow lines. The effects of Botox injections to correct cosmetic problems last from 3 to 6 months.

Critical Thinking 1.

You are with some friends in a crowded movie theater during the middle of the flu season. Some of the people seated around you are coughing and sneezing. Some of your friends develop influenza as a result of their movie-going experience. But, you don’t! Cite some reasons why you were one of the fortunate moviegoers.

2.

In this chapter, you learned that some pathogens must attach to host cells to cause disease. To accomplish this, molecules on their surface (adhesins or ligands) recognize and attach to molecules (receptors or integrins) on the surface on certain host cells. Can you think of a way that the host could prevent such attachment?

Answers to the Chapter 14 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

D A D B C B C (Mycoplasmas do not have cell walls and, thus do not have endotoxin.) B A D

Additional Chapter 14 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

coagulases enterotoxins kinases necrotizing enzymes neurotoxins

_____

1. The _______________ produced by Clostridium botulinum and Clostridium tetani are examples of virulence factors.

_____ 2.

The _______________ produced by Clostridium perfringens and Streptococcus pyogenes are examples of virulence factors.

_____ 3.

_______________ are exoenzymes that cause clot formation.

_____ 4.

_______________ are exoenzymes that dissolve clots.

_____ 5.

_______________ are produced by Clostridium difficile, Salmonella spp., Shigella spp., Vibrio cholerae, and certain serotypes of E. coli.

A. B. C. D. E.

adhesins endotoxin hyaluronidase integrins leukocidins

_____

6. _______________ is a virulence factor that is found in (and released from) the cell walls of Gram-negative bacteria.

_____ 7.

The molecules on the surfaces of host cells that pathogens are able to recognize and attach to are known as receptors or _______________.

_____ 8.

Molecules on the surfaces of pathogens that are able to recognize and bind to molecules on the surfaces of host cells are known as ligands or _______________.

_____ 9.

_______________ is also known as “spreading factor.”

_____ 10.

_______________ are toxins that destroy white blood cells.

True/False Questions _____ 1.

Bacterial capsules protect bacteria from being phagocytized by leukocytes.

_____ 2.

A headache is a classic example of a sign of a disease.

_____ 3.

To cause disease, all bacterial pathogens must first attach to some tissue in the body.

_____ 4.

Rickettsias and chlamydias are examples of obligate intracellular pathogens.

_____ 5.

Babesia spp., Ehrlichia spp., and Plasmodium spp. are examples of intraerythrocytic pathogens.

_____ 6.

The exoenzyme that causes toxic shock syndrome is called erythrogenic toxin.

_____ 7.

The neurotoxins produced by Clostridium botulinum and Clostridium tetani cause a spastic, rigid type of paralysis.

_____ 8.

Although most people use the terms “infection” and “infectious disease” synonymously, microbiologists define infection as colonization by a pathogen.

_____ 9.

Avirulent strains do not cause disease.

_____ 10.

It is thought that the waxes in the cell walls of Mycobacterium tuberculosis protect this pathogen from digestion within phagocytes.

Answers to the Additional Chapter 14 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9.

E D A C B B A D C

10.

E

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (a headache is a symptom, not a sign) False (some pathogens can cause disease without attaching to tissue) True False (Babesia and Plasmodium spp. are intraerythrocytic pathogens, but Ehrlichia spp. are intraleukocytic pathogens) False (erythrogenic toxin causes scarlet fever) False (the neurotoxin produced by Clostridium botulinum causes a flaccid type of paralysis, whereas the neurotoxin produced by Clostridium tetani causes a spastic, rigid type of paralysis) True True True

Chapter 15 Nonspecific Host Defense Mechanisms Terms Introduced in This Chapter After reading Chapter 15, you should be familiar with the following terms. These terms are defined in Chapter 15 and in the Glossary. Antibody Antigen Basophil Chemokines Chemotactic agents Chemotaxis Complement Complement cascade Edema Eosinophil Eosinophilia Fixed macrophages Granulocytes Host defense mechanisms Inflammation Inflammatory exudate Interferons Leukocytosis Leukopenia Macrophage Monocyte Neutrophil Nonspecific host defense mechanisms Opsonins Opsonization Phagolysosome Phagosome Purulent exudate Pyogenic Pyogenic microorganisms Reticuloendothelial system (RES) Specific host defense mechanisms Transferrin Vasodilation Wandering macrophages

Increase Your Knowledge A Closer Look at the Complement System. Activation of the complement system can occur by any of three pathways. (1) Activation by antigen–antibody complexes (immune complexes) is known as the classic pathway of activation. This pathway involves all nine of the complement proteins designated C1 through C9. (2) Certain microbial surface molecules, microbial secretions (e.g., endotoxin and proteases), and aggregated immunoglobulins can also activate the complement system; this is known as the alternative pathway of activation. Complement proteins C1, C2, and C4 do not participate in the alternative pathway. Instead, plasma protein factors (including properdin factors B and D) work in tandem with complement proteins C3 and C5 through C9 to attract phagocytes and enhance phagocytosis, inflammation, and the destruction of bacteria and certain viruses. (3) A third manner in which the complement system can be activated, called the lectin pathway of activation, is triggered by certain microbial products.

Microbiology—Hollywood Style Hollywood’s attempts to portray host defense mechanisms have included Fantastic Voyage, and Osmosis Jones. In the 1966 sci-fi movie, Fantastic Voyage, an elite team of scientists and medical specialists and their submarine-like vessel are reduced to microscopic size. They are then injected into the bloodstream of a top government scientist to locate and destroy a potentially fatal blood clot in his brain. The team encounters many obstacles within the scientist’s body, including white blood cells and antibodies. In the 2001 comedy, Osmosis Jones, the title character is an animated white blood cell living within a live-action character (“Frank”), played by comedian Bill Murray. When Frank’s body is invaded by a particularly nasty virus, the animated characters (cells that are part of Frank’s host defense mechanisms) work together to defeat the evil virus. (Caution! Some viewers might consider portions of Osmosis Jones to be offensive.)

Critical Thinking 1.

Ouch! A splinter has just jammed into your finger. List the sequence of events that will ultimately lead to the four cardinal signs and symptoms of inflammation.

2.

Interferons have been used to treat certain types of human cancers. Which types of

cancers would you expect to be treatable with interferons?

Answers to the Chapter 15 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

B A D D D A D D A C

Additional Chapter 15 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

bacteriocins chemotactic agents complement fragments cytokines interferons

_____

1. _______________ are chemical mediators that enable cells to communicate with each other.

_____ 2.

When attached to the surface of particles or cells, _______________ can facilitate phagocytosis.

_____ 3.

Proteins produced by one bacterial species that kill other bacterial species are known as _______________.

_____ 4.

_______________ are small, antiviral proteins that are produced by virusinfected cells.

_____ 5.

_______________ attract leukocytes to sites where they are needed.

A. B. C. D. E.

chemotaxis opsonization phagolysosome phagosome vasodilation

_____

6. A _______________ is a membrane-bound vesicle containing only an ingested object.

_____ 7.

The directed migration of leukocytes is known as _______________.

_____ 8.

A _______________ is a membranebound vesicle containing an ingested object and digestive enzymes.

_____ 9.

_______________ is an increase in the diameter of blood vessels.

_____ 10.

_______________ is a process by which phagocytosis is facilitated by the deposition of antibodies or complement fragments onto the surface of particles or cells.

True/False Questions _____ 1.

Lactoferrin and transferrin are proteins that bind iron, and therefore deprive pathogens of this essential nutrient.

_____ 2.

Pyrogenic substances cause the production of pus.

_____ 3.

Interferons are virus-specific, but are not species-specific.

_____ 4.

Complement is the name of a single plasma protein that “complements” the actions of the immune system.

_____ 5.

Eosinophils are much better phagocytes than neutrophils.

_____ 6.

Phagocytes can only ingest objects that they are able to attach to.

_____ 7.

The terms “leukemia” and “leukopenia” both refer to an abnormally low number of circulating leukocytes.

_____ 8.

Ehrlichia spp. are intraleukocytic pathogens.

_____ 9.

Chemokines are chemotactic agents that are produced by various cells of the human body.

_____ 10.

Perspiring, swallowing, and urinating are all considered to be part of the first line of defense.

Answers to the Additional Chapter 15 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9.

D C A E B D A C E

10.

B

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (pyrogenic substances cause the production of fever; pyogenic substances cause the production of pus) False (the reverse is true) False (complement is not a single plasma protein; the term refers to a group of approximately 30 different proteins found in the blood) False (the reverse is true) True False (leukemia is a type of cancer, in which there is a high number of abnormal leukocytes in the blood; the term leukopenia refers to an abnormally low number of circulating leukocytes) True True True

Chapter 16 Specific Host Defense Mechanisms: An Introduction to Immunology Terms Introduced in This Chapter After reading Chapter 16, you should be familiar with the following terms. These terms are defined in Chapter 16 and in the Glossary. Acquired immunity Active acquired immunity Agammaglobulinemia Allergen Anaphylactic reactions Anaphylactic shock Anaphylaxis Antigen–antibody complex Antigen-presenting cell (APC) Antigenic Antigenic determinant Antigenic variation Antiserum Antitoxins Artificial active acquired immunity Artificial passive acquire immunity Atopic person Attenuated Attenuated vaccine Attenuation Autogenous vaccine Autoimmune disease B cells (B lymphocytes) Blocking antibodies Cell-mediated immunity Conjugate vaccine Cutaneous anaphylaxis Delayed-type hypersensitivity reactions DNA vaccine Erythema Hapten Humoral immunity Hybridoma Hypersensitivity reactions

Hypogammaglobulinemia Immediate-type hypersensitivity reactions Immune Immunity Immunocompetent person Immunodiagnostic procedures Immunoglobulins Immunosuppressed person Immunology Inactivated vaccine Lymphokines Monoclonal antibodies Natural active acquired immunity Natural passive acquired immunity Passive acquired immunity Plasma cell Primary response Protective antibodies Regulatory T cells Secondary response Serologic procedures Subunit vaccine T cells (T lymphocytes) T-dependent antigens T-independent antigens Toxoid Toxoid vaccine Vaccine

Increase Your Knowledge It has been stated that “boosting your immune system is the single most important thing you can do for your health.” Students interested in learning how to improve their immune system should read The Immune Advantage: The Powerful, Natural Immune-Boosting Program to Help You Prevent Disease, Enhance Vitality, Live a Longer, Healthier Life, by Ellen Mazo, et al. (Rodale Inc., 2002).

Microbiology—Hollywood Style Severe combined immune deficiency (SCID) is sometimes called “the boy-in-the-bubble” disease, referring to a case involving a boy named David Vetter. David survived with

SCID until age 12 by living within a sterile plastic chamber. He died in 1984, as a result of complications of an experimental bone marrow transplant. A 1976 Hollywood movie, entitled The Boy in the Plastic Bubble, is loosely based on the case. John Travolta plays the boy with SCID.

Critical Thinking 1.

In Chapter 14, you learned that some bacteria possess polysaccharide capsules, which prevent phagocytes from ingesting these bacteria. Using information in Chapters 14, 15, and 16, explain why phagocytes are unable to attach to the encapsulated bacteria, and then describe two ways in which the host’s defense mechanisms can overcome this problem.

2.

Reread the information in Chapter 14 about adhesins. Then answer the following question. How might a vaccine containing Streptococcus pyogenes adhesins protect someone from getting strep throat?

3.

The blood of a newborn infant contains IgM antibodies against a particular pathogen (we’ll call it pathogen X). What conclusion can be drawn?

4.

A friend of yours has systemic lupus erythematosus (SLE). Use an Internet search engine (e.g., Google) to find out more about her disease. Be prepared to discuss your findings in class.

Answers to the Chapter 16 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

A C C C C D B D D C

Additional Chapter 16 Self-Assessment Exercises

(Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D.

A. B. C. D. E.

artificial active acquired immunity artificial passive acquired immunity natural active acquired immunity natural passive acquired immunity

antibodies antigens epitopes haptens immune complexes

_____

1. The immunity that a fetus acquires in utero, as a result of receiving protective antibodies from Mom’s blood is called _______________.

_____ 2.

The immunity that someone acquires as a result of an infection is called _______________.

_____ 3.

The immunity that someone acquires after receiving a shot of gamma globulin is called _______________.

_____ 4.

The immunity that someone acquires as a result of receiving a vaccine is called _______________.

_____ 5.

The immunity that an infant acquires as a result of breast-feeding is called _______________.

_____

6. _______________ are also known as immunogens.

_____ 7.

Molecules referred to as antigenic determinants are also known as _______________.

_____ 8.

_______________ are in a class of proteins called immunoglobulins.

_____ 9.

Small molecules called _______________ are antigenic only when they are coupled with large carrier molecules such as proteins.

_____ 10.

_______________ initiate type III hypersensitivity reactions.

True/False Questions _____ 1.

Technically speaking, all antibodies are immunoglobulins, but not all immunoglobulins are antibodies.

_____ 2.

IgG is the largest of the five classes of immunoglobulins.

_____ 3.

The primary function of NK and K cells is to kill foreign cells, virus-infected cells, and tumor cells.

_____ 4.

Common allergic reactions, such as those experienced in hayfever, are also known as anaphylactic reactions.

_____ 5.

IgM antibodies and basophils play major roles in anaphylactic reactions.

_____ 6.

The penicillin molecule is an example of a hapten.

_____ 7.

Autoimmune diseases are always the result of type II hypersensitivity reactions.

_____ 8.

With respect to a particular pathogen, detection of antibodies in a patient’s blood provides better proof of current infection than does detection of antigens.

_____ 9.

If a person’s immune system is not functioning properly, that person is said to be immunocompetent.

_____ 10.

An IgM molecule can bind to ten antigenic determinants, but they would all have to be the antigenic determinant that stimulated the production of that IgM molecule.

Answers to the Additional Chapter 16 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9.

D C B A D B C A D

10.

E

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (IgM is the largest of the five classes of immunoglobulins) True True False (IgE antibodies and basophils play major roles in anaphylactic reactions) True False (autoimmune diseases may be the result of type II, type III, or type IV hypersensitivity reactions) False (the reverse is true) False (if a person’s immune system is not functioning properly, that person is said to be immunosuppressed, immunodepressed, or immunocompromised) True

Chapter 17 Major Viral, Bacterial, and Fungal Diseases of Humans Terms Introduced in This Chapter After reading Chapter 17, you should be familiar with the following terms. These terms are defined in Chapter 17 and in the Glossary. Arbovirus Bacterial vaginosis (BV) Bartholinitis Bronchitis Bronchopneumonia Carbuncle Cervicitis Choleragen Colitis Conjunctiva Conjunctivitis Cystitis Dental caries Dermatitis Dermatophytes Dermis Diarrhea Dysentery Encephalitis Encephalomyelitis Endocarditis Endometritis Enteritis Epidermis Epididymitis Epiglottitis Exudate Fascia Fasciitis Folliculitis Furuncle Gangrene Gas gangrene Gastritis

Gastroenteritis Gingivitis Hepatitis Ischemia Keratitis Keratoconjunctivitis Laryngitis Lymphadenitis Lymphadenopathy Lymphangitis Malaise Meninges (sing. meninx) Mucormycosis (zygomycosis) Myelitis Myocarditis Necrosis Nephritis Oncogenic Oophoritis Orchitis Otitis externa Otitis media Parotitis Pelvic inflammatory disease (PID) Pericarditis Periodontal disease Periodontitis Pharyngitis Pneumonia Prostatitis Pustule Pyelonephritis Sebaceous gland Sebum Sinusitis Splenomegaly Sty (stye) Tinea infections Transient bacteremia Ureteritis Urethritis Vaginitis Vulvovaginitis

Increase Your Knowledge

Students seeking additional information about the major viral, bacterial, and fungal infections of humans should consult one of the following books or visit one of the following web sites: Control of Communicable Diseases Manual, 18th ed., by D.L. Heymann. Washington, D.C., American Public Health Association, 2004. The Merck Manual of Medical Information, by R. Berkow. Whitehouse Station, Merck & Company, 1997. The World Health Organization (WHO), www.who.int/en/. If you click on “Health Topics,” you can find information about many different infectious diseases. The Centers for Disease Control and Prevention (CDC), www.cdc.gov. If you click on “A–Z Index,” you can find information about many different infectious diseases.

Critical Thinking 1.

A group of your friends is discussing some recent meat recalls that involved Escherichia coli O157:H7. They say that, in the future, they are going to avoid hamburgers in fastfood establishments and eat salads only. Explain to them why this will not necessarily protect them from E. coli O157:H7 food poisoning.

2.

You’ve just finished hiking with a friend. You suggest that you check each other for ticks. Your friend thinks that your suggestion is silly. Explain to your friend why it is definitely not silly, and name as many tickborne infections as you can. (Refer back to Chapter 11 if necessary.)

3.

One of your friends is complaining about her sore throat. You suggest that she get checked for strep throat. She is reluctant. Step up your advice by listing as many complications of streptococcal infections as possible.

4.

A friend of yours has read that there is a connection between HIV infection and immunosuppression. However, she doesn’t have a clue as to how the two events are connected. Explain to her the mechanism by which HIV-infected individuals become immunosuppressed, and why AIDS patients die of overwhelming infections caused by a variety of different types of pathogens.

Case Studies 1.

A 19-year-old woman visits the clinic complaining of a frequent, urgent desire to urinate,

a burning sensation during urination, and pain above her pubic bone. The physician suspects cystitis and arranges for the patient to collect a clean-catch, midstream urine specimen. The urine is cloudy and tinged with blood. In the laboratory, a colony count confirms that the patient does have a urinary tract infection. The pathogen causing the infection is producing pink colonies on MacConkey agar. Which one of the following pathogens do you suspect is causing this patient’s cystitis? a. b. c. d. e. 2.

A 2-year-old girl is admitted to the hospital with massive tissue destruction along her right arm. The skin is a violet color, and large fluid-filled blisters are present. The patient has a fever, a rapid heart rate, and low blood pressure, and seems confused. Her mother informs the physician that the child had been recovering from chickenpox, and, for the past 2 days, had frequently been scratching at chickenpox lesions on that area of her arm. Once the area appeared to have become infected, the infection spread very rapidly. A Gram-stain of exudate from the infected tissue reveals Gram-positive cocci in chains. The physician suspects that her infection is being caused by _______________. a. b. c. d. e.

3.

Clostridium perfringens Clostridium tetani Staphylococcus aureus Streptococcus pneumoniae Streptococcus pyogenes (Group A strep)

A 16-year-old girl is admitted to the hospital with severe abdominal cramps and bloody diarrhea. She has a fever of 102°F. She has been experiencing her symptoms for the past 3 days, since several hours after eating at a fast-food restaurant with a group of her friends. She recalls that the hamburger she ate was not very well cooked. (It is later learned that the meat being used in that restaurant to prepare hamburgers has been recalled because of bacterial contamination.) All of the following organisms can cause diarrhea, but which is the most likely cause of her illness? a. b. c. d. e.

4.

Chlamydia trachomatis Escherichia coli Neisseria gonorrhoeae Proteus mirabilis Staphylococcus saprophyticus

A species of Salmonella A species of Shigella Escherichia coli O157:H7 Staphylococcus aureus Vibrio cholerae

A 20-year-old man is admitted to the hospital with fever, headache, stiff neck, sore throat, and vomiting. The attending physician suspects that the patient has meningitis and immediately performs a lumbar puncture. A cerebrospinal fluid (CSF) specimen is rushed to the laboratory, where it is processed immediately. After centrifuging an aliquot of the

specimen, the sediment is spread onto a microscope slide, fixed, and Gram-stained. Microscopic examination of the Gram-stained specimen reveals numerous white blood cells and numerous Gram-negative diplococci. This information is telephoned to the attending physician, who will now treat the patient for a meningitis caused by _______________. a. b. c. d. e. 5.

Haemophilus influenzae Neisseria meningitidis Streptococcus agalactiae (Group B strep) Streptococcus pneumoniae Streptococcus pyogenes (Group A strep)

An 80-year-old woman is transferred from a nursing home to the hospital because she is suspected of having pneumonia. She is experiencing chest pain, chills, fever, and shortness of breath. She has a productive cough (meaning that she is coughing up sputum). A Gram-stain of the sputum reveals numerous white blood cells and numerous Gram-positive diplococci. On receipt of the Gram-stain report, the physician treats the patient for a pneumonia caused by _______________. a. b. c. d. e.

Haemophilus influenzae Staphylococcus aureus Streptococcus agalactiae (Group B strep) Streptococcus pneumoniae Streptococcus pyogenes (Group A strep)

Answers to the Chapter 17 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

B A D D D D A B B A

Answers to the Chapter 17 Case Studies

1. 2. 3. 4. 5.

B E C B D

Additional Chapter 17 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D. E.

Staphylococcus aureus Staphylococcus epidermidis Streptococcus agalactiae Streptococcus pneumoniae Streptococcus pyogenes

_____

1. _______________ is a common cause of subacute bacterial endocarditis (SBE), and a less common cause of cystitis.

_____ 2.

Certain strains of _______________ are the so-called flesh-eating bacteria.

_____ 3.

_______________ is a common cause of bacterial pneumonia, meningitis, and otitis media.

_____ 4.

_______________ is the most common cause of toxic shock syndrome.

_____ 5.

_______________ is one of the most common causes of neonatal meningitis.

A. B. C D. E.

Chlamydia species mold Rickettsia species virus yeast

_____

6. A tinea infection is caused by a _______________.

_____ 7.

Trachoma is caused by a _______________.

_____ 8.

Cryptococcosis is caused by a _______________.

_____ 9.

Any type of wart is caused by a _______________.

_____ 10.

The most common cause of nongonococcal urethritis is a _______________.

True/False Questions _____ 1.

Tuberculosis and Hansen’s disease (leprosy) are caused by Mycoplasma species.

_____ 2.

It is possible for scarlet fever and toxic shock syndrome to be caused by the same pathogen.

_____ 3.

The most common cause of gas gangrene also causes a type of food poisoning.

_____ 4.

The diseases caused by Mycobacterium species are referred to as mycoses.

_____ 5.

Botulism, gas gangrene, and tetanus are all caused by Clostridium species.

_____ 6.

The causative agent of infectious mononucleosis also causes or is associated with various types of human cancers.

_____ 7.

Measles, German measles, mumps, and whooping cough are all caused by viruses.

_____ 8.

α-Hemolytic streptococci of oral origin and Staphylococcus epidermidis are common causes of subacute bacterial endocarditis (SBE).

_____ 9.

Haemophilus influenzae is the most common cause of influenza (“flu”).

_____ 10.

Meningitis could be caused by a virus, a bacterium, a fungus, or a protozoan.

Answers to the Additional Chapter 17 Self-Assessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7. 8. 9.

B E D A C B A E D

10.

A

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

False (tuberculosis and Hansen’s disease are caused by Mycobacterium species) True True False (diseases caused by fungi are referred to as mycoses) True True False (measles, German measles, and mumps are caused by viruses, but whooping cough is caused by a bacterium) True False (influenza is caused by influenza viruses) True

Chapter 18 Major Parasitic Diseases of Humans: An Introduction to Medical Parasitology Terms Introduced in This Chapter After reading Chapter 18, you should be familiar with the following terms. These terms are defined in Chapter 18 and in the Glossary. Biological vector Cestodes Definitive host Ectoparasite Endoparasite Facultative parasite Helminth Intermediate host Mechanical vector Nematodes Obligate parasite Trematodes

Insight A Closer Look at Helminths 1The following information about helminth infections supplements the material on helminths in Chapter 18 of the book. Nematodes (roundworms) Intestinal Nematodes Ascariasis: Ascaris lumbricoides is the large intestinal roundworm of humans, reaching a maximum length of approximately 35 cm (about 14 inches). Humans are the only hosts. Male and female worms live in the small intestine. Female worms release eggs, which pass in the feces. The eggs must reach moist, warm soil, where it takes about 2 weeks for the larvae within the eggs to become infective. Humans become infected by ingesting eggs, often by ingesting unwashed or inadequately washed vegetables. In the human body, the larva then matures into an adult worm. Adult worms can live in the body for about 1 year. Ascariasis is most common in

areas where human feces (“night soil”) is used to fertilize crops. Pinworm infection: Enterobius vermicularis (pinworm) infection is the most common helminth infection in the world. Humans are the only hosts. Male and female worms, which reach a maximum length of about 13 mm, live in the cecum (the first part of the colon). Female worms migrate down through the colon, emerge from the anus, and release eggs onto the perianal skin. The eggs are fully embryonated and infective within a few hours. Humans become infected by ingesting the eggs. In the human body, the larva then matures into an adult worm. Adult worms can live in the body for several months to several years. Hookworm infection: Necator americanus (the new world hookworm) lives in the small intestine, where it anchors itself to the intestinal mucosa by means of its well-developed mouth parts (called cutting plates). Female worms release eggs, which pass in the feces. The eggs must reach moist, shady, warm soil, where they hatch within 1 to 2 days. In the soil, it takes about 5 to 8 days for the immature larva to become a mature infective larva. The infective larvae remain viable in the soil for several weeks. Humans become infected by penetration of the skin (usually the soles of the feet) by the infective larvae. In the human body, the larva then matures into an adult worm. Adult worms can live in the body for 4 to 20 years. Humans are the only hosts. Tissue Nematode Dracunculiasis: The adult Dracunculus medinensis (guinea worm), which can be up to a meter in length, migrates in the deep connective tissues and subcutaneous tissues of the body. The female worm migrates to the ankle or foot (usually), where a blister forms. On contact with water, the blister bursts, and a portion of the worm protrudes through the opening. Larvae are discharged into the water. A larva is ingested by a small, freshwater crustacean called a Cyclops. Within the Cyclops, it takes about 8 days before the larva becomes infective for humans. Humans become infected by drinking water that contains the infected Cyclops. In the human body, the larva matures into an adult worm. In this life cycle, the human is the definitive host and the Cyclops is the intermediate host. Filarial Nematodes Filariasis: The adult worms (such as Brugia malayi and Wuchereria bancrofti) that cause filariasis live in lymph nodes, where they can block the flow of lymph (leading to elephantiasis). They reach lengths of up to 40 mm. Female worms release tiny, microscopic, prelarval stages called microfilariae, which get into the bloodstream. When a mosquito takes a blood meal, it ingests the microfilariae. Within the mosquito, the microfilariae mature into infective larvae. When the mosquito again takes a blood meal, it injects the infective larvae into the human. In the human body, a larva matures into an adult worm. In this life cycle, the human is the definitive host and the mosquito is the intermediate host. Onchocerciasis (river blindness): Adult Onchocerca volvulus worms live within fibrous tissue nodules. Female worms release tiny, microscopic, prelarval stages called microfilariae, which get into the skin, eyes, and bloodstream (occasionally). When a black fly (genus Simulium) takes a meal of tissue juices, it ingests the microfilariae. Within the black fly, the

microfilariae mature into infective larvae. When the black fly again takes a blood meal, it injects an infective larva into the human. In the human body, the larva matures into an adult worm. Adult worms may live for 15 years in the human body, producing microfilariae for about 10 years. In this life cycle, the human is the definitive host and the black fly is the intermediate host. Cestodes (tapeworms) (Note: tapeworms are hermaphroditic, meaning that each tapeworm contains both male and female reproductive organs; thus, it only takes one worm to produce fertile eggs.) Intestinal Cestodes Fish tapeworm infection: The adult Diphyllobothrium latum tapeworm lives in the human small intestine, where it can reach 10 m in length. Eggs released by the tapeworm are passed in the feces. An egg must reach fresh water, where a ciliated organism called a coracidium emerges from the egg. The coracidium is eaten by a Cyclops. Within the Cyclops, the coracidium matures into a procercoid larva. If the Cyclops is eaten by a fish, the procercoid larva matures into a plerocercoid larva in the muscle of the fish. If the raw or undercooked fish is then eaten by a human, the plerocercoid larva matures into an adult worm. Adult worms may live for up to 25 years in the human body. In this life cycle, the human is the definitive host, the Cyclops is the first intermediate host, and the fish is the second intermediate host. Dog tapeworm infection: The adult Dipylidium caninum tapeworm lives in the dog’s small intestine, where it can reach 70 cm in length. Egg packets released by the tapeworm are passed in the feces. If an egg is eaten by a larval flea, a cysticercoid larva develops within the flea. If the flea is then ingested by a dog (or a cat or a human), the larva matures into an adult worm. Adult worms usually live less than 1 year in the human body. In this life cycle, the dog is the usual definitive host and the flea is the intermediate host. Humans are considered accidental hosts. Rat tapeworm infection: In nature, the life cycle of Hymenolepis diminuta usually involves a rodent (the definitive host) and a beetle (the intermediate host). The adult Hymenolepis diminuta tapeworm lives in the rodent’s small intestine, where it can reach 60 cm in length. Eggs released by the tapeworm are passed in the feces. If an egg is eaten by a beetle, a cysticercoid larva develops within the beetle. If the beetle is then ingested by a rodent (or a human), the larva matures into an adult worm. Adult worms usually live less than 1 year in the human body. Humans are considered accidental hosts. Dwarf tapeworm infection: Adult Hymenolepis nana tapeworms live in the human small intestine, where they can reach 4 cm in length (a very small tapeworm; hence, the name “dwarf” tapeworm). Eggs released by the tapeworm are passed in the feces. If an egg is ingested by another human, a cysticercoid larva develops within the human. The cysticercoid larva then matures into an adult worm. Usually, humans are the only hosts; an intermediate host is not required. However, it is possible for an insect to ingest an egg, for the cysticercoid larva to develop within the insect, and then, for a human to ingest the insect. Beef tapeworm infection: The adult Taenia saginata tapeworm lives in the human small

intestine, where it can reach 8 m in length. Eggs released by the tapeworm are passed in the feces. The egg contains a six-hooked embryo, called an oncosphere. If an egg is ingested by a cow or bull, the oncosphere matures into a cysticercus larva in striated muscle of the animal. Humans become infected by ingestion of raw or undercooked beef containing a cysticercus larva. In the human body, the cysticercus larva matures into an adult worm. Adult worms can live for up to 25 years in the human body. In this life cycle, the human is the definitive host and the cow or bull is the intermediate host. Pork tapeworm infection: The adult Taenia solium tapeworm lives in the human small intestine, where it can reach 5 m in length. Eggs released by the tapeworm are passed in the feces. The egg contains a six-hooked embryo, called an oncosphere. If an egg is ingested by a pig, the embryo matures into a cysticercus larva in striated muscle of the animal. Humans become infected by ingestion of raw or undercooked pork containing a cysticercus larva. In the human body, the cysticercus larva matures into an adult worm. Adult worms can live for up to 25 years in the human body. In this life cycle, the human is the definitive host and the pig is the intermediate host. There is another medical problem associated with T. solium, however. If humans ingest the eggs, cysticercus larvae develop in various tissues within the body, e.g., the brain. Larvae in the brain can lead to seizures and other CNS problems. This disease—in which the larvae of T. solium are present in human tissues and organs—is known as cysticercosis. Tissue cestode In nature, the life cycle of Echinococcus granulosus usually involves a dog (the definitive host) and a sheep (the intermediate host). The adult Echinococcus granulosus tapeworm lives in the dog’s small intestine, where it can reach 6 mm in length (very small). Eggs released by the tapeworm are passed in the feces. Each egg contains an oncosphere. If an egg is eaten by a sheep, the oncosphere develops into a larva (a fluid-filled cyst called a hydatid cyst) somewhere in the internal organs of the sheep. The fluid within the hydatid cyst contains many daughter cysts and scolices (tapeworm heads). If the sheep’s viscera (internal organs), containing the hydatid cyst, are fed to a dog, each scolex can mature into an adult worm. Adult worms can live for up to 20 months in the dog’s intestine. If a human ingests an egg, a hydatid cyst develops somewhere in the human body. Humans are considered accidental hosts. Hydatid cysts must be very carefully removed from the human body by surgery. If the cyst is punctured during surgery, and the contents of the cyst spill out into a body cavity, each daughter cyst can mature into another hydatid cyst. Trematodes (flukes) Blood Flukes: The blood flukes—Schistosoma haematobium, Schistosoma mansoni, and Schistosoma japonicum—cause the disease known as schistosomiasis. Adult male and female worms, which are between 1 and 2 cm in length, live together in pairs within the human body in blood vessels that surround either the urinary bladder (in the case of S. haematobium) or the intestine (in the case of S. mansoni and S. japonicum). The eggs that are released by the female worms can penetrate through the blood vessel walls and migrate through tissues. Eggs of S. haematobium gain access to the lumen of the urinary bladder, and eggs of the other two species gain access to the lumen of the intestine. Eggs passed either in urine or feces must reach fresh

water. In the water, a ciliated organism called a miracidium emerges from the egg. The miracidium penetrates into a snail, where it matures into a mother sporocyst. The mother sporocyst produces daughter sporocysts, each of which matures into a cercaria. The mature cercariae are released from the snail into the water. Humans become infected by penetration of the skin by a cercaria. Within the human body, the cercaria matures into an adult worm. Adult worms may live throughout the lifetime of the infected human. In this life cycle, the human is the definitive host and the freshwater snail is the intermediate host.

Increase Your Knowledge 1.

Students seeking additional information about the major parasitic diseases of humans should consult one of the following books: Control of Communicable Diseases Manual, 18th ed., by D.L. Heymann. Washington, D.C., American Public Health Association, 2004. The Merck Manual of Medical Information, by R. Berkow. Whitehouse Station, Merck & Company, 1997.

2.

A veritable “treasure house” of parasitology information can be found at the CDC Division of Parasitic Diseases web site (www.dpd.cdc.gov/dpdx).

Critical Thinking 1.

Study the malarial parasite life cycle diagram in Chapter 18. Be prepared to discuss ways in which the life cycle could be interrupted, thus preventing malaria from occurring.

2.

Scientists have been attempting to develop a malaria vaccine for more than 20 years. Use the Internet to learn the latest status of a vaccine to prevent malaria. You might try using a search engine such as www.google.com or www.search.com.

3.

A friend of yours is being treated for trichomoniasis. She tells you that she’s pretty sure she contracted the disease from a toilet seat. Tactfully explain to her why that’s not very likely.

Case Studies

1.

A 20-year-old male soldier, who has just recently returned from duty in Panama, is admitted to a military hospital because of recurrent bouts of fever and shaking chills, headaches, muscle aches, and malaise. A physical examination reveals that the patient has splenomegaly (an enlarged spleen). A blood specimen is sent to the parasitology laboratory. A Giemsa-stained peripheral blood smear reveals the presence of intraerythrocytic parasites. Which one of the following pathogens do you suspect is causing this patient’s disease? a. b. c. d.

2.

A 19-year-old pregnant woman is visiting the clinic for a routine prenatal examination. Included in the advice that she is given are the following statements: (1) “Wash your hands thoroughly after handling raw meat.” (2) “Never eat raw or rare meat.” (3) “If you have a cat, wear latex gloves when changing the kitty liter, and wash your hands thoroughly afterward. Better yet, have someone else change the kitty litter.” (4) “Avoid contact with sand in sandboxes.” All of these precautions are necessary to avoid infection with which one of the following parasites? a. b. c. d.

3.

Balantidium coli Cryptosporidium parvum Toxoplasma gondii Trichomonas vaginalis

A 24-year-old man visits the clinic complaining of persistent diarrhea, crampy abdominal pain, and foul-smelling flatulence. He hasn’t had any fever or chills, but often feels nauseous after a meal. He states that the diarrhea has lasted for more than 2 weeks, and started about a week to 10 days after he returned from a backpacking trip high in the Colorado Rockies. When asked if he drank any stream or lake water on the trip, he replies “Sure, all the time! That water sure is pure!” Perhaps the water is not as pure as he thinks! The laboratory reports the presence of trophozoites and cysts of a flagellated protozoan in his stool specimens. Which one of the following parasites, all of which cause diarrheal illness, do you suspect? a. b. c. d.

4.

Ehrlichia Plasmodium Toxoplasma Trypanosoma cruzi

Balantidium coli Cryptosporidium parvum Entamoeba histolytica Giardia lamblia

A 26-year-old woman visits a public health clinic, concerned that she might have contracted some type of sexually transmitted disease. She states that she has experienced a greenish-yellow, frothy vaginal discharge and mild pain in her genital area. Physical examination reveals inflamed and swollen labia. Specimens of the discharge material are sent to the laboratory for a wet mount examination and culture and sensitivity. The wet

mount examination reveals the presence of actively moving flagellated protozoa. Which one of the following pathogens is causing her vaginitis? a. b. c. d. 5.

Chlamydia trachomatis Neisseria gonorrhoeae Treponema pallidum Trichomonas vaginalis

A 53-year-old man is admitted to the hospital with severe dysentery. Other symptoms that he reports include nausea, vomiting, anorexia, headache, insomnia, muscle weakness, and weight loss. The patient states that he is a farmer, and that his illness has made it impossible for him to care for his crops and animals. He also mentions that most of his pigs are experiencing a diarrheal illness. Examination of a trichrome-stained stool specimen reveals the presence of trophozoites and cysts of a ciliated protozoan. Which one of the following parasites, all of which cause diarrheal illness, do you suspect? a. b. c. d.

Balantidium coli Cryptosporidium parvum Entamoeba histolytica Giardia lamblia

Answers to the Chapter 18 Self-Assessment Exercises in the Text 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

C A D D D B C D C D

Answers to the Chapter 18 Case Studies 1. 2. 3. 4.

B C D D

5.

A

Additional Chapter 18 Self-Assessment Exercises (Note: Don’t peek at the answers before you attempt to solve these self-assessment exercises.) Matching Questions A. B. C. D.

Ciliophora Flagellates Amoebozoa Sporozoa

_____

1. African trypanosomiasis, American trypanosomiasis, giardiasis, and trichomoniasis are caused by protozoa in the category of protozoa known as _______________.

_____ 2.

Protozoa in the category of protozoa known as _______________ move by means of pseudopodia.

_____ 3.

Cryptosporidiosis, malaria, and toxoplasmosis are caused by protozoa in the category of protozoa known as _______________.

_____ 4.

In the category of protozoa known as _______________, only one protozoan causes human disease.

_____ 5.

A disease known as PAM is caused by a protozoan in the category of protozoa known as _______________.

A. B. C. D. E.

oocyst ookinete schizont trophozoite zygote

_____

6. In the malarial parasite’s life cycle, a/an _______________ contains numerous merozoites.

_____ 7.

In the malarial parasite’s life cycle, sporozoites are produced within a/an _______________.

_____ 8.

In the malarial parasite’s life cycle, a/an _______________ is a motile organism within the mosquito’s stomach.

_____ 9.

In the malarial parasite’s life cycle, a/an _______________ may mature to become a female gametocyte, a male gametocyte, or a schizont.

_____ 10.

In the malarial parasite’s life cycle, the _______________ is located on the outer wall of the mosquito’s stomach.

True/False Questions _____ 1.

In a parasite’s life cycle, the definitive host harbors the adult or sexual stage of the parasite or the sexual phase of the life cycle.

_____ 2.

The amebae that cause amebic keratitis and PAM are good examples of obligate parasites.

_____ 3.

In the malarial parasite’s life cycle, humans serve as definitive hosts.

_____ 4.

When causing infections, parasitic protozoa and helminths are endoparasites.

_____ 5.

Scabies is caused by an insect.

_____ 6.

In a parasite’s life cycle, it is possible for a particular arthropod to serve as both a host and a biologic vector.

_____ 7.

It is possible to acquire cryptosporidiosis, cyclosporiasis, and toxoplasmosis by ingesting oocysts.

_____ 8.

Trichomonas vaginalis cannot survive very long outside of the human body because it has no cyst form.

_____ 9.

Toxoplasmosis could be acquired by eating raw or rare meat.

_____ 10.

African trypanosomiasis and American trypanosomiasis are transmitted by the same type of arthropod vector.

Answers to the Additional Chapter 18 SelfAssessment Exercises Matching Questions 1. 2. 3. 4. 5. 6. 7.

B C D A C C A

8. 9. 10.

B D A

True/False Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

True False (the amebae that cause these diseases are good examples of facultative parasites) False (in the malaria parasite’s life cycle, humans serve as intermediate hosts and mosquitoes serve as definitive hosts) True False (scabies is caused by an arachnid—specifically, a mite) True True True True False (African trypanosomiasis is transmitted by a tsetse fly, whereas American trypanosomiasis is transmitted by a reduviid bug)