Introduction To Microbiology

INTRODUCTION TO MICROBIOLOGY HISTORY AND TERMINOLOGY            



Bio-life Ology- study of Micro- to small to be seen with naked eye Microbe- a very small living thing which can be only seen by microscope Microorganism- microbe an organism that is microscopic Microbiology- study of microbe Robert Hooke – observed the cell using a microscoe in 1665 Anton van Leeuwenhoek’s- discovered a microorganism in 1684 using a microscope of his own design. He is also known as the “Father of microbiology”. Edward Jenner 1796 discovered cowpox virus to treat small pox. Louis Pasteur introduced fermentation, pasteurization, vaccination and immunity. Joseph Lister 1800, developed antiseptic surgery which included heatsterilization of instruments and application of phenols to wounds and dressings Robert Koch 1876, provided a critical link between microbes and disease when he used a series of postulates to uncover the cause of anthrax. Koch's postulates are still in use today in order to prove the cause of an infectious disease. Further contributions of Koch • isolated the bacteria that cause cholera and tuberculosis • developed tuberculin, now used in a skin test for TB (originally intended for use as a vaccine against TB) • developed acid-fast staining • identified bacterial endospores • with colleagues, the first to grow cultures on solid media • received noble prize for medicine 1905.

 Alexander Fleming 1929 discovered penicillium mold inhibited growth of Staphylococci growing on a petri plate. Penicillin became widely available and known as the "wonder-drug".

Reva Subramaniam SEGI KL

Terminology Bacteriology Virology Mycology Parasitology Microbial pathogenesis Immunology Epidemiology Epidemic

Endemic Immunology Epidemiology Aerobic Anaerobic Antibiotics Bacteriacidal Bacteriastatic Carriers Contamination Contagious diseases Diseases Epidemiology Host Immunity Immunization

Study of prokaryotic microbes (bacteria) Study of acellular, intracellular parasites (viruses) Study of fungi including yeasts, molds and mushrooms Study of parasites. Typically this field has focused on protozoa and helminths (worms) How microbes produce disease An understanding of the body's defense system against infection and disease Become a 'disease detective' and understand the factors that contribute to disease origins and transmission. The unusual occurrence in a community of disease, specific health related behavior, or other health related events clearly in excess of expected occurrence” It refers to the constant presence of a disease or infectious agent within a given geographic area or population group. It is the usual or expected frequency of disease within a population. An understanding of the body's defense system against infection and disease Become a 'disease detective' and understand the factors that contribute to disease origins and transmission. Requires oxygen to survive Do not require oxygen to survive Are substances produced by microorganism and is effective in killing or inhibiting the growth of other organisms. Capable of killing bacteria Capable of inhibiting bacterial growth without killing An infected person or animal that harbors a specific infectious agent in the absence of discernible (visible) clinical disease and serves as a potential source of infection to others. The presence of an infectious agent on a body surface, on or in clothes, beddings, toys, surgical instruments or dressings, or other articles or substances including water and food A contagious disease is the one that is transmitted through contact. Examples include scabies, trachoma, STD and leprosy. An impairment of health or a condition of abnormal functioning. Is the study of the distribution and determination of diseases in a population Someone who gets the infection/exposed to the pathogen or infection. (has the symptoms) The ability for an organism to resist an infection Induction of specific immunity by injecting antigens, antibodies Reva Subramaniam SEGI KL

Infection Infectious agent Infectious diseases Infestation Inflammation Normal Flora

Nosocomial infection

Opportunistic infections Commensal flora Parasite Pathogen Pathogenicity Reservoir Spores Susceptible host Virulence Incubation period Latent period

Vaccine Vaccination Vectors Virulence Zoonosis

Infection is the entry and development or multiplication of an infectious agent in the body of man or animals. Microorganism that causes diseases and pathogen Colonies of the body and causes the diseases Colonization of the body by parasites. Characteristic reaction to foreign particles and noxious stimuli, resulting in redness, swelling heat and pain. Organism that resides on the surface and deep layers of the skin, in saliva and oral mucosa, GIT. Nosocomial (hospital acquired) infection is an infection originating in a patient while in a hospital or another health care facility. It has to be a new disorder unrelated to the patient’s primary condition. Examples include infection of surgical wounds, hepatitis B and urinary tract infections. This is infection by organisms that take the opportunity provided by a defect in host defense (e.g. immunity) to infect the host and thus cause disease. For example, opportunistic infections are very common in AIDS. Organisms include Herpes simplex, cytomegalovirus, Non-pathogenic' commensal organism. Will not cause harm. Is an organism that lives on or in another organism and getting benefits but provide nothing in return. Is a microorganism that causes diseases Is the ability to cause disease Place where microorganism (infectious agents) thrive and reproduce General term for resistant resting structures formed by many prokaryotes and fungi A person who cannot resist an infection. Is the degree of pathogenicity; the disease evoking power of a micro-organism in a given host. Time from exposure to development of disease. In other words, the time interval between invasion by an infectious agent and the appearance of the first sign or symptom of the disease in question. The period between exposure and the onset of infectiousness (this may be shorter or longer than the incubation period). Material used to induce specific protective immunity to a pthogen Inoculation of host with inactive, killed or weakened pathogen products to stimulate protective immunity Is a living creature that can transmit infection from one to another The power of the pathogens to cause severe disease Is an animal diseases that can spread to humans Reva Subramaniam SEGI KL

Types of microorganism  Microbiology is a broad term that includes bacteriology, virology, mycology, phycology, parasitology, and other branches of biology.  There are five kingdoms which are by Robert H. Whittaker (1969).  (Five-Kingdom System) • • • • •

Animals/ animalia- eukaryotic, multicellular Plants/ Plantae-eukaryotic, multicellular Fungi -eukaryotic, generally multicellular Protista- eukaryotic, generally unicellular like algae, protozoa Prokaryotic – unicellular

 Microorganisms belong to the group Protista.  This kingdom has broadly divided into viruses, prokaryotic and eukaryotic.  Note that viruses, though not always strictly classed as living organisms. It does not have the cellular structure but exhibits the properties of life.  All cellular organisms are divided into prokaryotic and eukaryotic.  The prokaryotic are simpler and smaller, does not posses a distinct nucleus.  Eukaryotic cells are larger, more complex possessing a distinct nucleus and subcellular organelles such as plastids and mitochondria cells. Eukaryotic and prokaryotic cell. Prokaryotic Cells Prokaryotes are evolutionarily ancient They were here first and for billions of years were the only form of life. And even with the evolution of more complex eukaryotic cells, prokaryotes are supremely successful.  All bacteria are prokaryotic organisms.    

 Eukaryotic Cells  Eukaryotic cells are more complex, evolving from a prokaryote-like predecessor.  Most of the living things that we are typically familiar with are composed of eukaryotic cells; animals, plants, fungi and protists.  Eukaryotic organisms can either be single-celled or multi-celled.

Reva Subramaniam SEGI KL

Gram Stain  Gram staining reaction is one of the first tests applied in studying bacteria.  The reaction is either positive or negative, (gram + or gram -).  Gram + the wall are made up of thick layer of peptidoglycan enclosing the plasma membrane.  Gram - the peptidoglycan layer is thin and has outer membrane enclosing the cell.  This outer membrane is made up of lipopolysaccarides and lipoproteins.  Gram positive

Reva Subramaniam SEGI KL

 Gram negative

   

High resistance spores are produced in some bacterial genera. They are resistant to heat and certain chemicals such as detergents. They are also resistant to desiccation and radiation. They are called as endospore as the form inside the cell wall.

Bacteria Shape, size and arrangement of Bacteria     

Spheroidal (coccus) Monococcus (Single cells) Diplococcus (Occurs in pairs) Bacilli/bacillus (rod shapped) Spirillar (sphirochaete) long and slender cells twisted or helical shapes Reva Subramaniam SEGI KL

 Short bacilli are called as coccobacilli.

 Some bacteria consist surface adherents and appendages such as capsule, slim, flagella and pili. Techniques to study the morphology  Microscopy and staining techniques are basic tolls for visualizing and study bacteria.  Types of microscope: light microscope, phase contrast microscope, fluorescence microscopy, dark field microscopy and electron microscopy.  Most common technique of staining are Gram staining, Ziehl-Neelsen staining, Romanowsky staining, Sudan staining. Factors influencing growth and reproduction of organism

Reva Subramaniam SEGI KL

 For optimal growth bacteria require proper nutrients, oxygen, pH and temperature.  Oxygen  Obligate anaerobes: will die when exposed to atmospheric levels of oxygen.  Facultative anaerobes: can use oxygen when it is present.  Obligatory aerobes: cannot grow unless oxygen is present  Temperature  Optimal growth temperature categories:  psychrophiles : optimum growth temperature 15°C to 20°C.  mesophiles: intermediate-temperature  thermophiles: growth temperature is warmer including the temperature of water boiling at sea level  pH  The growth of the majority of bacteria is limited to a pH range of approximately 2  pH range classifications include: • acidophile (pH < 5.4) • neutrophile (pH 5.4 - 8.5) • alkaliphile (pH 7.0 - 11.5) Virus  Viruses may be defined as acellular organisms whose genomes consist of nucleic acid, and which replicates inside host cells.  Uses host metabolic machinery and ribosomes to form a pool of components which assemble into particles called VIRIONS, which serve to protect the genome and to transfer it to other cells.  Properties of viruses  Consist of either RNA or DNA but never both  Obligate intracellular parasites  Divide by replication  Mostly limited host range  An outer shell, the capsid, made of protein.  The capsid is responsible for  protecting the contents of the core  establishing what kind of cell the virion can attach to the infecting cell  Life cycle  The virion attaches to the surface of the host cell and penetrates inside the host cell.  Once inside the cell, the virions are uncoated.  Viral genes begin translation, transcription and genome expression to produce specific protein.  The synthesis of proteins needed for  replication of the genome Reva Subramaniam SEGI KL

 synthesis of new proteins to make new capsids and cores.  Then followed by virion assembly in cytoplasm and released from the host cell and start their life cycle.  Duration of viral replication is around 3 to 30 hours.

 Structure of viruses helical, isohedral/polyhedral, enveloped and complex.

Reva Subramaniam SEGI KL

Helical

Enveloped

Reva Subramaniam SEGI KL

Icosahedral Complex

Mycology Study of fungus. Myco means fungus/fungi. Fungus is a general term encompassing such as molds and yeast. Yeast are oval spherical or elongated cells which reproduce by budding. Molds are characterized by tubular branching which consists of a hypa. Hypa are divided in may fungi by cross walls known as “septa” into multicellular septa. Intermingled hypa forms mycelium.  Most fungus or molds are dimorphic.  It means they are molds in their normal saprobic growth but are yeast in a tissue or incubated/enriched in enriched media.  Fungi do not produce their own food by means of photosynthesis.      

Reva Subramaniam SEGI KL

 Reproduce by means of spores (bottom right in the picture).  Fungi are a kingdom of organisms which share the following characteristics:  Their main body is in the form of thin (one cell thick) strands called mycelium (bottom left in the picture).  They cannot manufacture their own food through photosynthesis; rather, the mycelium secretes enzymes which digest part of their surroundings (a log, for example) and this is then absorbed by the mycelium.  Their cell walls are made mostly of chitin and similar compounds, not cellulose.  They reproduce by means of spores.  The reproduce by both sexual and asexual depending on the species and condition.

Reva Subramaniam SEGI KL

Parasite  Study of parasites from four large phyla in the animal kingdom, namely, o Protozoa (of the kingdom Protista) o Platyhelminthes (flatworms) o Nematodes (roundworms), o Arthropoda (arachnids, crustaceans, insects, etc.)  The worms and arthropods are multicellular organisms and often large enough to be seen with the naked eye.  Parasites, that live outside the body of a host are called Ectoparasites,  Ecotoparasaite which include fleas, mites, lice, ticks and leeches.  Endoparasites live inside the body of a host, and include amoebas, worms, and flukes  Human are infected to parasites through: o Via infected food or water (sources of roundworm, amoebas, and giardia). o Via such vectors as a mosquito (carriers of dog heartworm, filaria, and malaria), fleas (carriers of dog tapeworm), houseflies (carriers of amebic cysts), and sexual contact with partners transmitting trichomonas, giardia, and amoebas, to name a few. o Via the nose and skin. Pinworm eggs and Toxoplasma gondii can be inhaled from contaminated dust; hookworms, schistosomes, and strongyloides can penetrate exposed skin, especially bare feet.  Symptoms of parasite infections are constipation, diarrhea, gas and bloating, irritable bowel syndrome, joint and muscle aches and pains, anaemia, allergy, skin conditions, granulomas, sleep disturbances, chronic fatigue, immunie dysfunction.

Reva Subramaniam SEGI KL

Reva Subramaniam SEGI KL

Action of microorganisms in causing disease  A pathogen meets its requirements for life within the human body.  Depending on the organisms, it meets its own needs and also causes disease by entering human cells and using them to reproduce.  Producing substances that are poisonous to the body such as toxins.  Entering the body as a foreign entity, reproducing and causing disease or response (inflammatory) within the body .

Chain of infection  When disease occurs the infection cycle has been successfully completed.  If a microorganism is pathogenic (capable of causing disease) all elements of the chain of infection must be present in order for disease or infection to occur.  Elements of infection chain A.Infective agent: pathogen such as a bacteria or virus B.Reservoir 1.Place where causative agent can live 2.Common reservoirs include human body, animals, environment, and fomites or objects contaminated with infectious material that contains the pathogens C.Portal of exit 3.Way for causative agent to escape from the reservoir 4.Pathogens can leave the body through urine, feces, saliva, blood, tears, mucous discharge, sexual secretions, and draining wounds D.Means of transmission 5.Pathogen must be transmitted to another reservoir or host where it can live 6.Can be transmitted in different ways a.Direct Contact 1.Person-to-person spread by physical contact 2.Contact with the body secretions containing pathogen b.Indirect contact 3.Pathogen is transmitted from contaminated substances (i.e. food, air, soil, insects, feces, clothing, instruments, and equipment) 4.Touching contaminated equipment 5.Breathing in droplets carrying airborne pathogens 6.Receiving the bite of an insect carrying pathogen E.Portal of entry 7.Way to enter a new reservoir or host 8.Means of entry c.Breaks in the skin or mucous membrane d.Respiratory tract e.Digestive tract f.Genitourinary tract

Reva Subramaniam SEGI KL

g.Circulatory system F.Susceptible host 9.Individual who can contract the disease 10.Humans may fight off causative agents and do not contract disease if h.Defense mechanisms of body are intact i.Immune system functioning 11.Human becomes susceptible host in some instances j.Large numbers of the pathogen invade the body k.Body defenses are weak l.  The cycle of infection can be broken at any link of the chain G.The infectious agent can be neutralized or destroyed by treatment H.The reservoir host must maintain personal hygiene I.The portal of exit is closed by the use of proper attire (gowns, gloves, other clothing), control of body secretions, and proper handwashing J.The route of transmission is minimized through proper handwashing, disinfection and sterilization and proper disposal of contaminated materials. K.The portal of entry is blocked by asepsis, disinfection, and sterilization procedures. L.Host susceptibility is broken when the health and wellness of an individual is maintained. Sites of virus entry:

Immunity

Reva Subramaniam SEGI KL

A. First line of defense 1. Body parts and mechanisms that act to keep microorganisms out of body tissues and bloodstream. Interrupts the infection chain at the port of entry link 2. Include a. skin b. mucus membranes c. cilia d. tears e. coughing or sneezing f. pH of body areas B. Second line of defense 1. Microorganisms gain entrance to the body a. Body forms White Blood Cells that kill the invader by phagocytosis. b. Interrupts the infection chain at the susceptible host link C. Third line of defense – Immune response 1. Organism multiplies rapidly and cannot be destroyed fast enough by phagocytosis 2. A specialized white blood cell – lymphocyte forms antibodies a. antibodies are tiny substances that attach to specific pathogens and inactivates of destroys them. b. Another form of lymphocyte acts as a memory cell, remembering the pathogen over time, resisting further future infection. c. This process of long-term protection is called immunity. d. Antibodies are specific to disease. e. Immunity does not prevent pathogens from entering the body, it prevents Pathogens from doing harm. 3. Interrupts the infection chain at the susceptible host link. D. Vaccination 1. A small dose of killed or weakened microorganisms or similar substance that stimulates the third line of defense (immune response). 2. Antibodies are produced. 3. In time every encounter with the microorganisms will cause memory cells in the body to quickly produce antibodies. This is active immunity.

Reva Subramaniam SEGI KL

4. Antibodies can also be injected for some diseases, which gives immediate protection. This is passive immunity. 5. Immunity can be life-long or short term, depending on the disease.

Reva Subramaniam SEGI KL