All Till Parasite

BACTERIAL MORPHOLOGY  Study of structure, appearance.  Colony morphology - growth characteristics  Microscopic morphology - cell characteristics

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COLONY MORPHOLOGY A. Colony  1.Clump of organisms growing on the surface of solid medium.  2.Descendants of a single cell  3.Vary in appearance - characteristic of a genus 

B. Characteristics observed :  1.Shape, size  2.Margin  3.Elevation  4.Surface texture  5.Light transmitting property (color)  6.Consistency Tayyar M

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MICROSCOPIC MORPHOLOGY A. Size B. Shape C. Arrangement D. Cell Structure 1.Basic cell structure 2.Special cell structures Tayyar M

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SIZE A. Measured in micrometers (µm) 1000 µm = 1mm B. Ave. Range : Diameter = 0.1 µm to 2 µm Length = 0.1 µm to 8 µm Tayyar M

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4.CELL SHAPE, ARRANGEMENT  A. Three groups according to shape. In addition, variation of arrangement is characteristic of a genus. 1. Cocci (us)  a. Spherical, oval, egg shaped, bean shaped  b. Size and shape varies.  c. Singles, pairs, irregular clusters, tetrads, cubical packets of 8. 2.Bacilli (us)  a. Elongated, cylindrical, rod-like  b. Vary in diameter, length, shape of ends, arrangement. Tayyar M 6

3. Spirals  a. Curved rods  b. Vary in diameter, length, number of curves, tightness of curves, flexibility.  c. Three groups of spirals: 1. Vibrios - single curve, comma shaped 2. Spirillum - rigid, two or more curves, cork screw shape 3. Spirochetes - flexible, two or Tayyar M

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Sterilization And Disinfection

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Ignaz Semmelweis 

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1846: Physician at Vienna General Hospital Interested in ‘childbed fever’ (often fatal uterine infection that followed childbirth) in obstetrical clinic there. Two clinics, one staffed by physicians & medical students: mortality rate: 13% other staffed by midwives: mortality rate: 2%  Physicians/students were performing Tayyar M 9 autopsies, then after either not washing 

Ignaz Semmelweis 

For the physician/medical student ward, Semmelweis enforced a policy of handwashing with chlorinated lime; dropped mortality rate to 2%.

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Despite success, his policies were rejected because they went against current scientific beliefs (germ theory not developed yet); ultimately he was fired by Vienna General. Tayyar M

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Sterilization and disinfection 

Goal: reduce or completely eliminate the presence of potentially harmful life forms Bacteria  Virus  Fungi  Parasite  Bacterial spores (in general the hardest to kill; can survive even boiling water!) 

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IMPORTANT TERMS  Sterile/sterilization 

Absence of any life form/process of rendering something sterile (must kill spores)

 Disinfection  Agent that frees from infection – kills

bacteria/inactivates virus, but does not necessarily kill bacterial spores Tayyar M

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IMPORTANT TERMS 

Antisepsis 

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it is the destruction or inhibition of microorganisms in living tissue thereby limiting or preventing the harmful effect of infection. Term is usually used in reference to body surface or wound

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Sterilants these are chemical which under controlled conditions can kill sporing bacteria

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“-cide“ 

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Kills microbes/inactivates viruses

“-static“

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Terms 

Bacteriostatic  

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Bacteriocidal 

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Inhibit the growth of bacteria May be still viable or metabolically active Kill bacteria

Fungicidal; Fungistatic Viricidal; Viristatic Tayyar M

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Sterilization 

Sterilization agent are divided into: Chemical.  Physical agents. 

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Physical agent are usually preferred over chemical agent. Heat is the most important and widely used in sterilization. Heat are divided into : Moist Heat  Dry Heat 

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Moist Heat Moist Heat: means heating in the presnce of water and can be employed in the following ways:

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• • •

Temperature below 100○C Temperature around 100○C Temperature above 100○C

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Temperature Below 100 C ○

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Pasteurization is a good example of this technique. Two methods are used: Holder method: At 60 ºC  Flash modified methods at 71.1 for 15 seconds. 

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Temperature around 100 C ○

Tyndallization: is an example methodology in which steaming of the object is done for 30 minutes on each of three consecutive days.  The principle is that the spore which survive the heating process would germinate before the next thermal exposure and would then be killed. 

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Many hospital use hot water boilers. The maximum temperature is 100○C, and therefore will not kill spore. Boiled water could be efficient if it used properly:  Heat for 20 minutes  Exchange water regularly  Instruments from one patient not mixed with instruments from other patient. Tayyar M

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Temperature above 100 C ○

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Dry saturated steam act as am excellent agent for sterilization. Autoclave has been designed on the principles of moist heat. The moist heat (autoclave) used to sterilized surgical dressings, bacteriological material and decontamination of laboratory and hospital reusable goods. Tayyar M

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Dry Heat       

This is less efficient process as compared to moist heat, and bacterial spore are most resistant to it. Spore may require temperature of 140 0C for hours to get killed. Example of dry heat is flaming in microbiology laboratory. A good example of dry heat is hot oven. In dry heat it is essential that air circulate between the objects to be sterilized. Microbial inactivation by dry heat is due to oxidation process. Dry heat used to sterilize glassware, glass syringe, oils and oily injection as well as metal instruments. Tayyar M

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Time Temperature Relationship in Heat Sterilization

Process Dry Heat

Moist heat Autoclave

Temperature 170 ° C 160 °C

Time 1 hours 2 hours

121°C 121 ° C 126 ° C 134 ° C

16 hours 15 minutes 10 minutes 3 minutes

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2- Radiation two type of Radiation: A- Ultraviolet radiation B- Ionizing Radiation

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A-Ultraviolet Radiation: Sterilization 

radiation with wavelength of 240-280 nm have been found to be most efficient in sterilizing.  Bacterial spore are more resistant to UV rays.  Destroys DNA, cause noncoding lesions in DNA and bacterial death.  Sun has bactericidal activity due to the presence of UV light.  E.g. drying clothes in sunlight is a simple application of UV sterilization.

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A-Ultraviolet Radiation:

Sterilization 

This technique used for: sterilizing drinking water  Obtaining pyrogen free water  Air disinfection (especially in laboratory, hospital, operation theatre. 

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B- Ionizing radiation Includs: 3. X rays 4. Gamma rays 5. Beta rays (wavelengths from 0.1 to 40 nm)  

Kills microbes by damaging the DNA It is used to sterilize single used disposable medical items.

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3- Filtration  Filters have been used long time ago to purify water and sewage.  Application of Filtration: Sterilization of thermolabile substance and ophthalmic solution.  Sterility testing of pharmaceutical products.  Clarification of water supplies  Microbiological evaluation of water purity  Viable counting procedures  Determination of viral particle size  Air sterilization Tayyar M 

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Types of Filter 

Various type of filter available:  Unglazed ceramic filters (chamberland and doulton filters).  Asbestos filter (Seitz, Carlson and sterimat filters)  Sintered glass filters  Membrane filters

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Membrane filters are widely used nowadays. They are made up of cellulose ester. Membrane filter pore size vary form 0.05-12 μm. The sterilization pore size is in range of 0.2-0.22 μm.

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Sterilization 

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5- Chemical Agents: chemical disinfectant are highly toxic for all types of cells. They classified into different group according to their activity or their site of action. Table 3.3 and 3.4

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A- Chlorine and Iodine:   

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Most useful disinfectant Iodine as skin disinfectant There function is bactericidal and they are active against spore forming bacteria Different surface acting agent of iodine such as iodophores used for sterilization of diary products. Chlorine, inorganic chloramines, organic chloramines and hypochlorite are a good disinfectant. Tayyar M

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B- Hydrogen peroxide (H2O2): In 3% concentration is harmless, but very weak disinfectant.  Use for cleansing of the wound. 

C- Potassium Permanganate: 

Oxidizing agent use to treat urethritis

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D- Formaldehyde:    

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Act on protein Use as gas (37% solution in formalin) Kill bacteria and spore forming bacteria. Use to sterilize instruments and material that can be damage by heating. In this case the instrument are dipped into 2% glutaraldehyde solution for 15-20 minutes. This time efficient to kill both vegetative and spore forming bacteria.

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E- Ethylene Oxide   

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Alkylating agent Use in gaseous sterilization Active against all kind of bacteria and their spores. Use to sterilize heat labile substances and material (heart and lung machine) Useful for delicate instruments, optics Use for sterilization of powders and space craft

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Cystoscope and endoscope can be sterilized by glutaraldehyde. Filtration used to sterilize heat sensitive substances such as antibiotics, serum and vaccine. Ultraviolet radiation use to sterilize small and closed champers. For large rooms and theatre fumigation with formalin is the most effective method. Tayyar M

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Antimicrobials therapy

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Origins of antimicrobial therapy in folk medicine Cinchona tree used to treat malaria (quinine) Moldy bread applied to wounds (?penicillin) Foxglove plant for heart disease (digitalis) Willow bark for pain (aspirin-like compound)

Start of modern era of antimicrobial therapy is 1930’s  Sulfa drugs (sulfonamides) in 1935 could cure deadly systemic bacterial infections: a development of significance Tayyar M 36

Antimicrobial Therapy 

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A chemotherapeutic agent is a compound that can inhibit the proliferation of an infecting organism at drug concentration that are tolerated by host. Some of these agents are bacteriostatic (have reversible action) other are bactericidal ( have irreversible action). Antibiotics is a chemical substance, produced by various micro-organism which in small concentration capable of inhibiting the growth of other micro-organism. Tayyar M

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Desirable properties of Antibiotics: 1.

Selective toxicity: 

2. 3. 4. 5. 6. 7.

Drug must harm microbes without causing significant damage to the host

Bactericidal rather than bacteriostatic Effective against wide range of microorganism Should not be allergic Should remain active in various body fluids Stable and preferably water soluble Desired levels in body should be achieved rapidly and maintained fro adequate period. Tayyar M

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Inhibit cell Wall Formation

Damage Cell Membrane

Penicillin

Bacitracin

Polymyxin

Vancomcin

Cycloserine

Amphotericin B

Ristocetin

Cephalosporin

Nystatin

Impair DNA Function Nalidixic Acid

Bacterial cell

Novobiocin

Grisofulvin

Mitomycin

Nitrofurans

4-Quinolon

Protein synthesis inhibitor Actinomycin

Rifampicin

Streptomycin Gentamicin

Tetracycline Erythromycin Metabolites Antagonists 1-Sulfonamides

Chloramphenicol Fucidin

2-Sulfones 3-P-aminocalisalic acid 4-Isoniazid Tayyar M

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Combination therapy 

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More than one drug given at the same time only in the cases where there is a necessity of achieving high bactericidal activity. For example if patient infected with endocarditis to prevent emergence of drug resistance bacteria e.g. mycobacterium tuberculosis. Tayyar M

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Antifungal Agent 

Four antifungal are commonly used belong to tow different groups:

2.

Polyenes: e.g Nystatin Amphotericin B.

– –

3.

Imidazole: e.g. 1. 2.

Miconazole Fluconazole (ketoconzole) Tayyar M

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Antiviral Agents 

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Few antiviral agents are available these days. Idoxuridine and acyclovir are commonly prescribed for herpetic infections of the oral and perioral region.

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Drug resistance 

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3.

 5.

Bacteria species developed resistance to many antibiotics and thus minimize the activity of these drugs. Drug resistance is due to several reason includes: Chromosomal resistance: due to Spontaneous (random) mutation; when drug is given to the patients the resistant strain persist and multiply. mutation occur at rate of 1in 105 to 1010 Extra chromosomal resistance: this resistance is mediated by plasmid. Tayyar M

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Extra chromosomal resistance      

Plasmid mediated drug resistance also called as infectious drug resistance. This kind of resistance transfer form one bacteria to another by conjugation or transduction. Transmissible plasmid has two major parts: R determinant which encode resistance. RTF (resistance transfer factor) which mobiles the plasmid to another bacteria. Because of this phenomena many sensitive bacteria such as Salmonella typhi, have now become resistance to commonly used antibiotics. Tayyar M

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Chapter 5 Host-parasite Relationship

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HOST PARASITE INTERACTIONS   

WHAT IS A PARASITE? MUTUALISM vs. PARASITISM A parasite may be defined as “ An entity that lives on or within another organism (The Host) - Thus living at the expense of others” Tayyar M

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Host-Parasite Relationships 

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Parasitic organism  a symbiont that harms or lives at the expense of its host Parasitism  Is a life style that has be adopted by many types of living things. Parasite  All organism living in or on the bodies of other organisms and drawing their substance from them considered to be parasite. Tayyar M

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Symbiotic relation ship 

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Symbiotic is a general term used to described any relationship in which two organisms live together in an intimate association. Three different type of symbiotic relationship in nature: – Mutualistic: if both organism benefit – Commensal: if the symbiont benefit and the host is not harmed e.g. intestinal bacteria. – Parasitic: if the symbiont benefits and the host is harmed. Tayyar M

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The Dynamics of Symbiotic Relationships

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Parasitic organism 

Parasites include: 1. 2. 3. 4. 5.

Viruses Protozoa Worms Arthropods Fungi

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Parasitic Relationship 

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The bacteria, fungi, and viruses that are parasitic are usually described as infecting their host. Pathogens: referred to microbe that are capable of causing infection to a host. Contaminated host is used to described the host when it associated with a microorganism.

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Parasitism and disease 

infected host used to described a host when it invaded by a pathogen or a parasite.

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Infection 

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Infectious disease 

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growth and multiplication of parasite on or within host Part or all of the host body cannot perform normal functions due to the organism or its metabolic products

Pathogenicity 

ability of parasite to cause disease Tayyar M

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Dynamic of infection 

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Host-parasite interaction is a dynamic equilibrium. When host resistance decrease or the parasitic virulence increase this can result in development of the disease. There are various sources from which infection can be acquired by human. The vehicles can be food, water, air. Tayyar M

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Pathogenic Properties of Microbes 

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Bacteria are divided into three group when it is isolated from human: Pathogenic bacteria: agents of disease Opportunistic pathogenic bacteria: isolated from patient whose defense mechanism have been compromised. Non-pathogens: rarely or never cause disease. Tayyar M

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Microbial Pathogenicity attributes

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Microbes produce pathogenicity with help of a wide variety of attributes as single or group such as: Factor mediated adhesion

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Antiphagocytosis agent

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Capsule  M protein  Cytotoxin 

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Microbial Pathogenicity attributes 

Survival within phagocytes    

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Interference with oxidative burst Prevention of fusion and degranulation Resistance to lysosomal enzyme Escape from phagosomes

Siderphore and iron acquisition Enzyme and toxin     

Enzymes Endotoxin Exotoxin Genetic mechanism Tayyar M R factor

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Microbial toxin Toxin are the major toxic factor of microbes.  Exotoxin are the most potent poisons known.  Exotoxin are composed of two subunit:  

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Fragment B: the carrier which binds to the host cell receptors. Fragment A the fragment that enter the cell and cause damage to it.

Many organism produce exotoxin which have activity in the gastrointestinal tract and called enterotoxin. Tayyar M

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Microbial Toxin 

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B- Endotoxin: is a component of Gram negative (G-ve) bacterial cell wall. Endotoxin composed of lipopolysaccharide with outer membrane protein. Most of the toxic effects is due to lipid A which is part of the lipopolysaccharide.

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Generalized Infection 

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Bacteraemia, septicaemia and pyaemia are some of the important manifestations which are mediated through blood. Bacteraemia: defined as the circulation of bacteria in blood it may be A. B.

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Bacteraemia A-

Transient bacteraemia is a frequent event which occurs even in healthy individuals while: 1. 2. 3.

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Chewing Brushing of teeth. Staining of passing stool to any injury in the abdomen area.

The circulating bacteria in this case are usually Commensals of oral or intestinal tract and quickly killed by phagocytes thus preventing initiation of any Tayyar M 62 infection.

Bacteraemia B - Long duration bacteraemia occurs with pathogenic organisms such as Salmonella typhi, Brucella and is essential for the initiation of the disease.

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Septicaemia 

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When the bacteria circulate and multiply in the blood and causing a fever. This could be due to: Endotoxin producing bacteria e.g. E. coli, Salmonella, Shigella.  Exotoxin producing bacteria, e.g. Corynebacterium diphtheriae, Clostridium tetani 

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Pyaemia  

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Pyaemia Pyaemia is defined as a condition in which pyogenic bacteria produce septicemia with multiple abscesses in internal organs such as spleen, heart, liver, and kidneys. E.g. Lung abscesses which is due to Klebsiella species, Staphylococcus aureus. Multiple abscesses in the body caused by Mycobacterium Tayyar M

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Host Resistance

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There are two major type of immune system response to infection: Non specific or natural resistance Specific resistance or acquired immunity.

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Host Immune Response:

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Humoral immune responses  Cellular immune responses 

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Both help in controlling infection Tayyar M

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Natural Resistance   

Natural resistance called constitutive immunity. This resistance resulted from the action of the number of system : These factor are divided into External system: prevent entry of the pathogen.  Internal system : introduce physical barrier 

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Which are cooperate with the acquired immunity by the process of Tayyar M

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Natural resistance  

Components of Natural resistance: External defiance system: Skin  Respiratory tract  Mouth  Digestive tract  Urogenital tract  Eye 

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Natural resistance  

Components of Natural resistance: Internal defiance system: Phagocyte cells  Chemotaxis  Opsonization  Ingestion  Oxygen dependent killing of microbes  Oxygen independent killing of microbes  Destruction of ingested microbes. 

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Natural resistance  

Components of Natural resistance Inflammatory response: Local  Generalized 

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Acquired immunity 

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This is the immunity which a person a quires during his lifetime. Based on the pathogen antigen (Ag) been identified by 1. 2.

Antibodies (humoral immunity) Cell mediated which is associated with macrophages and T lymphocytes

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Classification of Acquired immunity (Table 5.4). Immunit Type y Cellular Engulfment Cytotoxic Humoral Agglutinatio n Precipitation

Outcome of defense phagocytosis Destruction of infected cells Clumping of organism

and phagocytosis Clumping of soluble molecules and Inactivation of toxin Neutralizatio phagocytosis n Blocking of viral infection Lyses of parasites

Complement fixation Phagocytosis of parasites

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Acquired immunity 

Humoral immunity can be Active immunity: the body synthesis its own antibodies.  Passive immunity: the body received a ready made antibody from other individual. 

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The acquisition could be: Natural: immunity for certain disease provide resistance for subsequent infection with the same microbes  Artificial: e.g. vaccine. 

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Acquired immunity 

Passive immunity: could be obtained by Natural Passive immunity : Tranplacental passage of antibodies from mother to unborn child during the later part of pregnancy.  Artificial Passive immunity: production of antibodies in some other individual (either human or animal) and the acquisition through parental routes 

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Table 5.5 models of acquisition of active and passive immunity

Active immunity

Passive immunity

By clinical infection

By transfer of maternal antibody a cross placenta Following sub-clinical Through breast milk infection Following immunization (Vaccine, antigen)

Following administration of antiserum or Tayyar M

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Acquired immunity 



This is the immunity which a person a quires during his lifetime. Based on the pathogen antigen (Ag) been identified by 1. 2.

Antibodies (humoral immunity) Cell mediated which is associated with macrophages and T lymphocytes (Table 5.4)

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Classification of Acquired immunity (Table 5.4). Immunity Type Cellular Engulfment Cytotoxic Humoral Agglutination

Outcome of defense phagocytosis Destruction of infected cells

Precipitation Neutralization

Clumping of organism and phagocytosis Clumping of soluble molecules and phagocytosis Inactivation of toxin Blocking of viral infection

Complement fixation

Lyses of parasites Phagocytosis of parasites Tayyar M

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Acquired immunity 

Humoral immunity can be Active immunity: the body synthesis its own antibodies.  Passive immunity: the body received a ready made antibody from other individual. 

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The acquisition could be: Natural: immunity for certain disease provide resistance for subsequent infection with the same microbes  Artificial: e.g. vaccine. 

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Chapter 6 Immunology  

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The word immune mean free from burden. Immunity: refer to the ability of an organism to recognize and defend itself against infectious disease. Susceptibility: the opposite of immunity, it is the vulnerability of the host to be harmed by an infectious agent. Specific immunity: is the ability of a host to mount a defense against particular infectious agent by physiological response specific to that infectious agent. Tayyar M

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Immunology 

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Immunology is the science study the specific immunity and how the immune system consists of various cells. Immune system consist of various parts, Such as : cells e.g. lymphocyte.  Organs e.g. thymus gland. 

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Immunity 

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The immune system protects an individual against invasion by foreign bodies specially microbial agents and their toxic products. consequence of immune defenses includes: Allergy  inflammatory tissue damage.  Autoimmune diseases 

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The duality of immune System 

2.

Immune system of human and all other vrtebrate divided into Humoral immunity: because it involves the antibodies that are dissolved in the blood plasma and lymph. 

3.

These antibodies are produce by lymphocytes called B-cells.

Cellular or cell mediated immunity: 

The immunity response depend on lymphocytes called T-cells, which are Tayyar M

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T-cells do not secrete antibodies into body fluid's but they do antibody like molecule that remain attached to cell surface. Humoral defense primarily against bacteria and viruses presents in body fluids. Cellular response against intracellular viruses, fungi, protozoa, helminthes, transplanted tissue and cancer cell. The word antigen come from Tayyar M

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Specific Immune Mechanism

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These mechanism are mediated by B and T lymphocytes which have receptors for antigenic determinants on their surface.

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The receptros on B cells are Immunoglobulin (Ig).

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The receptors on T cells are Ig like molecules.

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Those receptors are only for antigenic determinants which fits into the receptors like a key to lock. Tayyar M

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Lymphocyte that have receptors for same epitope initiated immune process which consist of proliferation of lymphocyte and their functional differentiation. The cells in human body may have receptors for more than 10 million epitopes. Immune system dose not initiate immune response against self-antigen Tayyar M

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Nonspecific Immune System 

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These mechanism deal with all antigen irrespective of their epitopes. The main component of this system are physical barriers, phagocytes, complement and inflammation (Fig 6.1)

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Inflammation Response 

Inflammation Response composed off:

2)

Blood flow increase.

3)

Phagocytes activated.

4)

Capillary permeability increased.

5)

Complement activated.

6)

Clotting reaction.

7)

Regional temperature increased.

8)

Specific defense activated. Tayyar M

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Nonspecific Immune System 

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The phagocytes engulf and destroy the infectious agent. The complement is system of enzyme that attack foreign substances and lymphokines are liberated by lymphocytes and act as functional communication system among the immune cells. Tayyar M

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T cells on stimulation, are differentiated into:

A- Regulator cells. B- Effector cells which differentiated into



1.

Helper cells

2.

Suppressor cells

The effector T cell produce cell mediated immune (CMI) response, that involve: 

cytotoxic T cell which specifically destroy body cells infected with the antigen.

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Delayed hypersensitivity T cells which further activate phagocyte cells to kill microbes. Tayyar M

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The activated T cells use a variety of soluble factors (Lymphokines) to activate macrophages for killing the ingested cells. B cells produce specific antibody against the presenting epitopes. The B cells response known as humoral immune response or antibody mediated immunity. Tayyar M

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The antibodies are secreted into circulation where they produce a powerful and specific effector mechanism. These may inactivate the antigen by neutralizing its infective (as with virus) or toxins and by removing the antigen from the system. Tayyar M

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The antibody binds to the antigen and the resulting complex is much more attractive to phagocytosed (opsonization) than the free antigen. Also antibody attract the antibody dependent cytotoxic cell (ADCC) to attack and destroy the infected cells

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Both B and T cells retain antigenic memory for the antigen after they get in contact with it. The second attack by the same antigen results in a faster and more vigorous immune response. The antibody, complement and polymorphs provide protection against most extracellullar oragnism

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The antibody, complement and polymorphs provide protection against most extracellular organism.

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T cells, soluble lymphokines and macrophages deal with intracellular infection.

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immunopathological tissue damage occur due to inappropirate hypersenstivityn reaction to foreign particle. Tayyar M

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Anatomy and Biology of Immune System 

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The tissue in which the immunological response system called lymphoid. Lymphoid tissue divided based on their function into 1- Primary lymphoid organ. 2- Secondary Lymphoid organ.

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Primary lymphoid organs are A- Thymus. B- Bone marrow. In which proliferation and differentiation of lymphocytes takes place independent of antigenic stimulation. Which mean that stem cell that give lymphocytes are presents in these tissue. Tayyar M

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The mature lymphocytes are seed into the peripheral system where they exposed to antigens.

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Organs that receive and maintain functioal lymphocytes are called secondary lymphoid organs.

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The maturation of T cells takes place in thymus whereas pre-B cell originate and mature in bone marrow. Tayyar M

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Secondary Lymphoid organs  2. 3. 4.

5. 6. 7.

Secondary Lymphoid organs include Lymph nodes. Spleen. Gut associated lymphoid tissue (GALT). Appendix. Tonsils. Adenoids. Tayyar M

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Biology of immune Response  2. 3.

Immune response are divided into Primary immune response. Secondary immune response.

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• Primary immune response 

 3. 4. 5. 6.

Few days (7-10 days) after the first infection antibody appears. This period depends on the Kind of antigen. Amount of antigen. Route of administration. The health status of the organism. Tayyar M

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• Primary immune response 



Normally B cells start produce antibody after 20 minute (low amount produce by few cells, not detected in the beginning). After that the titer of antibody increase over a few days to few weeks, until reaches the plateau and begins to drop. Tayyar M

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

2. 3. 4. 5. 6. 7.

The nature and extent of immune reposne to an antigen is determined by: Dose of antigen. Nature of antigen. Route of administration. Adjuvant. Nutritional status of the host. Presence of immuno-deficiency

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Secondary Immune Response 



 

After second injection of the same antigen Antibody in the circulation will drop sharply as they form complexes with the antigen. After 2-3 days a marked increase in the antibody occur for several days, this increase is higher than what is seen in primary response. Figure 7.2 page 31. This response called memory anamnestic Tayyar M 109 or booster response.

Secondary immune response 

Secondary Response differ from the primary response in the following:

2.

Shorter latent period.

3.

More rapid production of antibody.

4.

More abundant production of antibody

5.

Antibody response maintained a higher levels of longer periods

6.

Antibody produce has more capacity to bind the antigen. Tayyar M

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Immunosuppression 







This define as reduction in the activity of macrophages, B and T cells. Which could be measured as lowered capacity to phagocytose or to produce Ig or lymphokines. This cause the presence of not effective immune response. Immunosuppression could be due to chemical (corticosteroids) and physical (Radiation) agents, biological agent as well such as antibiotics (Actinomycin D, chloramphenicol and mitomycin C. Tayyar M

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Antigen and Antibody 

The word antigen come from Antibody and generator.



Antigen is a substance that catalyzes lymphocytes into specific adaptive response.



Lymphokines are called interleukins.



Antigen may alter the behaviour of phagocytosis, either directly during phagocytosis or indirectly in response to Tayyar M lymphokines (interleukins)

112

Antigen Characteristics 

The important Characteristics of antigens are:

2.

Macromolecular size >10.000 Dalton molecules are more antigenic than antigen with less molecular weight.

3.

Complex molecule.

4.

Solubility in body fluids. Tayyar M

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Classification 

Antigen can be classified into various group:  foreign (outside the host).  Microorganism or there products.  Drugs  Environmental antigen  Autoantigen  Thyroglobulin  Cellular nucleic acid (Cellular DNA).  Corneal components. Tayyar M

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

Antigen can be classified into various group: 

Isoantigen: is a type of antigen which is present only in subsets of a species  Histocompatibility  Blood



tissue antigen.

group antigen.

Heteroantigen: (definitions not necessary) antigens occurring on the surface of tissue cells of many different species and showing extensive interspecies cross relationship.  Heterophile

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115

 2.

3.







Antigen determinant sites (Epitope): Small part of an antigen molecule is inducer of B and T cell response. Also it is the part of the antigen with which the antibody reacts. The part of the antibody that comes in contact with epitope is known as paratope. One antigen molecule may have a large number of epitope. Number of epitope per antigen Tayyar M

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



Haptens: are small molecule to be antigen by themselves. Those haptens are capable of reacting with antibody by injection a hapten-carrier complex.

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Monoclonal antibody  

 



Antibodies or immunoglobulins were first identified in 1890. It start with the observation by Behring and Kitasato, that rabbits immune to tetanus have substance in their blood capable of destroying tetanus toxin. They called this molecule antitoxin. The first treatment application was in 1891 when both scientist treat children with diphtheria with antitoxin isolated from diphtheria toxin-immunized rabbit. Recently this immunoglobulin has been 118 Tayyar M

Antibody 

Immunolglobulin (Ig) molecules with symetrical structer, theose Ig have “Y” shaped in solution.



glycoprotein's consist of four polypeptide chains: 1.

Two identical so called heavy chain with molecular mass of approximately 50-55 kDa.

2.

Two light identical Tayyar M chains (25kDa)

119

The structure of antibodies



http://www.path.cam.ac.uk/~mrc7/igs/mikeimages.html

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Antibody Biology 

Antibody molecule are divided into several parts: 

Antigen binding fragment F(ab). Compose of two parts: Constant part: common to each immunoglobulin class  Variable domain: unique for every immunoglobulin. 



Constant region (Fc-fragment crystallizable) Tayyar M

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Prototype structure of lgG,

Basic str. of Ab

: revealed by chemical & enzymatic methods

& alkylation

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FIGURE 4-3

Classes (Isotypes) of antibody  In human there are five classes of Ig based on  





 

the Ig heavy chain structure. Human Ig: IgG (contain γ heavy chain): based on their distinctive heavy chain IgG are subdivided into: IgG1, IgG2, IgG3 AND IgG4. IgM (contain μ heavy chain): They subdivided into IgM1 and IgM2 IgA (contain α heavy chain) they subdivided into IgA1 and IgA2 IgD (contain δ heavy chain) M 124 IgE (contain ε heavy Tayyar chain)

Characteristic of Immunoglobulin G 1.

2.

3.

4.

5.

The IgG has the maximum concentration in serum. The major antibody to be produce during secondary infection. The major defense in newborn because of its capability to pass through the placenta as well as secretion in colostrums. Bacterial toxin are mainly neutralized by IgG. Tayyar M 125 IgG bind to the organism and enhance

Characteristic of Immunoglobulin A 1.

Appear selectively in saliva, tears, nasal fluids, sweat, colostrums and secretion of lungs, genitourinary (the organ system of all the reproductive organs and the urinary system) tract, and gastrointestinal tract.

2.

Defend external surface against infection.

3.

IgA synthesized locally by plasma cell and dimerized with TayyarJM chain

126

Characteristic of Immunoglobulin M 1.

2. 3.

4.

A polymer of five chain units each with four polypeptides (Molecular weight 900.00). Polymerization is done with J chain. IgM is an excellent agglutinating and cytolytic agents since they appear early in response. Play an important role in bacteraemia.

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Characteristic of Immunoglobulin E 1. 2. 3.

4.

5.

Has little concentration in serum. Synthesized by very few plasma cell. These antibody remain bound to basophiles when injected into skin. Contact with antigen release vaso-active amine. They protect the external mucosal surface by local recruitment of plasma factor and effectors cells by activating an acute inflammatory response Tayyar M

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Characteristic of Immunoglobulin D 



The first antibody to be produce in small amount. Its production switch on the synthesis of IgM.

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Antimicrobial Action 

2. 3.

Antimicrobial action of Immunoglobulin includes: (table 8.3) Opsonization for phagocytosis Complement activation, enhancing phagocytosis and inducing lyses

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General structures of the five major classes of secreted antibody

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

The most abundant type of antibodies found in blood, IgG are 150 kDa glycoprotein's consist of four polypeptide chains:

2.

Two identical so called heavy chain with molecular mass of approximately 50-55 kDa. Two light identical chains (25kDa)

3.

–

The hinge of the Y-shaped Ig is rich in proline (amino acid) and highly vulnerable to attack by proteolytic enzymes. Tayyar M

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Discovery of Viruses Before 1892 bacteria were the smallest infectious agents.



In 1892 Dmitri Iwanowski (Russian scientist) reported that

filtration did not sterilized tobacco plant extracts because the liquid that come through the filter was still able to cause mosaic disease. He was not able to see any bacteria under his light microscope. He also was not able to cultivate from it using standard bacteriological media.  Six years later Beijerinck reported the same observation. Beijerinck reported that the infectious agents of tobacco mosaic disease was an organism small enough to pass through the pores in the filter. Tayyar M 133

Discovery of Viruses   

 

Beijerinck called the organism a filterable virus (Virus (Latin)= poison or slime. Beijerinck predict that other filterable virus would be detected. In 1898, Freidrich Loeffler & Paul Frosch showed that a similar agent was responsible for foot-andmouth disease in cattle In 1935 stanley purified and crystallized tobacco mosaic virus. Causing disease is biological capacity, while Crystallization is a property of purified chemicals. Tayyar M

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Are the virus alive? Virus are non living organism. As they are: 2. Not able to carry on metabolism. 3. Viruses lack most cellular structures including cytoplasm, ribosome's, a nucleus or nucleoid. But viruses are 5. Able to evolve and adapt to a changing environments. 6. They contain some macromolecules similar to those in the cellular organisms. Virus are packaged bits of genetic information that tell the host cells to make more viruses. 

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Virology  

Virus is a Latin word mean poison. Virus as identified by Luria and Darnell in 1978: viruses are entities whose genomes are element of nucleic acid that replicate inside living cells, using cellular synthetic machinery and causing the synthesis of specialized elements that can the viral genome to other cells. Tayyar M

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General properties of viruses 

       

Consist of either DNA or RNA but neither both. Obligate intracellular parasites. Fail to grow on artificial media Smallest infectious agents Nucleic acid is enclosed in a protein shell. Entire infectious unit is also called virion. Not inactivated by antibiotics. Divided by replication Mostly limited hostTayyar range. M 137

Virus classification based on their host    

Human and animal viruses Insect viruses Bacterial viruses (bacteriophage) Plant viruses

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Viral Modern classification 

Modern classification based on their genetic material (nucleic acid) content (figure 28-1): 1. 2. 3. 4. 5. 6.

Double strand DNA (dsDNA) Single strand DNA (ssDNA) Complex DNA ssRNA negative sense. ssRNA positive sense dsRNA Tayyar M

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Morphology of viruses 











The viruses are composed of nucleic acid and protein. The genome contain all necessary information for viruses multiplication. The genome surrounded by protein coat called capsid. Both genome and the capsid are called nucleocapsid. Viral envelope is a coat surrounding the nucleocapsid made of lipid. Complete viral particle called Tayyar M virion figure 28.2.

140

  

Capsid are aggregate of arranged repeating subunits call capsomers. The capsomers are made of protein. Capsid and viral envelope has two function:  

 

Protect the genome from external harmful factors or agents Introduce the viral genome into the host cells.

Viral enveloped present in most viruses families except. The lipid of the viral enveloped is derived from the host cytoplasmic membrane. Tayyar M

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 

 

Size of viruses: Viruses vary in diameter from 300 to 20nm. Box-viruses are the lagest viruses. The picorna and parvo-viruses are the smallest.

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Viral proteins  

– – –

Viral protein different on their size as well as number of protein species. Viral envelope may posses glycoprotein's which are presents as 1. Spikes or projection (rabies virus) 2. Matrix protein, present in the inner surface of the envelope and provide extra-strength. In addition there are two types of viral proteinsheamaglutinins and enzymes. Protein found in the coat are called structural protein. Heamaglutinins and enzymes are called nonstructural protein. Tayyar M 143

Preservation of viral infectivity Viruses are very fragile and more sensitive to environmental changes than other organism. 1- Temperature: increase temperature destroy viruses rapidly:  General roles: 

 

viruses survive for seconds at 60ºC At 37ºC for minutes, hours at 20ºC, days at 4ºC, and years at minus 70ºC or below.

2- pH viruses prefer physiological pH and any alteration mat cause deterioration of viral infectivity. 3- Lipid solvent: ether or chlorophorm, detergent and any lipid solvent come in contact with viruses, Tayyar M may destroy them. 144 especially enveloped viruses

Viral Replication  

The virus is intracellular parasite, make use of host metabolic process for its own benefit. Viral replication consist off:  Attachment or adsorption  Penetration  Uncoating  Transcription  Translation  Genome replication  assembly  Release Tayyar M

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Attachment or Adsorption 

For a virus to infect a host cell, that cell must have receptors for the virus on its surface and also be capable of supporting viral replication.

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Penetration  • • •

•

Enveloped viruses enter the host cell in one of four methods: Translocation: when the whole non-enveloped virus enter the host cells by moving across cell membrane. Virus enters by endocytosis (formation of an invagination of the plasma membrane that engulfs the virus). Viral envelope fuse with the host cell cytoplasmic membrane and the nucleocapsid is released into the cytoplasm. Direct fusion of the viral envelope with the surface membrane of the cell.

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Uncoating 





Uncoating is the release of the viral genome from the remainder of the virus. The viral capsid is removed by the action of host components and enzymes. Viral genome replication starts at this stage

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Transcription 





Positive sense (polarity) single stranded RNA bind to ribosome's to synthesize protein. negative sense ssRNA use RNA dependent RNA polymerase to produce positive since RNA (mRNA). While DNA virus use DNA dependent DNA polymerase to perform this function Tayyar M

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Translation 



Viral mRNA uses the ribosome's to synthesis protein in the same ways the host mRNA did. Two type of protein are synthesized upon time of appearance Early protein  Late protein 

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Genome Replication 

The viral genome directs the host cell's metabolic machinery (ribosome's, tRNA, nutrients, energy, enzymes, etc.) to synthesize viral enzymes and viral parts.

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Assembly 



Virion assembly may take place in the cytoplasm or cell nucleus of the host. The process of acquiring envelope is through the process of budding through the cellular membrane.

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Release 

2. 3. 4.

There are three machinery of mature virions release from the host cell and start their life cycle again. Cell lysis Cell degeneration budding

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

 





Duration of viral replication between 5-15 hours in DNA viruses and 3-10 hours in RNA viruses. Viral infections is not always productive Sometimes the virus protein are not synthesized or their assembly is defective, such process called an abortive viral infection. Some viruses fail to replicate in a responsive host cell, these are known as defective viruses. Some replicate in the presence of helper 154 Tayyar M

Naked Virus Replication

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Cultivation of viruses 

Since viruses are obligate intracellular parasites, a living cell system needed to grow them such as. 1. 2. 3.

Laboratory animals Embryonated eggs Cell lines (tissue culture)

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Recognition of Viral Growth in Cells 

Viral growth in cells can be detected by one of the following: Cytopathic effect (count dead cells)  Haemagglutinin and haemadsorption  Immunofluorescence  Interference  DNA methods (Polymerase Chain Reaction, (PCR)) 

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Adenovirus     

Adenoviruses has a dsDNA genome, non enveloped virus. Adenovirus infection occur world wide. By age of five almost all children have been infected with at least one serotype. Few serotypes are pathogenic to man. Adenovirus infections of human include:     

Acute respiratory disease Sore throat Pneumonia Meningoencephalitis Swimming pool conjunctives. Tayyar M

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Herpes viruses   

The family Herpesviridae consist of more than 80 viruses. All Herpes viruses are enveloped virions with dsDNA genomes. Herpes simplex virus: Exist in two serotype HSV-1 and HSV-2.  HSV-1 infect region above the waist.  HSV-2 infect genital and anal regions.  Latency for HSV-1 in trigeminal ganglia  HSV-2 latency in sacral ganglia. 

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Herpes simplex virus Disease caused by herpes simplex virus 2. Stomatits. 3. Herpes labialis 4. Eczema herpeticum. 5. Traumatic herpes

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Varicella Zoster Virus    

Varicella Zoster Virus Etiological (responsible) agent for two disease of man, Varicella and herpes zoster. Varicella follows exogenous contact with the causative virus. Zoster reflects endogenous activation of the Varicella Zoster virus infection that has survived in latent form following an attack of Varicella.

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

 

Varicella is contagious disease of seasonally epidemic propensities the follows primary exposure of Varicella Zoster a susceptible person, most often child. The disease known as chickenpox. Herpes zoster is an endemic sporadic disease, most frequent in elderly people, characterized by  Unilateral  Painful  Vesicular or eruption localized. Tayyar M

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Cytomegalovirus  

 



Cytomegalovirus Most of CMV infection is asymptomatic. In rare cases the infection is fatal. Some times CMV cause permanent brain damage. CMV might transfer through placenta causing cytoplasmic inclusion disease (CMID) of newborn Tayyar M

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Epstein-Barr virus (EBV) 



Epstein-Barr virus cause glandular fever. Characterized by: Fever  Lymphoadenopathy  Sore throat  Malaise  Fatigue 

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Acquired Immunodeficiency virus (AIDS)  

RNA enveloped viruses. HIV can be transmitted by any of the following routes: 1. 2. 3. 4. 5. 6.



Sexual intercourse Blood transfusion Transplacenta IV drug Breast milk Accidental needle-stick injury

Chronic infection with HIV has diverse symptoms, due to the destruction of immune system. Tayyar M

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Rubella   

Rubella Known as German measles. Clinical features of rubella virus: 1. 2. 3.

Rash Lymphoadenopathy with fever. congenital malformations in children if the mother contracts this infection during the first trimester of pregnancy. Tayyar M

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Hepatitis Virus 

Hepatitis virus refer to primary infection of the liver by one of the four etiological agents: 1. 2. 3. 4.



Hepatitis type A (HAV) HBV Non-A, non-B hepatitis (NANB) HDV

The newer type are known as: 1. 2. 3. 4.

HEV HCV HGV HFV

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HAV  

ssRNA non-enveloped virus. Clinical feature: 1. 2. 3. 4. 5. 6. 7. 8.

Fever Headache Fatigue Vague pains Anorexia Nausea Vomiting Dark urine Tayyar M

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HBV    





Circular ssDNA, enveloped virus. Clinical feature similar to those in HAV. HAV does not persist in the host. HBV may give rise to persistence infection of liver (prolonged carrier state to chronic infection). HBV may lead to hepato-cellular carcinoma. HCV also could cause hepato-cellular carcinoma. Tayyar M

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Medical Mycology 



Medical mycology is the study of human diseases caused by fungi and mycosis. Around 100 or more species of fungi are recognized as human pathogen.

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Fungi Differences from Bacteria 1. 2. 3. 4. 5. 6.

Have larger size, more complex morphological development. Fungi can be unicellular or multicellular. Having ridged cell wall compose of chitin, mannan and other polysaccharide. Presence of true nuclei with nuclear membrane and pair chromosome. Presence of sterols in the cytoplasmic membrane. Reproduction can be asexual or sexual or by both these modes. Tayyar M

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Medical Mycology 



Medical mycology is the study of human diseases caused by fungi and mycosis. Around 100 or more species of fungi are recognized as human pathogen.

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Fungi Differences from Bacteria 1. 2. 3. 4. 5. 6.

Have larger size, more complex morphological development. Fungi can be unicellular or multicellular. Having ridged cell wall compose of chitin, mannan and other polysaccharide. Presence of true nuclei with nuclear membrane and pair chromosome. Presence of sterols in the cytoplasmic membrane. Reproduction can be asexual or sexual or by both these modes. Tayyar M

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Dermatophytes 

 

Dermatophytes are group of closely related filamentous fungi that infect only superficial keratinised tissue, i.e. skin, hair and nails. They caused dermatophytoses, or Ringworm or Tinea. Tinea (moth) used to describe the dermatophytes infection that give the hair of the head a moth-eaten appearance Tayyar M

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

Epidermophyton is the most important genera of dermatophytes.

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Candidiasis 



  

Candidiasis is the disease which affect the skin, the mucosa, the skin appendages and the internal organs as well as cause septicemias due to yeast fungi of the genus Candida. 7 out of 81 Candida species are pathogenic. The most common is Candida albicans. Candida reproduce by budding. They are able to ferment a number of sugars. Tayyar M 176

Predisposing Factors for Candidiasis 1. 2. 3. 4. 5. 6. 7.

Impaired immune defences. Spontaneous hormonal changes Corticosteroids Immunosuppression Long term antibiotic therapy Oral contraceptive Preexisting lesion of skin or mucosa or internal organ

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

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Pregnancy Menopause Premature birth Obesity Child birth Diabetes mellitus Adrenal insufficiency Thyroid

177

Clinical features Candidiasis 1.

2.

3. 4.

5. 6. 7.

Candidiasis of visera Bronchopulmonar y Candidiasis Septicemia Intestinal Candidiasis Granuloma Vaginitis Balanitis

     

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Thrush Cheilosis Intertrigo Onychia Paronychia Erythema mycoticum infantile.

178

Fungi Diagnosis  

Microscopic examination Culture

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Aspergillosis 

   

Aspergillosis name given to a number of different diseases states: Allergic aspergillosis Aspergilloma Invasive aspergillosis Aspergillosis is secondary infection in tuberculosis, carcinoma etc. Tayyar M

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Etiological Agents 

  

Common specie causing aspergillosis are: Aspergillus fumigatus A. niger A. flavus

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Parasitology  

   

Medical Parasitology deals with the parasites which infect man and disease produce by them. Parasite: an organism which is dependent on another organism for its survival. It obtain nutrient and shelter from the host. Host: an organism which harbours the parasite and is usually larger than the parasite. Ectoparasite: parasite which lives on the outer surface of the host. Endoparasite: parasite which lives within the body of host. Commensal: a parasite which does not damage the host while deriving its advantage. A commensal is capable of independent life Tayyar M

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

  



Symbiosis: A parasitic relationship which results in great advantage to each other as compared to disadvantage. Obligate parasite: A parasite which is completely dependent upon the host. Pathogen: a parasite which is able to produce disease. Intermediate host: a host in which the intermediate stage of the parasite develops. Definitive host: a host is which sexual reproduction takes place or the adult form of the parasite resides. Tayyar M

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

  

Paratenic host: a host which acts as a transporting agent for the parasite and in which parasites dose not undergo any development. Infection: refer to the presence of parasite in or on the tissue of the host. Infestation: presence of arthropods on the skin of the host. Incubation period: the time interval between the entrance of the parasite into host and the beginning of disease. Tayyar M

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



Zoonosis: disease which are transmissible between man and animals. Virulence: refer to the degree of pathogenicity.

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Mode of infection in parasite disease 

Infection can be acquired by various routes. 1.

Through animals : A. B.

2. 3. 4. 5. 6. 7.

pig : e.g. porktapeworm Cat : e.g. toxoplasmosis

Autoinfection: threadworm Water-borne: e.g. Amoebiasis, giardisis. Vector borne: e.g. mosquito (malaria) Contaminated food: Ascaris, Amoebiasis Vertical transmission: malaria, toxoplasmosis Penetration through skin: Hookworm, Schistosomiasis Tayyar M 186

Ascariasis (roundworm infection) 











Etiological agent: nematode called Ascaris lumbricoides. Habitat: the adult worm live in the lumen of the small intestine mainly jejunum. Morphology: the mature worm is cylindrical with tapering ends, resembling an ordinary earthworm. Characteristics of eggs:both fertilized and nonfertilized egg could be found in the faeces of patient suffering from ascaris. A mature female can liberate more than 200,000 eggs daily. Tayyar M 187 The characteristic of this eggs help in their



Life cycle:



Infection occur from ingestion of the empryonated eggs.



The infective larva hatch out in the small intestine and penetrate the intestinal wall to enter the portal circulation.



From the liver these are carried to the heart and via the pulmonary artery to the lungs.



In the lungs these break out of the capillaries into alveoli and undergo another moulting to become the fourth stage larva.



These larvae move up to bronchi and are either swallowed with saliva or crawl over epiglottis to enter the digestive system.



In the intestine these again moult to become sexually mature worms.



The lifespan of an adult worm is about one year after which it is spontaneously expelled.` Tayyar M

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Pathogenicity A) Hinder



normal development in children B) Fever, abdominal pain, urticaria. C) Nausea, vomiting, diarrhea. D) Pneumonitis E) Acute intestinal obstruction F) Appendicitis G) Biliary tract infection H) Malnutrition. Treatment : Mebendazole is the drug of choice.

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Malaria 

Aetiological Agents: four specie of Plasmodium could cause Malaria in human: P. vivax  P. falciparum  P. malariae.  P. ovale 

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Life cycle

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Entamoeba Histolytica 

This microorganism cause amoebiasis.

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Normal Microbial Flora of the Human Body 

The normal microbial flora refers to the population of microorganism that inhibit the skin and mucous membranes of healthy normal persons.



Normal flora could be of two type: 

Residential flora: fixed type of microorganism regularly found in a given area at a given age.



Transient flora: this consist of nonpathgenic or potentially pathogenic microorganism



Function of resident flora:



Maintain prober health by perform various function.



Benifictal function of resident flora: 

Help in absorption of nutirent



Synthesise vitamin espically vitamin K



Prevent colonization by pathogens having related to shared antigen.



Bacteriocins produced, inhibit growth of

• Harmful function of residental Flora 

Oppurtinistic pathogens



Produce disease if introduced in large number in forigne location with predisposing factor.



Penicillinaze produced can antagonize therapy.



Excessive production of endotoxin may cause shock.



May transfer organism from one part of the world to the another.



Ubiquitous presence creates problems in establishing accurate diagnosis.





For microbiological diagnosis purpose the specimen must be obtained from the suspect lesion and not from an adjacent non-involved area. The site of sampling should be properly prepared.

Human body divided into 

Site normally sterile.  Bone Marrow  Cerebrospinal fluid  Serous fluids  Tissues



Sites with normal flora:  Skin  Upper respiratory tact  Gastrointestinal tract



   

Bacteriological examination of air is required following conditions such as: Surgical theaters Premises where food articles are prepared and packed Premises where pharmaceutical preparation are made Hospital words when nosocomial infection have occurred.

Hospital associated infections 

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Hospital is the place which help people in getting cured of illness. Some times hospital become potential transmittance of disease. Infection which acquired in the hospital called hospital infections or nosocomial infections

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Source of hospital infection: 

Exogenous route : From other patient  From a member of the hospital staff.  From the inanimate environment in the hospital. 

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Endogenous From the patient own flora which may invade the patient tissue spontaneously  Or introduce into tissue by surgical operation. 

Persons at Risk 

Hospital acquired infection may be affect the discharge patent.  In patient  Out patient  Hospital staff  It may spell over the community 

Modes of spread of Hospital Acquired pathogen  Airborne     

Direct contact Food borne infection Water borne infection From hospital equipment Infectious by inoculation.

Common agents of Nosocomial Infections 

Any pathogen present in the hospital can cause infection becuase of the comprised immune status of some patients.

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Example of nosocomial patogen are listed in taple 37.1

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Gram Positive: e.g. Staphylococcu aures , Clostirdium tetani. Gram negative: Escherichia coli, Pesudomonas

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Viruses: Hepatitis B, HCV, HDV, HIV.

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Fungi: Aspergillus, Candida albicans

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Parasites: Toxoplasma gondii, Entamoeba histolytica

Common Type of Hospital Infection 

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Wound infection : due to Staphylococcus aureus, Pseudomonas. Urinary tract infection (UTI): associated with urethral catheterization. E. coli is responsible in most cases Respiratory infection: 15-20% of nosocomial infection Skin infection Bacteraemia and septicemia Gastrointestinal infections.

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Burns provide suitable place for infection. The risk of septicemia can be avoided by by pre-operative or peri-operative administration of antibiotics in patient with colonized urine.

Control and Prevention 

Patient with community acquired infection are part of the nosocomial infections, because these community acquired infection could spread in the hospital.

Prevention of Nosocomial Infection        

Hand washing Intelligent use of instrumentation. Limitation of use of antibiotics. Prophylactic antibiotics in specific sitaution fro short periods. Limitation of transfusions Barrier precautions Surveillance. Frequent change of intravenous lines.