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13 Cards in this Set
- Front
- Back
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Subclinical infection |
a microbial infection that end without the occurence of a disease. |
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Saprophytic bacteria |
bacteria that doesn't require a living host, it lives freely in nature, on decaying organic matter, in soil or water. |
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Parasitic bacteria |
bacteria that live on or in a living host |
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Opportunistic pathogens |
potentially pathogenic bacteria that do not cause disease under normal conditions but can cause disease in immunocompromised patients, or when they find their way to another site other than their normal habitat. |
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Virulence factors |
either a structure (e.g. capsule) or a product (e.g. toxins) that enables the organism to cause disease. |
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Toxoid |
treatment of exotoxin with formalin removes its toxicity and retains its antigenicity |
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Pathogenicity
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a qualitative description of a species of bacteria denoting its ability to produce disease.
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Virulence |
a quantitative character of a strain belonging to a pathogenic species denoting to the degree of pathogenicity. |
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Adherence factors of virulance |
They enable bacteria to attach to the host surface, thus contributing to the establishment of the infection: - Fimbriae of Neisseria gonorrhoeae & E. coli help attachment to the urinary tract - Glycocalyx of Staphylococcus epidermis & certain viridans streptococci allow it to adhere strongly to the heart valves. |
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Invasion factors:
1- Enzymes |
a- Collagenase & Hyaluronidase
b- Immunoglobulin A protease c- Leukocidin d- Deoxyribonuclease e- Lecithinase "CHILD LL" |
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Invasion factor: 2- Antiphagocytic |
a- Capsule: prevent phagocytic attachment to the complement e.g. Strept. pneumoniae b- Cell wall proteins of Gram-positive cocci (e.g. M ptn of Strept. pyogenes & ptn A of Staph. aureus) c- Coagulase: accelerates the formation of a fibrin clot from fibrinogen e.g. Staph. aureus. |
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Give reason: - Endotoxins are encoded by genes on the chromosome. |
bec the endotoxin is an integral part of the cell wall of Gram-negative organisms. |
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Give reason: - Exotoxins are unstable to temp. above 60*C. |
bec it's protein in nature. |
