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12 Cards in this Set
- Front
- Back
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what is the first step of Koch's postulates? |
the suspected agent (bacterium, virus, etc.) must be present in every case of the disease |
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what is the second step of Koch's postulates? |
that agent must be isolated and grown in pure culture. |
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what is the third step of Koch's postulates? |
the cultured agent must cause the disease when it is inoculated into a healthy, susceptible experimental host. |
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what is the fourth step of Koch's postulates? |
The same agent must be reisolated from the diseased experimental host. |
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List exceptions to Koch's Postulates |
1. some cannot be cultured in lab 2. some are complex and require a co-infectionof another microbe to become pathogenic. 3. ethical reasons (some bacteria can only be grown in humans. 4. it's not possible to establish a single cause 5. Some pathogens have been ignored. |
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define pathogenicity |
the ability of a microorganism to cause disease |
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define virulence |
relative ability of a pathogen to infect a host and cause disease. |
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virulence factors |
pathogens have a variety of traits that interact with a host and enable the pathogen to enter a host, adhere to host cells, gain access to nutrients, and escape detection or removal by the immune system. |
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name some extracellular enzymes |
Hyaluronidase and collagenase, Coagulase and kinases |
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what does hyaluronidase do? |
it degrades specific molecules to enable bacteria to invade deeper tissues, it digests hyaluronic acid, the "glue" that holds animal cells together. |
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what does collagenase do? |
it degrades specific molecules to enable bacteria to invade deeper tissues, it breaks down collagen, the body's chief structural protein. |
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what does Coagulase do? |
causes blood proteins to clot, providing a "hiding place" for bacteria within a clot. |
