Chapter 15 micro notes

Chapter 15 micro notes - Chapter 15 notes Microbial...

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Chapter 15 notes Microbial Mechanisms of pthogenicity pathogenicity- the ability to cause disease by overcoming the defenses of the ost virulence- the degree or extent of pathogenicity Portals of Entry – Skin, mucous, membranes, parenteral route conjuctiva, a delicate membrane that covers the eyebalss and lines the eyelids microbes in the gastrointestinal tract can cause poliomyelitis, hepatitis A, typhoid fever, ameoebic dysentery, giardiasis, shigellosis and cholera STI's – sexually transmitted infections parenteral route-punctures, injections, bites, cuts, wounds, surgery , and splitting of th eksin or mucous membrane due to swelli8ng or drying can all establish parenteral routes The preferred portal of entry- Many organismshave a preferred portal of entry that is a prerequisite to their being able to cause the disease. If they gain access to the body by another portal , disease might not occur Numbers of Invading microbes- ID50- infectious dose – the infectious dose for 50% of the population, an expression of virulence LD50- lethal dose for 50% of the population, the potency of a toxin Adherence (adhesion) – means of attacment to host tissues at their preffered portal of entry, a necessary step in pathogenicity adhesins/ligands- attachment between pathogen and host by means of surface molecules on the pathogen that bind specifically to complementaryt surface receptors on the cells of certain host tissues, may be located on a aglycocalyx or on other microbial surface structurse such as pili, fimbriae, and flagella The receptors on host cells are typically sugars, such as mannose. Adhesins on different strains of the same species of pathogen can vary in structure. An enzyme produced by S. Mutans called glucosyltransferase, conversts glucose into a sticky poysaccharide called dextran which forms the
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Chapter 15 micro notes - Chapter 15 notes Microbial...

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