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Microbiology Chapter 15 Troy University

Terms in this set (63)

pathogenicity
the ability to cause disease by overcoming host defenses
virulence
the degree of pathogenicity
what are the 3 portals of entry for a microbe
-mucous membrane
-skin
-parenteral route
mucous membrane entry
-respiratory tract (easiest and most frequent)
-gastrointestinal tract (food, water, fingers; most die due to stomach acid, bile, enzymes; eliminated in feces)
-genitourinary tract (sexually contracted diseases)
skin
-impenetrable by most microbes
-accessed by openings, hair follicles, sweat gland ducts
parenteral route
deposited directly into tissues when barriers are penetrated
punctures, bites, injections, cuts, wounds, surgery, skin splits
ID50
infectious dose for 50% of a sample population
-measures virulence of a microbe
LD50
lethal dose for 50% of a sample population
-measures potency of a toxin
adherance
a process in which all pathogens attach to host tissues at the portal entry
what are the 2 methods of adherance
1. adhesions on the pathogen bind to receptors on the host cells
2. biofilms
why do most pathogens invade host tissues
to cause disease
what are the factors that contribute to invasion of a host
-capsules
-cell wall components
-enzymes
-antigenic variation
-penetration of the host cytoskeleton
describe a capsule
-glycocalyx around the cell wall
-increase virulence
-impairs phagocytosis
M protein
-found on cell surface and fimbriae
-mediates attachment to epithelial cells
-helps bacteria resist phagocytosis
-streptococcus pyogenes
Opa Protein
-outer membrane protein
-allows attachment to host cell as do fimbriae
-following attachment the host cell takes up the bacteria where it resides
-neisseria gonorrhoeae
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