Disease and Epidemiology Flashcards
commensalism
bacteria benefits, no known effect on host
e coli
mutualism
benefits bacteria and host
skin flora
parasitism
one benefits, other is harmed
tb in lungs
transient flora
in body for short amount of time, can’t persist due to competition, body’s elimination, physiological changes
opportunistic flora
normal flora that cause disease if immunosuppressed, change in normal flora, or move to new body site
portals of entry
skin
parenteral (hospital-acquired)
mucous membranes*
placenta
adherence
protozoa- adhesion disks
helminths- suckers and hooks
viruses- capsid and envelope molecules
bacteria- fimbriae, capsules, biofilms, cell wall components
koch’s postulates
way of assigning certain disease to certain microbe
- same microbe present in every case
- microbe isolated from host and grown in culture
- microbe causes disease in test animal
- microbe reisolated, same as original
problems: difficulty in culture, no non-human host, multiple causes/interactions
virulence factors
adhesins
enzymes (hyaluronidase, coagulase, kinase)
toxins (exotoxins (neuro, entero, cyto, hemolysins), endotoxins (lipid A of LPS of G- cell wall, released when cell lyses, cause fever, lethargy, shock))
antiphagocytic factors (capsules, M protein of Strep pyogenes, leukocidins)
capsules as antiphagocytic factors
slippery
not recognized as foreign
leukocidins as antiphagocytic factors
prevent lysosome and phagosome fusion
destroy phagocytic WBCs
stages of infection
incubation prodromal phase illness decline convalescence/ resolution
zoonoses
livestock- brucella
wildlife- lyme disease
transmitted by direct contact, eating animals, bloodsuckers
contact transmission
direct (env viruses)
indirect
droplet <1 m from res to host
vehicle transmission
water
air
food
body fluids
