Bacterial pathogenesis

Question 1

exogenous encounter

Answer 1

microorganism from environment -food, water, soil, insect bites or from exchange in body fluids

Question 2

endogenous encounter

Answer 2

microorganisms in or on body

normal flora can be in wrong place or have too many

Question 3

Ingress entry

Answer 3

entry w/o crossing epithelial barriers

ex: inhalation

Question 4

penetration entry

Answer 4

entering by crossing epithelial barriers

ex: cut, insect bite

Question 5

how do microbes cause damage to host?

Answer 5

1) adherence. for example pili bind to oligosaccharide receptors on epithelial cells
2) mechanical obstruction (parasites)
3) Toxins example; botulinum and tetanus
4) host mediated: inflammation and immunoprotective mechanisms

Question 6

5 avoidance of host defense?

Answer 6

evading pagocytosis
inhibit phagolysosome fusion
intracellular replication
proteolysis of sIgA at mucosal surface
antigenic variation

Question 7

how does S. pneumonia evade phagocytosis 1 ?

Answer 7

prevents C3b and Ab from interacting with human cell receptors.

Question 8

how does S. aureus protein A evade phagocytosis 2 ?

Answer 8

it inhibits opsonization by Ab

Question 9

what is inhibition of phagolysosome fusioin?

Answer 9

when microbe prevents the lysosome fusing with the phagosome for degradation

Question 10

what is intracellular replication?

Answer 10

when microbe escapes phagosome and grows in cytoplasm