W04_02 Microbial pathogenesis

Question 1

what are virulence factors?

Answer 1

traits that render microorganisms pathogenic;

divided into facilitators of: microbial invasion and host damage

Question 2

fimbriae adhesins are characteristic of which type of bacteria?

Answer 2

gram-negative

Question 3

what is bacterial biofilm?

Answer 3

complex polysaccharide slime layer that protects the bacteria from exposure to the immune system

Question 4

what are leukocidins?

Answer 4

exotoxins from bacteria that kill WBCs

Question 5

what are 4 ways a bacteria can survive phagocytosis?

Answer 5

inhibit lysosome-phagosome fusion;
escape into cytoplasm;
resist lysosomal enzymes;
inhibit oxidative pathway

Question 6

name examples of how bacteria can survive specific immune defenses

Answer 6

immunosuppression;
nonspecific lymphocyte activation;
antigenic variation;
proteolysis of antibodies;
prevention of opsonization (protein A);
viruses can use latency

Question 7

what are 4 ways microbial agents can cause damage?

Answer 7

damage due to host response;
toxins;
apoptosis (e.g. HPV immortalizes host cell);
mechanical causes (parasitic worm obstructs bowels)

Question 8

how do exotoxins help bacteria pathogenesis?

Answer 8

help spread bacteria (hyaluronidase);
lyse cells (leukocidins)
block protein synthesis;
elevate/suppress normal cell function;
block nerves (e.g. tetanus/botulinin)

Question 9

how does tetanus work?

Answer 9

infection at wound, then retrograde transport up an axon to the spinal cord;
inhibits release of inhibitory GABA from interneurons

Question 10

what is risus sardonicus?

Answer 10

facial gesture of contortion (e.g. in tetanus toxicity)

Question 11

what is opisthotonus?

Answer 11

when the body is rigid in contraction (e.g. due to tetanus)

Question 12

how does botulism toxin work?

Answer 12

affects peripheral nerve endings and prevents the release of Ach in the synaptic vesicles (SNARE). get irreversible relaxation of muscles;

Question 13

how can we protect against toxins?

Answer 13

vaccination with toxoids (e.g. tetanus shot);

antitoxin acute treatment

Question 14

what are opportunistic pathogens?

Answer 14

don’t cause disease unless given the opportunity (wimpy). e.g. coagulase negative staphylococcus in patients with IV lines

Question 15

what are true pathogens?

Answer 15

cause disease. extremely virulent. e.g. shigella, where 10 bacteria can cause profuse bloody diarrhea

Question 16

staphylococcus is part of which normal flora?

Answer 16

skin

Question 17

corynebacterium is part of which normal flora?

Answer 17

skin

Question 18

bacillus is part of which normal flora?

Answer 18

skin

Question 19

viridans group streptococci is part of which normal flora?

Answer 19

oropharynx;

vagina

Question 20

neisseria is part of which normal flora?

Answer 20

oropharynx

Question 21

haemophilus is part of which normal flora?

Answer 21

oropharynx

Question 22

candida is part of which normal flora?

Answer 22

oropharynx;
large colon;
vagina

Question 23

enterococcus is part of which normal flora?

Answer 23

large colon

Question 24

enteric bacilli/enterobacteriaceae is part of which normal flora?

Answer 24

large colon

Question 25

bacteroides is part of which normal flora?

Answer 25

large colon

Question 26

clostridium is part of which normal flora?

Answer 26

large colon

Question 27

peptostreptococcus is part of which normal flora?

Answer 27

vagina

Question 28

lactobacillus is part of which normal flora?

Answer 28

vagina