Microbiology

Question 1

diphtheria toxin

Answer 1

Corynebacterium diphtheriae
Inactive elongation factor (EF-2)
Pharyngitis w/ pseudomembranes in throat and severe lymphadenopathy (bull neck)

Question 2

exotoxin A

Answer 2

Pseudomonas aeruginosa
Inactive elongation factor (EF-2)
Host cell death

Question 3

shiga toxin (ST)

Answer 3

Shigella spp.
Inactive 60S ribosome by removing adenine from rRNA
GI mucosal damage–> dysentery
Enhances cytokine release–> hemolytic uremic syndrome (HUS)

Question 4

shiga-like toxin (SLT

Answer 4

Enterohemorrhagic E.coli (EHEC)- O157:H7 strain
Inactive 60S ribosome by removing adenine from rRNA
Enhances cytokine release–> HUS
does NOT invade host cells

Question 5

heat-labile toxin (LT)

Answer 5

Enterotoxigenic E. coli (ETEC)

overactivates adenylate cyclase–> increase Cl- secretsion in gut and H2O efflux–> watery diarrhea

Question 6

heat-stable toxin (ST)

Answer 6

Enterotoxigenic E. coli (ETEC)

overactivates guanylate cyclase–> decrease reabsorption of NaCl and H2 in gut–> watery diarrhea

Question 7

edema factor

Answer 7

Bacillus anthracis

mimics adenylate cyclase enzyme

Question 8

cholera toxin

Answer 8

Vibrio cholerae
overactivates adenylate cyclase by permanently activating Gs–> increase Cl- secretion in gut and H2 efflux–> rice-water diarrhea

Question 9

pertussis toxin

Answer 9

Bordetella pertussis
overactivates adenylate cyclase by disabling Gi–> impair phagocytosis
Whooping cough

Question 10

tetanospasmin

Answer 10

Clostridium tetani
protease that cleaves SNARE proteins required for neurotransmitter release
prevents release of GABA and glycine from Renshaw cells in spinal cord–> lockjaw, spasticity

Question 11

botulinum toxin

Answer 11

Clostridium botulinum
protease that cleaves SNARE proteins required for neurotransmitter release
prevents release of ACh at neuromuscular junction–> flaccid paralysis

Question 12

alpha toxin

Answer 12

Clostridium perfringens
phospholipase (lecithinase) degrades tissue and cell membranes–> myonecrosis and hemolysis
gas gangrene

Question 13

streptolysin O

Answer 13

Streptococcus pyogenes
degrades cell membrane
lyses RBCs, Beta hemolysis, diagnose rheumatic fever

Question 14

toxic shock syndrome toxin (TSST-1)

Answer 14

S. aureus
Bring MHC II and TCR close--> overwhelming release of IFN-gamma and IL-2--> shock
TSS: fever, rash, shock
exfoliate toxin: scalded skin syndrome
exotoxin: food poisoning

Question 15

exotoxin A

Answer 15

S. pyogenes
Bring MHC II and TCR close–> overwhelming release of IFN-gamma and IL-2–> shock
TSS: fever, rash, shock