Sunday, March 24, 2013

Bugs With Exotoxines

Q1: Patient develops an infection in the legs after a car accident. Physical exam shows crepitus of the tissue of the legs. Which Clostridium toxin produce these findings?
A1: Alpha toxin.

  • A = Active ADP ribosyl / B = Binding receptor
  •  Bugs:
    1. Corynebacterium diphteriae (inactive EF-2) = Pseudomona exotoxin A
    2. Bordetella pertusis (disables Gi -> increases AMPc).
    3. Escherichia coli (heat labil & heat stable toxins) = Stimulator
    4. Vibrio cholerae (actives Gs -> stimulates Adenylate cyclase)
Binds to MHC-II & T-cell receptors, stimulates IFN-Y, and IL-2
  • Staphylococcus aureus, TSST-1
  • Streptococcus pyogenes
  • Clostridium:
    1. DIfficile (DIarrhea), citotoxin kills enterocytes
    2. PERfringens (PERforate), Alpha toxin (lecithinase) ->gangrene
    3. tetani, block release GABA and Glycine
    4. BOTulinum, (BOTtle), block release Ach - floppy baby
  • Bacillus anthracis, edema factor (adenylate cyclase) - inhibit phagocytosis
  • Shigella, shiga toxin (inactive 60s ribosome) causes HUS
Q2: Patient to begins to experience bloody diarrhea a few days after eating at a fast food restaurant. Patient is treated with plasmapheresis and eventually recovers from acute renal failure. Which mechanisms is used by the toxin?
A2: Inactivation ribosome unit 60S.

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