Toxin review

Question 1

C botulinum toxin

Answer 1

Botulinum
- multiple antigenic types
Neurotoxin:
- NMJ -> blocks Ach release -> flaccid paralysis

Antitoxin (specific for type)

Question 2

C tetani toxin

Answer 2

Tetanus - single antigen
Neurotoxin:
- retrograde -> blocks glycine release from inhibitory neurons -> spastic paralysis

Toxoid vaccine
Antitoxin

Question 3

C perfringens toxin

Answer 3

Alpha toxin

Lecithinase -> disrupts cell membrane -> gas gangrene, necrosis

Antitoxin effective?

Question 4

C difficile toxins

Answer 4

TcdA, TcdB

Cytotoxins:
depolymerize actin -> disrupts tight jx -> pseudomembrane, watery diarrhea

Question 5

Corynebacterium diphtherae toxin

Answer 5

Diphtheria toxin

Inhibits protein synthesis (ADP ribosylation of EF2) -> kills cells -> pseudomembrane

Toxoid vaccine

Question 6

Pseudomonas aeruginosa toxins

Answer 6

Exotoxin A - similar to diphtheria -> kills cells

T3SS (Exo U, S, T) -> kills cells

Phospholipase C -> lysis

Phenazines -> inflammation

Question 7

Staph aureus toxins

Answer 7

Alpha toxin
Lytic pores in membrane
 -> beta hemolytic
-> smooth muscle paralysis
-> local necrosis

Only present in some strains:

Enterotoxin = superantigen -> n/v/d
Toxic Shock toxin = superantigen -> IL1, IL2, TNF
Exfoliatin = protease -> desquamation (scalded skin)

Question 8

Strep pyogenes toxins

Answer 8

Erythrogenic:
superantigen -> rash (scarlet fever)
carried by lysogenic phage

Pyrogenic exotoxin A
superantigen -> TSS
(related to erythrogenic)

Question 9

V cholerae toxin

Answer 9

Cholera

Adenylate cyclase -> massive diarrhea

Question 10

E coli toxins

Answer 10

Only produced by some strains

Enterotoxigenic
Heat labile = identical to cholera
Heat stable -> guanylate cyclase -> diarrhea

Enterohemorrhagic (STEC)
Shiga toxin -> bloody diarrhea, hemolytic uremic syndrome
Undercooked hamburger, cow shit

Question 11

Shigella dysenteria toxin

Answer 11

Shiga toxin
Inhibits protein synthesis (60S ribosome) -> kills cells
-> dysentery (mechanism unclear)

Question 12

Bordetella pertussis toxin

Answer 12

Pertussis toxin
Adenylate cyclase -> whooping couch

Toxoid vaccine

Question 13

Bacillus anthracis toxins

Answer 13

Edema factor -> adenylate cyclase -> edema
Lethal factor -> protease -> inhibits cell division
Protective antigen - binds edema and lethal to cells

Toxoid vaccine = protective antigen