Exotoxins & Endotoxins

Question 1

Corynebacterium diphtheriae

Answer 1

(X) DIPHTHERIA TOXIN: inactivates EF-2

pharyngitis with pseudomembranes in throat and severe LAD (bull neck)

Question 2

Pseudomonas aeruginosa

Answer 2

(X) EXOTOXIN A: inactivates EF-2

host cell death

Question 3

Shigella

Answer 3

(X) SHIGA TOXIN: inactivates 60S ribosome by removing adenine from rRNA

GI mucosal damage = dysentery
enhances cytokine release = HUS

Question 4

EHEC

Answer 4

(X) SHIGA-LIKE TOXIN: inactivates 60S ribosome by removing adenine from rRNA

enhances cytokine release = HUS
DOES NOT invade host cells

Question 5

name 4 that inhibit protein synthesis with exotoxin

Answer 5

Corynebacterium diphtheriae
Pseudomonas aeruginosa
Shigella
EHEC

Question 6

name 3 that increase fluid secretion with exotoxin

Answer 6

ETEC
Bacillus anthracis
Vibrio cholerae

Question 7

ETEC

Answer 7

(X)
1. HEAT-LABILE TOXIN (aka cholera-like toxin): overactivates AC, increasing cAMP = increase Cl secretion in gut and H2O efflux

2. HEAT-STABILE TOXIN: overactivates GC, increasing cGMP = decrease resorption of NaCl and H2O in gut

watery diarrhea

Question 8

Bacillus anthracis

Answer 8

(X) EDEMA FACTOR: mimics adenylate cyclase = increase cAMP

edematous borders of black eschar in cutaneous anthrax

Question 9

Vibrio cholera

Answer 9

(X) CHOLERA TOXIN: overactivates AC by permanently activating Gs = increase Cl secretion in gut and H2O efflux

voluminous rice-water diarrhea

Question 10

name 1 that inhibits phagocytic ability with exotoxin

Answer 10

Bordetella pertussis

Question 11

Bordetella pertussis

Answer 11

(X) PERTUSSIS TOXIN: overactivates AC by disabling Gi = impairs phagocytosis of microbe

whooping cough

Question 12

name 2 that inhibit release of neurotransmitter with exotoxin

Answer 12

Clostridium tetani

Clostridium botulinum

Question 13

Clostridium tetani

Answer 13

(X) TETANOSPASMIN: cleave SNARE protein, which is required for NT release

muscle rigidity and lock jaw
toxin prevents release of inhibitory NTs in spinal cord (GABA, glycine)

Question 14

Clostridium botulinum

Answer 14

(X) BOTULINUM TOXIN: cleave SNARE protein, which is required for NT release

flaccid paralysis, floppy baby
toxin prevents release of stimulatory NTs at NMJ (ACh)

Question 15

name 2 that lyse cell membranes with exotoxin

Answer 15

Clostridium perfringens

Streptococcus pyogenes

Question 16

Clostridium perfringens

Answer 16

(X) ALPHA TOXIN: phospholipase that degrades tissue and cell membranes

degradation of phospholipid C = myonecrosis (gas gangrene) and hemolysis (double zone of hemolysis on blood agar)

Question 17

Streptococcus pyogenes

Answer 17

(X) STREPTOLYSIN O: protein that degrades cell membrane

lyses RBCs
contributes to B-hemolysis
ASO used to diagnose rheumatic fever

Question 18

name 2 that act as superantigens causing shock with exotoxin

Answer 18

Staphylococcus aureus

Streptococcus pyogenes

Question 19

Staphylococcus aureus

Answer 19

(X) bring MHC II and TCR in proximity to outside of Ag binding site, resulting in polyclonal T cell activation and overwhelming release of IFN-y and IL2 => shock

1. TOXIN SHOCK SYNDROME TOXIN (TSST-1): TSS: fever, rash, vomiting, desquamation, shock, end-organ failure
2. EXFOLIATIVE TOXIN: scalded skin syndrome
3. ENTEROTOXIN: food poisoning

Question 20

Streptococcus pyogenes

Answer 20

(X) EXOTOXIN A: bring MHC II and TCR in proximity to outside of Ag binding site to cause overwhelming release of IFN-y and IL2 => shock

TSS

Question 21

ENDOTOXIN

Answer 21

LPS in outer membrane of Gr(-)
(LIPID A especially)

Edema
Nitric oxide
DIC/Death
Outer membrane
TNF-a
O-antigen
eXtremely heat stable
IL-1
Neutrophil chemotaxis

Question 22

endotoxin - name 3 that activates macrophages

Answer 22

1. NITRIC OXIDE = hypotension
2. IL-1 = fever
3. TNF-a = fever, hypotension

Question 23

endotoxin - name 2 that activate complement

Answer 23

1. C3a = hypotension, edema

2. C5a = neutrophil chemotaxis

Question 24

endotoxin - name 1 that activates tissue factor

Answer 24

coagulation cascade = DIC