Bacteria Exotoxins

Question 1

ADP ribosylating AB Toxin Mechanism (I’ll denote this by a)

Answer 1

B (binding) component binds to host cell surface receptor, enabling endocytosis
Then the A (active) component attaches ADP-ribosyl to disrupt host cell proteins

Question 2

Corynebacterium diptheriae Toxin and Mechanism

Answer 2

Diphtheria toxin (a)
Inactivates elongation factor (EF2) thus inhibiting protein synthesis

Question 3

Pseudomonas aeruginosa Toxin and Mechanism

Answer 3

Exotoxin A (a)
Inactivates elongation factor (EF2) thus inhibiting protein synthesis

Question 4

Shigella Toxin and Mechanism

Answer 4

Shiga toxin (a)
Inactivates 60S ribosome thus inhibiting protein synthesis
Can cause HUS

Question 5

Shigella Toxin, Mechanism, and Manifestation

Answer 5

Shiga toxin (a)
Inactivates 60S ribosome thus inhibiting protein synthesis
Mucosal damage causes dystentery and the enhanced cytokine release causes HUS

Question 6

EHEC Toxin, Mechanism, and Manifestation

Answer 6

Shiga-like toxin (a)
Inactivates 60S ribosome thus inhibiting protein synthesis
Enhances cytokine release, causing HUS (does not invade host cells like Shigella)

Question 7

ETEC Toxins, Mechanism, and Manifestation

Answer 7

Heat labile toxin (a) overactivates adenylate cyclase
Heat stabile toxin overactivates guanylate cyclase
Both lead to watery diarrhea

Question 8

Bacillus anthracis Toxin and Mechanism

Answer 8

Edema factor

Mimics the adenylate cyclase, thus increasing fluid secretion

Question 9

Vibrio cholerae toxin, Mechanism, and Manifestation

Answer 9

Cholera toxin (a)
Overactivates adenylate cyclase by activating Gs, thus causing rice water diarrhea

Question 10

B. pertussis toxin and Mechanism

Answer 10

Pertussis toxin (a)
Overactives adenylate cyclase by DISABLING Gi, thus impairing phagocytosis to permit survival of microbe

Question 11

B. pertussis toxin and Mechanism

Answer 11

Pertussis toxin (a)
Overactives adenylate cyclase by DISABLING Gi, thus impairing phagocytosis to permit survival of microbe

Question 12

Clostridium tetani and botulinum Toxins and Mechanisms

Answer 12

Cleave SNARE Proteins required for neurotransmitter release

Question 13

Clostridium perfringens Toxin, Mechanism, and Manifestations

Answer 13

Alpha toxin
Phospholipase that degrades tissues and cell membranes
Thus causes myonecrosis (gas gangrene and hemolysis)

Question 14

Streptococcus pyogenes Toxin, Mechanism, Manifestation, and Clinical Use

Answer 14

Streptolysin O
Protein that degrades cell membrane
Thus lyses RBCs
Antibodies against it used to diagnose rheumtaic fever

Question 15

S. aureus and S. pyogenes Toxins (that cause shock) and Mechanisms

Answer 15

S. aureus: TSST-1
S. pyogenes: Exotoxin A
Mechanism: Bring MHCII and TCR in proximity to outside of antigen binding site to cause overwhelming release of IFNgamma and IL2