Lecture 33: Neurotoxins

Question 1

What are the 3 types of botulism?

Answer 1

1. Food Poisoning Botulism
2. Wound Botulism
3. Infant Botulism

Question 2

Which types of botulism can human get?

Answer 2

Types A, B, or E

Question 3

What is required to get sick from food botulism: the bacteria, the toxin, or both?

Answer 3

Just the toxin

Question 4

What bacteria genus are both botulism and tetanus a member of?

Answer 4

Clostridium

Question 5

What are the steps of botulism pathogenesis?

Answer 5

1. Spores contaminate spiced, smoked, vacuum-paced, or canned foods
2. Spores germinate
3. Vegetative form grows in anaerobic conditions and produces toxin
4. Food consumed; toxin absorbed from stomach and small bowel

Question 6

Why can’t adults get infant botulism?

Answer 6

Spores cannot become rods in adults’ GI tract

Question 7

What is the common mechanism in all 3 forms of botulism?

Answer 7

Toxin interferes with the release of the neurotransmitter acetylcholine at neuromuscular junctions

Question 8

What is the physical result of botulism?

Answer 8

Flaccid paralysis

Question 9

What metal is associated with botulism?

Answer 9

BoNT (Botulinum NeroToxin) is a zinc-dependent endoprotease that cleaves a component of the neurosecretory apparatus such as a vesicle-associated membrane protein

Question 10

Through what mechanism does both botulism and tetanus attack a cell?

Answer 10

1. Toxin is single protein that contain A and B domains that enter the cell through receptor-mediated endocytosis
2. B domain binds to receptors on the surface of neurons
3. A domain is protease that cleaves intracellular proteins responsible for fusion of intracellular synaptic vesicles with plasma membrane

Question 11

Botulism and tetanus are examples of: endotoxins, exotoxins, or exoenzymes?

Answer 11

Exotoxin - toxin is secreted into surrounding medium, attach to receptor on host cells, and are endocytosed

Question 12

What is the physical result of tetanus?

Answer 12

Spastic paralysis - muscles contract uncontrollably

Question 13

What treatments are appropriate for botulism?

Answer 13

Heptavalent antitoxin (expect hypersensitivity), parenteral nutrition, possible respirator

Question 14

How can botulism be prevented?

Answer 14

Proper canning methods

Question 15

What treatments are appropriate for tetanus?

Answer 15

Antitoxin ASAP (may be futile since toxin would be already irreversibly fixed to nerve cells)

Question 16

How can tetanus be prevented?

Answer 16

Immunization (i.e. DPT shot); not the actual toxin (too deadly), but a similar compound to stimulate immune response