Microbiology: Enteric Bugs - Bacteria 3

Question 1

Gram+ “Boxcar” bacilli. Found in colon, produce spores, and found on surface of unrefrigerated meats, what are they?

Answer 1

Clostridium perfringens

Question 2

How common are C. perfringens infections and how in what populations are they more common?

Answer 2

3rd most common food borne illness in US

Found more commonly in diabetics

Question 3

What diseases can be caused by C. perfringens?

Answer 3

Gas gangrene

Anaerobic cellulitis

Question 4

What is the pathogenesis of C. perfringens infections?

Answer 4

alpha-PLC, collagenases, proteases –> Chew through tissue –> Gas –> Muscle necrosis and spread –> Shock, renal failure, Death

Question 5

What is the pathogenesis of C. perfringens food poisoning?

Answer 5

spore germinates on meat –> toxin production (enterotoxin) –> Non-inflammatory watery diarrhea (8-12 hrs)

No vomiting, No fever

Question 6

What is the treatment for C. perfringens infections?

Answer 6

1. Surgery/maggots for Gas gangrene
2. antibiotics (Penicillin + protein inhibitor)
3. Hyperbaric oxygen

Recovery usually occurs within 24 hours.

Question 7

G+ “tennis rackets” / “lollipops” / “drum sticks”

Found in spores / GI tract / contamination of wounds?

Answer 7

Clostridium Tetani

Question 8

What is the presentation of C. tetani infection?

Answer 8

1-2 weeks post exposure –> Lockjaw + Risus sardonicus + muscle spasms + exhaustion

Question 9

How is C. tetani contracted?

Answer 9

Spore containing rusty nail penetrates skin.

Question 10

What is the pathogenesis of C. tetani?

Answer 10

AB neurotoxin –> enters NMJ –> travels retrograde to ganglia –> clips V-SNARE –> No release of inhibitory GABA + Glycine –> constant muscle stimulation

Question 11

What are the virulence factors for C. tetani?

Answer 11

Tetanospasmin (AB neurotoxin, plasmid encoded)

Question 12

What is the treatment of C. tetani?

Answer 12

Antibiotics don’t work (exotoxin mediated)

1. sedative
2. Anti-tetanus Immunoglobulin (HTIG)
3. Vaccine for wound management

Question 13

What is the vaccine for C. tetani?

Answer 13

Formalin inactivated toxin

patient < 7 = DTaP
Patient 10-64 = TdaP

Question 14

Anaerobic, gram+, spore forming bacilli, found in canned food, wounds, and honey?

Answer 14

Clostridium botulinum

Question 15

What is the presentation of C. botulinum?

Answer 15

Descending flaccid paralysis + No fever + clear sensorium

Nausea, dry mouth, diarrhea –> double vision, dysphagia –> Respiratory failure, death (takes about 12-36 hours)

Question 16

How is C. botulinum contracted?

Answer 16

consumption of contaminated canned foods, honey, or contact with infected wound or carpet.

Question 17

What is the pathogenesis of C. botulinum infection?

Answer 17

Botulinum toxin is a metalloproteinase that cleaves T-Snare + V-snares. This leads to decreased Ach release and flaccid paralysis

Question 18

What is the treatment for C. botulinum?

Answer 18

1. Ventilation
2. Horse anti-botulism Ig
3. Vaccine for military only