Ch. 39 - Clostridium

Question 0

Clostridium perfringens

Answer 0

Large boxcar G+b

Spores are rare

Double zone of beta hem

5 types a-e subdivided by toxin

non-motile

Gastroenteritis, myonecrosis, gas gangrene

Virulence: toxins and enzymes

• alpha toxin - massive hemolysis
  Type a produces the most alpha toxin

Enterotoxin - mainly type a; heat labile; acts as superantigen

Beta, epsilon, iota toxins

Diagnosis: G+b no WBC

Question 1

Clostridium

Answer 1

Anaerobic spore-forming G+b

Some are aero tolerant
Some rarely form spores
Some stain G-

Soil, water, sewage, normal GI flora

Question 2

Clostridium perfringens disease

Answer 2

Soft tissue: cellulitis (with gas formation), fasciitis (supprative myositis) (no necrosis), myonecrosis

Food poisoning - intoxication not infection
From ingestion of cont meat (enterotoxin) (spores)

Septicemia - isolation in blood culture could be due to contamination (skin flora)

Question 3

Clostridium tetani

Answer 3

Large motile spore-forming G+b

Terminal spores (tennis racket)

Very oxygen sensitive

No colonies, film over agar

Don’t ferment carbs

2 toxins: O2 labile hemolysin tetanolysin (unknown function) and heat labile neurotoxin tetanospasmin (clinical manifestation of tetanus)

Toxins bind too quickly to neurons to detect in the blood

Treatment: debridement of wound, immunization with tetanus Ig, and vaccination with tetanus toxoid

Question 4

Clostridium tetani disease

Answer 4

Spastic paralysis

Tetanus: incubation period is directly related to the distance of wound infection to CNS

Generalized tetanus: lockjaw; characteristic smile

Localized tetanus: disease remains confined to muscles at site of primary infection

Neonatal tetanus: initial infection is umbilical stump; 90% mortality rate

Question 5

Clostridium botulinum

Answer 5

Large, fastidious spore-forming anaerobic G+b

4 groups
7 botulinum toxins a-g
Causes botulism

Soil and water; some food borne (home canned foods)

Question 6

Botulinum toxin

Answer 6

By C. botulinum

A-B complexed with nontoxin proteins that protect toxin thru GI

Toxin remains in NMJ

Inactivates the proteins that activate ACh (needed for excitation of muscle)

Question 7

C. botulinum disease

Answer 7

Foodborne botulism (bilateral weakness of peripheral muscles)

Infant botulism (lack of competitive flora in infant GI tracts) (failure to thrive)

Wound botulism (similar to foodborne)

Question 8

Clostridium difficile

Answer 8

Normal GI flora; causes disease when normal enteric flora is eliminated

Antib associated disease

Self limiting to severe pseudomembranous colitis

Enterotoxin a (release of cytokines and diarrhea)

Cytotoxin b (destroys cellular cytoskeleton)

Question 9

Tetanospasmin

Answer 9

C. tetani toxin that binds to motor neurons and blocks glycine release in the spinal cord

Toxins bind too quickly to neurons to detect in the blood

Antitoxin binds free tetanospasmin