Clostridium perfringens (anaerobic)

Question 1

Diseases

Answer 1

2 Diseases

1) gas gangrene
2) food poisoning

depends on body entry route.

Question 2

Disease: Gas Gangrene

Answer 2

(myonecrosis, necrotizing fasciitis)

• Also by C.histolyticum, C. septicum, C. novyi, & C.sordellii (causes TSS in postpartum & postabortion women).

Question 3

Transmission: Gas Gangrene

Answer 3

• Spores in soil
• vegetative cells members
  of colon & vagina normal flora.
• war wounds, automobile & motorcycle accidents, & septic abortions (endometritis).

Question 4

Pathogenesis: Gas Gangrene

Answer 4

• grow in traumatized tissue (muscle) & produce alpha toxin (lecithinase)-> damages cell membranes + erythrocytes-> hemolysis.
• Degradative enzymes produce gas in tissues.

Question 5

Clinical Findings: Gas Gangrene

Answer 5

• Pain, edema, cellulitis, & gangrene (necrosis) occur in wound area.
• crepitus palpated in
  affected tissue-> hydrogen gas in tissue produced by anaerobic bacteria.
• Hemolysis & jaundice blood-tinged exudates-> Shock & death.
• High Mortality rates.

Question 6

Laboratory Diagnosis

Answer 6

• Tissue Smears & exudate samples -> large gram-positive rods.
• Spores not seen-> formed under nutritionally deficient conditions.
• cultured anaerobically-> identified by sugar fermentation reactions & organic acid production.

Colonies exhibit double
zone of hemolysis on blood agar & produce precipitate in egg yolk agar by action of lecithinase.

Serologic tests not useful.

Question 7

Treatment

Answer 7

• Penicillin G
• Wounds debrided.

Question 8

Prevention

Answer 8

• Wounds cleansed & debrided.
• Penicillin->prophylaxis.
• no vaccine.

Question 9

Transmission: Food Poisoning

Answer 9

• Spores in soil & contaminate food.
• heat-resistant spores survive cooking & germinate.
• organisms grow to large numbers in reheated foods
  (meat dishes).

Question 10

Pathogenesis

Answer 10

• normal flora in colon but not in small bowel, where enterotoxin acts-> diarrhea.
• enterotoxin action same as S.aureus (superantigen).

Question 11

Laboratory Diagnosis: Food Poisoning

Answer 11

• not done.
• no assay for toxin.
• Large numbers isolated from uneaten food.

Question 12

Clinical Findings: Food Poisoning

Answer 12

• 8- to 16-hour incubation period
• watery diarrhea with cramps & little vomiting.
• resolves in 24 hours.

Question 13

Treatment: Food Poisoning

Answer 13

Symptomatic

Question 14

Prevention: Food Poisoning

Answer 14

Adequately cooked food to kill organism.