Updated: 11/13/2019

Clostridium perfringens

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Snapshot
  • A 45-year-old man presents to the emergency room after stepping on a nail resulting in a puncture wound on his right foot. He was given a tetanus booster and he left against medical advice refusing antibiotics. Two days later, he returned to the emergency room for increasing pain in his right foot. Physical exam reveals dark purple and black discoloration of the right sole with multiple ruptured bullae oozing serous drainage. On palpation, there is soft tissue crepitus. A wound culture is sent, which shows gram-positive bacilli. He is started on the appropriate antibiotics immediately.
Introduction
  • Classification
    • Clostridium perfringens
      • anaerobic, spore-forming gram-positive bacillus
      • produces gas, exotoxin (alpha toxin), and enterotoxin
      • clinical syndromes
        • gas gangrene (exotoxin-mediated) 
          • necrotizing soft tissue infection
        • food poisoning (enterotoxin-mediated)
  • Epidemiology
    • incidence
      • low
    • risk factors
      • gas gangrene
        • traumatic open wounds
        • previous surgery
        • diabetes mellitus
        • peripheral vascular disease
        • alcoholism
        • frostbite
        • immunosuppression
      • food poisoning
        • reheated meat (spores that produce enterotoxin)
  • Pathogenesis 
    • forms spores, which lack metabolic activity and are highly resistant to both chemicals and heat
    • produces exotoxin alpha toxin 
      • a phospholipase or lecithinase that lyses cell membranes and tissues
      • causes myonecrosis or gas gangrene
    • when spores are ingested, bacteria release heat-labile enterotoxin and cause food poisoning
  • Prognosis
    • mortality up to 30% if treated
    • fatal if untreated
Presentation
  • Food poisoning
    • watery diarrhea
    • nausea
  • Gas gangrene 
    • erythema with purple-black discoloration of affected limb
      • soft tissue crepitus
        • indicates gas
      • bullae with serous drainage
    • increasing pain
Imaging
  • Computed tomography (CT)
    • indication
      • if diagnosis is unclear
    • findings
      • gas bubbles within soft tissues
Studies
  • Wound culture and Gram stain
    • gram-positive bacilli without polymorphonuclear cells
    • “stormy fermentation” in milk media
    • double zone of hemolysis on blood agar
  • Clostridium assay
    • detects neuraminidase produced by the bacteria
  • Making the diagnosis
    • based on clinical presentation
Differential
  • Cellulitis
    • distinguishing factor
      • typically does not present with dark colored skin, bullae, and crepitus
Treatment
  • Management approach
    • gas gangrene requires early treatment as it is a surgical emergency
    • food poisoning is typically self-limited and can be treated supportively
  • Medical
    • penicillin
      • indication
        • gas gangrene
        • first-line
    • clindamycin
      • indication
        • gas gangrene
        • patients allergic to penicillin
  • Operative
    • debridement
      • indication
        • gas gangrene
Complications
  • Gas gangrene
    • amputation
    • permanent disability
 

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(M1.MC.14.1) A microbiology student was given a swab containing an unknown bacteria taken from the wound of a soldier and asked to identify the causative agent. She determined that the bacteria was a gram-positive, spore-forming bacili, but had difficulty narrowing it down to the specific bacteria. The next test she performed was the Nagler's test, in which she grew the bacteria on a plate made from egg yolk, which would demonstrate the ability of the bacteria to hydrolyze phospholipids and produce an area of opacity. Half the plate contained a specific antitoxin which prevented hydrolysis of phospholipids while the other half did not contain any antitoxin. The bacteria produced an area of opacity only on half of the plate containing no antitoxin. Which of the following toxins was the antitoxin targeting? Tested Concept

QID: 106316
FIGURES:
1

Alpha toxin

70%

(30/43)

2

Tetanus toxin

14%

(6/43)

3

Botulinum toxin

2%

(1/43)

4

Exotoxin A

12%

(5/43)

5

Diphtheria toxin

0%

(0/43)

L 2 D

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