Introduction
Gas gangrene (Clostridial myonecrosis) is a rapidly progressive, life-threatening necrotizing infection of soft tissue and muscle, caused predominantly by Clostridium perfringens and other clostridial species under anaerobic conditions.
Causative Agents
- Primary: Clostridium perfringens (Type A)
- Others:
- Clostridium septicum
- Clostridium novyi
- Clostridium histolyticum
- Clostridium fallax
- Clostridium bifermentans
- Clostridium sporogenes
- Non-clostridial contributors:
- Anaerobic streptococci
- Bacteroides spp.
- Proteus, E. coli, Staphylococcus (facultative anaerobes)
Clinical Features
- Local symptoms:
- Pain (even before skin changes)
- Swelling, edema
- Bullae, vesicles, purplish discoloration
- Foul-smelling serosanguinous discharge
- Crepitus on palpation (gas in tissue)
- Systemic:
- Tachycardia, hypotension
- Fever, septic shock
- Organ failure if untreated
Laboratory Diagnosis
Specimens:
- Deep muscle tissue near necrosis
- Wound exudate
- Necrotic tissue
Microscopy:
- Few or no pus cells
- Gram-positive boxcar-shaped rods (± spores)
Culture:
- Media: Schaedler, blood agar, thioglycollate broth
- On blood agar: C. perfringens shows double zone hemolysis
- Anaerobic methods: GasPak, McIntosh-Fildes jar, Fortner’s method
Toxin Testing:
- Nagler reaction (egg yolk medium + antitoxin neutralization) for alpha toxin
- Enzyme immunoassays for toxins A & B