• Clinical science

Gas gangrene (Clostridial myonecrosis)

Summary

Gas gangrene (also known as clostridial myonecrosis) is a life-threatening necrotizing soft tissue infection commonly caused by the rapid proliferation and spread of Clostridium perfringens from a contaminated wound. The clinical picture includes excruciating muscle pain, edema with subsequent skin discoloration (red-purple to black) and gas production. Crepitus, as well as a feathering pattern of gas in soft tissue imaging, are generally present. Without treatment, gas gangrene is fatal in almost 100% of cases. Surgical debridement in combination with antibiotic therapy reduces this figure by half.

Etiology

  • Pathogen
    • Clostridium perfringens (> 80% of cases): a gram-positive, obligate anaerobic, spore-forming bacterium
    • Less common: C. septicum , C. histolyticum
  • Path of infection: wounds with compromised blood supply create an optimal anaerobic environment for the proliferation of C. perfringens necrosis that progresses within 24–36 hours

Pathophysiology

Ubiquitous C. perfringens spores contaminate a wound → bacterial reproduction under anaerobic conditions ↑ secretion of exotoxins, especially C. perfringens alpha-toxin (a phospholipase lecithinase) → degradation of phospholipids → tissue destruction (myonecrosis), inhibition of leukocyte function, and gas production gas separation into healthy tissue → further colonization and more local tissue destruction further exacerbation of anaerobic conditions by the development of edema

Clinical features

Gas gangrene is a medical emergency that can rapidly progress to multi-organ failure.

Perfringens perforates: C. perfringens causes gas gangrene that leads to severe tissue damage.

Diagnostics

  • Imaging: Radiography, CT, or MRI typically show a characteristic feathering pattern of the soft tissue.
  • Laboratory tests
    • Gram staining: large, gram-positive rods
    • Wound culture: double zone of hemolysis on blood agar
    • Blood cultures
    • PCR or ELISA for detection of toxin in wound material (not widely available)
  • Surgical exploration
    • Affected muscle does not bleed or contract, and may be pale or discolored red-purple to black.
    • Histopathological findings of biopsy [1]
      • Myonecrosis and destruction of surrounding degenerative tissue (muscle, skin fat, subcutaneous tissue)
      • Presence of pathogens; without inflammatory infiltrate


Differential diagnoses

The differential diagnoses listed here are not exhaustive.

Treatment

The most important steps of management are immediate surgical debridement and antibiotic therapy. Patients should receive supportive therapy and intensive care.

References:[1]

Prognosis

  • Mortality rate [3]
    • Untreated: ∼ 100%
    • With appropriate treatment: 20–30%