• Clinical science

Gas gangrene

Abstract

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
  • Path of infection
    • Ubiquitous clostridial spores contaminate the wound
    • Wounds with compromised blood supply create an anaerobic environment → optimal for the proliferation of C. perfringensnecrosis progresses within 24–36 hours. Such wounds include:

Pathophysiology

Ubiquitous C. perfringens spores contaminate a wound → bacteria reproduce under anaerobic wound conditions → these bacteria secrete exotoxins; , especially alpha toxin, a phospholipase → degrades phospholipids → tissue destruction, inhibition of leukocyte function, and gas production → the gas separates healthy tissue, which facilitates further colonization and causes more local tissue destruction → anaerobic conditions are further exacerbated by the development of edema

Clinical features

  • Incubation period: hours to days
  • Local signs and symptoms
    • Spreading infection (see classic signs of inflammation)
    • Excruciating muscle pain
    • Massive edema with bronze → red-purple → black skin discoloration and overlying bullae
    • Sweet, foul-smelling, or nonodorous discharge produced by anaerobic metabolic products
    • Crepitus
  • Systemic toxicity
    • Can progress to systemic infection within a few hours
    • Early signs: fever, tachycardia, altered mental status
    • Late signs: shock,; hemolytic anemia, ARDS, kidney and liver failure, multi-organ failure [1][2]

Gas gangrene is a medical emergency that can rapidly progress to a severe clinical course with multi-organ failure!

Diagnostics

  • Imaging: radiography, CT, or MRI typically show a characteristic feathering pattern of the soft tissue.
  • Laboratory tests
    • Gram staining: large, gram-variable rods
    • Blood cultures (although only 1% are positive)
    • 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
      • Myonecrosis and destruction of surrounding degenerative tissue(muscle, skin fat, subcutaneous tissue)
      • Presence of organisms; without inflammatory infiltrate [1]

Differential diagnoses

  • Necrotizing fasciitis
  • Vibrio vulnificus infection
    • May occur after an open wound is exposed to seawater contaminated with V. vulnificus
    • Gram stain and culture to distinguish (V. vulnificus is gram-negative)
  • Group A Streptococcus infection
  • Rhabdomyolysis [1]
  • Pyomyositis

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.

[1][3]

Prognosis