Gas Gangrene

• AKA Clostridial Myonecrosis

Definition

• Life threatening, rapidly progressive, necrotising, gas-producing infection of skeletal muscle due to Clostridia
• Characterised by
  • Massive muscle necrosis
  • Gas production
  • Due to invasive anaerobic Clostridial infection
• Clostridial infections are
  • Cl perfringens (welchii)
    • gas gangrene
  • Cl tetani
    • tetanus
  • Cl botulinum
    • botulism
  • Cl difficile
    • pseudomembranous colitis

Epidemiology

• Seen with
  • Open fractures
  • Penetrating wounds
  • War & farmyard wounds
  • Arterial insufficiency in an extremity
  • Surgical wounds
    • Bowel & Biliary surgery
    • Poor technique
• USA 1000 cases/ year
• 0.05% of open fractures
• Need 3 things
  • Necrotic tissue
  • Especially buttock & thigh
    • Ischaemia with low PO2
  • Contamination with Clostridium perfringens or other histotoxic Clostridia
• Greatly ↑ by
  • Poor debridement
  • Poor antibiotics
  • Primary wound closure

Aetiology

• Clostridium perfringens (welchii) 80%
• Clostridium novyi 15%
• Clostridium septicum 5%

Clostridium Perfringens

• Large gram positive bacillus
• Non-motile
• Encapsulated
• Obligate anaerobe
• Produces spores
• Found in soil & faeces
• Ubiquitous
  • 20% of patients skin
  • Saprophytic commensal of GIT
  • Theatres & A&E

Exotoxins (Histotoxins)

• Production of large variety of toxins/ enzymes that result in myofascial spread
• Necrotising & Haemolysing nature
• Proteolytic or Sacrolytic
  • Based on Nagler reaction
• Sweet or foul odour
• 9 types
  • Most important is Alpha Toxin (Lecithinase)
  • Others include
    • Haemolysin
    • Collagenase
    • Hyaluronidase
    • Leucocidin
    • Deoxyribonuclease
    • Protease
    • Lipase

Vicious Cycle

• Necrotic closed wound is contaminated
• Clostridium colonization
• Low PO2
• Production of histotoxins
• Destruction of cell wall
• Local tissue death
• Further colonization
• Overwhelms WBC
• Further tissue destruction

Pathology

• Involved muscle rapidly undergoes disintegration & necrosis
• Initially pale, swollen & inelastic
• Later becomes discoloured & friable
  • Reddish purple then
  • Greenish purple & gangrenous
• Gas in tissues
• Histology shows coagulation necrosis

Clinical Features

• Incubation
• Usually ~ 2-3/7
• Can be as short as 6/24

Symptoms

• History muscle penetrating injury
• Earliest & most sensitive symptom is pain
  • Pain/ heaviness out of proportion to injury or procedure
• Initially alert & anxious
• Later fearful of death

Signs

• General
  • Pale & sweaty
  • Moderate fever
  • Marked tachycardia
  • Hypotension & shock follows
  • Delirium » Stupor » Coma » Death
• Wound
  • Early
    • Skin swollen & white
    • Tense oedema & local tenderness
    • Serosanguinous & brown discharge
    • Foul or Sweet odour
    • ± Crepitus due to gas
    • Progress over 2-4 hours with advancing crepitus & oedema
  • Later
    • Bronze discolouration
    • Blebs containing dark fluid
    • Areas of green-black cutaneous necrosis

Investigations

• Clinical diagnosis only

Laboratory

• Positive blood culture in 15%
• Gram-stain of exudate
  • Not diagnostic
  • Many organisms » Large gram positive rods
  • But few leukocytes & no spores
• Positive Nagler’s test
  • Lecithinase turns egg yolk opaque in agar

X-ray

• Gaseous distension of muscle & fascial planes

Differential Diagnosis

• Pain with myonecrosis is the key

Anaerobic Clostridial Cellulitis

• Clostridial infection of necrotic soft tissue
  • Onset > 3/7
  • Poorly debrided wound
• Gradual onset
• Slight toxaemia & no pain
• Slight brown, seropurulent exudate
• No skin lesions
• Foul gas +++
  • More than Clostridium myonecrosis
• No muscle invasion

Streptococcal Myonecrosis

• Group A ß Haemolytic Streptococcus
  • S pyogenes
  • “Flesh-eating bug”
• Similar to Clostridium myonecrosis
  • Longer incubation period (> 3/7)
  • Characteristic pain not present
  • Little gas formation & profuse seropurulent discharge

Infected Vascular Gangrene

• Due to saprophytic Clostridia
• Proliferates & produces gas
• Gangrenous muscle
• Line of demarcation
• No acute toxaemia
• Can develop into Clostridial myonecrosis

Other Gas-Producing Organisms

• Coliform Bacteria
• Anaerobic Streptococcus
• Anaerobic Bacteroids

Prophylaxis

• Awareness
  • Open fractures
  • Deep penetrating injuries – buttock / thigh
• Early meticulous surgical debridement
• Leave wound open with no pack
• Appropriate AB
  • Cephalothin
  • + Gentamicin if extensive
  • + Penicillin if farmyard, crush or vascular injury

Management

Surgery

• Most important
• Delay » Death
• Emergency exploration
• Examine muscles directly
  • Differentiate Myonecrosis from anaerobic Cellulitis (crepitant cellulitis)
• Appropriate debridement
  • Radical myoexcision
  • Fasciotomies
  • ± Amputation

Antibiotics

• Penicillin G 3MU (1.8mg) q3h IVI
  • If allergic to penicillin
    • Metronidazole
    • Chloramphenicol
    • Tetracycline 2-4g/ day
  • Beware penicillin resistance (developing recently)
• Gentamicin for co-infection with other organisms
• Cephalosporins less effective

Resuscitation

• Fluid loss +++
• Prompt replacement
• Monitor fluid balance

Hyperbaric O2

• Controversial
• 3 atmospheres for 60-90 minutes every 8-12 hours for 4-6 sessions
• Appears to allow peroxides to develop & so destroy organism
  • Bacterostatic
  • Bacterocidal
• Also appears to neutralise clostridial toxin
• May reduce extent of debridement required
• Hazards
  • Barotrauma
  • Decompression sickness
  • Convulsions
  • Otitis media
  • Lung damage
• Useful where trunk involved
• Don’t delay debridement to transfer to hyperbaric chamber

Prognosis

• Mortality
  • WWI – 50%
  • WWII – 25%
  • 50% if reaches trunk

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.