Clostridial myonecrosis (gas gangrene)
Gangrene refers to death of tissue, and myonecrosis refers specifically to muscle. Clostridial infection of wounds may result in significant infection of muscle, which develops rapidly and is potentially life-threatening.
The most common cause is Clostridium perfringens found in soil and in the faeces of animals and humans. Infection occurs after deep penetrating trauma. Compromise of the blood supply as a result of the traumatic damage or as a result of longstanding vascular disease, creates an acidic anaerobic environment and facilitates bacterial proliferation. It is thought thatτ -toxin pro-duced by Clostridium prevents the normal inflammatory cell infiltration and therefore allows the infection to spread rapidly causing extensive necrosis. α-toxin has a direct negative inotropic effect on the heart and may lead to shock.
Patients develop severe pain due to myonecrosis at a site of trauma with induration, blistering and oedema. In a limb distal pulses may be lost and crepitus is felt in the muscle late in the disease process. Systemic signs include pyrexia, tachycardia, progressing to multiorgan failure.
Imaging may allow detection of gas in muscle too deep for palpation (crepitus on palpation is as sensitive in superficial muscle).
Diagnosis is confirmed by identifying clostridia in the wound.
Prevention of clostridial infections involves adequate wound care at the time of original trauma including excision and debridement of necrotic tissue. Wounds that may be infected should not undergo primary closure. In established cases penicillin is the drug of choice. Aggressive surgical intervention with wide excision, opening of fascial compartments, and meticulous debridement of all necrotic tissue is essential. This may require subsequent reconstruction and skin grafting. The use of hyperbaric oxygen (HBO) to reduce anaerobic conditions is controversial.