Necrotising fasciitis is a rapidly spreading infection of the subcutaneous tissues, with characteristic widespread fascial destruction. There may also be necrosis of the underlying muscle, depending on the organisms involved.

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It may be caused by single bacterial species (Clostridium perfringens or Group A Streptococci, Bacteroides and Staphylococcus aureus), or be polymicrobial.

Anaerobic organisms are often present in addition to aerobes and can form gas (gas gangrene). A saltwater variant also exists, in which a minor skin wound becomes infected with a vibrio species. All varieties are rapidly progressive, resulting in massive tissue loss, multiorgan failure and death if not rapidly treated with surgical debridement.

Initially diagnosis may be very difficult with presentations similar to cellulitis, and so a high clinical index of suspicion is required.

Predisposing factors

Groups at increased risk of necrotising fasciitis include intravenous drug abusers, alcoholics, those with immunosuppression, chronic disease and haematological malignancies. However, half of cases occur in young and previously healthy individuals.