Necrotizing fasciitis
Necrotizing fasciitis is a rapidly progressive, life-threatening infection of the subcutaneous tissue and superficial fascia driven by vessel thrombosis and bacterial exotoxin production. The hallmark is pain out of proportion to visible skin findings, with crepitus, bullae, and woody induration in advanced disease. Diagnosis is confirmed by direct surgical exploration; the LRINEC score aids risk stratification. Treatment is emergent surgical debridement combined with broad-spectrum empiric antibiotics.
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What this article covers
- Overview
Necrotizing fasciitis (NF) is a rapidly spreading, life-threatening infection of the subcutaneous tissue and superficial fascia.
- Epidemiology
NF is uncommon relative to simple cellulitis, and a reliable incidence figure is not established.
- Risk factors
Diabetes mellitus: the most consistently cited host factor, common in polymicrobial cases and associated with more extensive disease.
- Pathophysiology
Bacteria seed the subcutaneous plane through a break in the skin and spread horizontally along the loose areolar tissue of the superficial fascia.
- Clinical features
Onset resembles ordinary cellulitis, erythema, warmth, and edema, but progresses over hours rather than days, with margins moving visibly into normal-appearing skin.
- Differential diagnosis
Cellulitis or erysipelas: similar erythema and warmth, but pain is proportional to the visible findings, there is no crepitus or bullae, and it responds to antibiotics alone without necrosis.
- Diagnosis
Establishing the diagnosis: direct surgical exploration establishes it, showing gray fascia that fails to bleed, with blunt dissection separating fascia from adjacent tissue with minimal resistance…
- Management
First, emergent surgical debridement of all necrotic tissue: this is the primary, time-critical intervention, and the speed of the initial debridement has the greatest impact on survival; avoid…
- Complications
Septic shock and multi-organ dysfunction: the leading immediate cause of death, driven by exotoxin-mediated cytokine release and ongoing bacteremia from unresected tissue.
- Prognosis
Reported mortality varies with organism, host, and speed of source control.
- Prevention
Prompt evaluation of rapidly progressive skin infection: treat pain out of proportion to exam, systemic toxicity, or an LRINEC score of 6 or higher as grounds for immediate surgical consultation, not a trial of oral antibiotics.
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- Fournier gangrene
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- Clostridial myonecrosis (gas gangrene)
Clostridial myonecrosis is a fulminant, toxin-mediated necrotizing infection of skeletal muscle, most often from Clostridium perfringens, presenting with pain out of proportion, bullae, and gas in the tissue. Diagnosis is confirmed at surgery. Treatment is emergent surgical debridement plus penicillin and clindamycin.
- Diabetic foot infection
Diabetic foot infection is a skin, soft tissue, or bone infection arising in an ulcer on a neuropathic, vasculopathic diabetic foot, diagnosed when pus or two or more inflammatory signs are present. Severity dictates therapy: mild infection is treated with oral dicloxacillin or cephalexin, while severe infection needs intravenous piperacillin-tazobactam plus vancomycin and urgent surgical debridement.
- Surgical site infections
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