Infectious DiseasesTier 2Disease (DEADMAN)

Necrotising fasciitis

Description

Necrotising fasciitis is a rapidly progressive, life-threatening soft tissue infection spreading along the fascial planes, causing tissue necrosis disproportionate to visible skin findings - a true surgical emergency requiring urgent debridement alongside antibiotics, since antibiotics alone cannot control established fascial necrosis

Rare but rapidly fatal if unrecognised or treatment delayed, with mortality remaining substantial even with prompt treatment - early recognition and surgical referral are the dominant determinants of outcome

Type I (polymicrobial, often in patients with diabetes/vascular disease) and Type II (monomicrobial, classically group A Streptococcus, can affect healthy individuals) - both cause rapidly spreading necrosis via bacterial toxin production and thrombosis of fascial blood vessels, explaining the classic finding of pain disproportionate to visible skin changes (deep tissue is more severely affected than the skin surface suggests)

Clinical diagnosis with a low threshold for surgical exploration - pain out of proportion to examination findings, rapid progression, systemic toxicity, and "hard" skin/crepitus are red flags; imaging (CT showing fascial gas/fluid) can support but should never delay surgical referral when clinical suspicion is high, given the emergency nature of the diagnosis
Bedside surgical exploration ("finger test" - lack of resistance to blunt dissection along the fascial plane) is itself diagnostic and therapeutic

Emergency surgical debridement is the primary, life-saving intervention - repeated debridement is often required until all necrotic tissue is removed
Broad-spectrum empirical antibiotics (covering Gram-positive, Gram-negative, and anaerobic organisms) alongside clindamycin (for its antitoxin effect against toxin-producing Streptococcus/Staphylococcus) started immediately, refined once culture results are available
Haemodynamic support for associated septic shock, which is common given the severity of this infection

Toxic shock syndrome (may co-occur with Group A Streptococcus necrotising fasciitis), diabetes/immunosuppression as Type I risk factors, mortality correlating strongly with time to surgical debridement

Imaging should never delay surgical referral when clinical suspicion for necrotising fasciitis is high - this is a clinical diagnosis requiring emergency surgical exploration, and waiting for confirmatory imaging in a rapidly deteriorating patient is a recognised, dangerous pitfall

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