Synopsis
Recognise necrotising soft-tissue infection before late skin signs, resuscitate toxin-mediated shock and secure immediate operative exploration, debridement and organism-directed therapy.
- Necrotising soft-tissue infection spreads along fascia, thromboses small vessels and destroys tissue faster than antibiotics can achieve source control.
- Early skin may look modest; severe escalating pain, oedema beyond erythema and systemic toxicity carry more weight than colour.
- Do not use a low LRINEC score, normal radiograph or absent gas to rule out disease.
- First management priority is immediate surgical exploration and excisional debridement; imaging is reserved for uncertainty in a stable patient when it will not delay theatre.
- Start broad intravenous antibacterial therapy immediately after useful cultures, covering streptococci, staphylococci, Gram-negative organisms and anaerobes according to local policy.
- Add high-dose clindamycin for suspected streptococcal or clostridial toxin suppression even if laboratory susceptibility to a beta-lactam is expected.
- Confirmed group A streptococcal disease can be narrowed with microbiology to benzylpenicillin 2.4 g intravenously every four hours plus clindamycin 1.2 g every six hours.
- Expect serial operations, intensive organ support, nutritional rehabilitation and reconstructive planning rather than a single debridement and short antibiotic course.
Key red flags
Pain out of proportion to visible skin change is an early necrotising-infection warning.
Rapid progression over hours despite antibiotics requires immediate senior surgical reassessment.
Haemorrhagic bullae, dusky skin, anaesthesia or necrosis indicates advanced tissue and nerve injury.
Crepitus or gas on imaging supports gas-forming infection but its absence does not reassure.
Hypotension, confusion, coagulopathy, lactate rise or acute kidney injury signals toxin-mediated shock.
Recent surgery, penetrating trauma, childbirth, injection, immune compromise or water exposure changes organism risk.
Deep severe pain beyond the visible erythematous margin, particularly when rapidly worsening, is an important early feature before skin necrosis develops.
Tense swelling extending beyond erythema, woody induration and progression over hours suggest fascial-plane spread rather than routine cellulitis.
Dusky discoloration, haemorrhagic bullae, skin anaesthesia, necrosis and crepitus indicate microvascular failure and advanced destructive disease.
Rigors, vomiting, diarrhoea, confusion, hypotension, coagulopathy and multiorgan dysfunction may dominate the presentation, especially with streptococcal infection.
Recent surgery, perineal infection, childbirth, injection, penetrating injury, chronic ulcer or seawater and freshwater exposure provides an organism and anatomy clue.
Investigation priorities
Determine whether clinical suspicion warrants operative exploration without diagnostic delay.
Management branches
Disproportionate pain, rapid progression, fascial signs or systemic toxicity creates meaningful suspicion.
- Use ABCDE, obtain large-bore access, measure lactate and glucose, send blood cultures and organ-function tests and begin physiology-guided crystalloid resuscitation.
- Contact senior surgery, anaesthesia, critical care and microbiology simultaneously and communicate why operative exploration cannot wait for diagnostic certainty.
- Start broad intravenous antibacterial therapy plus toxin-suppressing clindamycin according to the local necrotising-infection pathway after cultures when feasible.
- Provide strong analgesia, keep the patient fasted, correct major coagulopathy when possible and transfer to theatre without waiting for imaging or a LRINEC score.