Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 13 Sept 2026Clinical review pending
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Pus and necrosis are time-critical
Sepsis, necrotising infection, deep abscess, compartment spread, extensive gangrene or infection with severe ischaemia can destroy tissue quickly despite modest pain.
Action: Refer immediately to acute services, resuscitate, obtain prompt blood and deep cultures without delaying therapy, start severity-appropriate antibiotics, and secure urgent surgical and vascular assessment.
Synopsis
Recognise when a diabetic foot infection needs immediate drainage, debridement and coordinated vascular care rather than antibiotics or imaging alone.
Sepsis, necrotising change, deep abscess, gangrene or infection with severe ischaemia requires immediate acute referral and urgent surgical assessment; do not wait for MRI.
Antibiotics penetrate viable tissue but cannot drain pus or remove necrotic material; obtain source control while resuscitation and antimicrobial therapy proceed in parallel.
When PAD accompanies infection or gangrene, involve surgical and vascular specialists urgently to sequence drainage, debridement and revascularisation without sacrificing viable tissue.
Key red flags
Hypotension, confusion, fever or hypothermia, tachycardia, tachypnoea, oliguria or metabolic deterioration indicates systemic infection and possible organ dysfunction.
Crepitus, bullae, dusky anaesthesia, disproportionate pain, rapid spread or gas in deep tissues raises concern for necrotising soft-tissue infection.
Fluctuance, purulent tracking, a tense swollen compartment, exposed joint or tendon, or deep focal tenderness suggests a collection requiring drainage.
Gangrene, new coolness, absent Doppler signals or sharply worsening necrosis makes vascular assessment and revascularisation planning urgent alongside infection control.
Systemic severity
Use observations, mental state, urine output, glucose, ketones, lactate and organ function to identify severe infection and sepsis. Formal IWGDF severe grading requires at least two SIRS findings.
Investigation priorities
01
Immediate clinical and perfusion assessmentFirst step
Determine sepsis severity, anatomical source and whether ischaemia changes operative timing and healing potential.
Management branches
Emergency pathwayDrain the threatened foot
Sepsis, necrotising features, deep abscess, compartment infection, extensive gangrene or rapidly deteriorating tissue is present.
Refer immediately, activate senior surgical and multidisciplinary foot care input, resuscitate using sepsis principles and start intravenous antibiotics after prompt cultures when feasible.
Obtain urgent vascular assessment when ischaemia or gangrene is present, while preparing for incision, drainage and debridement; do not wait for outpatient tests or MRI.
Preferred branchStable deep infection mapping
Deep extension is suspected but the patient is stable and there is no clinically obvious collection demanding immediate drainage.
Key medicines
Co-amoxiclavFor moderate or severe infection, 500/125 mg orally three times daily or 1.2 g intravenously three times daily; treat at least 7 days and extend only by clinical indication.Avoid in serious penicillin allergy or previous co-amoxiclav-associated jaundice. If creatinine clearance is >30 mL/min use the stated dose; at 10–30 use 500/125 mg orally twice daily, or after an initial 1.2 g IV dose use 500/100 mg IV twice daily; below 10 use the oral dose once daily, or initial 1.2 g IV then 500/100 mg IV every 24 hours. During haemodialysis, give oral 500/125 mg every 24 hours plus a dose during and after dialysis, or IV initial 1.2 g then 500/100 mg every 24 hours plus 500/100 mg after dialysis. Review IV therapy by 48 hours, monitor hepatic toxicity and narrow by cultures.
GentamicinGive an initial 5–7 mg/kg intravenously once daily when selected; determine later doses from serum concentrations, renal function and the local monitored dosing protocol.Use measured weight, drug levels and repeated renal assessment; minimise other nephrotoxic or ototoxic drugs. Frailty, pregnancy and kidney impairment require specialist review, and treatment should stop when narrower therapy is adequate.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 13 Sept 2026; clinical approval remains outstanding.