Synopsis
Recognise acute bacterial skin and soft-tissue infection, exclude common mimics and limb-threatening disease, choose oral or intravenous antibiotics by severity and review response within the expected trajectory.
- Cellulitis is an acute, usually unilateral, tender warm expanding infection of dermis and subcutis; erysipelas is more superficial, raised and sharply demarcated.
- Mark the edge with date and time when appropriate, but judge deterioration by physiology, pain, function and new features as well as millimetres of redness.
- Exclude an abscess, necrotising infection, septic joint, orbital disease and common non-infective mimics before issuing routine oral antibiotics.
Key red flags
Sepsis physiology, necrotising features, orbital or facial danger-site infection, compartment syndrome, septic joint, osteomyelitis, severe immunocompromise, rapidly spreading disease or inability to take oral treatment requires hospital assessment.
Pain out of proportion, rapid spread, skin anaesthesia, crepitus, haemorrhagic bullae, necrosis or shock demands immediate surgery.
Investigation priorities
Identify systemic severity and determine hospital or intravenous-treatment need.
Management branches
Cellulitis is localised, the patient is stable, oral treatment is feasible and no danger-site or unusual exposure applies.
- Mark and document extent, portal, pain and observations, then start oral flucloxacillin for five to seven days after allergy assessment.
- Advise elevation, fluids, analgesia and treatment of toe-web fungal disease, eczema or wounds while avoiding compression during intolerable acute pain.