Bites / Clenched Fist Injuries

Mammalian bites (and clenched-fist fight-bite” injuries over the MCP joints) are polymicrobial. Core wound care: irrigate and debride, assess for deep-structure (tendon/joint/bone) involvement and foreign material, check tetanus status, and consider rabies/ABLV risk for animal bites (Rabies & other lyssaviruses). “Clenched-fist injuries over a joint need a low threshold for hand-surgery referral. For assessing the tendon itself over the MCP joint, see Hand Tendon & Nerve Lacerations.

When to give antibiotics

Treat all infected bites. Give prophylactic antibiotics for:

• presentation >8 hours after the bite
• puncture wounds that can’t be debrided
• hand, foot or face wounds
• deep-structure involvement (bone/tendon/joint) or open fracture
• immunocompromise
• cat bites (deep puncture; high infection rate)

Antibiotic choice (eTG)

• First-line: amoxicillin–clavulanate BD for 5 days (prophylaxis 3 days; longer if established infection).
• If oral therapy is delayed: procaine benzylpenicillin 1.5 g IM, then amoxicillin–clavulanate when available.
• Penicillin allergy: doxycycline 100 mg + metronidazole 400 mg BD.

Water-immersed wounds:

• Seawater — add cover for Vibrio (doxycycline) + di/flucloxacillin.
• Fresh/brackish/aquarium — cover Aeromonas (co-trimoxazole, or ciprofloxacin) + di/flucloxacillin.
• Sewage/contaminated freshwater (e.g. after a natural disaster) — add metronidazole.