What is the treatment for a human bite?

Treatment of Human Bite Wounds

All human bite wounds should receive prophylactic antibiotics regardless of appearance, with amoxicillin-clavulanate as the first-line agent. 1, 2

Immediate Wound Management

Irrigation and Cleaning

• Irrigate immediately with copious amounts of sterile normal saline or water to minimize bacterial contamination 2
• Remove superficial debris with gentle cleaning—avoid iodine or antibiotic-containing solutions which may impair healing 1
• Deeper debridement should be performed cautiously to avoid enlarging the wound and compromising closure 1

Wound Closure Decisions

• Do not close infected wounds under any circumstances 1, 2
• For non-infected wounds presenting within 8 hours: approximate margins with Steri-Strips rather than sutures, allowing for delayed primary or secondary closure 1
• Facial wounds are the exception: these may be closed primarily after meticulous irrigation and prophylactic antibiotics, ideally by a plastic surgeon 1, 2

Antibiotic Therapy

First-Line Treatment

• Amoxicillin-clavulanate 875/125 mg twice daily orally is the preferred agent for both prophylaxis and treatment 1, 2
• For intravenous therapy: ampicillin-sulbactam 1.5-3.0 g every 6 hours 1, 2

Penicillin-Allergic Patients

• Moxifloxacin 400 mg daily as monotherapy (covers both aerobes and anaerobes) 1, 2
• Alternatively: ciprofloxacin 500-750 mg twice daily or levofloxacin 750 mg daily PLUS metronidazole 500 mg three times daily 1, 2
• Doxycycline 100 mg twice daily is another option, though some streptococci may be resistant 1, 2

Rationale for Antibiotic Coverage

Human bite wounds contain complex polymicrobial flora including viridans streptococci (80% of wounds), S. aureus, Eikenella corrodens, and multiple anaerobes (Fusobacterium, Prevotella, Porphyromonas species) 1. Eikenella corrodens is notably resistant to first-generation cephalosporins, macrolides, clindamycin, and aminoglycosides, making beta-lactam/beta-lactamase inhibitor combinations essential 1.

Special Considerations

Clenched-Fist Injuries

• Require immediate evaluation by a hand specialist to assess for penetration into synovium, joint capsule, or bone 1, 2
• These carry the highest risk of serious complications including septic arthritis and osteomyelitis 2, 3
• Duration of therapy: 4 weeks for septic arthritis, 6 weeks for osteomyelitis 1, 2

Tetanus Prophylaxis

• Administer tetanus toxoid 0.5 mL intramuscularly if vaccination status is outdated (>10 years) or unknown 1, 2
• Tdap is preferred over Td if not previously given 1

Rabies Considerations

• Rabies transmission from human bites is extraordinarily rare in the United States 2
• Consider rabies prophylaxis only in exceptional circumstances where the biting person has suspected rabies exposure or compatible clinical signs 2

Follow-Up and Monitoring

Outpatient Management

• Elevate the injured extremity using a sling or similar device to reduce swelling 1, 2
• Mandatory follow-up within 24 hours by phone or office visit 1, 2
• Monitor for signs of infection progression: increasing pain, redness, swelling, purulent discharge 2

Indications for Hospitalization

• Infection progressing despite appropriate oral antimicrobial therapy 1, 2
• Deep tissue involvement (septic arthritis, osteomyelitis, tenosynovitis) 2
• Consider single initial dose of parenteral antimicrobial before transitioning to oral therapy for high-risk wounds 1

Common Pitfalls to Avoid

• Never use first-generation cephalosporins, clindamycin alone, or macrolides—these miss Eikenella corrodens, a key pathogen in human bites 1, 4
• Do not underestimate hand bites, particularly clenched-fist injuries, which have infection rates of 10-20% and require aggressive management 1, 5
• Avoid primary closure of wounds presenting >8 hours after injury (except facial wounds with specialist consultation) 1

Human bite wounds occurring on the hand warrant the most aggressive approach given their substantially higher complication rates compared to bites elsewhere on the body 5.