What antibiotics are recommended for a human bite?

Antibiotic Treatment for Human Bites

For human bite infections, amoxicillin-clavulanate (875/125 mg twice daily orally) is the first-line antibiotic treatment, as it provides coverage against both aerobic and anaerobic bacteria commonly found in human bite wounds. 1

First-Line Treatment Options

Outpatient Treatment

• Oral options:
  • Amoxicillin-clavulanate: 875/125 mg twice daily 1
  • Doxycycline: 100 mg twice daily (particularly good for Eikenella species) 1

Inpatient Treatment (for severe infections)

• Intravenous options:
  • Ampicillin-sulbactam: 1.5-3.0 g every 6 hours 1
  • Carbapenems (ertapenem, meropenem, imipenem-cilastatin) 1
  • Piperacillin-tazobactam: 3.37 g every 6-8 hours 1

Microbiology Considerations

Human bite wounds contain a complex polymicrobial mix:

• Aerobic bacteria: Streptococci, Staphylococci, Eikenella corrodens
• Anaerobic bacteria: Fusobacterium, Peptostreptococcus, Prevotella
• Eikenella corrodens is particularly important in human bites and is sensitive to penicillin but resistant to clindamycin 2

Treatment Algorithm Based on Wound Severity

1. Uninfected Wounds (Prophylaxis)

• For high-risk wounds (hand injuries, deep punctures, immunocompromised patients):
  • Amoxicillin-clavulanate 875/125 mg twice daily for 3-5 days 1

2. Infected Wounds

• Mild to moderate infection:

  • Amoxicillin-clavulanate 875/125 mg twice daily for 5-7 days 1

• Severe infection or systemic symptoms:

  • Hospitalization with IV antibiotics (ampicillin-sulbactam or piperacillin-tazobactam)
  • Consider adding vancomycin if MRSA is suspected 1

3. Penicillin-Allergic Patients

• For mild infections:

  • Doxycycline 100 mg twice daily 1
  • Fluoroquinolone (e.g., moxifloxacin 400 mg daily) 1

• For severe infections:

  • Clindamycin plus fluoroquinolone
  • Note: Clindamycin alone is not recommended due to Eikenella resistance 2

Special Considerations

Closed-Fist Injuries

These injuries have particularly high infection rates and require aggressive management:

• Surgical consultation for possible debridement
• Broader spectrum IV antibiotics initially
• Penicillin plus dicloxacillin combination may be needed to cover both Eikenella and Staphylococcus 3

Duration of Treatment

• Uninfected wounds (prophylaxis): 3-5 days
• Infected wounds: 5-14 days depending on severity and clinical response

Important Caveats

• Wound care (irrigation, debridement) is as important as antibiotic therapy 4
• Tetanus prophylaxis should be considered if vaccination is not current 1
• Human bites of the face have lower infection rates than those on the hand 3
• Delayed presentation (>24 hours) is associated with higher complication rates 5
• While the evidence supports amoxicillin-clavulanate as first-line therapy, the choice may need to be modified based on local resistance patterns

Remember that proper wound management including thorough irrigation and debridement is crucial and may be more important than antibiotics in preventing infection complications from human bites.