What is the recommended antibiotic regimen for a 13-year-old patient with a category 3 dog bite?

Antibiotic Regimen for Category 3 Dog Bite in a 13-Year-Old

For a 13-year-old patient with a category 3 dog bite, amoxicillin-clavulanate is the recommended first-line antibiotic therapy at a dose of 45 mg/kg/day divided every 12 hours (based on the amoxicillin component) for 3-5 days. 1, 2

Antibiotic Selection Rationale

• Amoxicillin-clavulanate is strongly recommended as the first-line agent for dog bite wounds as it provides coverage against both aerobic and anaerobic bacteria commonly found in these wounds 1
• Category 3 dog bites (severe injuries) require preemptive antimicrobial therapy due to the high risk of infection 1
• The polymicrobial nature of dog bite wounds includes Pasteurella multocida, streptococci, staphylococci, and anaerobic bacteria such as Bacteroides and Fusobacterium species 3, 4

Pediatric Dosing for Amoxicillin-Clavulanate

• For a 13-year-old with a severe infection (category 3 bite):

  • 45 mg/kg/day divided every 12 hours based on the amoxicillin component 2
  • This dosing regimen is associated with significantly less diarrhea than 8-hour dosing 2
  • Duration of therapy should be 3-5 days 1

• If the child weighs ≥40 kg:

  • May be dosed according to adult recommendations: 875/125 mg twice daily 2
  • Alternative adult dosing: 500/125 mg every 8 hours 2

Alternative Antibiotic Options (for penicillin allergy)

• For patients with non-anaphylactic penicillin allergy:

  • Doxycycline 100 mg twice daily (if ≥8 years old) 1
  • Clindamycin 10-13 mg/kg/dose every 8 hours (note: misses Pasteurella multocida) plus trimethoprim-sulfamethoxazole 1

• For patients with severe penicillin allergy:

  • Fluoroquinolones (e.g., ciprofloxacin) plus metronidazole (generally avoided in children if possible) 1
  • Moxifloxacin 400 mg daily as monotherapy (provides good anaerobic coverage, but generally avoided in children) 1

Additional Management Considerations

• Tetanus prophylaxis should be administered if not vaccinated within the past 10 years 1
• Tdap is preferred over Td if not previously given 1
• Consultation with local health officials regarding rabies post-exposure prophylaxis 1
• Copious irrigation and cautious debridement of the wound 1
• Primary wound closure is not recommended except for facial wounds 1

Factors Supporting Preemptive Antibiotic Therapy

• Category 3 dog bites (severe injuries) always warrant antibiotic prophylaxis 1
• Additional factors supporting antibiotic use include:
  • Moderate to severe injuries, especially to the hand or face 1
  • Wounds that may have penetrated the periosteum or joint capsule 1
  • Wounds with resultant edema 1
  • Presentation >9 hours after injury 1

Evidence Quality and Considerations

• Meta-analyses show antibiotics reduce infection risk in dog bite wounds by approximately 44% 1, 5
• The cumulative incidence of infection in untreated dog bite wounds is approximately 16% 5
• The Infectious Diseases Society of America guidelines (2014) provide strong recommendations for amoxicillin-clavulanate as first-line therapy 1
• Recent studies continue to support amoxicillin-clavulanate as appropriate empiric therapy for dog bite wounds 6