What is the recommended antibiotic coverage for a dog bite?

Recommended Antibiotic Coverage for Dog Bites

Amoxicillin-clavulanate (Augmentin) 875/125 mg twice daily is the recommended first-line antibiotic for dog bite wounds, providing effective coverage against both aerobic and anaerobic bacteria commonly found in these infections. 1, 2

Microbiology of Dog Bite Wounds

• Dog bite wounds are typically polymicrobial, containing a mixture of aerobic and anaerobic bacteria from the animal's oral flora and human skin organisms 1
• Pasteurella species are isolated from approximately 50% of dog bite wounds 1
• Staphylococci and streptococci are found in about 40% of dog bites 1
• Other common organisms include Capnocytophaga canimorsus, Bacteroides species, fusobacteria, Porphyromonas species, and anaerobes 1, 3

First-Line Antibiotic Therapy

• Amoxicillin-clavulanate is strongly recommended by the Infectious Diseases Society of America guidelines as it provides coverage against both aerobic and anaerobic bacteria 1, 2
• The combination effectively targets beta-lactamase producing organisms commonly present in animal bites 2
• This recommendation is supported by clinical studies, though limited in size 1

Alternative Antibiotic Options for Penicillin-Allergic Patients

• Doxycycline 100 mg twice daily is an excellent alternative with good activity against Pasteurella multocida 1, 2
• Other options include:
  • Fluoroquinolones (ciprofloxacin, levofloxacin) plus metronidazole for anaerobic coverage 1
  • Moxifloxacin 400 mg daily as monotherapy (covers both aerobes and anaerobes) 2

Intravenous Antibiotic Options

For severe infections requiring intravenous therapy:

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

Antibiotics to Avoid

• First-generation cephalosporins (e.g., cephalexin) have poor activity against Pasteurella multocida and should be avoided 1, 2
• Penicillinase-resistant penicillins (e.g., dicloxacillin) are ineffective against many organisms in dog bites 1
• Macrolides (e.g., erythromycin) and clindamycin alone have poor coverage against Pasteurella and should not be used as monotherapy 1, 2

Duration of Therapy and Indications

• Prophylactic antibiotics are recommended for 3-5 days for:
  • Immunocompromised patients
  • Moderate to severe injuries, especially to the hand or face
  • Injuries that may have penetrated periosteum or joint capsule
  • Patients with advanced liver disease or asplenia
  • Wounds with resultant edema 1, 4

Additional Management Considerations

• Thorough wound cleansing with copious irrigation is essential 1, 5
• Tetanus prophylaxis should be administered if vaccination is not current within 10 years 1
• Consider rabies prophylaxis in consultation with local health officials 1
• Primary wound closure is not generally recommended except for facial wounds 1

Special Considerations

• Hand wounds are often more serious than wounds to fleshy parts of the body and may require longer therapy (4-6 weeks) if complications develop 1
• Complications of dog bites can include septic arthritis, osteomyelitis, subcutaneous abscess formation, tendonitis, and rarely bacteremia 1, 3
• Capnocytophaga canimorsus, though uncommon, can cause fatal sepsis, especially in asplenic or immunocompromised patients 1, 4