Antibiotic Treatment for Cat Bites
Give amoxicillin-clavulanate 875/125 mg orally twice daily as first-line therapy for all cat bites, whether for prophylaxis of fresh wounds or treatment of established infection. 1, 2
Why Amoxicillin-Clavulanate is the Definitive Choice
Amoxicillin-clavulanate provides 100% coverage against Pasteurella multocida, the pathogen isolated in over 50% of cat bite wounds, plus excellent activity against staphylococci, streptococci, and anaerobes that comprise the polymicrobial flora. 1, 2, 3
Approximately 90% of domestic cats carry P. multocida in their oral cavity, and cat bites become infected in 20-80% of cases (compared to only 3-18% for dog bites), making prophylactic antibiotics essential. 3, 4
The average cat bite yields 5 different bacterial isolates, with 60% having mixed aerobic and anaerobic bacteria, requiring broad-spectrum coverage. 2
Dosing and Administration
Standard dose: Amoxicillin-clavulanate 875/125 mg orally twice daily for 3-5 days for prophylaxis, or 7-10 days for established infection. 1, 2, 5
Take at the start of meals to minimize gastrointestinal side effects and enhance clavulanate absorption. 5
High-Risk Wounds Requiring Immediate Prophylaxis
Deep puncture wounds (cat teeth create deep, narrow wounds with high infection risk). 1
Hand, foot, face, or near-joint wounds (hand bites have the highest complication rate, including septic arthritis, osteomyelitis, and tendosynovitis). 1, 2
Wounds presenting >8-12 hours after injury with early infection signs. 1
Immunocompromised patients (require more aggressive treatment with lower threshold for antibiotics). 1, 6
Alternative Regimens for Penicillin Allergy
For Mild Penicillin Allergies:
- Doxycycline 100 mg orally twice daily has excellent P. multocida activity, though some streptococci may be resistant. 1, 2
For Severe Penicillin Allergies:
Fluoroquinolone: Ciprofloxacin 500-750 mg twice daily OR levofloxacin 750 mg daily, though these miss MRSA and some anaerobes. 1, 2
Trimethoprim-sulfamethoxazole PLUS metronidazole for combined aerobic/anaerobic coverage. 1, 2
Critical Antibiotics to AVOID
First-generation cephalosporins (cephalexin, cefazolin) have poor P. multocida activity and should never be used as monotherapy. 1, 2
Penicillinase-resistant penicillins (dicloxacillin, nafcillin) have inadequate P. multocida coverage. 1, 2
Clindamycin alone misses P. multocida entirely and should not be used as monotherapy. 1, 2
Erythromycin has poor P. multocida activity. 1
When to Escalate to IV Antibiotics
Indications: Systemic signs (fever, lymphangitis, significant cellulitis), deep tissue involvement, or immunocompromised patients with moderate-to-severe injury. 1, 2
First-line IV therapy: Ampicillin-sulbactam 1.5-3.0 g IV every 6-8 hours. 1, 2
Alternative IV therapy: Piperacillin-tazobactam 3.37 g IV every 6-8 hours. 2
Duration: 3-5 days IV, then transition to oral amoxicillin-clavulanate to complete 7-10 days total. 2
Essential Adjunctive Wound Care
Copious irrigation with sterile normal saline using a 20-mL or larger syringe to remove debris and bacteria. 1, 7
Avoid primary closure of puncture wounds (increases infection risk by trapping bacteria). 1
Elevate the affected extremity to reduce swelling and accelerate healing. 1, 6
Red Flags Requiring Immediate Return
Increasing pain, redness, or swelling. 1
Decreased range of motion (suggests deep tissue involvement). 1
Special Consideration: Cat Scratch Disease
If lymphadenopathy develops 1-3 weeks after a cat scratch (not a bite), this suggests Bartonella henselae infection (cat scratch disease). 6
Treatment: Azithromycin 500 mg on day 1, then 250 mg daily for 4 additional days (total 5 days). 6, 8
This is distinct from acute cat bite wound management, which requires amoxicillin-clavulanate. 6