What is the best medication for a cat bite?

Best Medication for Cat Bites

Amoxicillin-clavulanate 875/125 mg twice daily is the definitive first-line antibiotic for all cat bite wounds, whether for prophylaxis of fresh wounds or treatment of established infection. 1

Why Amoxicillin-Clavulanate is Superior

• Cat bites have an exceptionally high infection rate of 30-50%, far exceeding dog bites (3-18%), making antibiotic therapy critical 2, 3
• The medication provides 100% susceptibility against Pasteurella multocida, which is isolated from 75-90% of cat bite wounds 1, 4, 3
• Cat bite wounds yield an average of 5 different bacterial isolates, with 60-65% containing mixed aerobic and anaerobic bacteria, requiring broad-spectrum coverage 1, 4
• Amoxicillin-clavulanate covers the complete polymicrobial flora: P. multocida, staphylococci, streptococci, and anaerobic organisms like Bacteroides species 1, 5

Treatment Duration

• Uncomplicated soft tissue infections require 7-10 days of oral therapy 1
• Deep tissue involvement or hand bites may require 3-5 days of IV therapy followed by oral completion 1
• Extensive infections or those in diabetic patients may need up to 3-4 weeks 2

Alternative Regimens for Penicillin Allergy

If truly penicillin-allergic, use doxycycline 100 mg twice daily as the preferred alternative 1, 4

• Doxycycline has excellent P. multocida activity, though some streptococci may be resistant 1, 4
• Fluoroquinolones (ciprofloxacin 500-750 mg twice daily, levofloxacin 750 mg daily, or moxifloxacin 400 mg daily) are second-line alternatives but miss MRSA and some anaerobes 1, 4

Critical Antibiotics to AVOID

Never use these as monotherapy for cat bites:

• First-generation cephalosporins (cephalexin, cefazolin) miss P. multocida and anaerobes entirely 1, 4
• Penicillinase-resistant penicillins (dicloxacillin, nafcillin) have poor P. multocida activity 1
• Clindamycin alone misses P. multocida despite good anaerobic coverage 2
• Macrolides have inadequate P. multocida coverage 4

High-Risk Wounds Requiring Aggressive Treatment

Hand and finger bites demand immediate attention and have the highest complication rates 1

• Hand bites carry the greatest risk of infection and complications including tendosynovitis, septic arthritis, and osteomyelitis 1, 6
• Prophylactic antibiotics reduce infection rates in hand bites with NNT = 4 7
• Approximately 18% of infected cat bite patients develop complications including abscess formation, tendonitis, bacteremia, and meningitis 1

When to Hospitalize and Use IV Therapy

Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours IV is first-line for severe infections 1, 4

• Indications for hospitalization: systemic signs (fever, lymphangitis), rapidly progressing infection despite oral antibiotics, deep tissue involvement, or immunocompromised status 4
• Piperacillin-tazobactam 3.37 g every 6-8 hours IV is an alternative for severe infections 1, 4
• Transition to oral amoxicillin-clavulanate after 3-5 days of IV therapy to complete the course 1

Special Considerations for MRSA Coverage

• If MRSA is suspected, add TMP-SMX 1-2 double-strength tablets twice daily to amoxicillin-clavulanate 1
• For penicillin-allergic patients with MRSA concern, use clindamycin 300-450 mg three times daily PLUS a fluoroquinolone (not clindamycin alone) 1, 2

Common Pitfalls

• Do not delay antibiotics for cat bites to the hand—infection develops rapidly and prophylaxis is highly effective 7
• Always order both aerobic and anaerobic cultures for infected wounds, as anaerobes are present in 65% of cases 4, 5
• Surgical consultation is mandatory if there is concern for deep space infection, abscess, or involvement of tendons/joints 1
• Evaluate tetanus status and rabies risk with every cat bite 2, 8