What antibiotics are recommended for prophylaxis in cat bites?

Antibiotic Prophylaxis for Cat Bites

Amoxicillin-clavulanate 875/125 mg twice daily is the first-line antibiotic for prophylaxis of cat bites, providing optimal coverage against Pasteurella multocida (present in 75% of cat bites) and the polymicrobial flora typically found in these wounds. 1, 2

When to Prescribe Prophylactic Antibiotics

Prophylactic antibiotics are indicated for: 1

• Deep puncture wounds (cat bites characteristically create deep punctures with their sharp teeth)
• Wounds on the hands, feet, face, or near joints (hand wounds carry the highest infection risk)
• Immunocompromised patients
• Any wound presenting >8-12 hours after injury with signs of early infection

Cat bites have a 20-50% infection rate, significantly higher than dog bites (3-18%), making prophylaxis particularly important. 3, 4

First-Line Therapy

Amoxicillin-clavulanate 875/125 mg orally twice daily is the definitive choice because: 1, 2

• Excellent activity against P. multocida (found in ~90% of cat oral cavities and 75% of cat bite wounds) 5, 2
• Covers staphylococci and streptococci (present in ~40% of bites) 2
• Effective against anaerobes (present in 65% of cat bites) 2
• Maintains 100% susceptibility rates against P. multocida isolates 5

The average cat bite yields 5 different bacterial isolates, requiring broad-spectrum coverage. 2

Alternative Regimens for Penicillin Allergy

For patients with penicillin allergies: 1, 2

Mild allergies:

• Doxycycline 100 mg twice daily (excellent P. multocida activity) 1, 2

Severe allergies:

• Fluoroquinolone (ciprofloxacin 500-750 mg twice daily OR levofloxacin 750 mg daily) 1, 2
• Trimethoprim-sulfamethoxazole PLUS metronidazole (for combined aerobic/anaerobic coverage) 6, 1

Critical Pitfalls to Avoid

Never use these antibiotics as monotherapy for cat bites: 2

• First-generation cephalosporins (e.g., cephalexin)
• Penicillinase-resistant penicillins (e.g., dicloxacillin)
• Macrolides (e.g., azithromycin, erythromycin)
• Clindamycin alone

These agents have poor or absent activity against P. multocida and are associated with clinical failures. 1, 2 Azithromycin specifically has documented treatment failures despite being a macrolide. 2

Duration of Prophylaxis

• 3-5 days for prophylaxis of uncomplicated wounds 1
• 7-14 days if early signs of infection are present 1

Essential Adjunctive Measures

Beyond antibiotics: 1

• Thorough wound irrigation with sterile normal saline (use 20-mL syringe or 20-gauge catheter for high-pressure irrigation) 1, 4
• Evaluate tetanus immunization status and update if needed 1
• Assess rabies risk for unknown or feral cats 1
• Elevate the affected extremity if swollen 1
• Avoid primary closure of puncture wounds (high infection risk) 2

When to Escalate to IV Antibiotics

Transition to intravenous therapy if: 2

• Systemic signs develop (fever, lymphangitis, significant cellulitis)
• Deep tissue involvement (septic arthritis, osteomyelitis, tenosynovitis)
• Patient is immunocompromised with moderate-to-severe injury

IV first-line: Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 2

Special Population: Hand Wounds

Hand bites deserve particular attention because: 1, 7

• Highest risk of infection and complications (septic arthritis, osteomyelitis, tendonitis) 2
• Prophylactic antibiotics reduce infection risk significantly (NNT = 4) 7
• Require close follow-up within 24-48 hours 1

Follow-Up Instructions

Patients must return immediately if: 1

• Increasing pain, redness, or swelling
• Purulent drainage
• Fever
• Decreased range of motion (especially hand wounds)