What antibiotics are recommended for managing cat bites?

Cat Bite Antibiotic Management

First-Line Treatment

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

This recommendation is based on:

• 100% susceptibility of Pasteurella multocida (the most common pathogen in cat bites, present in >50% of wounds) to amoxicillin-clavulanate 2, 3
• Excellent coverage against the polymicrobial flora typical of cat bites, including staphylococci, streptococci, and anaerobes 1
• Cat bite wounds yield an average of 5 different bacterial isolates, with 60% having mixed aerobic and anaerobic bacteria 1

Treatment Duration

• 7-10 days for uncomplicated cellulitis or soft tissue infection 1
• 3-5 days IV therapy followed by oral amoxicillin-clavulanate for deep tissue involvement requiring hospitalization 1

Penicillin-Allergic Patients

Doxycycline 100 mg twice daily is the preferred alternative for penicillin allergy 1, 4

• Excellent activity against P. multocida 1
• Some streptococci may be resistant 1

Fluoroquinolones are second-line alternatives:

• Ciprofloxacin 500-750 mg twice daily 1, 4
• Moxifloxacin 400 mg daily 1
• Levofloxacin 750 mg daily 1
• Caveat: Miss MRSA and some anaerobes 1

Antibiotics to ABSOLUTELY AVOID

Never use these as monotherapy for cat bites:

• First-generation cephalosporins (cephalexin, cefazolin) - miss P. multocida and anaerobes 1
• Penicillinase-resistant penicillins (dicloxacillin, nafcillin, oxacillin) - poor P. multocida activity despite one older study showing benefit with oxacillin 1, 5

Severe Infections Requiring Hospitalization

Ampicillin-sulbactam 1.5-3.0 g IV every 6-8 hours is first-line for patients with systemic signs (fever, lymphangitis, significant cellulitis) 1

Piperacillin-tazobactam 3.37 g IV every 6-8 hours is an alternative for severe infections 1

High-Risk Wounds Requiring Aggressive Treatment

Hand bites have the highest infection risk and complication rate 1, 6:

• Risk of tendosynovitis, septic arthritis, and osteomyelitis 1
• Prophylactic antibiotics reduce infection risk in hand bites (NNT = 4) 6
• Always consider surgical consultation if deep space infection or abscess is suspected 1

MRSA Coverage Considerations

If MRSA is suspected (not routine):

• Add TMP-SMZ 1-2 double-strength tablets twice daily to amoxicillin-clavulanate 1
• Or use clindamycin 300-450 mg three times daily as monotherapy if penicillin-allergic (but this misses P. multocida) 1

Special Populations

Diabetic patients require:

• More aggressive treatment due to impaired immune response 4
• 1-2 weeks for mild infections, extending to 3-4 weeks if extensive or slow to resolve 4
• Urgent surgical consultation for deep abscess, extensive necrosis, or necrotizing fasciitis 4

Additional Wound Management

• Thorough cleansing with sterile normal saline 4
• Debridement only if significant devitalized tissue present 4
• Update tetanus immunization if needed 4, 2
• Assess rabies risk for unknown or feral cats 4

Common Pitfalls

• Cat bites have 20-80% infection rate (much higher than dog bites at 3-18%) 3
• Approximately 18% of infected cat bite patients develop complications including abscess, tendonitis, bacteremia, and meningitis 1
• Puncture wounds (typical of cat bites) carry higher infection risk than lacerations 1