What is the recommended antibiotic regimen for a cat bite?

Antibiotic Treatment for Cat Bites

Amoxicillin-clavulanate 875/125 mg twice daily is the first-line antibiotic for cat bite infections, whether for prophylaxis or treatment. 1, 2, 3

Why Amoxicillin-Clavulanate is First-Line

Cat bites are particularly high-risk wounds that require systemic antibiotic coverage due to their unique microbiology and injury pattern:

• Pasteurella multocida is present in approximately 75% of cat bite wounds and is the predominant pathogen requiring coverage 1, 2, 3
• Cat bites contain an average of 5 different bacterial species per wound, including both aerobic and anaerobic organisms 1, 3
• Staphylococci and streptococci are present in ~40% of wounds 1, 3
• Anaerobic bacteria (Bacteroides, fusobacteria, Porphyromonas, peptostreptococci) are present in 65% of cat bites 1, 2, 3
• Cat bites have a higher infection rate (20-80%) compared to dog bites (3-18%) 4
• Cat bites typically cause deep puncture wounds that seed bacteria into deeper tissues 5

Oral Antibiotic Options

First-Line Therapy

• Amoxicillin-clavulanate 875/125 mg twice daily 6, 1, 2, 3, 7

Alternative Oral Regimens (if penicillin allergy or intolerance)

• Doxycycline 100 mg twice daily - excellent activity against P. multocida, though some streptococci may be resistant 6, 1, 2, 3
• Moxifloxacin 400 mg daily - provides monotherapy coverage including anaerobes 6, 2
• Levofloxacin 750 mg daily - good P. multocida coverage but may miss some anaerobes 6, 2
• Ciprofloxacin 500-750 mg twice daily - good P. multocida activity but misses MRSA and some anaerobes 6, 2
• Penicillin VK plus dicloxacillin (500 mg four times daily for each) 6, 3

Antibiotics to AVOID

These agents have poor activity against P. multocida and should not be used as monotherapy:

• First-generation cephalosporins (e.g., cephalexin) 1, 2, 3
• Penicillinase-resistant penicillins alone (e.g., dicloxacillin monotherapy) 1, 3
• Macrolides (e.g., erythromycin, azithromycin) 2, 3
• Clindamycin alone - misses P. multocida despite good anaerobic coverage 6, 1, 3

Intravenous Options for Severe Infections

Consider hospitalization and IV therapy for systemic infection, rapidly progressing infection despite oral antibiotics, deep tissue involvement (septic arthritis, osteomyelitis, tendonitis), immunocompromised hosts, or need for surgical intervention 1, 2, 3:

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 6, 2, 3
• Piperacillin-tazobactam 3.37 g every 6-8 hours 6, 2, 3
• Cefoxitin 1 g every 6-8 hours (second-generation cephalosporin) 6, 2, 3
• Carbapenems (ertapenem, imipenem, meropenem) 6, 2, 3

Note: All IV beta-lactam options miss MRSA; add vancomycin if MRSA is suspected 6

Treatment Duration for Complications

• Osteomyelitis: 4-6 weeks of antibiotic therapy 3
• Septic arthritis/synovitis: 3-4 weeks of antibiotic therapy 3

Essential Wound Management

Beyond antibiotics, proper wound care is critical:

• Thoroughly cleanse wounds with sterile normal saline using copious irrigation 1, 3, 5
• Remove superficial debris and devitalized tissue 1, 3
• Do NOT close infected wounds 1, 3
• Elevate the injured body part to accelerate healing 1, 3
• Administer tetanus prophylaxis if vaccination status is outdated or unknown 1, 3, 5
• Evaluate need for rabies postexposure prophylaxis 8, 5

Follow-Up Protocol

• All outpatients require follow-up within 24 hours (phone or office visit) 1, 3
• If infection progresses despite appropriate therapy, hospitalize immediately 1, 3

Critical Pitfalls to Avoid

• Never rely solely on topical antibiotics without systemic coverage for cat bites 1
• Never delay treatment - complications such as septic arthritis, osteomyelitis, or tendonitis can develop rapidly 1, 3
• Hand bites require special attention - they have the greatest risk of infection and benefit significantly from prophylactic antibiotics 9, 10
• Prophylactic antibiotics reduce infection risk in hand bites with a number needed to treat of 4 10