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, 4

Why Cat Bites Require Aggressive Antibiotic Coverage

Cat bites have a uniquely high infection risk compared to other animal bites:

• Infection rates reach 20-80% for cat bites versus only 3-18% for dog bites 5
• Cat bites typically create deep puncture wounds that seed bacteria into deeper tissues, particularly dangerous when involving the hand 6, 7
• Pasteurella multocida is present in approximately 75% of cat bite wounds and is the predominant pathogen requiring coverage 2, 3, 4
• Cat bites contain an average of 5 different bacterial species per wound, including both aerobes and anaerobes 2, 4
• Anaerobic bacteria are present in 65% of cat bites, including Bacteroides, fusobacteria, and Porphyromonas species 2, 3, 4
• Staphylococci and streptococci are found in approximately 40% of bites 2, 4

First-Line Oral Antibiotic Regimen

Amoxicillin-clavulanate 875/125 mg twice daily is the definitive first-line choice because:

• It provides comprehensive coverage against P. multocida, staphylococci, streptococci, and anaerobes 1, 2, 3, 4
• Studies demonstrate 100% susceptibility of P. multocida isolates to amoxicillin-clavulanate 5
• It is specifically recommended by both the Infectious Diseases Society of America and the American College of Physicians 1, 2

Alternative Oral Options (When Amoxicillin-Clavulanate Cannot Be Used)

If the patient has a penicillin allergy or other contraindication:

• Doxycycline 100 mg twice daily has excellent activity against P. multocida, though some streptococci may be resistant 1, 2, 3, 4
• Penicillin VK plus dicloxacillin (500 mg four times daily for each) provides dual coverage 1, 4
• Fluoroquinolones (moxifloxacin 400 mg daily preferred for anaerobic coverage; ciprofloxacin 500-750 mg twice daily or levofloxacin 750 mg daily as alternatives) have good P. multocida activity but may miss MRSA and some anaerobes 1, 3

Antibiotics to AVOID for Cat Bites

These commonly prescribed antibiotics have inadequate coverage of P. multocida and should never be used as monotherapy:

• First-generation cephalosporins (e.g., cephalexin) - poor P. multocida activity 2, 3, 4
• Penicillinase-resistant penicillins (e.g., dicloxacillin alone) - poor P. multocida activity 2, 3, 4
• Macrolides (e.g., erythromycin, azithromycin) - poor P. multocida activity 3, 4
• Clindamycin alone - misses P. multocida entirely 1, 2, 3, 4

Intravenous Options for Severe Infections

Hospitalization and IV antibiotics are indicated for:

• Systemic infection (fever, sepsis) 2, 3
• Rapidly progressing infection despite oral antibiotics 2, 3, 4
• Deep tissue involvement (tendonitis, septic arthritis, osteomyelitis) 2, 3, 4
• Immunocompromised hosts 2, 3

IV antibiotic options include:

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 1, 3, 4
• Piperacillin-tazobactam 3.37 g every 6-8 hours 1, 3, 4
• Second-generation cephalosporins (cefoxitin 1 g every 6-8 hours or cefuroxime 1 g every 12 hours) 1, 3, 4
• Carbapenems (ertapenem 1 g daily, imipenem 1 g every 6-8 hours, or meropenem 1 g every 8 hours) 1, 3, 4

Note: All IV options miss MRSA; add vancomycin if MRSA is suspected or confirmed 1

Treatment Duration for Complications

• Uncomplicated wound infections: 7-10 days of oral antibiotics 2, 4
• Septic arthritis/synovitis: 3-4 weeks of antibiotics 4
• Osteomyelitis: 4-6 weeks of antibiotics 4

Critical Wound Management Steps

Beyond antibiotics, proper wound care is essential:

• Thoroughly cleanse with sterile normal saline using a 20-mL or larger syringe 4, 8, 7
• Remove superficial debris and explore for foreign bodies 4, 7
• Do NOT close infected wounds - this traps bacteria and worsens infection 2, 4
• Elevate the injured body part to accelerate healing 2, 4
• Update tetanus prophylaxis if vaccination status is outdated or unknown 2, 4, 8
• Follow up within 24 hours by phone or office visit 2, 4

Special Consideration: Hand Bites

Cat bites to the hand deserve particular attention:

• Hand bites have the greatest risk of infection due to limited blood supply and proximity to tendons, joints, and bone 6
• Prophylactic antibiotics for hand bites reduce infection risk significantly (NNT = 4) 9
• Never delay treatment - complications like septic arthritis, osteomyelitis, and tendonitis can develop rapidly 2, 4

Common Pitfall to Avoid

Do not rely on topical antibiotics alone (such as mupirocin) - they do not adequately penetrate to reach the deep-seated infections that commonly occur with cat bites 2