Antibiotic Treatment for Cat Bite Wounds
Amoxicillin-clavulanate 875 mg/125 mg twice daily for 7–10 days is the first-line treatment for cat bite wounds in adults with normal renal function. 1, 2
First-Line Therapy and Dosing
Amoxicillin-clavulanate 875/125 mg orally twice daily provides comprehensive coverage against the polymicrobial flora of cat bites, including Pasteurella multocida (present in 75% of cat wounds), staphylococci, streptococci, and anaerobes. 1, 2
This regimen demonstrates 100% susceptibility against P. multocida and is supported by IDSA guidelines as a Class I, Level A recommendation. 2
Treatment duration: 7–10 days for uncomplicated cat bite infections. 2
Cat bites carry higher infection risk than dog bites (20–80% vs. 3–18%) and have greater prevalence of anaerobes (65%) and P. multocida (75%), making appropriate antibiotic selection critical. 1, 3
Alternatives for Penicillin-Allergic Patients
For patients with penicillin allergy, combination therapy is required because no single alternative agent covers all necessary pathogens:
Doxycycline 100 mg twice daily (oral or IV) provides excellent activity against P. multocida but misses some streptococci and has limited anaerobic coverage. 1
Moxifloxacin 400 mg once daily (oral or IV) offers monotherapy coverage including anaerobes and P. multocida, making it the best single-agent alternative. 1
Combination options include:
Critical Agents to Avoid
Never use these as monotherapy for cat bites:
First-generation cephalosporins (cephalexin, cefazolin) have poor activity against P. multocida and should be avoided entirely. 1, 2
Penicillinase-resistant penicillins (dicloxacillin), macrolides (erythromycin), and clindamycin alone all have inadequate P. multocida coverage. 1
Indications for Intravenous Therapy
Escalate to IV antibiotics when:
- No clinical improvement within 48–72 hours of oral therapy 2
- Systemic signs develop (fever, lymphangitis, altered mental status) 2
- Deep tissue involvement, abscess formation, or complications such as osteomyelitis or septic arthritis are present 1, 4
IV options include:
- Ampicillin-sulbactam 1.5–3.0 g every 6–8 hours (first choice) 1, 2
- Piperacillin-tazobactam 3.37 g every 6–8 hours 1
- Carbapenems (ertapenem, imipenem, meropenem) 1
- Cefoxitin 1 g every 6–8 hours or ceftriaxone 1 g every 12 hours 1
Special Considerations for High-Risk Wounds
Hand wounds require heightened vigilance as they carry the greatest infection risk and are more likely to develop complications including septic arthritis, osteomyelitis, and tendonitis. 1, 5
Elderly patients (≥85 years) warrant closer monitoring due to diminished immune responses and higher complication rates (approximately 18% of infected cat bites develop complications). 2
When MRSA is suspected (purulent drainage, local epidemiology), add trimethoprim-sulfamethoxazole 1–2 double-strength tablets twice daily to the amoxicillin-clavulanate regimen. 2
Key Clinical Pitfalls
Cat bites often appear trivial but create deep puncture wounds with higher infection rates than dog bites. 6, 5
Pain disproportionate to injury severity, especially near bones or joints, suggests periosteal penetration and potential osteomyelitis requiring 4–6 weeks of therapy. 1
Both aerobic AND anaerobic cultures should be ordered, as anaerobes (including Bacteroides pyogenes) are present in 65% of cat bite infections but may be missed without specific culture requests. 1, 4
Renal function assessment is necessary before initiating therapy in elderly patients, though the standard 875 mg twice-daily dose is generally well tolerated. 2