Antibiotic Management for Infected Cat Bite Wounds
Amoxicillin-clavulanate is the first-line antibiotic treatment for infected cat bite wounds due to its excellent coverage of common pathogens including Pasteurella multocida, which is present in 75% of cat bite infections. 1
Microbiology and Rationale
Cat bite wounds have a high infection rate due to their specific microbiology:
- Pasteurella multocida (present in 75% of cat bites)
- Staphylococci and streptococci (approximately 40%)
- Anaerobic bacteria (65% of cat bites)
- Other potential pathogens: Capnocytophaga canimorsus, Bacteroides species, fusobacteria, Porphyromonas species
Antibiotic Recommendations
First-line Treatment (Outpatient):
- Amoxicillin-clavulanate 875/125 mg orally twice daily 1, 2, 3
- For adults weighing ≥40 kg
- Duration: 5-7 days for uncomplicated infections
- Provides coverage against both aerobic and anaerobic pathogens
Alternative Oral Regimens (for penicillin-allergic patients):
- Doxycycline 100 mg orally twice daily 1, 2
- Clindamycin 300-450 mg orally every 6-8 hours PLUS one of the following: 1, 2, 4
- Trimethoprim-sulfamethoxazole
- Fluoroquinolone (ciprofloxacin, levofloxacin)
Intravenous Options (for severe infections):
- Ampicillin-sulbactam
- Piperacillin-tazobactam
- Second-generation cephalosporins (cefoxitin)
- Carbapenems (ertapenem, imipenem, meropenem) 1
Antibiotics to AVOID:
- First-generation cephalosporins (cephalexin)
- Penicillinase-resistant penicillins (dicloxacillin)
- Macrolides (erythromycin)
- Clindamycin alone (poor activity against P. multocida) 1
Management Algorithm
Wound Assessment:
- Determine severity: non-purulent, purulent, or abscess
- Assess for signs of systemic infection
- Evaluate for bone/joint involvement (particularly in hand wounds)
Wound Care:
- Copious irrigation with sterile normal saline
- Debridement of devitalized tissue
- Leave infected wounds open (do not close)
- Elevate affected limb to reduce swelling 1
Antibiotic Selection:
- For mild-moderate infections: oral amoxicillin-clavulanate
- For severe infections: IV antibiotics as listed above
- For penicillin-allergic patients: alternatives as listed above
Special Considerations:
- Hand wounds require particular attention due to higher risk of complications
- Consider longer treatment (3-4 weeks) for tendonitis or synovitis
- Extend to 4-6 weeks for osteomyelitis 1
Follow-up and Complications
- Follow up within 24-48 hours to assess response
- Watch for complications:
- Septic arthritis
- Osteomyelitis
- Tendonitis
- Subcutaneous abscess formation
- Bacteremia (rare)
Clinical Pearls and Pitfalls
- Cat bites have a higher infection rate than dog bites despite causing less tissue trauma 1, 5
- Hand wounds are at particularly high risk for infection and complications 6
- Pain disproportionate to wound appearance may indicate bone or joint involvement 1
- Prompt antibiotic therapy is crucial - studies show significant reduction in infection rates with early antibiotic administration 7
- Cat scratch disease (caused by Bartonella henselae) should be considered if lymphadenopathy develops; treat with azithromycin 1, 8
- Tetanus prophylaxis should be administered if not up to date (within 5 years for contaminated wounds) 1, 2
By following this evidence-based approach to antibiotic selection and wound management, you can effectively treat infected cat bite wounds and prevent serious complications.