Cat Bite Antibiotic Treatment
Amoxicillin-clavulanate 875/125 mg twice daily is the first-line antibiotic for cat bites, whether for prophylaxis or treatment of established infection. 1, 2
Why Amoxicillin-Clavulanate is First-Line
Cat bites have an exceptionally high infection rate of 30-50%, significantly higher than dog bites (5-25%), making antibiotic coverage critical 3. The microbiology drives this recommendation:
- Pasteurella multocida is isolated from approximately 75% of cat bite wounds and is carried in ~90% of cats' oral cavities 1, 4
- Cat bites contain an average of 5 different bacterial species per wound, including both aerobic and anaerobic organisms 1
- Staphylococci and streptococci are present in ~40% of bites 1
- Anaerobes (Bacteroides, Fusobacterium, Porphyromonas, peptostreptococci) are found in 65% of cat bites 1, 2
Amoxicillin-clavulanate provides comprehensive coverage against this polymicrobial mix, with 100% susceptibility demonstrated for P. multocida 4.
Alternative Oral Antibiotics
If amoxicillin-clavulanate is not tolerated or contraindicated:
- Doxycycline 100 mg twice daily has excellent activity against P. multocida, though some streptococci may be resistant 1, 2
- Fluoroquinolones (ciprofloxacin 500-750 mg twice daily, levofloxacin 750 mg daily, or moxifloxacin 400 mg daily) have good P. multocida coverage but may miss MRSA and some anaerobes 2
- Penicillin VK plus dicloxacillin (500 mg four times daily for each) is an alternative combination 1
Antibiotics to AVOID
Critical pitfall: Several commonly prescribed antibiotics have poor activity against P. multocida and should never be used for cat bites 1, 2:
- First-generation cephalosporins (e.g., cephalexin)
- Penicillinase-resistant penicillins as monotherapy (e.g., dicloxacillin alone)
- Macrolides (e.g., erythromycin, azithromycin)
- Clindamycin as monotherapy
Intravenous Options for Severe Infections
Hospitalization and IV antibiotics are warranted for systemic infection, rapidly progressing infection despite oral therapy, deep tissue involvement, immunocompromised patients, or need for surgical intervention 2:
- Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 1, 2
- Piperacillin-tazobactam 3.37 g every 6-8 hours 1, 2
- Second-generation cephalosporins (cefoxitin 1 g every 6-8 hours) 1, 2
- Carbapenems (ertapenem, imipenem, meropenem) 1
Treatment Duration Based on Complications
- Uncomplicated cellulitis: Standard course (typically 5-7 days, though guidelines don't specify exact duration)
- Osteomyelitis: 4-6 weeks of antibiotic therapy 1
- Septic arthritis/synovitis: 3-4 weeks of antibiotic therapy 1
Cat bites to the hand carry the greatest infection risk and can rapidly progress to tendonitis, septic arthritis, or osteomyelitis 1, 5, 6. P. multocida characteristically causes rapidly developing cellulitis within 12-24 hours of the bite 7.
Essential Wound Management
- Thoroughly cleanse wounds with sterile normal saline 1
- Deep irrigation to remove foreign bodies and pathogens, but avoid high-pressure irrigation as it may spread bacteria into deeper tissues 3
- Remove superficial debris and necrotic tissue 3, 1
- Do not close infected wounds 1
- Elevate the injured body part if swollen 1
- Update tetanus prophylaxis if vaccination status is outdated or unknown 1, 8
- Consider rabies post-exposure prophylaxis (immune globulin plus vaccination on days 0,3,7, and 14) 8