Antibiotic for Cat Bite
Amoxicillin-clavulanate (875/125 mg twice daily) is the first-line antibiotic for cat bite wounds, whether for prophylaxis or treatment of established infection. 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 clinical characteristics:
- Pasteurella multocida is present in 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, with 65% harboring anaerobic bacteria (including Bacteroides, fusobacteria, and Porphyromonas species) 1, 2, 3
- Staphylococci and streptococci are found in approximately 40% of cat bites 1, 2
- Cat bites have infection rates of 20-80%, significantly higher than dog bites (3-18%) 4
- Cat bites to the hand carry the highest risk of serious complications including septic arthritis and osteomyelitis 2, 5
Amoxicillin-clavulanate provides comprehensive coverage against all these pathogens and maintains excellent susceptibility profiles, with 100% of P. multocida isolates remaining susceptible 4.
Alternative Oral Regimens
For patients with penicillin allergies or intolerance:
- Doxycycline (100 mg twice daily) is an excellent alternative with good activity against P. multocida, though some streptococci may be resistant 1, 2, 3
- Fluoroquinolones (ciprofloxacin 500-750 mg twice daily, levofloxacin, or moxifloxacin) plus metronidazole or clindamycin for anaerobic coverage 1, 3
- Penicillin VK plus dicloxacillin (500 mg four times daily for each) is another option 1, 2
Intravenous Options for Severe Infections
IV antibiotics are indicated for systemic signs (fever, lymphangitis), deep tissue involvement (septic arthritis, osteomyelitis, tenosynovitis), or immunocompromised patients 3:
- Ampicillin-sulbactam (1.5-3.0 g every 6-8 hours) is first-line IV therapy 1, 3
- Piperacillin-tazobactam (3.37 g every 6-8 hours) is an alternative 1, 3
- Carbapenems (ertapenem 1 g daily, imipenem 1 g every 6-8 hours, or meropenem 1 g every 8 hours) for severe infections 1, 3
Treatment duration: 3-5 days IV for cellulitis before transitioning to oral therapy; 3-4 weeks total for septic arthritis; 4-6 weeks for osteomyelitis 3.
Critical Antibiotics to AVOID
The following antibiotics have poor activity against P. multocida and should never be used for cat bites:
- First-generation cephalosporins (e.g., cephalexin) 1, 2, 3
- Penicillinase-resistant penicillins alone (e.g., dicloxacillin monotherapy) 1, 2
- Macrolides (e.g., erythromycin, azithromycin) - clinical failures documented 1, 2, 3
- Clindamycin monotherapy 1, 2, 3
Essential Wound Management
Beyond antibiotics, proper wound care is critical:
- Thoroughly cleanse with sterile normal saline irrigation using a 20-mL or larger syringe 2, 6
- Remove superficial debris and explore for tendon, bone involvement, or foreign bodies 2, 6
- Do not close infected wounds - allow healing by secondary intention 2, 3
- Elevate the injured extremity to reduce swelling and accelerate healing 1, 2
- Update tetanus prophylaxis if vaccination status is outdated or unknown 2, 6
Follow-Up and Monitoring
- Outpatients require follow-up within 24 hours by phone or office visit 2
- Consider hospitalization if infection progresses despite appropriate therapy, or for rapidly advancing infection, deep tissue involvement, or immunocompromised hosts 2
- Hand bites warrant particularly close observation given the high risk of serious complications 2, 5, 7
Common Pitfalls
- Never rely on topical antibiotics alone without systemic coverage for cat bites 2
- Do not delay treatment - this can lead to devastating complications including septic arthritis, osteomyelitis, tendonitis, bacteremia, or meningitis 2, 3
- Even small external wounds from cat bites can harbor deep infections requiring early prophylactic antibiotics and close observation 8
- Prophylactic antibiotics for hand bites specifically reduce infection risk (NNT = 4) 7