Preferred Antibiotic for Cat Bite

"In a penicillin-allergic patient, what antibiotic would be the best prophylaxis for a deep laceration from a cat bite?"

     Although cat bite-related infections are often polymicrobial in nature, one organism, namely Pasteurella multocida, tends to predominate. P. multocida is very adept at causing significant soft tissue infections including those complicated by fasciitis, abscess formation or underlying septic arthritis/osteomyelitis.

     There's no clear consensus or conclusive studies about the efficacy of prophylaxis for cat bite infections, but it's not unreasonable to administer a short (three- to five-day) course of therapy for significant bites without evidence of infection at the time of presentation.

     Treatment of established infection (as well as prophylaxis) should be aimed at P. multocida first and foremost, as well as the usual mixture of oropharyngeal flora. P. multocida is most sensitive to penicillin, ampicillin, "third-generation" cephalosporins, tetracyclines and fluoroquinolones. Oral therapy is most easily achieved with amoxicillin-clavulinate.

     In the penicillin-allergic patient, consider intravenous ceftriaxone if the prior reaction wasn't an immediate one. Otherwise, a combination of oral clindamycin and either doxycycline or ciprofloxacin would be best. DM