What is the recommended management for a cat bite in the emergency department?

Management of Cat Bite in the Emergency Department

Amoxicillin-clavulanate (875/125 mg twice daily) is the recommended first-line therapy for cat bite infections due to its excellent coverage against Pasteurella multocida and other common pathogens found in cat bites. 1

Microbiology of Cat Bites

• Cat bites contain an average of 5 different bacterial species per wound, including both aerobic and anaerobic bacteria 2
• Pasteurella multocida is found in approximately 75% of cat bite wounds and is the predominant pathogen requiring targeted antibiotic coverage 2, 1
• Staphylococci and streptococci are present in ~40% of cat bites 2, 1
• Anaerobic bacteria, including Bacteroides species, fusobacteria, Porphyromonas species, and peptostreptococci, are present in 65% of cat bites 2, 1
• Cat bites have a higher proportion of osteomyelitis and septic arthritis compared to dog bites 2

Initial Wound Management

• Thoroughly cleanse the wound with sterile normal saline (not iodine or antibiotic-containing solutions) 2, 1
• Remove superficial debris but avoid aggressive debridement unless necessary 2, 1
• Do not close infected wounds or wounds presenting >8 hours after injury 2, 1
• Elevate the injured body part, especially if swollen, to accelerate healing 2, 1
• Administer tetanus prophylaxis if vaccination status is outdated or unknown 1

Antibiotic Therapy

First-line oral therapy:

• Amoxicillin-clavulanate 875/125 mg twice daily 2, 1

Alternative oral options (for penicillin-allergic patients):

• Doxycycline 100 mg twice daily (excellent activity against P. multocida, though some streptococci may be resistant) 2, 1
• Penicillin plus dicloxacillin 500 mg four times daily for each 2, 1
• Moxifloxacin 400 mg daily (good monotherapy with activity against anaerobes) 2

Antibiotics to avoid:

• First-generation cephalosporins (e.g., cephalexin) due to poor activity against P. multocida 2, 1
• Penicillinase-resistant penicillins alone (e.g., dicloxacillin) 2, 1
• Clindamycin alone as it misses P. multocida 2, 1
• Trimethoprim-sulfamethoxazole alone has good activity against aerobes but poor activity against anaerobes 2

Intravenous therapy (for severe infections):

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 2
• Piperacillin-tazobactam 3.37 g every 6-8 hours 2
• Second-generation cephalosporins (e.g., cefoxitin 1 g every 6-8 hours) 2
• Carbapenems (e.g., ertapenem, imipenem, meropenem) 2

Indications for Hospitalization

• Systemic infection (fever, elevated white blood cell count) 1, 3
• Rapidly progressing infection 1
• Deep tissue involvement (tendon, joint, bone) 1, 4
• Immunocompromised host 1
• Hand infections, which are particularly prone to complications 4, 5
• Presentation >24 hours after injury with signs of infection 4

Follow-up and Monitoring

• Outpatients should be followed up within 24 hours either by phone or during an office visit 1
• If infection progresses despite appropriate therapy, hospitalization should be considered 1
• Patients with hand wounds require particularly close monitoring due to risk of tendon involvement and functional impairment 4, 5

Common Pitfalls to Avoid

• Relying solely on topical antibiotics without systemic coverage 1
• Delaying treatment, which can lead to complications such as septic arthritis, osteomyelitis, or tendonitis 1, 4
• Using antibiotics with poor activity against P. multocida (e.g., first-generation cephalosporins, macrolides) 2, 1
• Closing infected wounds or wounds presenting >8 hours after injury 2, 1
• Inadequate follow-up, especially for hand wounds 4, 5

Special Considerations

• Cat bites to the hand carry a particularly high risk of infection and complications due to the proximity of joints, tendons, and bones to the skin surface 4, 5
• Studies have shown that prophylactic antibiotics significantly reduce infection rates in cat bite wounds 6
• Even seemingly minor cat puncture wounds can introduce bacteria deep into tissues 7