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

Management of Cat Bite Wounds in the Emergency Department

Cat bites require thorough wound cleansing, appropriate antibiotic therapy with amoxicillin-clavulanate, and consideration for tetanus prophylaxis to prevent serious infections. 1

Initial Assessment and Wound Management

• Cat bites have a high risk of infection (30-50%) compared to dog bites (5-25%), despite having less crush injury 2
• Cat bites often lead to more severe infections with higher rates of osteomyelitis and septic arthritis than dog bites 2
• Thorough wound cleansing with sterile normal saline is essential to remove superficial debris 1
• Infected wounds should not be closed, as this may trap bacteria and promote deeper infection 1
• Elevation of the injured body part, especially if swollen, accelerates healing 1

Microbiology of Cat Bite Wounds

• Cat bite wounds typically contain an average of 5 different bacterial species per wound, with approximately 60% yielding mixed aerobic and anaerobic bacteria 2
• Pasteurella multocida is the predominant pathogen, found in approximately 75% of cat bite wounds 2, 1
• Staphylococci and streptococci are present in approximately 40% of cat bite wounds 2, 1
• Anaerobic bacteria (including Bacteroides species, fusobacteria, Porphyromonas species, and peptostreptococci) are present in 65% of cat bites 2, 1
• Capnocytophaga canimorsus, a fastidious gram-negative rod, can cause bacteremia and fatal sepsis, especially in patients with asplenia or underlying hepatic disease 2

Antibiotic Therapy

• Amoxicillin-clavulanate (875/125 mg twice daily for adults) is the recommended first-line therapy for cat bite infections 2, 1
• Alternative oral options for penicillin-allergic patients include:
  • Doxycycline (100 mg twice daily), which has excellent activity against P. multocida 1
  • Penicillin VK plus dicloxacillin (500 mg four times daily for each) 2
• Avoid the following antibiotics as monotherapy due to poor activity against P. multocida:
  • First-generation cephalosporins (e.g., cephalexin) 2, 1
  • Penicillinase-resistant penicillins (e.g., dicloxacillin) alone 1
  • Macrolides (e.g., erythromycin) 2
  • Clindamycin alone 2, 1
• Fluoroquinolones, trimethoprim-sulfamethoxazole, and cefuroxime may require additional anaerobic coverage (e.g., metronidazole) 2

Intravenous Antibiotic Options

• For severe infections requiring hospitalization, intravenous options include:
  • Beta-lactam/beta-lactamase combinations (e.g., ampicillin-sulbactam) 2
  • Piperacillin-tazobactam 2
  • Second-generation cephalosporins (e.g., cefoxitin) 2
  • Carbapenems (e.g., ertapenem, imipenem, meropenem) 2

Additional Considerations

• Tetanus prophylaxis should be administered if vaccination status is outdated or unknown 1, 3
• Consider rabies risk assessment, especially for bites from unknown or feral cats 4, 3
• Patients who present within 8 hours of injury typically seek wound care or tetanus prophylaxis 2
• Patients who present after 8-12 hours of injury typically have established infection 2

Follow-Up and Monitoring

• Outpatients should be followed up within 24 hours either by phone or during an office visit 1
• Monitor for signs of progressive infection (increasing pain, redness, swelling, purulent drainage, fever) 4
• Watch for complications such as septic arthritis, osteomyelitis, or tendonitis, especially with hand wounds 1, 5
• Consider hospitalization for systemic infection, rapidly progressing infection, deep tissue involvement, or immunocompromised hosts 1

Common Pitfalls to Avoid

• Relying solely on topical antibiotics without systemic coverage 1
• Using antibiotics with poor activity against P. multocida (e.g., first-generation cephalosporins, penicillinase-resistant penicillins, macrolides, or clindamycin alone) 2, 1
• Delaying treatment, which can lead to serious complications including sepsis 6
• Closing infected wounds, which can trap bacteria and worsen infection 1