What antibiotics are recommended for an adult patient with no underlying medical conditions who has been bitten by a cat?

Antibiotic Management for Cat Bites

Amoxicillin-clavulanate 875/125 mg orally twice daily is the definitive first-line antibiotic for cat bite prophylaxis and treatment in adults without underlying medical conditions. 1, 2

Why Amoxicillin-Clavulanate is the Clear Choice

This recommendation is based on the microbiology of cat bite wounds, which are highly polymicrobial:

• Pasteurella multocida is present in approximately 75% of cat bite wounds and is the predominant pathogen requiring coverage 2
• Cat bites contain an average of 5 different bacterial species per wound, including both aerobic and anaerobic organisms 2
• Staphylococci and streptococci are present in ~40% of wounds 2
• Anaerobic bacteria (Bacteroides, fusobacteria, Porphyromonas, peptostreptococci) are present in 65% of cat bites 2
• Research confirms approximately 90% carriage rate of P. multocida in the feline oral cavity 3
• 20-80% of all cat bites become infected, making prophylaxis critical 3

Amoxicillin-clavulanate provides optimal coverage against this entire polymicrobial spectrum with excellent activity against P. multocida, staphylococci, streptococci, and anaerobes. 1, 2

Dosing and Administration

• Dose: 875/125 mg orally twice daily 1, 4
• Duration: 3-5 days for prophylaxis of uncomplicated wounds; 7-14 days if early signs of infection are present 1
• Timing: Take at the start of meals to enhance clavulanate absorption and minimize gastrointestinal intolerance 4

Indications for Prophylactic Antibiotics

Prophylaxis is indicated for: 1

• Deep puncture wounds (cat bites characteristically cause deeper puncture-type wounds) 5
• Wounds on the hands, feet, face, or near joints (hand wounds carry the highest infection risk) 1, 2
• Any wound presenting >8-12 hours after injury with signs of early infection 1

Alternative Regimens for Penicillin Allergy

For Mild Penicillin Allergies:

• Doxycycline 100 mg orally twice daily has excellent P. multocida activity 1, 2

For Severe Penicillin Allergies:

• Fluoroquinolone (ciprofloxacin 500-750 mg twice daily OR levofloxacin 750 mg daily) PLUS metronidazole to provide anaerobic coverage 1
• Alternatively, trimethoprim-sulfamethoxazole PLUS metronidazole 1

Critical Pitfalls to Avoid

Never use these as monotherapy for cat bites: 1, 2

• First-generation cephalosporins (e.g., cephalexin) - poor activity against P. multocida
• Penicillinase-resistant penicillins alone (e.g., dicloxacillin) - inadequate P. multocida coverage
• Clindamycin alone - misses P. multocida entirely
• Erythromycin - poor activity against P. multocida

These antibiotics will fail to treat the infection despite appearing appropriate for skin and soft tissue infections in other contexts. 1, 2

When to Escalate to IV Antibiotics

Transition to intravenous therapy if: 1, 2

• Systemic signs develop (fever, sepsis)
• Deep tissue involvement occurs (tendon penetration, bone involvement, joint space violation)
• Rapidly progressing infection despite oral therapy
• Patient requires hospitalization

First-line IV antibiotic: Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 1

Alternative IV options include piperacillin-tazobactam, second-generation cephalosporins, or carbapenems. 2

Essential Adjunctive Wound Management

Beyond antibiotics, proper wound care is critical: 1, 2

• Thoroughly irrigate with sterile normal saline
• Remove superficial debris and devitalized tissue 5
• Do NOT close infected wounds or deep puncture wounds 1, 2
• Elevate the affected extremity to accelerate healing 2
• Update tetanus immunization if status is outdated or unknown 2, 5
• Assess rabies risk (healthy cat should be confined and observed for 10 days) 2

Special Attention to Hand Wounds

Hand bites deserve particular vigilance: 1, 2

• Highest risk of infection and serious complications
• Can lead to septic arthritis, osteomyelitis, and tendonitis
• Require aggressive management and close follow-up
• Consider early surgical consultation for deep hand wounds

Follow-Up Instructions

Patients must return immediately if they experience: 1

• Increasing pain, redness, or swelling
• Purulent drainage
• Fever
• Decreased range of motion

All outpatients should be followed up within 24 hours either by phone or office visit. 2