Antibiotic Treatment for Cat Bites

Microbiology of Cat Bite Wounds

• Pasteurella multocida is found in approximately 75% of cat bite wounds and is the predominant pathogen 2
• Cat bites contain an average of 5 different bacterial species per wound, including both aerobic and anaerobic bacteria 2
• Staphylococci and streptococci are found in ~40% of bites 2
• Anaerobes, including Bacteroides species, fusobacteria, Porphyromonas species, and peptostreptococci, are present in 65% of cat bites 2

First-Line Oral Treatment Options

• Amoxicillin-clavulanate (875/125 mg twice daily) is recommended as first-line therapy based on clinical studies and guidelines 1, 3
• Doxycycline (100 mg twice daily) has excellent activity against P. multocida, though some streptococci may be resistant 1
• Penicillin VK plus dicloxacillin (500 mg four times daily for each) is an alternative oral option 1

Medications to Avoid for Cat Bites

• First-generation cephalosporins (e.g., cephalexin) should be avoided due to poor activity against P. multocida 3
• Penicillinase-resistant penicillins (e.g., dicloxacillin) should be avoided due to poor activity against P. multocida 3
• Macrolides (e.g., erythromycin) should be avoided due to poor activity against P. multocida 3
• Clindamycin alone should be avoided as it misses P. multocida 1

Intravenous Treatment Options

• Ampicillin-sulbactam (1.5-3.0 g every 6-8 hours) is a recommended intravenous treatment option 1
• Piperacillin-tazobactam (3.37 g every 6-8 hours) is a recommended intravenous treatment option 1
• Second-generation cephalosporins (e.g., cefoxitin 1 g every 6-8 hours) are recommended intravenous treatment options 3
• Carbapenems (e.g., ertapenem, imipenem, meropenem) are recommended intravenous treatment options 1

Special Considerations

• Septic arthritis and osteomyelitis can occur as complications of cat bites 2
• Tendonitis can occur as a complication of cat bites 4

Treatment Duration

• Osteomyelitis requires 4-6 weeks of antibiotic therapy 4
• Septic arthritis/synovitis requires 3-4 weeks of antibiotic therapy 4

Wound Management

• Wounds should be thoroughly cleansed with sterile normal saline 4
• Superficial debris should be removed 4
• Infected wounds should not be closed 4
• Elevation of the injured body part, especially if swollen, accelerates healing 4
• Tetanus prophylaxis should be administered if vaccination status is outdated or unknown 4

Follow-Up

• Outpatients should be followed up within 24 hours either by phone or during an office visit 4
• If infection progresses despite appropriate therapy, hospitalization should be considered 4