Cat Bite Antibiotic Prophylaxis
First-Line Recommendation
Amoxicillin-clavulanate 875/125 mg orally twice daily for 3-5 days is the definitive first-line antibiotic for cat bite prophylaxis in healthy adults. 1, 2
This regimen provides comprehensive coverage against the polymicrobial flora typical of cat bites, which average 5 different bacterial species per wound, including Pasteurella multocida (present in ~75-90% of cat bites), staphylococci, streptococci, and anaerobes. 2, 3
Indications for Prophylaxis
Prophylactic antibiotics are strongly indicated for: 1
- Deep puncture wounds (cat bites characteristically cause deep punctures rather than crush injuries)
- Hand, foot, face, or near-joint wounds (hand wounds carry the highest infection risk)
- Immunocompromised patients
- Wounds presenting >8-12 hours after injury with early infection signs
- Any full-thickness wound (20-80% of cat bites become infected without prophylaxis, compared to only 3-18% of dog bites) 3, 4
Alternative Regimens for Penicillin Allergy
Mild/Non-Anaphylactic Allergy
Doxycycline 100 mg orally twice daily for 3-5 days is the preferred alternative, offering excellent P. multocida activity with reliable staphylococcal and anaerobic coverage. 1, 2 Occasional streptococcal resistance is clinically acceptable in this context.
Severe Allergy (Anaphylaxis History)
Two dual-agent regimens provide adequate coverage: 1, 2
Ciprofloxacin 500-750 mg twice daily PLUS clindamycin 300 mg three times daily (or levofloxacin 750 mg daily plus clindamycin)—the fluoroquinolone covers P. multocida and gram-negatives while clindamycin adds anaerobic and gram-positive activity 5, 1
Trimethoprim-sulfamethoxazole 160/800 mg twice daily PLUS metronidazole 250-500 mg four times daily—TMP-SMZ provides aerobic coverage while metronidazole ensures anaerobic activity 5, 1
Critical Pitfalls: Antibiotics to AVOID as Monotherapy
The following agents have inadequate P. multocida coverage and should never be used alone for cat bites: 5, 1, 2
- First-generation cephalosporins (cephalexin, cefazolin)—poor P. multocida activity
- Penicillinase-resistant penicillins (dicloxacillin)—inadequate P. multocida coverage
- Clindamycin alone—completely misses P. multocida
- Macrolides (erythromycin)—poor P. multocida activity
- Second/third-generation cephalosporins alone (cefuroxime, ceftriaxone)—insufficient anaerobic coverage despite good P. multocida activity
Duration of Therapy
- 3-5 days for uncomplicated prophylaxis in clean wounds 1, 2
- 5-7 days if early infection signs are present 2
- 7-14 days for established infections 1
- 3-4 weeks for complications such as synovitis, osteomyelitis, or deep tissue involvement 2
When to Escalate to Intravenous Therapy
Transition to IV antibiotics if: 1
- Systemic signs develop (fever, lymphangitis)
- Deep tissue involvement occurs
- Patient is immunocompromised with moderate-to-severe injury
- Oral therapy fails after 48-72 hours
IV regimen: Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 5, 1
IV regimen for penicillin allergy: Carbapenems (ertapenem 1 g daily, meropenem 1 g every 8 hours, or imipenem 1 g every 6-8 hours) 5, 1
Essential Adjunctive Wound Care
Beyond antibiotics, proper wound management is equally critical: 1, 2, 6
- Thorough irrigation with copious sterile normal saline or warm water
- Debridement of devitalized tissue and removal of foreign bodies
- Avoid primary closure of puncture wounds (high infection risk)
- Tetanus immunization update if >5 years since last booster
- Rabies risk assessment (though domestic cats rarely require prophylaxis)
- Elevation of affected extremity to reduce edema
- Neurovascular examination and documentation of range of motion
High-Risk Wound Alert: Hand Bites
Hand wounds deserve particular vigilance as they carry the highest risk of infection and functional complications, including tenosynovitis, septic arthritis, and osteomyelitis. 1, 2 Consider lower threshold for IV therapy, surgical consultation, and extended antibiotic courses for hand injuries.
Return Precautions
Instruct patients to return immediately for: 1
- Increasing pain, redness, or swelling
- Purulent drainage
- Fever or chills
- Decreased range of motion
- Red streaking (lymphangitis)
- Pain disproportionate to visible inflammation (suggests deeper infection)