What alternative antibiotic treatment is recommended for a cat bite that is resistant to Augmentin (amoxicillin/clavulanate)?

Alternative Antibiotic Treatment for Cat Bite Resistant to Augmentin

For a cat bite infection that is resistant to Augmentin (amoxicillin/clavulanate), the recommended alternative antibiotic treatment is doxycycline 100 mg twice daily, which has excellent activity against Pasteurella multocida, the most common pathogen in cat bite infections. 1

Microbiology of Cat Bite Infections

Cat bite infections typically involve a complex polymicrobial mix with:

• Pasteurella multocida: Present in 75% of cat bite wounds (compared to 50% in dog bites) 1, 2
• Anaerobic bacteria: Found in 65% of cat bite infections 1
• Other common pathogens: Streptococci, staphylococci, anaerobes including Bacteroides, Fusobacterium, Porphyromonas, and Prevotella species 2, 3

Alternative Antibiotic Options

When Augmentin resistance is encountered, consider the following alternatives:

First-line alternative:

• Doxycycline: 100 mg twice daily (oral) 1
  • Excellent activity against Pasteurella multocida
  • Good coverage of staphylococci and anaerobes
  • Some streptococci may be resistant

Other oral alternatives:

• Moxifloxacin: 400 mg daily (monotherapy with good anaerobic coverage) 1
• Ciprofloxacin: 500-750 mg twice daily (plus metronidazole for anaerobic coverage) 1
• Levofloxacin: 750 mg daily (plus metronidazole for anaerobic coverage) 1, 4
• Clindamycin: 300-400 mg three times daily (good coverage for staphylococci, streptococci, and anaerobes but misses Pasteurella multocida) 1

Intravenous options (for severe infections):

• Piperacillin-tazobactam: 3.37 g every 6-8 hours 1
• Carbapenems (imipenem, meropenem, ertapenem) 1, 5
• Ceftriaxone: 1-2 g daily (plus metronidazole for anaerobic coverage) 1
• Cefotaxime: 1-2 g every 6-8 hours (plus metronidazole for anaerobic coverage) 1

Treatment Algorithm

1. For mild to moderate infections resistant to Augmentin:

   • Switch to doxycycline 100 mg twice daily for 7-10 days
   • If patient has contraindication to doxycycline (pregnancy, young children):
     • Use moxifloxacin 400 mg daily OR
     • Ciprofloxacin 500-750 mg twice daily plus metronidazole 500 mg three times daily

2. For severe infections:

   • Hospitalize for IV antibiotics
   • Piperacillin-tazobactam OR
   • A carbapenem (imipenem, meropenem, ertapenem) OR
   • Ceftriaxone plus metronidazole

3. For patients with penicillin allergy:

   • Doxycycline (first choice) OR
   • Fluoroquinolone plus metronidazole OR
   • Clindamycin (with caution due to poor activity against Pasteurella)

Important Considerations

• Location matters: Hand and face bites have higher risk of complications and may require more aggressive treatment 1, 6
• Timing: Patients presenting >8-12 hours after injury typically have established infection 1
• Adjunctive measures: Wound cleansing, debridement of necrotic tissue, and drainage of abscesses are critical components of treatment 5
• Monitoring: Watch for signs of deeper infection such as tenosynovitis, especially with hand wounds 6
• Duration: 7-10 days for uncomplicated infections; 3-4 weeks for complications like osteomyelitis or septic arthritis 1

Common Pitfalls to Avoid

1. Inadequate anaerobic coverage: Cat bite infections frequently involve anaerobes that may not be covered by some antibiotics 3
2. Relying on first-generation cephalosporins: Cephalexin, dicloxacillin, macrolides, and clindamycin all have poor activity against Pasteurella multocida and should be avoided as monotherapy 1
3. Failure to recognize complications: Deep space infections, tenosynovitis, and osteomyelitis require longer treatment courses and possibly surgical intervention 6
4. Delayed treatment: Cat bites have a higher proportion of osteomyelitis and septic arthritis than dog bites despite having less crush injury 1

By following these recommendations, you can effectively manage cat bite infections that have proven resistant to Augmentin, reducing the risk of serious complications and ensuring optimal patient outcomes.