What is the alternative treatment for a cat bite infection resistant to Augmentin (amoxicillin-clavulanate)?

Treatment for Cat Bite Infection Resistant to Augmentin

For cat bite infections resistant to amoxicillin-clavulanate (Augmentin), doxycycline 100 mg twice daily is the recommended alternative treatment due to its excellent activity against Pasteurella multocida and anaerobes commonly found in cat bite wounds. 1

Microbiology of Cat Bite Infections

Cat bites have a high risk of infection due to their unique microbial profile:

• Pasteurella multocida is present in 75% of cat bite wounds (compared to 50% in dog bites) 1
• Higher prevalence of anaerobes (65% vs 50% in dog bites) 1
• Other common organisms include:
  • Staphylococci and streptococci (found in ~40% of bites)
  • Bacteroides species, fusobacteria, Porphyromonas species
  • Prevotella heparinolytica, proprionibacteria, and peptostreptococci 1

Alternative Oral Treatment Options

When Augmentin resistance is encountered, the following alternatives are recommended:

1. First choice: Doxycycline 100 mg twice daily 1

   • Excellent activity against Pasteurella multocida
   • Good coverage of anaerobes, staphylococci
   • Contraindicated in children under 8 years and pregnant women

2. Second choice options:

   • Moxifloxacin 400 mg daily (monotherapy with good anaerobic coverage) 1
   • Ciprofloxacin 500-750 mg twice daily (good activity against P. multocida but may miss some anaerobes) 1
   • Levofloxacin 750 mg daily with metronidazole for anaerobic coverage 1
   • Trimethoprim-sulfamethoxazole with metronidazole (for anaerobic coverage) 1

Intravenous Treatment Options

For severe infections requiring parenteral therapy:

1. First choice options:

   • Ampicillin-sulbactam 1.5-3.0 g every 6 hours 1
   • Piperacillin-tazobactam 3.37 g every 6-8 hours 1

2. Alternative options:

   • Second-generation cephalosporins (cefoxitin) 1
   • Carbapenems (ertapenem, imipenem, meropenem) 1

Treatment Algorithm

1. Assess severity of infection:

   • Localized infection: oral therapy
   • Systemic symptoms, rapidly spreading infection, or immunocompromised host: IV therapy

2. For oral therapy in Augmentin-resistant cases:

   • Start doxycycline 100 mg twice daily for 5-6 days 1, 2
   • If contraindicated (children <8 years, pregnancy), use fluoroquinolone plus metronidazole

3. For IV therapy in Augmentin-resistant cases:

   • Ampicillin-sulbactam or piperacillin-tazobactam
   • For penicillin allergy: carbapenem or fluoroquinolone plus metronidazole

4. Duration of therapy:

   • Uncomplicated infections: 5-6 days 2
   • Complicated infections (osteomyelitis, septic arthritis): 3-6 weeks 1

Important Considerations and Pitfalls

• Avoid first-generation cephalosporins (cephalexin), penicillinase-resistant penicillins (dicloxacillin), macrolides (erythromycin), and clindamycin alone as they have poor activity against P. multocida 1

• Wound care is crucial:

  • Thorough cleansing with sterile normal saline
  • Removal of superficial debris
  • Elevation of affected area to accelerate healing 1

• Monitor for complications:

  • Septic arthritis, osteomyelitis, abscess formation
  • Pain disproportionate to injury near bone/joint suggests periosteal penetration 1

• Hand wounds are often more serious and may require more aggressive treatment 1

• Recent case report highlights the importance of obtaining both aerobic and anaerobic cultures in cat bite infections, as Bacteroides species with increasing antibiotic resistance can be present 3

Special Situations

• For confirmed MRSA infection: Consider adding or switching to trimethoprim-sulfamethoxazole, doxycycline, or linezolid 1

• For immunocompromised patients: Lower threshold for IV therapy and consider broader spectrum coverage

• For diabetic patients: More aggressive treatment approach with careful monitoring for complications 1

By following this approach, most cat bite infections resistant to Augmentin can be effectively treated while minimizing complications and ensuring optimal outcomes.