What to do for a cat bite infection that doesn't respond to Augmentin (amoxicillin-clavulanate)?

Treatment for Cat Bite Infection Not Responding to Augmentin

For a cat bite infection that doesn't respond to amoxicillin-clavulanate (Augmentin), switch to doxycycline 100 mg twice daily as it has excellent activity against Pasteurella multocida, which is present in 75% of cat bite infections. 1

Microbiology of Cat Bite Infections

• Cat bite wounds have a higher infection rate than dog bites and typically contain mixed aerobic and anaerobic bacteria 1
• Pasteurella multocida is isolated from 75% of cat bite wounds and is the predominant pathogen 1, 2
• Anaerobic bacteria are present in 65% of cat bite infections, often concurrently with P. multocida 1
• Staphylococci and streptococci are found in approximately 40% of cat bites 1
• Other potential pathogens include Bacteroides species, fusobacteria, Porphyromonas species, and Prevotella heparinolytica 1

Why Augmentin Failure Occurs

• Some gram-negative rods may be resistant to amoxicillin-clavulanate 1
• Infection may have progressed to deeper tissues (tendon sheaths, joints, or bone) requiring more aggressive therapy 1
• Potential presence of resistant organisms not covered by Augmentin 1
• Complications such as abscess formation may require drainage in addition to antibiotics 1

Alternative Treatment Options

First-line alternative (oral therapy):

• Doxycycline 100 mg twice daily - excellent activity against P. multocida; some streptococci may be resistant 1

Other oral alternatives:

• Fluoroquinolones (with good activity against P. multocida but miss MRSA and some anaerobes) 1:
  • Ciprofloxacin 500-750 mg twice daily
  • Levofloxacin 750 mg daily
  • Moxifloxacin 400 mg daily (good monotherapy option as it also covers anaerobes)

For severe infections requiring IV therapy:

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 1
• Piperacillin-tazobactam 3.37 g every 6-8 hours 1
• Second-generation cephalosporins like cefoxitin 1 g every 6-8 hours 1
• Carbapenems (imipenem, meropenem, or ertapenem) 1

Important Considerations

• Avoid first-generation cephalosporins (cephalexin), penicillinase-resistant penicillins (dicloxacillin), macrolides (erythromycin), and clindamycin as monotherapy as they have poor activity against P. multocida 1
• If using trimethoprim-sulfamethoxazole or cefuroxime, consider adding metronidazole or clindamycin for anaerobic coverage 1
• Evaluate for complications that may require surgical intervention, such as abscess formation, osteomyelitis, or septic arthritis 1
• Hand wounds are often more serious and may require more aggressive management 1

Adjunctive Measures

• Ensure adequate wound care with thorough cleansing using sterile normal saline 1
• Consider surgical debridement if there is evidence of necrotic tissue 1
• Elevate the affected body part, especially if swollen, to accelerate healing 1
• For deep or complicated infections (osteomyelitis, septic arthritis), extended therapy may be required (4-6 weeks for osteomyelitis, 3-4 weeks for synovitis) 1

When to Consider Hospitalization

• Evidence of systemic infection (fever, chills) 1
• Rapidly progressing infection despite oral antibiotics 1
• Deep tissue involvement (tendon, joint, bone) 1
• Immunocompromised host 1
• Need for surgical intervention 1