What alternative antibiotic regimen can be used for a patient with gastrointestinal (GI) intolerance to Augmentin (amoxicillin-clavulanate) who is being treated for a cat bite?

Alternative Antibiotic for Cat Bite with GI Intolerance to Augmentin

For a patient with GI intolerance to amoxicillin-clavulanate (Augmentin) being treated for a cat bite, doxycycline 100 mg twice daily is the preferred alternative oral antibiotic. 1

Primary Recommendation

• Doxycycline 100 mg orally twice daily provides excellent coverage against Pasteurella multocida (the most common pathogen in cat bites, present in 75% of cases) while also covering staphylococci, streptococci, and anaerobes 1, 2
• This regimen is specifically highlighted in IDSA guidelines as having "excellent activity against Pasteurella multocida" with the caveat that some streptococci may be resistant 1

Alternative Options Based on Clinical Context

For Outpatient Oral Therapy:

Second-line monotherapy options:

• Moxifloxacin 400 mg daily - provides good coverage for both P. multocida and anaerobes as monotherapy 1
• Levofloxacin 750 mg daily or ciprofloxacin 500-750 mg twice daily - good activity against P. multocida but misses some anaerobes, so consider adding metronidazole 250-500 mg three times daily for deeper wounds 1

Combination therapy if doxycycline contraindicated:

• Trimethoprim-sulfamethoxazole 160-800 mg (double-strength) twice daily PLUS metronidazole 250-500 mg three times daily - TMP-SMX covers aerobes but has poor anaerobic activity, requiring metronidazole addition 1

For Intravenous Therapy (if severe infection):

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 1
• Piperacillin-tazobactam 3.37 g every 6-8 hours 1
• Ertapenem 1 g daily or other carbapenems 1
• Ceftriaxone 1 g every 12 hours or cefotaxime 1-2 g every 6-8 hours (third-generation cephalosporins with good P. multocida coverage) 1

Critical Pitfalls to Avoid

Do NOT use the following antibiotics for cat bites:

• First-generation cephalosporins (cephalexin, cefazolin) - poor activity against P. multocida 1
• Penicillinase-resistant penicillins (dicloxacillin) - inadequate P. multocida coverage 1
• Clindamycin monotherapy - good for staphylococci, streptococci, and anaerobes but specifically "misses P. multocida" 1
• Macrolides (erythromycin) - poor P. multocida activity 1

Key Clinical Considerations

Cat bites carry higher infection risk than dog bites:

• Cat bites become infected in 20-80% of cases versus only 3-18% for dog bites 3
• Cat bites have deeper puncture wounds with higher rates of osteomyelitis and septic arthritis 1
• P. multocida is isolated from 75% of infected cat bite wounds 1, 2

Hand wounds require special attention:

• Hand bites have the greatest infection risk and may benefit most from prophylactic antibiotics 4, 5
• Pain disproportionate to injury near bone or joint suggests periosteal penetration requiring prolonged therapy (4-6 weeks for osteomyelitis) 1

Duration of therapy:

• Standard treatment is 7-10 days for uncomplicated bite wounds 1
• Extend to 3-4 weeks for synovitis and 4-6 weeks for osteomyelitis 1

Microbiologic Rationale

• Cat bite wounds yield an average of 5 bacterial isolates (range 0-16), with 60% showing mixed aerobic and anaerobic bacteria 1, 2
• P. multocida remains highly susceptible to penicillins (100% susceptibility to amoxicillin-clavulanate), but doxycycline and fluoroquinolones also maintain excellent activity 3
• Common co-pathogens include Staphylococcus aureus, Bacteroides, Fusobacterium, Capnocytophaga, and Porphyromonas species 1