Bactrim Dosing for Wound Infections
For wound infections in adults, prescribe Bactrim 1-2 double-strength tablets (160mg/800mg trimethoprim/sulfamethoxazole) orally twice daily for 7-10 days. 1, 2
Adult Dosing Regimen
- Standard oral dose: 1-2 double-strength tablets (160mg/800mg TMP/SMX) twice daily for 7-10 days 1, 2
- For MRSA-confirmed infections: Extend treatment to 10 days to reduce recurrence risk 1
- Severe/complicated infections requiring IV therapy: 8-12 mg/kg/day (based on trimethoprim component) divided into 4 doses 3, 1
Pediatric Dosing
- Children >2 months: 8-12 mg/kg/day (based on trimethoprim component) divided into 2 doses orally or 4 doses IV 3, 1, 2
- Contraindicated in infants <2 months of age 1
Clinical Context for Appropriate Use
When Bactrim is Appropriate:
- Purulent wound infections or abscesses where MRSA is suspected or confirmed 1
- Surgical site infections involving trunk or extremity away from axilla/perineum 3
- After beta-lactam failure as empiric coverage 1
- Bactrim achieves excellent skin penetration with blister fluid concentrations reaching 82-94% of plasma levels 4
Critical Limitation - Streptococcal Coverage:
- Bactrim lacks reliable streptococcal coverage and should be combined with a beta-lactam (e.g., amoxicillin or cephalexin) for non-purulent cellulitis 1
- For surgical wounds near axilla or perineum, add metronidazole for anaerobic coverage 3
- For animal/human bites, combine with metronidazole or use amoxicillin-clavulanate instead due to poor anaerobic activity 1
Evidence Supporting Efficacy
- A 2016 randomized trial demonstrated 92% cure rates for uncomplicated wound infections with TMP-SMX, equivalent to clindamycin, though clindamycin showed lower recurrence rates (2.0% vs 7.1%) 5
- For drained abscesses, TMP-SMX achieved 92.9% cure rates versus 85.7% with placebo, with significantly fewer subsequent infections at new sites (3.1% vs 10.3%) 6
Safety Considerations and Contraindications
- Avoid in third trimester pregnancy (FDA Category C/D) 1
- Monitor carefully with methotrexate due to severe drug interactions 1
- Sulfa allergy: Use alternatives (clindamycin 300mg TID, doxycycline 100mg BID, or linezolid) 1
- Mild gastrointestinal side effects are common but generally well-tolerated 6