Trimethoprim-Sulfamethoxazole Dosage for MRSA Skin Infections
For MRSA skin infections, the recommended dosage of trimethoprim-sulfamethoxazole (TMP-SMX) is 1-2 double-strength tablets (160mg/800mg) twice daily for 5-10 days. 1
Oral Treatment Options for MRSA Skin Infections
- TMP-SMX is a bactericidal agent with established efficacy against MRSA skin and soft tissue infections (SSTIs) 1
- Standard adult dosing: 1-2 double-strength tablets (160mg/800mg) twice daily 1
- Pediatric dosing: 8-12 mg/kg/day (based on the trimethoprim component) in either 4 divided doses IV or 2 divided doses orally 1
- Duration of therapy: 5-10 days is recommended, based on clinical response 1
Evidence for TMP-SMX Efficacy in MRSA Skin Infections
- TMP-SMX is recommended as first-line empiric therapy for community-acquired MRSA (CA-MRSA) skin infections 1
- In a randomized controlled trial, TMP-SMX treatment resulted in higher cure rates for drained cutaneous abscesses compared to placebo in settings where MRSA was prevalent 2
- For purulent cellulitis (cellulitis with purulent drainage or exudate), empirical therapy with TMP-SMX is recommended pending culture results 1
Dosage Considerations
- Standard dose (160mg/800mg twice daily) versus high dose (320mg/1600mg twice daily) showed similar clinical resolution rates in patients with MRSA SSTIs 3
- However, for pediatric patients with MRSA abscesses, a 10-day course of TMP-SMX was associated with lower failure and recurrence rates compared to a 3-day course 4
- TMP-SMX may decrease formation of subsequent lesions after incision and drainage of uncomplicated abscesses 5
Alternative Oral Agents for MRSA Skin Infections
If TMP-SMX cannot be used, alternative oral options include:
- Clindamycin: 300-450mg three times daily 1
- Doxycycline or minocycline: 100mg twice daily (not recommended for children <8 years) 1
- Linezolid: 600mg twice daily 1
When to Consider Intravenous Therapy
- For complicated SSTIs (deeper infections, surgical/traumatic wound infections, major abscesses)
- Options include vancomycin, linezolid, daptomycin, telavancin, or clindamycin 1
- Duration of 7-14 days is recommended for complicated infections 1
Important Considerations and Caveats
- Incision and drainage is the primary treatment for purulent skin abscesses; antibiotics are adjunctive therapy 1
- Antibiotic therapy is recommended for abscesses with severe or extensive disease, rapid progression with cellulitis, systemic illness, immunosuppression, extremes of age, or difficult-to-drain locations 1
- TMP-SMX has good activity against aerobes but poor activity against anaerobes 1
- Gastrointestinal side effects (mostly mild) may occur with TMP-SMX 2
- If coverage for both β-hemolytic streptococci and MRSA is desired, consider adding a β-lactam (e.g., amoxicillin) to TMP-SMX 1
Remember that clinical response should guide the duration of therapy, and cultures from abscesses are recommended to guide appropriate antibiotic selection 1.