TMP/SMX for Outpatient Treatment
Yes, send them out with trimethoprim-sulfamethoxazole (TMP/SMX) if treating a simple skin abscess after incision and drainage, as this combination significantly improves cure rates compared to drainage alone. 1
Evidence-Based Recommendation
For Skin Abscesses (Most Likely Context)
TMP/SMX demonstrates clear benefit when combined with incision and drainage for uncomplicated skin abscesses ≤5 cm in diameter. 1 A high-quality placebo-controlled trial showed:
- Cure rates at 7-10 days post-treatment were 81.7% with TMP/SMX versus 68.9% with drainage alone (P<0.001) 1
- This benefit was specifically restricted to participants with Staphylococcus aureus infection, including community-acquired MRSA strains 1
- TMP/SMX provides effective coverage against CA-MRSA and β-hemolytic streptococci, though it is not considered first-line for streptococcal infections 2
Dosing Recommendations
Standard adult dosing: 1-2 double-strength tablets (160 mg TMP/800 mg SMX) twice daily for 7-14 days based on clinical response 3, 2
For pediatric patients: TMP 4-6 mg/kg/dose with SMX 20-30 mg/kg/dose orally every 12 hours 3
Important Clinical Considerations
Adverse events occur more frequently with clindamycin (21.9%) than TMP/SMX (11.1%), making TMP/SMX a reasonable first choice from a tolerability standpoint 1. However, TMP/SMX may be associated with severe reactions including Stevens-Johnson syndrome/toxic epidermal necrolysis, though these are rare 4
When treating infections where both streptococcal and MRSA coverage is needed, TMP/SMX should be combined with a β-lactam (e.g., amoxicillin) since it is not first-line for streptococcal coverage 2
Critical Contraindications
Avoid TMP/SMX in the third trimester of pregnancy due to potential risks 2, 5
Do not use in areas with high local resistance rates (>20%) without confirming susceptibility 5
Alternative Applications
For UTI prophylaxis in women with recurrent infections, postcoital TMP/SMX administration reduces UTI incidence compared to placebo 4. The medication achieves high urinary concentrations, with 84.5% of total sulfonamide and 66.8% of trimethoprim recovered in urine 6
For MRSA infections including osteomyelitis and septic arthritis, TMP/SMX at TMP 4 mg/kg/dose every 8-12 hours plus rifampin represents an alternative regimen 4
Monitoring
If symptoms do not resolve by end of treatment or recur within 2 weeks, obtain culture and susceptibility testing 5. Routine post-treatment cultures are not indicated for asymptomatic patients 5