Bactrim for Skin Infections
Trimethoprim-sulfamethoxazole (Bactrim) is effective for treating purulent skin infections, especially those caused by MRSA, but should not be used alone for nonpurulent cellulitis due to poor activity against Group A Streptococcus. 1, 2
Appropriate Uses for Bactrim in Skin Infections
- Bactrim is recommended for purulent skin infections including abscesses, furuncles, and carbuncles, particularly when MRSA is suspected or confirmed 2
- It is an effective oral option for methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections 1
- Standard adult dosing is 1-2 double-strength tablets (160mg/800mg) twice daily 2
- Treatment duration should be 7-14 days, individualized based on clinical response 1
When NOT to Use Bactrim Alone
- Bactrim should not be used as monotherapy for nonpurulent cellulitis, as these infections are commonly caused by beta-hemolytic streptococci which may have intrinsic resistance to this medication 2, 3
- It has poor activity against anaerobic bacteria, making it suboptimal for polymicrobial infections 2
- For mixed infections or when Group A Streptococcus is a concern, combination therapy with a beta-lactam may be warranted 2
Evidence for Efficacy
- The 2018 World Society of Emergency Surgery/Surgical Infection Society-Europe consensus conference recommends Bactrim as a first-line oral agent for MRSA skin infections 1
- Multiple observational studies support the use of Bactrim compared with clindamycin or β-lactams for S. aureus skin infections 3
- Randomized controlled trials have demonstrated efficacy for impetigo and purulent cellulitis 3
- For drained abscesses, evidence suggests Bactrim may not reduce 7-day treatment failure rates but may decrease formation of new lesions within 30 days 4
Important Clinical Considerations
- Incision and drainage should be considered the primary intervention for purulent collections, with antibiotics as adjunctive therapy 2
- For nonpurulent cellulitis, beta-lactams remain the treatment of choice 3
- Bactrim can cause DNA damage in S. aureus via both thymidine limitation and oxidative stress, which may contribute to the development of resistance 5
- The Infectious Diseases Society of America guidelines recommend doxycycline, clindamycin, or Bactrim when MRSA is suspected or confirmed in impetigo or ecthyma 1
Potential Adverse Effects and Monitoring
- Common side effects include rash, gastrointestinal disturbances, and photosensitivity 1
- Rare but serious adverse effects include Stevens-Johnson syndrome, toxic epidermal necrolysis, and bone marrow suppression 1
- Monitor for signs of treatment failure, which may necessitate changing antibiotics or adding additional agents 1