Management of MRSA Skin and Soft Tissue Infections

First-Line Oral Agents for MRSA SSTI

The Infectious Diseases Society of America recommends trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets twice daily, doxycycline 100 mg twice daily, or clindamycin 300-450 mg three times daily as first-line oral options for MRSA skin and soft tissue infections, with TMP-SMX and doxycycline preferred due to lower cost and comparable efficacy to more expensive alternatives like linezolid 1, 2, 3
For adult patients, TMP-SMX is recommended at a dose of 1-2 double-strength tablets orally twice daily, with a key advantage of bactericidal activity and demonstrated effectiveness in randomized trials 1, 2
Doxycycline is recommended at a dose of 100 mg orally twice daily for adults, with good in vitro activity against CA-MRSA and proven clinical effectiveness 1, 2
Clindamycin is recommended at a dose of 300-450 mg orally three times daily for adults, with a key advantage of being active against both MRSA and β-hemolytic streptococci, making it useful for nonpurulent cellulitis 1, 2

The standard treatment duration for MRSA SSTI is 7-14 days, based on clinical response, and treatment should continue for at least 48 hours after the patient becomes afebrile and asymptomatic in severe cases 1, 2, 3
Oral therapy is appropriate for simple abscesses after incision and drainage, purulent cellulitis without systemic signs, and patients who can tolerate oral medications and have reliable follow-up 1, 2

Incision and drainage alone may be adequate without antibiotics for simple abscesses or boils, but empirical coverage for β-hemolytic streptococci is recommended with a β-lactam (e.g., cephalexin) for nonpurulent cellulitis 1, 2
If MRSA coverage is also needed for nonpurulent cellulitis, use clindamycin alone OR combine TMP-SMX or doxycycline with a β-lactam (e.g., amoxicillin, cephalexin) 1, 2, 3
Rifampin should never be used as monotherapy due to rapid development of resistance, and adjunctive rifampin with another active drug is not recommended for SSTI in the absence of supporting data 1, 2
It is essential to obtain culture specimens for documentation and susceptibility testing, and to test for inducible clindamycin resistance (D-test) before using clindamycin for serious infections 1, 2