Recommended Antibiotic Regimens for Outpatient Treatment of MRSA Infections
For outpatient treatment of MRSA infections, the first-line options include clindamycin (300-450 mg PO TID), trimethoprim-sulfamethoxazole (1-2 DS tablets PO BID), doxycycline (100 mg PO BID), minocycline (200 mg x1, then 100 mg PO BID), or linezolid (600 mg PO BID), with treatment duration of 5-10 days for uncomplicated infections. 1, 2
Initial Management Approach
- Surgical debridement and drainage of abscesses is the mainstay of therapy and should be performed whenever feasible for MRSA infections 2
- Obtaining cultures from purulent drainage before starting antibiotics is crucial to confirm MRSA and guide definitive therapy 2
- For simple abscesses or boils, incision and drainage alone may be adequate without antibiotics 1
Antibiotic Selection Based on Infection Type
Purulent Cellulitis
- Clindamycin 300-450 mg PO TID (adult dose) is recommended as it provides coverage for both MRSA and beta-hemolytic streptococci 1, 3
- TMP-SMX 1-2 DS tablets PO BID is an effective alternative but may not provide adequate coverage for beta-hemolytic streptococci 1, 2
- Doxycycline 100 mg PO BID or minocycline 200 mg x1, then 100 mg PO BID are also effective options 1
- Linezolid 600 mg PO BID is highly effective but more expensive compared with other alternatives 1, 4
Non-purulent Cellulitis
- For non-purulent cellulitis, empirical coverage for beta-hemolytic streptococci is recommended with a beta-lactam (e.g., cephalexin) 1
- If MRSA is suspected or patient has a history of MRSA, consider clindamycin which covers both MRSA and streptococci 1, 3
- For patients who do not respond to beta-lactam therapy, consider adding MRSA coverage 1
Treatment Duration
- 5-10 days of therapy is recommended for uncomplicated MRSA skin infections 2, 5
- Treatment should be extended to 7-14 days for complicated infections 5
- Clinical reassessment within 48-72 hours is essential to ensure appropriate response to therapy 5
Special Considerations
Antibiotic Resistance Patterns
- Local resistance patterns should guide antibiotic selection 2, 6
- Clindamycin resistance has been increasing (10% in 2012 vs 3.5% in 2007) 6
- TMP-SMX resistance has also been increasing (6% in 2012 vs 3.4% in 2007) 6
Pediatric Patients
- For children, clindamycin 10-13 mg/kg/dose PO every 6-8 hours is recommended 1
- TMP-SMX 4-6 mg/kg/dose (trimethoprim component) PO every 12 hours is an alternative 1
- Tetracyclines should not be used in children under 8 years of age 1, 5
Complicated MRSA Infections Requiring Hospitalization
- For patients with systemic toxicity or rapidly progressive infections, inpatient management with IV antibiotics is recommended 1
- Vancomycin 15-20 mg/kg/dose IV every 8-12 hours is the first-line option for hospitalized patients 1, 2
- Linezolid 600 mg PO/IV BID has shown excellent efficacy against MRSA skin and soft tissue infections 1, 4, 7
- Daptomycin 4 mg/kg/dose IV QD is another effective option for complicated skin infections 1, 7
Common Pitfalls to Avoid
- Using beta-lactam antibiotics alone is inadequate for MRSA coverage 2, 7
- Failure to drain abscesses when present can lead to treatment failure regardless of antibiotic choice 2
- TMP-SMX alone may not provide adequate coverage for beta-hemolytic streptococci, which can co-exist with MRSA 2, 8
- Minocycline is often forgotten but may be preferred when doxycycline or TMP-SMX fails in the treatment of uncomplicated cutaneous abscesses due to CA-MRSA 8