What is the first-line treatment for Methicillin-resistant Staphylococcus aureus (MRSA) skin infections?

First-Line Treatment for MRSA Skin Infections

For outpatients with MRSA skin infections, clindamycin is the recommended first-line oral antibiotic treatment, providing coverage for both MRSA and beta-hemolytic streptococci as a single agent (A-II). 1, 2

Treatment Algorithm for MRSA Skin Infections

Step 1: Determine Type of Infection

• Simple abscess: Incision and drainage (I&D) is the primary treatment 1
• Purulent cellulitis (with drainage/exudate but no drainable abscess): Empirical MRSA coverage required 1
• Non-purulent cellulitis: Initial beta-lactam therapy; add MRSA coverage if no response 1

Step 2: Determine Need for Antibiotics

Antibiotics are indicated for abscesses with:

• Severe or extensive disease
• Rapid progression with associated cellulitis
• Signs of systemic illness
• Immunosuppression or significant comorbidities
• Extremes of age (very young or elderly)
• Difficult-to-drain locations (face, hand, genitalia)
• Associated septic phlebitis
• Lack of response to I&D alone 1, 2

Step 3: Select Appropriate Antibiotic

For outpatient MRSA treatment, options include:

1. First-line: Clindamycin (A-II)

   • Adult dosing: 300-450 mg PO TID 1, 2
   • Pediatric dosing: 10-13 mg/kg/dose PO every 6-8 hours (max 40 mg/kg/day) 2
   • Advantages: Covers both MRSA and beta-hemolytic streptococci as a single agent 1
   • Caution: Check local resistance patterns; D-zone testing for inducible resistance may be needed 2

2. Alternative options (if clindamycin cannot be used):

   • Trimethoprim-sulfamethoxazole (TMP-SMX) (A-II) 1
   • Tetracyclines (doxycycline or minocycline) (A-II) 1
   • Linezolid (A-II) 1

Step 4: Determine Duration of Treatment

• 5-10 days for uncomplicated infections 1
• 7-14 days for complicated infections 1, 2
• Duration should be based on clinical response 1

Special Considerations

Pediatric Patients

• Mupirocin 2% topical ointment can be used for minor skin infections 1
• Tetracyclines should not be used in children <8 years of age 1
• For hospitalized children with complicated SSTI, vancomycin is recommended 1

Hospitalized Patients with Complicated SSTI

For inpatient treatment, options include:

• IV vancomycin (A-I) 1
• IV/PO linezolid (A-I) 1
• IV daptomycin (A-I) 1
• IV telavancin (A-I) 1
• IV clindamycin (A-III) 1

Important Clinical Pearls

• Always obtain cultures from abscesses when antibiotic therapy is initiated 1, 2
• Incision and drainage alone is often adequate for simple abscesses without antibiotics 1
• Rifampin should not be used as a single agent or as adjunctive therapy for MRSA skin infections 1
• Monitor for clindamycin resistance, which can develop during treatment, especially in areas with high resistance rates 2
• Consider combination therapy with TMP-SMX or tetracycline plus a beta-lactam if coverage for both MRSA and streptococci is needed and clindamycin cannot be used 1

While studies have shown similar efficacy between TMP-SMX and clindamycin for CA-MRSA skin infections 3, the IDSA guidelines specifically recommend clindamycin as first-line therapy due to its coverage of both MRSA and streptococci as a single agent 1, 2.