What is the recommended treatment for an otherwise healthy patient with uncomplicated community-acquired Staphylococcus (S.) aureus skin or soft tissue infection?

Treatment of Community-Acquired Staphylococcus aureus Skin and Soft Tissue Infections

For uncomplicated community-acquired S. aureus skin infections in otherwise healthy patients, incision and drainage is the primary treatment for any purulent collection (abscess), and when antibiotics are indicated, the choice depends on whether the infection is purulent or nonpurulent and local MRSA prevalence. 1

Initial Assessment and Drainage

• Incision and drainage must be performed for any abscess, furuncle, or carbuncle before or concurrent with antibiotic therapy—this is the cornerstone of treatment and may be adequate as monotherapy for simple, localized abscesses without systemic signs. 1, 2

• Obtain cultures from purulent drainage before starting antibiotics to confirm the pathogen and guide definitive therapy, particularly if antibiotics will be used or if there are systemic signs. 1

• For small furuncles without systemic symptoms, moist heat to promote drainage may be sufficient without antibiotics. 1

Antibiotic Selection Algorithm

For Purulent Infections (cellulitis with purulent drainage or abscesses requiring antibiotics):

• Empirical coverage for CA-MRSA is recommended pending culture results because MRSA now predominates in community-acquired purulent infections. 1

• First-line oral options for outpatients include:

  • Trimethoprim-sulfamethoxazole (TMP-SMX) 1-2 double-strength tablets (160mg/800mg) twice daily 1, 3
  • Doxycycline 100 mg twice daily 1, 3
  • Clindamycin 300-450 mg three to four times daily 1, 3

• Duration: 5-10 days, individualized based on clinical response. 1

• Clindamycin is preferred when coverage for both MRSA and β-hemolytic streptococci is needed, but only use if local clindamycin resistance rates are low (e.g., <10%), as cross-resistance with erythromycin-resistant strains can occur. 1

For Nonpurulent Cellulitis (no purulent drainage or abscess):

• Empirical therapy targeting β-hemolytic streptococci is recommended first-line, as these organisms are the primary cause of nonpurulent cellulitis. 1

• For methicillin-susceptible S. aureus (MSSA), use:

  • Cephalexin 500 mg four times daily 3, 2
  • Dicloxacillin 500 mg four times daily 3, 2

• Duration: 5-7 days based on clinical response. 1

• Add MRSA coverage only if the patient fails to respond to β-lactam therapy or has risk factors such as penetrating trauma, known MRSA colonization, injection drug use, or systemic inflammatory response syndrome (SIRS). 1

Hospitalized Patients with Complicated Infections

• For hospitalized patients with complicated skin and soft tissue infections (deeper infections, major abscesses, surgical/traumatic wounds, infected ulcers/burns), empirical IV therapy for MRSA should be initiated pending culture data. 1

• IV options include:

  • Vancomycin 15-20 mg/kg every 8-12 hours (first-line) 1, 2
  • Linezolid 600 mg IV/PO twice daily 1
  • Daptomycin 4 mg/kg IV once daily 1
  • Ceftaroline 600 mg IV twice daily 1

• Duration: 7-14 days, adjusted based on clinical response. 1

Pediatric Considerations

• For minor infections like impetigo, mupirocin 2% topical ointment twice daily is appropriate. 1, 2

• For children requiring systemic therapy:

  • Clindamycin 10-13 mg/kg/dose every 6-8 hours (up to 40 mg/kg/day) is preferred if local resistance is low 1, 3
  • TMP-SMX 8-12 mg/kg/day (based on trimethoprim component) in 2-4 divided doses 1
  • Linezolid 10 mg/kg every 8 hours for children <12 years; 600 mg twice daily for ≥12 years 1

• Avoid tetracyclines (doxycycline, minocycline) in children <8 years old due to tooth discoloration and bone growth effects. 1, 3

Critical Pitfalls to Avoid

• Never use rifampin as monotherapy or adjunctive therapy for skin infections—resistance develops rapidly and it provides no benefit. 1, 2

• Do not prescribe antibiotics for simple abscesses that can be adequately drained—incision and drainage alone achieves 85-90% cure rates even with CA-MRSA. 4, 2

• Do not assume all cellulitis requires MRSA coverage—nonpurulent cellulitis is typically streptococcal and should be treated with a β-lactam first, reserving MRSA-active agents for treatment failures. 1, 2

• Vancomycin is not absorbed orally and requires IV administration—it cannot be used for outpatient oral therapy. 2

• Beta-lactam antibiotics (cephalexin, dicloxacillin) are ineffective against MRSA despite good outcomes in some retrospective studies where drainage was adequate. 4

Evidence Quality Note

The 2014 IDSA guidelines 1 represent the most recent comprehensive evidence-based recommendations and supersede the 2011 MRSA-specific guidelines 1 for general management principles, though both remain highly relevant. Research demonstrates that for uncomplicated abscesses, drainage alone may suffice without antibiotics 4, but antibiotics are recommended for extensive disease, systemic symptoms, immunosuppression, extremes of age, or difficult-to-drain locations. 1