What is the recommended treatment for a patient with a Methicillin-resistant Staphylococcus aureus (MRSA) positive abscess?

Treatment of MRSA-Positive Abscess

For a MRSA-positive abscess, incision and drainage is the primary treatment, with antibiotics added for severe/extensive infection, surrounding cellulitis, systemic signs, or multiple abscesses. 1

Initial Management: Source Control First

• Surgical drainage is the mainstay of therapy and must be performed whenever feasible - antibiotics alone are insufficient without adequate drainage 1
• Obtain cultures from purulent drainage before starting antibiotics to confirm MRSA and guide definitive therapy 2, 1
• For simple, small abscesses without surrounding cellulitis or systemic symptoms, incision and drainage alone may be adequate without antibiotics 1

When to Add Antibiotics

Add antibiotic therapy if any of the following are present:

• Severe or extensive local infection 1
• Surrounding cellulitis 1
• Multiple abscesses 1
• Signs of systemic illness (fever, tachycardia, elevated WBC) 1, 3
• Immunocompromised status 3
• Failure to respond to drainage alone 3

Outpatient Oral Antibiotic Options

First-line choices for non-severe MRSA abscesses:

• Trimethoprim-sulfamethoxazole (TMP-SMX): 1-2 double-strength tablets (160-320/800-1600 mg) orally twice daily 2, 1

  • Excellent MRSA coverage but lacks streptococcal activity 3
  • No dose adjustment needed unless GFR <15 mL/min 1

• Doxycycline or minocycline: 100 mg orally twice daily 2, 1

  • Minocycline may be more reliably effective than doxycycline when other agents fail 4
  • Contraindicated in children under 8 years of age 2, 3

• Clindamycin: 300-450 mg orally three times daily (adults); 10-13 mg/kg/dose every 6-8 hours for children 2, 1

  • Only use if local MRSA resistance rates are <10% 1, 3
  • Provides coverage for both MRSA and streptococci as a single agent 1
  • Resistance rates are increasing, so verify local susceptibility patterns 3

Inpatient IV Antibiotic Options

For severe infections, rapid progression, systemic toxicity, or failure of oral therapy:

• Vancomycin: 15-20 mg/kg IV every 8-12 hours (first-line for hospitalized patients) 1, 3

  • Dose adjust for renal function and perform therapeutic drug monitoring 3
  • Remains standard of care for serious MRSA infections 5

• Daptomycin: 4-6 mg/kg IV once daily 1, 3, 6

  • Excellent alternative for patients intolerant to vancomycin 3
  • FDA-approved for MRSA bacteremia and complicated skin infections 7, 6
  • Achieves similar clinical success rates to vancomycin 8

• Linezolid: 600 mg IV or orally twice daily 1, 7

  • Can transition seamlessly from IV to oral 1
  • FDA data shows 79% cure rate for MRSA skin infections 7
  • Superior MRSA eradication compared to vancomycin, though higher adverse reaction rates 3

Treatment Duration

• 5-10 days for uncomplicated abscesses with adequate drainage 2, 1
• 7-14 days for complicated skin and soft tissue infections 1
• Adjust based on clinical response: resolution of fever, decreased erythema/swelling, and adequate drainage 3

Pediatric Considerations

• IV vancomycin is the preferred agent for hospitalized children with MRSA infections 1
• Clindamycin can be used if the patient is stable, no ongoing bacteremia, and local resistance <10% 1
• Age-dependent dosing for daptomycin: 7 mg/kg (12-17 years), 9 mg/kg (7-11 years), 12 mg/kg (2-6 years) 6

Critical Pitfalls to Avoid

• Never use beta-lactam antibiotics (amoxicillin, cephalexin, Augmentin) for MRSA coverage - the mecA gene confers complete resistance 1
• Failure to drain abscesses leads to treatment failure regardless of antibiotic choice 1
• Never use rifampin as monotherapy or adjunctive therapy for skin infections - rapid resistance develops 1, 3
• Fluoroquinolones should not be used as monotherapy due to high MRSA resistance rates 1

Prevention of Recurrence

• Keep draining wounds covered with clean, dry bandages 2, 1
• Regular handwashing with soap and water or alcohol-based gel 1
• Avoid sharing personal items 1
• Consider decolonization (mupirocin nasal + chlorhexidine body wash) for recurrent infections despite optimal wound care 2, 1
• Evaluate and potentially treat household contacts if recurrent infections persist 1