What is the best treatment approach for a patient with a surgical site infection that has progressed to an abscess, considering potential methicillin-resistant Staphylococcus aureus (MRSA) infection?

Treatment of Surgical Site Abscess with Potential MRSA

Immediate surgical drainage through suture removal and incision is mandatory before any antibiotic therapy—antibiotics alone will fail without adequate source control. 1, 2

Immediate Surgical Management

Perform incision and drainage as the cornerstone of therapy:

• Remove sutures and open the surgical wound completely to drain all purulent material 1
• Obtain wound cultures before starting antibiotics to confirm MRSA and guide definitive therapy 2
• Do not rely on antibiotics alone without adequate surgical drainage, as this guarantees treatment failure regardless of antibiotic choice 2, 3

Indications for Systemic Antibiotics

Add systemic antibiotics when any of the following are present: 1, 2

• Temperature >38.5°C
• Heart rate >110 beats/minute
• WBC count >12,000 cells/µL
• Erythema and induration extending >5 cm from the wound edge

For uncomplicated surgical site infections without these systemic signs, drainage alone may be sufficient—a randomized trial showed 90.5% cure rates with drainage alone for MRSA abscesses 4

Antibiotic Selection for MRSA Coverage

When antibiotics are indicated, linezolid is superior to vancomycin for post-surgical MRSA infections: 2

• Linezolid 600 mg IV every 12 hours initially, with transition to oral 600 mg every 12 hours once afebrile for 48-72 hours 2
• Linezolid demonstrates superior clinical and microbiological cure rates, shorter hospital stays (3 days shorter median stay vs vancomycin), and excellent tissue penetration 2
• This is a 1A recommendation from the World Society of Emergency Surgery 2

Alternative MRSA-active agents include: 1, 2

• Vancomycin 15-20 mg/kg IV every 8-12 hours (acceptable 1A recommendation, though inferior to linezolid) 1, 2
• Daptomycin 10 mg/kg IV daily (superior for MRSA bacteremia with endocarditis) 2
• Ceftaroline (alternative glycopeptide-sparing option) 1

Special Considerations for Surgical Site Location

For operations involving the axilla, GI tract, perineum, or female genital tract, add anaerobic and gram-negative coverage: 1, 2

• Combine MRSA-active agent with metronidazole PLUS either a cephalosporin or fluoroquinolone 1
• Never forget anaerobic coverage for these anatomic locations—this is a common pitfall 2

Treatment Duration

Continue therapy for 7-14 days total based on clinical response: 2

• Most uncomplicated surgical site infections require 7-10 days 2
• Complicated infections with systemic symptoms require 7-14 days 2

Transition to Oral Therapy

Switch to oral linezolid 600 mg every 12 hours when: 2

• Patient is afebrile for 48-72 hours
• Tolerating oral intake
• Showing clinical improvement

Critical Pitfalls to Avoid

Do not use beta-lactam antibiotics (cephalexin, cefazolin) for suspected MRSA: 1, 3

• First-generation cephalosporins and antistaphylococcal penicillins are only appropriate for confirmed methicillin-susceptible S. aureus (MSSA) 1
• In a population with 87.8% MRSA prevalence, cephalexin showed no benefit over placebo after drainage 4

Monitor for linezolid toxicity: 2

• Avoid courses exceeding 14 days without monitoring complete blood counts for thrombocytopenia 2

Never use rifampin as monotherapy or adjunctive therapy: 3

• Resistance develops rapidly without proven benefit 3