What is the treatment for Methicillin-Resistant Staphylococcus epidermidis (MRSE) bacteremia?

Treatment of Methicillin-Resistant Staphylococcus Epidermidis (MRSE) Bacteremia

For MRSE bacteremia, intravenous vancomycin is the first-line treatment, with daptomycin being a reasonable alternative when vancomycin cannot be used or in cases of treatment failure. 1

Initial Treatment Approach

Uncomplicated MRSE Bacteremia

• First-line therapy: Vancomycin IV 15-20 mg/kg/dose every 8-12 hours (not to exceed 2g per dose) 1, 2
  • Target trough concentrations: 15-20 μg/mL 1
  • Duration: At least 2 weeks 1

Complicated MRSE Bacteremia

• First-line therapy: Same vancomycin dosing as above
  • Duration: 4-6 weeks depending on extent of infection 1
  • Complicated bacteremia includes: presence of endocarditis, implanted prostheses, persistent bacteremia beyond 2-4 days of therapy, failure to defervesce within 72 hours, or evidence of metastatic sites of infection 1

Alternative Therapy Options

• Daptomycin: 6 mg/kg IV once daily (some experts recommend 8-10 mg/kg/day for complicated infections) 1, 3
  • Particularly useful when:
    • Vancomycin MIC ≥1.5 mg/L 4
    • Vancomycin treatment failure 4
    • Patient intolerance to vancomycin 3

Management Principles

Source Control

• Identify and eliminate/debride the source of infection 1
• Remove infected intravascular devices when possible 1
• For prosthetic valve endocarditis caused by S. epidermidis:
  • Vancomycin + rifampin + aminoglycoside 2
  • Rifampin should be added after clearance of bacteremia 1

Monitoring

• Obtain follow-up blood cultures 2-4 days after initial positive cultures to document clearance 1
• Monitor vancomycin trough levels to ensure target concentration of 15-20 μg/mL 1
• Echocardiography is recommended for all adult patients with bacteremia to rule out endocarditis 1
  • Transesophageal echocardiography (TEE) is preferred over transthoracic echocardiography (TTE) in adults 1

Special Considerations

Endocarditis

• Treatment duration: 6 weeks of therapy 1
• First-line: Vancomycin IV (same dosing as above) 1
• Alternative: Daptomycin 6 mg/kg IV once daily (some experts recommend 8-10 mg/kg/day) 1
• Important: Addition of gentamicin or rifampin to vancomycin is NOT recommended for native valve endocarditis 1

Pediatric Patients

• First-line: Vancomycin IV 1
• Alternative options (if patient is stable without ongoing bacteremia):
  • Clindamycin 10-13 mg/kg/dose IV every 6-8 hours (if clindamycin resistance rate is low) 1
  • Linezolid: 10 mg/kg/dose every 8 hours for children <12 years; 600 mg twice daily for children >12 years 1

Common Pitfalls to Avoid

1. Underdosing vancomycin: Ensure adequate dosing to achieve target trough concentrations of 15-20 μg/mL 1

2. Inadequate duration of therapy: Treat uncomplicated bacteremia for at least 2 weeks and complicated bacteremia for 4-6 weeks 1

3. Failure to obtain follow-up blood cultures: Essential to document clearance of bacteremia 1

4. Missing endocarditis: Perform echocardiography in all adult patients with MRSE bacteremia 1

5. Continuing vancomycin despite treatment failure: Consider switching to daptomycin if there is persistent bacteremia or clinical deterioration 5, 4

6. Neglecting source control: Identify and eliminate/debride the source of infection when possible 1

7. Adding unnecessary combination therapy: Addition of gentamicin to vancomycin is not recommended for bacteremia or native valve endocarditis 1

Daptomycin has been shown to be more effective than vancomycin in experimental models of MRSE endocarditis, including glycopeptide-intermediate S. epidermidis strains 5, making it a valuable alternative when vancomycin is not appropriate.