What is the recommended dose of vancomycin (Vancomycin) for the treatment of Enterococcus faecium (E. faecium) infection?

Vancomycin Dosing for Enterococcus faecium Treatment

For treatment of Enterococcus faecium infections, vancomycin should be administered at a dose of 30 mg/kg per 24 hours intravenously in 2 equally divided doses, with serum trough concentrations maintained between 10-20 μg/mL. 1

Dosing Considerations

Standard Dosing Regimen

• Vancomycin: 30 mg/kg/day IV divided into 2 equal doses (e.g., every 12 hours) 1
• Duration of therapy:
  • Native valve endocarditis: 6 weeks 1
  • Prosthetic valve endocarditis: minimum of 6 weeks 1
  • Other serious infections: 4-6 weeks depending on infection site and severity

Therapeutic Drug Monitoring

• Target serum trough concentrations: 10-20 μg/mL 1
• Timing of levels: Draw trough levels just before the next scheduled dose
• Frequency of monitoring: Initially after 3-4 doses, then weekly once stable

Special Considerations

Vancomycin Resistance

• E. faecium strains are considered resistant to vancomycin if MICs are >4 μg/mL 1
• For vancomycin-resistant E. faecium (VRE), alternative agents must be used:
  • Linezolid: 600 mg IV or orally every 12 hours for ≥6 weeks 1
  • Daptomycin: 10-12 mg/kg IV once daily for ≥6 weeks 1

Combination Therapy

• For susceptible strains, vancomycin is often combined with gentamicin:
  • Gentamicin: 3 mg/kg/day IV divided into 3 equal doses 1
  • Gentamicin should be administered in multiple daily doses rather than once daily 1
  • Adjust gentamicin to achieve peak concentrations of 3-4 μg/mL and trough <1 μg/mL 1

Renal Adjustment

• Dose adjustment required for patients with renal impairment
• For patients with creatinine clearance <50 mL/min, consider alternative agents or adjusted dosing
• Monitor renal function regularly during therapy

Clinical Pitfalls and Caveats

1. Vancomycin tolerance: Some E. faecium strains may be "tolerant" to vancomycin (susceptible by MIC but resistant in vivo), requiring higher doses or alternative agents 2

2. Emerging resistance: Up to 95% of E. faecium strains may express multidrug resistance to vancomycin, aminoglycosides, and penicillins 1

3. Treatment failure: Persistent bacteremia despite appropriate vancomycin therapy may indicate:

   • Vancomycin tolerance
   • Development of resistance during therapy
   • Inadequate source control
   • Deep-seated infection requiring surgical intervention

4. Mortality impact: Vancomycin resistance significantly impacts survival in patients with E. faecium bacteremia and leads to higher healthcare costs 3

5. Alternative considerations: For serious infections with vancomycin-resistant strains, consider infectious disease consultation for guidance on alternative therapies 1, 4

Remember that proper dosing and monitoring of vancomycin is critical for successful treatment of E. faecium infections, and resistance patterns should guide therapy selection.