What is the recommended treatment for Enterococcus faecalis infections?

Treatment of Enterococcus faecalis Infections

For Enterococcus faecalis infections, linezolid 600 mg IV or PO every 12 hours is strongly recommended as first-line therapy, with treatment duration dependent on the infection site and clinical response. 1

First-Line Treatment Options

For Susceptible E. faecalis:

• Ampicillin: 18-30g IV daily in divided doses (for severe infections) 1
• Amoxicillin: 500 mg PO/IV every 8 hours (for less severe infections) 1
• Piperacillin-tazobactam: Can be used based on susceptibility testing 1

For Vancomycin-Resistant E. faecalis (VRE):

1. Linezolid: 600 mg IV/PO every 12 hours 1, 2

   • Strong recommendation with documented clinical efficacy
   • FDA-approved for VRE infections with 67% overall cure rate 2
   • Can be administered orally or intravenously with excellent bioavailability

2. Daptomycin: 8-12 mg/kg/day IV 1

   • Consider high-dose regimen for serious infections
   • May be combined with β-lactams for synergistic effect
   • Particularly effective for VRE bacteremia

Treatment by Infection Site

Bloodstream Infections:

• Linezolid: 600 mg IV/PO every 12 hours 1, 2
• Daptomycin: 8-12 mg/kg/day (high-dose regimen) 1
  • Consider combination with β-lactams for synergy

Intra-abdominal Infections:

• Tigecycline: 100 mg IV loading dose, then 50 mg IV every 12 hours 1
• Linezolid: 600 mg IV/PO every 12 hours 1, 2

Urinary Tract Infections:

• Uncomplicated VRE UTI options:
  • Fosfomycin: 3 g PO single dose 1, 3
  • Nitrofurantoin: 100 mg PO every 6 hours 1, 3
  • Ampicillin/Amoxicillin: If susceptible 1, 3

Endocarditis:

• Ampicillin plus gentamicin for susceptible strains 1
• Linezolid or daptomycin (high-dose) for resistant strains 1

Treatment Duration

• Uncomplicated UTI: 3-5 days 3
• Complicated UTI: 7-10 days 3
• Bacteremia: 14 days (minimum) 1
• Endocarditis: 4-6 weeks 1
• Other infections: Based on clinical response and source control 1

Special Considerations

Antimicrobial Resistance

• E. faecalis is increasingly resistant to fluoroquinolones (47% resistance to ciprofloxacin in some studies) 4
• Vancomycin resistance is less common in E. faecalis (7.2%) compared to E. faecium (82.1%) 1
• Always obtain susceptibility testing before finalizing therapy 3

Combination Therapy

• For severe VRE infections, particularly bacteremia, combination therapy may be considered 5
• Daptomycin combined with β-lactams shows synergistic effects 1
• Aminoglycosides are no longer recommended for native valve E. faecalis endocarditis due to increased renal toxicity without improved outcomes 1

Treatment Pitfalls to Avoid

1. Inadequate dosing: Use high-dose regimens for serious infections
2. Failure to remove infected devices: Catheter removal is essential for catheter-associated infections 6
3. Treating asymptomatic bacteriuria: Not recommended, especially in elderly patients 3
4. Prolonged therapy: Unnecessarily long courses increase resistance risk 3
5. Ignoring local resistance patterns: Use local antibiograms to guide empiric therapy 3

Algorithm for Treatment Selection

1. Obtain cultures and susceptibility testing
2. Assess infection severity and site
3. Choose antimicrobial based on:
   • If susceptible to ampicillin → Ampicillin or amoxicillin
   • If resistant to ampicillin but susceptible to vancomycin → Vancomycin
   • If VRE → Linezolid (preferred) or daptomycin (for bacteremia)
   • If UTI only → Consider fosfomycin or nitrofurantoin
4. Evaluate for source control needs (device removal, drainage)
5. Monitor clinical response and adjust therapy accordingly

For complex cases, particularly those with vancomycin-resistant strains or treatment failure, consultation with infectious disease specialists is strongly recommended 3.