What is the recommended treatment for Enterococcus (E) faecalis urinary tract infection (UTI)?

Treatment of Enterococcus faecalis Urinary Tract Infection

For uncomplicated E. faecalis UTI, nitrofurantoin 100 mg twice daily for 5 days is the optimal first-line treatment due to its effectiveness, low resistance rates, and minimal collateral damage to gut flora. 1

First-Line Treatment Options

Uncomplicated Lower UTI

1. Nitrofurantoin

   • Dosage: 100 mg orally twice daily
   • Duration: 5 days
   • Advantages: FDA-approved for E. faecalis UTI, excellent activity against E. faecalis, low resistance rates despite years of use 1
   • Contraindication: CrCl <30 mL/min 1

2. Fosfomycin

   • Dosage: 3 g single oral dose
   • FDA-approved specifically for UTIs caused by E. faecalis 2
   • Convenient single-dose regimen with good patient compliance 1

3. Ampicillin/Amoxicillin

   • Dosage: Amoxicillin 500 mg orally three times daily
   • Duration: 5-7 days
   • Ampicillin is the drug of choice for enterococcal infections, even in some cases of ampicillin-resistant strains due to high urinary concentrations 2
   • Clinical and microbiological eradication rates of 88.1% and 86% respectively have been reported even for ampicillin-resistant E. faecalis UTIs 2

Alternative Options for Resistant Strains

For Vancomycin-Resistant E. faecalis (VRE)

1. Linezolid

   • Effective against VRE with high clinical success rates (>90%) for UTIs 3
   • Consider for multidrug-resistant strains 4

2. Daptomycin

   • Active against E. faecalis including vancomycin-resistant isolates 5
   • Consider for complicated UTIs when oral options aren't suitable 4

3. High-dose Ampicillin

   • High urinary concentrations may overcome resistance 2
   • Dosage: 18-30 g IV daily (for severe infections) 2

Treatment Algorithm

1. Assess UTI severity and patient factors:

   • Uncomplicated lower UTI vs. complicated/upper UTI
   • Renal function (avoid nitrofurantoin if CrCl <30 mL/min)
   • Previous antibiotic exposure and local resistance patterns
   • Patient allergies and comorbidities

2. For uncomplicated lower UTI:

   • First choice: Nitrofurantoin 100 mg BID for 5 days
   • Alternative: Fosfomycin 3 g single dose
   • If both contraindicated: Amoxicillin 500 mg TID for 5-7 days

3. For complicated UTI or pyelonephritis:

   • Consider parenteral therapy initially
   • Ampicillin 2 g IV every 4-6 hours
   • Duration: 7-14 days depending on clinical response

4. For resistant strains:

   • Obtain susceptibility testing
   • Consider fosfomycin, linezolid, or daptomycin based on susceptibility results
   • For VRE UTI: Linezolid or high-dose ampicillin (if urinary tract-only infection)

Important Clinical Considerations

• Differentiate colonization from true infection before initiating therapy, especially in catheterized patients 2
• Avoid unnecessary treatment of asymptomatic bacteriuria to prevent resistance development 1
• Remove indwelling catheters when possible to improve treatment outcomes 4
• Recent research shows aminopenicillins (ampicillin/amoxicillin) are non-inferior to non-aminopenicillins for treating enterococcal lower UTIs, even for E. faecium strains 6

Treatment Pitfalls to Avoid

1. Fluoroquinolones should be reserved due to increasing resistance and risk of adverse effects, despite their historical use 1
2. Cephalosporins generally have poor activity against enterococci and should not be used as monotherapy
3. Aminoglycosides alone are not recommended due to poor efficacy and nephrotoxicity risk 2
4. Failure to adjust therapy based on susceptibility results can lead to treatment failure
5. Inadequate treatment duration may result in relapse, particularly in complicated UTIs

By following this evidence-based approach, clinicians can effectively treat E. faecalis UTIs while minimizing the risk of treatment failure and antimicrobial resistance.