Treatment of Enterococcus faecalis Urinary Tract Infection
For uncomplicated E. faecalis UTI, treat with amoxicillin 500 mg orally every 8 hours for 7 days as first-line therapy, which achieves 88.1% clinical and 86% microbiological eradication rates. 1, 2
Critical First Step: Distinguish Infection from Colonization
- Do not treat asymptomatic bacteriuria with E. faecalis, as colonization does not routinely require antimicrobial therapy 1, 3
- Only treat when clinical symptoms of UTI are present (dysuria, frequency, urgency, fever, flank pain) 1
- Always obtain susceptibility testing before initiating therapy, even for strains described as "pansensitive," as resistance patterns vary significantly by institution 1, 2
Treatment Algorithm for Symptomatic UTI
Uncomplicated Cystitis (Susceptible Strains)
First-line options:
- Amoxicillin 500 mg orally every 8 hours for 7 days (preferred) 1, 2, 4
- Ampicillin 500 mg orally every 8 hours for 7 days (equivalent alternative) 1, 2
Alternative oral agents:
- Fosfomycin 3 g orally as single dose (FDA-approved specifically for E. faecalis UTI, convenient single-dose therapy) 1, 5, 2
- Nitrofurantoin 100 mg orally every 6 hours for 7 days (resistance rates below 6%, excellent option) 1, 5, 6, 7
Complicated UTI or Pyelonephritis Requiring IV Therapy
- Ampicillin 2 g IV every 4 hours (high-dose regimen achieves sufficient urinary concentrations) 1, 2
- Alternative: Amoxicillin 500 mg IV every 8 hours 1
- Longer treatment durations may be necessary based on clinical response 1, 2
Vancomycin-Resistant E. faecalis (VRE)
For uncomplicated VRE UTI:
- Fosfomycin 3 g orally as single dose (first choice) 2
- Nitrofurantoin 100 mg orally every 6 hours 2, 3
For complicated VRE UTI or severe infections:
- Consider daptomycin 8-12 mg/kg/day IV for severe infections with bacteremia 2, 8
- Linezolid may be considered for parenteral therapy 3
Important Caveats and Pitfalls
Avoid Fluoroquinolones
- Do not use ciprofloxacin or levofloxacin due to high resistance rates (46-47%) and unfavorable risk-benefit ratio for uncomplicated UTIs 5, 2, 9
- Fluoroquinolone resistance is particularly high in hospital-acquired infections and patients transferred from healthcare centers 9
Ampicillin/Amoxicillin Remains Effective Despite In Vitro Resistance
- High urinary concentrations of ampicillin can overcome elevated MICs even when in vitro susceptibility testing suggests resistance 1
- This is particularly important for ampicillin-resistant VRE strains where urinary concentrations may still be therapeutic 1
Beta-Lactamase Producing Strains
- If beta-lactamase production is documented, replace amoxicillin with amoxicillin-clavulanate for 7 days 1
Penicillin Allergy
- Use nitrofurantoin 100 mg orally every 6 hours for 7 days as the appropriate alternative 1
Special Clinical Considerations
Pediatric Patients
- E. faecalis UTI in children is highly indicative of underlying urinary tract abnormalities 7
- These patients have higher rates of anatomical abnormalities, renal scarring, recurrences, and need for corrective surgery 7
- All strains in pediatric studies showed susceptibility to ampicillin, vancomycin, and nitrofurantoin 7
Antibiotic Prophylaxis Concerns
- Nitrofurantoin prophylaxis may increase virulence properties of E. faecalis and may not be suitable for preventing recurrent enterococcal UTI 10
Hospital-Acquired Infections
- Patients with hospital-acquired E. faecalis UTI have 18-fold increased risk of ciprofloxacin resistance 9
- Ampicillin/sulbactam is recommended as alternative for ciprofloxacin-resistant strains 9