What is the best treatment approach for a patient with a urinary tract infection (UTI) caused by Enterococcus faecalis?

Treatment of Urinary Tract Infection Caused by Enterococcus faecalis

For uncomplicated E. faecalis UTI, prescribe amoxicillin 500 mg orally every 8 hours for 7 days as first-line therapy, which achieves 88% clinical cure rates. 1

First-Line Treatment Selection

Oral Therapy for Uncomplicated UTI

• Amoxicillin 500 mg orally every 8 hours for 7 days is the preferred first-line agent, with demonstrated clinical eradication rates of 88.1% and microbiological eradication of 86% 1
• Ampicillin 500 mg orally every 8 hours for 7 days is an equivalent alternative with similar efficacy 1
• Amoxicillin may be preferred over ampicillin due to lower minimum inhibitory concentrations (MICs) 2

Alternative Oral Agents

• Nitrofurantoin 100 mg orally every 6 hours for 7 days is an effective alternative with resistance rates below 6% in E. faecalis 1
• Fosfomycin 3 g orally as a single dose is FDA-approved specifically for E. faecalis UTI and recommended for uncomplicated infections 1
• Recent data from 2025 confirms fosfomycin maintains high activity against E. faecalis in bacteremic UTIs 3

Intravenous Therapy for Hospitalized Patients

• High-dose ampicillin (18-30 g IV daily in divided doses) or amoxicillin 500 mg IV every 8 hours achieves sufficient urinary concentrations 1
• High urinary concentrations of ampicillin can overcome high MICs even in ampicillin-resistant strains, making it effective when in vitro testing suggests resistance 1

Critical Treatment Considerations

Avoid Fluoroquinolones

• Do not use ciprofloxacin or levofloxacin due to high resistance rates (46-47%) and unfavorable risk-benefit ratios for uncomplicated UTIs 1
• A 2013 study confirmed 47% ciprofloxacin resistance in E. faecalis from complicated UTIs in men 4

Differentiate Infection from Colonization

• Always confirm true infection versus asymptomatic bacteriuria before initiating treatment, as colonization does not routinely require anti-enterococcal therapy 1
• Routine therapy for asymptomatic bacteriuria with enterococci is not recommended 5

Obtain Susceptibility Testing

• Always obtain susceptibility testing before initiating therapy, even for strains described as "pansensitive," as resistance patterns vary significantly by institution 1
• Verify the antibiogram and adjust therapy when culture results are available 2

Special Clinical Scenarios

Penicillin Allergy

• Nitrofurantoin 100 mg orally every 6 hours for 7 days is the appropriate alternative for patients with penicillin allergy 1

Beta-Lactamase Producing Strains

• Replace amoxicillin with amoxicillin-clavulanate for 7 days if beta-lactamase production is documented 1

Complicated UTI or Pyelonephritis

• Do not use nitrofurantoin for complicated UTI or pyelonephritis, as it achieves poor tissue and serum concentrations 1
• Longer treatment durations may be necessary for complicated infections, though specific evidence for E. faecalis is limited 1
• Consider ampicillin-based IV regimens for serious infections requiring hospitalization 1

Renal Impairment

• Patients with creatinine clearance <60 mL/min should not receive nitrofurantoin, as urinary concentrations become inadequate 1

Common Pitfalls to Avoid

Catheter Management

• Consider removal of indwelling urinary catheters, as 59.3% of enterococcal UTI patients have catheters that serve as a nidus for infection 5, 6

Antibiotic Prophylaxis Concerns

• Antibiotic prophylaxis may not be suitable for enterococcal recurrent UTI, as exposure to nitrofurantoin can increase virulence properties 7
• Before considering prophylaxis, advise self-care measures including adequate hydration, post-coital voiding, and avoiding spermicidal contraceptives 8

Vancomycin Misuse

• Do not prescribe vancomycin empirically for E. faecalis, as ampicillin is superior and vancomycin should be reserved for documented beta-lactam allergy 2
• Only 3% of E. faecalis strains are multidrug-resistant, and many vancomycin-resistant strains remain penicillin-susceptible 2

Clinical Response Monitoring

• Check the antibiogram and consider resistance or alternative diagnosis if no clinical improvement occurs after 48-72 hours of therapy 2