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

Treatment of E. faecalis UTI

Amoxicillin 500 mg orally every 8 hours for 7 days is the first-line treatment for uncomplicated E. faecalis urinary tract infections, achieving 88.1% clinical and 86% microbiological eradication rates. 1, 2

First-Line Treatment Algorithm

For Uncomplicated UTI (Outpatient)

• Amoxicillin 500 mg PO every 8 hours for 7 days is the preferred agent recommended by the American College of Physicians 1, 2, 3
• Ampicillin 500 mg PO every 8 hours for 7 days is an equivalent alternative with similar efficacy 1, 2, 3
• These beta-lactams remain the drugs of choice even when in vitro testing suggests resistance, because high urinary concentrations can overcome elevated MICs 1

For Hospitalized Patients Requiring IV Therapy

• Ampicillin 2 g IV every 4 hours is recommended by the Infectious Diseases Society of America 2
• Alternative high-dose regimens include ampicillin 18-30 g IV daily in divided doses or amoxicillin 500 mg IV every 8 hours to achieve sufficient urinary concentrations 1

Alternative Oral Agents

Single-Dose Option

• Fosfomycin 3 g orally as a single dose is FDA-approved specifically for uncomplicated UTI caused by E. faecalis 1, 2, 3, 4
• This offers convenient single-dose therapy with proven efficacy 3
• The FDA label explicitly states fosfomycin is indicated for acute cystitis in women due to E. faecalis 4

For Penicillin Allergy

• Nitrofurantoin 100 mg orally every 6 hours for 7 days is the appropriate alternative 1, 2, 3
• Resistance rates remain below 6% for E. faecalis 1, 3
• All E. faecalis strains in one study showed 100% sensitivity to nitrofurantoin 5

Critical Treatment Considerations

Always Obtain Susceptibility Testing

• Confirm susceptibility testing before initiating therapy, even for strains described as "pansensitive," as recommended by the Infectious Diseases Society of America and Centers for Disease Control and Prevention 1, 2, 3
• Resistance patterns vary significantly by institution and patient population 1

Avoid Fluoroquinolones

• Do not use ciprofloxacin or levofloxacin due to high resistance rates of 46-47% 1, 2, 3
• Research confirms 46% levofloxacin resistance and 47% ciprofloxacin resistance in E. faecalis from complicated UTI 6
• The American College of Physicians specifically advises avoiding fluoroquinolones due to unfavorable risk-benefit ratios for uncomplicated UTIs 2, 3

Differentiate Colonization from Infection

• Asymptomatic bacteriuria with E. faecalis does not routinely require treatment 1
• Only treat true symptomatic infections, not colonization 1

Treatment for Vancomycin-Resistant E. faecalis (VRE)

For Uncomplicated VRE UTI

• Fosfomycin 3 g PO single dose is recommended by the Infectious Diseases Society of America 2
• Nitrofurantoin 100 mg PO every 6 hours is also effective for VRE UTIs 2
• High urinary concentrations of ampicillin can overcome high MICs even in ampicillin-resistant VRE strains 1

Special Situations

Complicated UTI or Pyelonephritis

• Longer treatment durations may be necessary based on clinical response and site of infection 1, 2
• Fosfomycin is not indicated for pyelonephritis or perinephric abscess per FDA labeling 4

Beta-Lactamase Producing Strains

• Consider replacing amoxicillin with amoxicillin-clavulanate for 7 days 1

Common Pitfalls to Avoid

• Do not rely on fluoroquinolones despite their historical use in UTI—resistance is now too high 2, 3, 6
• Do not assume susceptibility without testing—always obtain culture and susceptibility data 1, 2, 3
• Do not treat asymptomatic bacteriuria—differentiate colonization from true infection 1
• Do not use fosfomycin for upper tract infections—it is only FDA-approved for acute cystitis 4
• Do not underdose ampicillin/amoxicillin—adequate urinary concentrations are critical for efficacy 1