What is the recommended treatment for a patient with a urine culture positive for Enterococcus faecalis?

Treatment of Enterococcus faecalis Urinary Tract Infection

For symptomatic urinary tract infections caused by Enterococcus faecalis, amoxicillin 500 mg orally every 8 hours for 7 days is the first-line treatment, achieving high clinical (88.1%) and microbiological (86%) eradication rates. 1, 2

Initial Assessment: Determine Need for Treatment

Before initiating antibiotics, distinguish between infection requiring treatment versus asymptomatic colonization:

• Treat only if: Patient has urinary symptoms (dysuria, frequency, urgency, suprapubic pain) OR patient is pregnant 1
• Do not treat: Asymptomatic bacteriuria in non-pregnant patients, even with positive culture 1, 3
• Pregnancy exception: Always treat asymptomatic bacteriuria in pregnancy, as 20-35% progress to pyelonephritis and increase preterm birth risk 1

The colony count of 50,000-60,000 CFU/mL meets the threshold for significant bacteriuria (≥50,000 CFU/mL) when symptoms are present 1

First-Line Treatment Options

For Uncomplicated Cystitis (Oral Therapy)

Preferred regimen:

• Amoxicillin 500 mg orally every 8 hours for 7 days 1, 2
• Alternative: Ampicillin 500 mg orally every 8 hours for 7 days 1, 2

Rationale: Ampicillin/amoxicillin remains the drug of choice because high urinary concentrations can overcome elevated MICs even in some resistant strains 4, 1, 2

For Hospitalized Patients Requiring IV Therapy

• High-dose ampicillin 18-30 g IV daily in divided doses 4, 1, 2
• Alternative: Amoxicillin 500 mg IV every 8 hours 4, 1

Alternative Agents for Penicillin Allergy or Resistance

Second-Line Oral Options

Nitrofurantoin:

• Dosing: 100 mg orally every 6 hours for 5-7 days 4, 1, 2
• Advantages: Excellent in vitro activity with resistance rates below 6% in E. faecalis 1, 2, 5, 6
• Preferred alternative for penicillin allergy 1, 2

Fosfomycin:

• Dosing: 3 g orally as single dose 4, 1, 2
• FDA-approved specifically for E. faecalis UTI 1, 2
• Best suited for uncomplicated infections 1, 2

Treatment for Vancomycin-Resistant E. faecalis

If patient has prior antibiotic exposure (particularly cephalosporins) or known VRE colonization:

• Linezolid 600 mg IV or PO every 12 hours 4, 1, 7
• Alternative: Daptomycin 8-12 mg/kg/day IV 4, 1
• Duration depends on infection site and clinical response 4

Linezolid is FDA-approved for vancomycin-resistant E. faecium infections including concurrent bacteremia, with cure rates of 67% in documented VRE infections 7

Critical Pitfalls to Avoid

Do NOT Use Fluoroquinolones

• Ciprofloxacin and levofloxacin have 46-47% resistance rates in E. faecalis 1, 2
• Fluoroquinolones are unreliable first-line agents and should be avoided 1, 2

Distinguish E. faecalis from E. faecium

• E. faecalis: Generally more susceptible to ampicillin (only 3% multidrug-resistant strains) 1
• E. faecium: Up to 95% multidrug-resistant, requires different approach 1
• E. faecium infections have significantly higher mortality (23% vs 10.1%) and longer hospital stays 8

Always Obtain Susceptibility Testing

• Even for "pansensitive" strains, confirm susceptibilities before finalizing therapy 1, 2
• Resistance patterns vary significantly by institution and patient population 1, 2

Remove Urinary Catheters When Possible

• 59.3% of enterococcal UTIs occur in catheterized patients 8
• Catheter removal should be considered as part of management 3

Special Population: Pregnancy

• Screen all pregnant women for asymptomatic bacteriuria early in pregnancy 1
• First-line: Amoxicillin 500 mg PO every 8 hours for 7 days 1
• Always treat asymptomatic bacteriuria in pregnancy 1

Treatment Duration

• Uncomplicated lower UTI: 7 days 1, 2
• Complicated UTI or pyelonephritis: Longer durations may be necessary based on clinical response 1, 2
• Single-dose fosfomycin: Only for uncomplicated infections 4, 1, 2

When to Consider Combination Therapy

For severe infections with sepsis/septic shock in hospitalized patients:

• Consider tigecycline-based combinations with polymyxin or meropenem 4
• This applies primarily to intra-abdominal infections with enterococcal involvement, not simple UTI 4