What is the recommended amoxicillin (amoxicillin) dose and duration for treating an enterococcus urinary tract infection (UTI)?

Amoxicillin for Enterococcus UTI

Recommended Dosing and Duration

For uncomplicated enterococcal UTI with confirmed susceptibility, amoxicillin 500 mg orally every 8 hours for 7 days is the recommended first-line treatment. 1, 2

Standard Dosing Regimen

• Amoxicillin 500 mg orally every 8 hours for 7 days achieves high clinical (88.1%) and microbiological (86%) eradication rates for susceptible Enterococcus faecalis UTIs 2
• Take at the start of meals to minimize gastrointestinal intolerance 3
• Ampicillin 500 mg orally every 8 hours for 7 days is an equivalent alternative with similar efficacy 2

When Longer Duration is Required

Extend treatment to 7-14 days for complicated UTIs or those with associated bacteremia 2

• Complicated UTIs or pyelonephritis caused by Enterococcus require longer treatment durations beyond the standard 7 days 2
• Patients with signs of endocarditis, persistent bacteremia >72 hours, or metastatic infection require extended therapy and specialist consultation 2
• For hospitalized patients with cUTI and bacteremia, 10 days of therapy is optimal when using antibiotics without comparable IV/oral bioavailability 4

Pediatric Dosing

For children aged 3 months and older:

• 20-40 mg/kg/day divided into 3 doses (using amoxicillin-clavulanate formulation) 5, 1
• Treatment duration: 7-14 days 1
• Maximum dose: 4000 mg/day 1

For infants less than 3 months:

• Maximum 30 mg/kg/day divided every 12 hours due to immature renal function 3

Renal Impairment Adjustments

Dose reduction is required for severe renal impairment 3:

• GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours 3
• GFR <10 mL/min: 500 mg or 250 mg every 24 hours 3
• Hemodialysis: 500 mg or 250 mg every 24 hours, with additional dose during and at end of dialysis 3

Critical Pre-Treatment Considerations

Always obtain urine culture and susceptibility testing before initiating amoxicillin for enterococcal UTI 2

• Approximately 60% of E. faecium and 2% of E. faecalis are vancomycin-resistant, with variable ampicillin susceptibility 2
• Amoxicillin should be reserved for culture-proven susceptible organisms rather than used empirically 1, 2
• High-dose ampicillin (18-30 g IV daily in divided doses) or amoxicillin 500 mg IV/PO every 8 hours is recommended for uncomplicated VRE UTIs only when susceptibility is confirmed 5

Alternative Agents for Resistant Enterococcus

For Vancomycin-Resistant Enterococcus (VRE) with Uncomplicated UTI:

Oral options 5, 2:

• Fosfomycin 3 g as a single oral dose 5, 2
• Nitrofurantoin 100 mg orally every 6 hours for 7 days 5, 2

For Severe VRE Infections Requiring IV Therapy:

• Ampicillin 2 g IV every 4 hours (if susceptible) 2
• Linezolid 600 mg IV or PO every 12 hours for bacteremia or complicated infection 5, 2
• Daptomycin based on susceptibility for bacteremia or complicated infection 2

Common Pitfalls to Avoid

Do not extend treatment duration beyond 7 days for uncomplicated UTI without clear indication, as this increases antibiotic resistance risk without proven benefit 2

• Avoid fluoroquinolones for enterococcal UTI due to high resistance rates (46-47%) and unfavorable risk-benefit profile 2
• Do not use nitrofurantoin for pyelonephritis or urosepsis, as it does not achieve therapeutic concentrations in bloodstream or parenchyma 5
• Do not treat asymptomatic bacteriuria with VRE—unnecessary antibiotic use in colonized patients has become a major problem in hospitals and long-term care facilities 6, 7
• Consider removing indwelling urinary catheters when managing MDR-Enterococcus UTIs 7