Oral Antibiotic Options for Enterococcus faecalis UTI
Switch from Augmentin to oral amoxicillin 500 mg every 8 hours for 7 days, as this is the first-line treatment for ampicillin-sensitive E. faecalis UTI with proven efficacy. 1
Why Continue Beta-Lactam Therapy
- Augmentin (amoxicillin-clavulanate) already contains the optimal drug (amoxicillin) for this infection, and since your culture shows ampicillin sensitivity, you can simplify to amoxicillin alone without the clavulanate component 1
- Ampicillin/amoxicillin remains the drug of choice for enterococcal UTIs, achieving clinical eradication rates of 88.1% and microbiological eradication of 86% 1
- The high urinary concentrations achieved by ampicillin can overcome even elevated MICs, making it highly effective for urinary tract infections 1
Alternative Oral Options Based on Your Sensitivities
Nitrofurantoin (Second Choice)
- Nitrofurantoin 100 mg orally every 6 hours for 7 days is an effective alternative with resistance rates below 6% in E. faecalis 1
- This is particularly useful if the patient has a penicillin allergy 1
- Critical caveat: Do NOT use nitrofurantoin if this is a complicated UTI, pyelonephritis, or if creatinine clearance is <60 mL/min, as it achieves poor tissue concentrations and inadequate urinary levels in renal impairment 1
Fosfomycin (Third Choice)
- Fosfomycin 3 g orally as a single dose is FDA-approved specifically for E. faecalis UTI 1, 2
- Best reserved for uncomplicated cystitis only 1
- Has minimal resistance and low propensity for collateral damage 3
- May have slightly inferior efficacy compared to standard 7-day regimens 3
Why NOT to Use Levofloxacin Despite Sensitivity
- Avoid fluoroquinolones (levofloxacin) even though your culture shows sensitivity because E. faecalis has high fluoroquinolone resistance rates of 46-47% in general populations 1
- Fluoroquinolones should be reserved for more important indications and have an unfavorable risk-benefit ratio for uncomplicated UTIs 1
- Multiple studies confirm 34-47% ciprofloxacin/levofloxacin resistance in E. faecalis from complicated UTIs 4, 5
Why Vancomycin is Not an Option
- Vancomycin has no oral formulation that achieves adequate urinary concentrations for UTI treatment 3
- It is reserved for IV use in serious systemic enterococcal infections like endocarditis or bacteremia 1
Treatment Duration and Monitoring
- 7 days is the standard duration for uncomplicated E. faecalis UTI 1
- Longer durations may be necessary if this is a complicated UTI (catheter-associated, anatomic abnormality, immunosuppression, or upper tract involvement) 1
- Always confirm susceptibility testing even for "pansensitive" strains, as resistance patterns vary by institution 1
Common Pitfall to Avoid
- Do not assume all enterococci are the same: E. faecium has much higher resistance rates (84.8% to ampicillin) compared to E. faecalis (4.8% to ampicillin), but your culture specifies E. faecalis, which is fortunately the more susceptible species 6
- Cephalosporins (including those in some combination products) have NO activity against Enterococcus species due to natural resistance 1