What is the oral (PO) treatment for Enterococcus urinary tract infections (UTIs)?

Oral Treatment Options for Enterococcus Urinary Tract Infections

For uncomplicated Enterococcus UTIs, the recommended oral treatments are nitrofurantoin 100mg twice daily for 5 days, fosfomycin 3g single dose, or linezolid 600mg twice daily, with the choice depending on susceptibility testing and infection severity. 1, 2

First-Line Oral Treatment Options

For Uncomplicated Enterococcus UTIs:

• Nitrofurantoin: 100mg PO every 6 hours or 100mg twice daily for 5 days 1, 3
• Fosfomycin: 3g PO single dose 1, 3, 2
• Linezolid: 600mg PO every 12 hours 1

For Vancomycin-Resistant Enterococcus (VRE) UTIs:

• Linezolid: 600mg PO every 12 hours (strong recommendation for enterococcal infections) 1
• Nitrofurantoin: 100mg PO every 6 hours (for lower UTIs only) 1, 2
• Fosfomycin: 3g PO single dose (for uncomplicated UTIs) 1, 2
• High-dose ampicillin: 500mg PO every 8 hours (if susceptible) 1
• Amoxicillin: 500mg PO every 8 hours (if susceptible) 3, 2

Treatment Algorithm Based on Clinical Scenario

1. For uncomplicated lower UTI (cystitis):

   • First obtain urine culture and susceptibility testing
   • Empiric therapy: Nitrofurantoin 100mg twice daily for 5 days or fosfomycin 3g single dose 3
   • Adjust based on susceptibility results

2. For VRE cystitis:

   • If ampicillin-susceptible: Amoxicillin 500mg PO every 8 hours 1, 2
   • If ampicillin-resistant: Nitrofurantoin 100mg PO every 6 hours or fosfomycin 3g single dose 1, 2, 4

3. For complicated UTI or pyelonephritis:

   • Linezolid 600mg PO every 12 hours 1
   • Consider parenteral therapy initially if severe symptoms 1

Important Clinical Considerations

• Duration of therapy:

  • Uncomplicated UTIs: 5-7 days
  • Complicated UTIs: 7-14 days 1

• Susceptibility testing is crucial as enterococci frequently demonstrate resistance to multiple antibiotics 5, 6

• Biofilm formation is common in enterococcal UTIs (up to 76.6% of isolates), which may contribute to treatment failure and recurrence 6

• Avoid fluoroquinolones as empiric therapy due to increasing resistance rates, unless susceptibility is confirmed 3, 5

Special Considerations

• Aminopenicillins (amoxicillin/ampicillin) may be effective for lower UTIs even when in vitro testing shows resistance, due to high urinary concentrations achieved 7

• Doxycycline may be considered as an alternative for lower UTIs if other options are unavailable 2

• For ampicillin-resistant enterococci, nitrofurantoin and fosfomycin remain the most reliable oral options 2, 4

• Linezolid should be reserved for serious infections or when other options are unavailable due to concerns about resistance development 1, 2

Common Pitfalls to Avoid

• Don't treat asymptomatic bacteriuria with enterococci, especially in catheterized patients 4

• Don't use nitrofurantoin for upper UTIs (pyelonephritis) as it doesn't achieve adequate tissue concentrations 1, 2

• Don't use fluoroquinolones empirically due to high resistance rates 3, 5

• Don't forget to remove indwelling catheters when possible, as this is a major risk factor for enterococcal UTIs 4