What are the recommended antibiotics for treating Enterococcus urinary tract infections (UTI)?

Recommended Antibiotics for Enterococcus UTI

For Enterococcus urinary tract infections, nitrofurantoin (100mg twice daily for 5 days) and fosfomycin (3g single dose) are the first-line treatments for uncomplicated lower UTIs, while ampicillin is the drug of choice for ampicillin-susceptible strains. 1

First-Line Treatment Options

Uncomplicated Lower UTIs

• Nitrofurantoin: 100mg twice daily for 5 days 1
• Fosfomycin: 3g single dose 1
• Trimethoprim-sulfamethoxazole: 160/800mg twice daily for 3 days (if susceptible) 1

Ampicillin-Susceptible Enterococcus

• Ampicillin: First choice for susceptible strains 2, 3
  • Even for isolates with MICs above susceptibility breakpoints, aminopenicillins may be effective for lower UTIs due to high urinary concentrations 3

Treatment for Resistant Strains

Vancomycin-Resistant Enterococcus (VRE)

• Linezolid: Reserve for confirmed upper/bacteremic VRE UTIs with ampicillin resistance 2
• Daptomycin: Alternative for upper/bacteremic VRE UTIs 2

High-Level Aminoglycoside Resistance

• Avoid aminoglycosides if high-level resistance is detected (MIC ≥2,000 μg/ml) 4
• Consider alternative agents based on susceptibility testing 1

Treatment Duration

• 5-7 days for uncomplicated UTIs 1
• 7-14 days for complicated infections or pyelonephritis 5, 1

Important Considerations

Susceptibility Testing

• Always obtain urine culture and susceptibility testing to guide therapy 6
• Local resistance patterns should inform empiric therapy choices 1
• Enterococci have intrinsic resistance to cephalosporins, making these ineffective 4, 7

Resistance Patterns

• E. faecalis is generally more susceptible to antibiotics than E. faecium 8
• Increasing resistance to ampicillin/sulbactam has been observed over time 7
• All enterococcal species have intrinsic resistance to cephalosporins 4

Special Situations

• For complicated or upper tract infections, parenteral therapy may be necessary initially 5
• Avoid nitrofurantoin in patients with pyelonephritis or urosepsis as it doesn't achieve adequate serum concentrations 5

Treatment Algorithm

1. Obtain urine culture and susceptibility testing
2. For uncomplicated lower UTI while awaiting results:
   • Nitrofurantoin 100mg twice daily, or
   • Fosfomycin 3g single dose
3. Once susceptibility results available:
   • If ampicillin-susceptible: Use ampicillin
   • If ampicillin-resistant but nitrofurantoin/fosfomycin-susceptible: Continue with either agent
   • If VRE or multi-drug resistant: Consider linezolid or daptomycin for upper/bacteremic infections
4. Treatment duration:
   • 5 days for uncomplicated lower UTI
   • 7-14 days for complicated infections or pyelonephritis

Remember that enterococci are intrinsically resistant to cephalosporins, and inappropriate antibiotic use has contributed to increasing resistance patterns. Always base final treatment decisions on culture and susceptibility results to ensure optimal outcomes.