What is the recommended treatment for Enterococcus (a type of bacteria) urinary tract infection (UTI)?

Treatment of Enterococcus Urinary Tract Infections

For Enterococcus urinary tract infections, ampicillin is the first-line treatment for susceptible strains, while nitrofurantoin and fosfomycin are excellent oral options for uncomplicated cystitis caused by vancomycin-resistant enterococci (VRE). 1, 2

Treatment Algorithm for Enterococcal UTIs

Step 1: Determine Susceptibility

• Obtain urine culture with susceptibility testing before initiating therapy 1
• Differentiate between colonization and true infection to avoid unnecessary antibiotic use 2

Step 2: Select Appropriate Antibiotic Based on Susceptibility

For Ampicillin-Susceptible Enterococci:

• First-line: Ampicillin (preferred) or amoxicillin 1, 2
  • Dosing: Ampicillin 1-2g IV q6h or amoxicillin 500mg PO q8h
  • High urinary concentrations may overcome intermediate resistance 3

For Vancomycin-Resistant Enterococci (VRE):

• For uncomplicated cystitis:

  • Nitrofurantoin 100mg PO twice daily for 5 days (if CrCl >60 mL/min) 1, 2
  • Fosfomycin 3g single oral dose 1, 2
  • Doxycycline (if susceptible) 2

• For complicated UTI or pyelonephritis:

  • Linezolid 600mg PO/IV q12h (shown to be effective for VRE urinary infections with 63% cure rate) 4, 2
  • Daptomycin (if susceptible) - reserve for upper/bacteremic UTIs 2

Step 3: Treatment Duration

• Uncomplicated cystitis: 5 days
• Complicated UTI or pyelonephritis: 7-14 days 1

Special Considerations

Synergistic Therapy for Severe Infections

• For severe enterococcal infections, consider combination therapy with cell wall-active agent plus aminoglycoside 5, 6
• Only use aminoglycoside combination if no high-level aminoglycoside resistance is present (MIC ≤2000 μg/ml) 7

Antimicrobial Stewardship

• Avoid treating asymptomatic bacteriuria with enterococci 2
• Remove indwelling catheters when possible to aid in clearance 8
• Tailor broad-spectrum therapy when culture and susceptibility results become available 3

Monitoring and Follow-up

• Assess clinical response within 48-72 hours
• If symptoms persist or recur within 2 weeks, obtain repeat urine culture and select a different antibiotic class 1
• Routine post-treatment cultures not indicated for asymptomatic patients 1

Antimicrobial Options for VRE UTIs

• First-line oral options: Nitrofurantoin, fosfomycin (for lower UTI) 2, 8
• Parenteral options: Linezolid, daptomycin (reserve for serious infections) 4, 2
• Alternative agents (use based on susceptibility testing):
  • Tigecycline (not for bacteremia due to low serum levels) 3
  • Quinupristin-dalfopristin (limited data, significant side effects) 2, 8

Common Pitfalls to Avoid

• Treating asymptomatic bacteriuria with VRE, especially in catheterized patients
• Using fluoroquinolones empirically without susceptibility data (high resistance rates)
• Failing to adjust therapy based on culture results
• Using broad-spectrum agents when narrower options are available
• Not considering local resistance patterns when selecting empiric therapy

Remember that ampicillin remains the drug of choice for susceptible enterococcal UTIs, and nitrofurantoin or fosfomycin are excellent options for uncomplicated VRE cystitis, while linezolid should be reserved for more serious VRE infections.