Can a urinary tract infection (UTI) caused by Enterococcus be treated with cephalosporins?

Treatment of Enterococcus Urinary Tract Infections

Cephalosporins should not be used to treat UTIs caused by Enterococcus species due to intrinsic resistance, making these antibiotics ineffective regardless of susceptibility testing results. 1

Pathogen Characteristics and Resistance Patterns

Enterococci possess intrinsic resistance to several antibiotics, with cephalosporins being particularly notable:

• Enterococci have natural (intrinsic) resistance to all generations of cephalosporins 1, 2
• This resistance is consistent across Enterococcus species, including both E. faecalis and E. faecium 2
• Even newer cephalosporins like ceftaroline exhibit poor activity against enterococci and should not be used for treating enterococcal infections 3

Recommended Treatment Options

For uncomplicated Enterococcus UTIs, the following agents are recommended:

• First-line options:

  • Nitrofurantoin 100mg twice daily for 5 days 1, 4
  • Fosfomycin 3g single dose 1, 4
  • Ampicillin (for susceptible strains) 3

• For ampicillin-resistant or vancomycin-resistant Enterococcus (VRE):

  • High-dose ampicillin (18-30g IV daily) or amoxicillin (500mg every 8h) may still be effective for UTIs due to high urinary concentrations 3
  • Clinical and microbiological eradication rates of 88.1% and 86% respectively have been reported with ampicillin for ampicillin-resistant VRE UTIs 3

Treatment Considerations for Complicated UTIs

For complicated or upper tract infections with Enterococcus:

• Parenteral options include:

  • Daptomycin (≥8 mg/kg, up to 10-12 mg/kg) 3, 4
  • Linezolid 1, 4
  • Quinupristin-dalfopristin (for E. faecium only) 4

• Aminoglycosides may be considered as adjunctive therapy in serious infections 4

Important Clinical Considerations

• Always obtain urine culture and susceptibility testing to guide therapy 1
• Differentiate colonization from true infection before initiating treatment 3
• Remove indwelling urinary catheters when possible 4
• E. faecalis is generally more susceptible to antibiotics than E. faecium 1
• Biofilm formation is common in enterococcal UTIs (up to 76.6-100% of isolates), which may contribute to treatment failure and antibiotic resistance 5

Common Pitfalls to Avoid

1. Never use cephalosporins for Enterococcus UTIs - regardless of generation, as they have intrinsic resistance 1, 2
2. Don't treat asymptomatic bacteriuria with MDR-Enterococcus unless clinically indicated 4
3. Avoid fluoroquinolones as empiric therapy due to high rates of resistance in E. faecalis strains 1
4. Don't assume susceptibility based on species - always check susceptibility testing, especially for E. faecium which tends to be more resistant 1

By following these evidence-based recommendations, you can effectively manage UTIs caused by Enterococcus while avoiding ineffective treatments like cephalosporins that would lead to treatment failure and potentially worse outcomes.