Treatment of Drug-Resistant Enterococcus Infections
For drug-resistant Enterococcus infections, high-dose daptomycin (8-12 mg/kg IV daily) is the first-line treatment for vancomycin-resistant enterococci (VRE), while ampicillin plus gentamicin remains the standard therapy for susceptible strains. 1
Treatment Algorithm Based on Resistance Pattern
1. Susceptible Enterococcus Strains
- First-line therapy: Combination of penicillin G or ampicillin with gentamicin
- For penicillin-allergic patients: Vancomycin 30 mg/kg/day IV in two divided doses plus gentamicin for 6 weeks 2
2. Aminoglycoside-Resistant Enterococcus
- Recommended therapy: Ampicillin plus ceftriaxone 2
- This combination has proven effective for aminoglycoside-nonsusceptible E. faecalis strains
- Note: Ceftriaxone alone is not effective against enterococci
3. Vancomycin-Resistant Enterococcus (VRE)
- First-line therapy: Daptomycin 8-12 mg/kg IV daily 1
- Higher doses (≥11 mg/kg) recommended for isolates with MICs ≥2 mg/L
- Monitor creatine kinase (CK) levels regularly to detect muscle toxicity
- Alternative therapy: Linezolid 600 mg IV q12h 1
- For severe infections: Consider combination therapy with daptomycin plus a beta-lactam for synergistic effect 1
Special Considerations
Treatment Duration
- Standard duration: 10-14 days for bloodstream infections 1
- Extended duration (4-6 weeks) for endocarditis 2
- For prosthetic valve endocarditis: Minimum 6 weeks 2
Monitoring and Resistance Management
- Regular monitoring of renal function with aminoglycoside therapy
- For daptomycin therapy, monitor CK levels to detect muscle toxicity 1, 3
- Avoid prior daptomycin exposure within 90 days if possible to prevent development of resistance 1
Urinary Tract Infections
- For uncomplicated UTIs caused by MDR-Enterococcus: Consider nitrofurantoin or fosfomycin 4
- For complicated UTIs: Parenteral therapy with daptomycin or linezolid 4
Important Pitfalls to Avoid
Do not use cephalosporins alone for enterococcal infections - enterococci are intrinsically resistant to cephalosporins 2
Do not treat asymptomatic bacteriuria with MDR-Enterococcus - routine therapy is not recommended 4
Avoid single-drug therapy for serious enterococcal infections - combination therapy is typically required for bactericidal activity 2
Do not use standard doses of daptomycin (6 mg/kg) for VRE infections - higher doses (8-12 mg/kg) are associated with better outcomes 1
Always involve infectious disease consultation for management of enterococcal IE as the standard of care 2
The emergence of multidrug-resistant enterococci presents significant clinical challenges, but with appropriate antimicrobial selection based on susceptibility testing and understanding of resistance mechanisms, successful treatment is possible even in complex cases.