What is the recommended treatment duration for gram-positive Enterococcus faecium (E. faecium) infections?

Treatment Duration for Enterococcus faecium Infections

Treatment duration for E. faecium infections is site-specific: uncomplicated urinary tract infections require single-dose or short-course therapy (3-7 days), complicated skin and soft tissue infections require 7-14 days, bacteremia requires 7-14 days (longer if complicated), intra-abdominal infections are treated based on source control and clinical response (typically 4-7 days after source control), and infective endocarditis requires 4-6 weeks of therapy. 1, 2

Site-Specific Treatment Durations

Uncomplicated Urinary Tract Infections

• Single-dose fosfomycin 3 g PO is recommended for uncomplicated UTIs due to vancomycin-resistant E. faecium (VRE) 1
• Nitrofurantoin 100 mg PO every 6 hours for uncomplicated UTIs, typically 5-7 days 1
• High-dose ampicillin (18-30 g IV daily in divided doses) or amoxicillin 500 mg PO/IV every 8 hours can be used for uncomplicated UTIs even with ampicillin-resistant strains due to high urinary concentrations 1

Complicated Skin and Soft Tissue Infections

• Linezolid 600 mg IV or PO every 12 hours for 10-28 days, with duration dependent on clinical response 2
• The FDA label indicates treatment duration of 7-28 days for documented VRE infections, with most patients requiring 10-14 days 2
• Daptomycin at 4 mg/kg once daily was FDA-approved for complicated skin infections, though higher doses (8-12 mg/kg) are now preferred for serious infections 3

Bacteremia and Serious Infections

• Linezolid 600 mg IV or PO every 12 hours, with treatment duration dependent on the site of infection and clinical response 1
• For VRE bacteremia, the FDA label shows treatment durations of 7-28 days in clinical trials, with cure rates of 67% at high dose 2
• High-dose daptomycin 8-12 mg/kg/day or in combination with β-lactams is recommended for VRE bacteremia, typically for 14 days minimum (longer if complicated by endocarditis or metastatic foci) 1
• E. faecium bacteremia is associated with higher mortality (50%) compared to E. faecalis (11%), particularly in severely ill patients, requiring aggressive treatment 4

Intra-Abdominal Infections

• Tigecycline 100 mg IV loading dose then 50 mg IV every 12 hours, with duration based on clinical response and adequate source control 1
• Typical duration is 4-7 days after adequate source control has been achieved 1
• Clinical cure rates of 80.6% were observed with tigecycline for complicated intra-abdominal infections including VRE 1

Infective Endocarditis

• Minimum 4-6 weeks of therapy is required for enterococcal endocarditis 1
• VRE endocarditis associated with E. faecium has higher mortality and longer duration of bacteremia compared to E. faecalis 1
• Cardiac surgery and combination antibiotic therapy improve survival outcomes in VRE endocarditis 1

Critical Clinical Considerations

Differentiate Colonization from Infection

• It is essential to differentiate colonization from true infection before initiating anti-VRE therapy, as unnecessary treatment contributes to resistance 1

Pediatric Dosing

• Linezolid 10 mg/kg IV or PO every 8 hours for 10-28 days in pediatric patients from birth through 11 years 2
• Cure rates of 75% were achieved for VRE infections in pediatric patients 2

Common Pitfalls

• Do not use ceftaroline for E. faecium infections despite its broad Gram-positive activity, as it has poor activity against enterococci 1
• E. faecium is often nosocomial, associated with cancer, neutropenia, renal insufficiency, corticosteroid therapy, and prior broad-spectrum antibiotic use 4
• Vancomycin-resistant E. faecium represents a clonal population that has transitioned from commensal to nosocomial pathogen with enhanced virulence 5