Enterococcus faecium
One-Sentence Definition
Enterococcus faecium is a Gram-positive coccus of the gut microbiota that is a leading cause of hospital bacteremia and device infection — and a core ESKAPE pathogen driven by vancomycin-resistant (VRE) clones.
Taxonomy & Morphology
- Gram-positive cocci in pairs/short chains; catalase-negative
- Grows in high salt / bile; Lancefield group D historically
- Closely related clinical counterpart: E. faecalis (often more virulent toxins; E. faecium more MDR)
Virulence Highlights
- Surface adhesins for endocarditis/device colonization
- Biofilm on catheters and prosthetic material (Biofilm)
- Intrinsic low-level resistance to many β-lactams/aminoglycosides shapes therapy
Clinical Syndromes
- CLABSI, intra-abdominal infection, UTI, endocarditis
- VRE outbreaks in ICUs and transplant units
Diagnosis
- Culture + MALDI; differentiate faecium vs faecalis
- AST with vancomycin; molecular vanA/vanB when available
- WGS for outbreak clustering (Population Structure and Clustering)
Treatment Notes (conceptual)
- Ampicillin if susceptible (faecalis more often); faecium often ampicillin-resistant
- VRE: linezolid, daptomycin (optimize dosing), sometimes combination strategies — stewardship critical
- Source control for devices
AMR
- VanA/VanB operons on Tn1546-like elements / plasmids — inducible via Two-Component Regulatory Systems (VanRS)
- Hospital clade (E. faecium clade A) concentrates MDR
- Member of ESKAPE Pathogens
Genomics & Computational Notes
- Plasmid and ICE traffic of van and linezolid resistance alleles
- cgMLST schemes used in VRE hospital epi
- See Plasmid and Mobile Element Analysis · Clinical WGS Pipelines
Related Notes
- ESKAPE Pathogens · Persisters and Antibiotic Tolerance · Antimicrobial Stewardship
- MOCs: MOC - Bacteriology · MOC - Antimicrobial Resistance (AMR) · MOC - Clinical Microbiology
Active Recall
- VanA vs VanB — which typically has higher-level vancomycin resistance and teicoplanin cross-resistance?
- Why is E. faecium central to ICU infection control?
- Which TCS induces van genes?