Enterococcus faecium

Enterococcus faecium
Photo Credit: Janice Haney Carr Content Providers(s): CDC/ Janice Carr · Public domain · source
Name	Enterococcus faecium
Domain	Bacteria
Phylum	Firmicutes
Class	Bacilli
Order	Lactobacillales
Family	Enterococcaceae
Genus	Enterococcus
Species	E. faecium

Contents

Enterococcus faecium Enterococcus faecium is a Gram-positive, facultatively anaerobic bacterium commonly found in the gastrointestinal tracts of humans and animals. First isolated in the early 20th century, it has gained prominence due to its role in nosocomial infections and its capacity to acquire resistance to multiple antibiotics. Research on Enterococcus faecium intersects with work at institutions like Centers for Disease Control and Prevention, World Health Organization, Wellcome Trust, National Institutes of Health, and European Centre for Disease Prevention and Control.

Taxonomy and Description

E. faecium belongs to the order Lactobacillales and the family Enterococcaceae, a placement informed by comparative analyses at laboratories such as Pasteur Institute, Sanger Institute, Max Planck Society, and Broad Institute. Morphologically, it appears as short chains or pairs of cocci under microscopy observed in facilities like Mayo Clinic Laboratories, Johns Hopkins Hospital, and Karolinska Institutet. Classical phenotypic tests used historically at universities including Harvard University, University of Oxford, and University of Cambridge have been complemented by 16S rRNA sequencing methods standardized by groups at Cold Spring Harbor Laboratory and University of California, Berkeley. Taxonomic revisions have been discussed at international meetings involving delegates from American Society for Microbiology, European Society of Clinical Microbiology and Infectious Diseases, and the International Union of Microbiological Societies.

E. faecium is a commensal of the gastrointestinal tracts of mammals and birds, with ecological surveys conducted by teams at University of Tokyo, University of São Paulo, University of Cape Town, and University of Melbourne. It is detected in environmental reservoirs sampled by agencies such as Environmental Protection Agency and research programs like those at Smithsonian Institution and United States Geological Survey. Studies of livestock-associated populations have involved collaborations with Food and Agriculture Organization and veterinary schools at Cornell University and University of Illinois Urbana-Champaign. Wastewater and surface water monitoring implicating E. faecium have been reported in projects funded by European Commission and assessed by consortia including Bill & Melinda Gates Foundation.

E. faecium is implicated in bloodstream infections, endocarditis, urinary tract infections, and surgical site infections, with clinical case series published by Cleveland Clinic, Mount Sinai Health System, and Massachusetts General Hospital. Outbreak investigations have engaged public health authorities like Public Health England, Agence nationale de santé publique (France), and Robert Koch Institute. Patient populations at elevated risk include those in intensive care units at institutions such as Johns Hopkins Hospital and University Hospital Zurich, oncology wards associated with Dana-Farber Cancer Institute and MD Anderson Cancer Center, and transplant centers including Mayo Clinic and Cleveland Clinic. Clinical guidelines referencing management of enterococcal infections have been issued by societies including Infectious Diseases Society of America, European Society of Clinical Microbiology and Infectious Diseases, and Society for Healthcare Epidemiology of America.

Vancomycin-resistant strains (VRE) of E. faecium have emerged through acquisition of transposons and plasmids characterized in studies at University of Wisconsin–Madison, University of Groningen, and University of Copenhagen. Mobile genetic elements described by researchers at Harvard Medical School, University of Basel, and University of Toronto carry resistance determinants such as vanA and vanB, analogous to resistance gene studies cataloged by the National Center for Biotechnology Information and curated in databases at the European Molecular Biology Laboratory. Mechanistic work on horizontal gene transfer has involved collaborators at ETH Zurich, John Innes Centre, and Weizmann Institute of Science. Surveillance programs run by CDC and WHO track multidrug-resistant clones linked to hospital outbreaks investigated by groups at Imperial College London and University College London.

Clinical laboratories employ culture-based identification using chromogenic media used in studies at University of Pennsylvania and automated systems developed by companies with ties to Siemens Healthineers and bioMérieux. MALDI-TOF mass spectrometry, validated at Karolinska Institutet and McMaster University, complements molecular assays. Whole-genome sequencing efforts at centers including Wellcome Sanger Institute, Broad Institute, and Genome Institute at Washington University have characterized population structure, single nucleotide polymorphisms, and plasmid repertoires. Comparative genomics linking E. faecium isolates across continents has been presented at conferences hosted by American Society for Microbiology, European Society of Clinical Microbiology and Infectious Diseases, and International Congress of Bacteriology.

Infection prevention strategies in healthcare settings are informed by guidelines from Centers for Disease Control and Prevention, World Health Organization, and European Centre for Disease Prevention and Control, and implemented through stewardship programs at hospitals such as Guy's and St Thomas' NHS Foundation Trust and Barnes-Jewish Hospital. Therapeutic options for resistant E. faecium—studied in clinical trials at National Institutes of Health Clinical Center, Vanderbilt University Medical Center, and University of California, San Francisco—include linezolid, daptomycin, and newer agents evaluated by pharmaceutical research groups at Pfizer, Novartis, and Merck & Co.. Public health responses to VRE incidents have involved outbreak teams from Public Health England and multidisciplinary collaborations with academic centers including University of Toronto and Monash University. Surveillance, antimicrobial stewardship, and cross-sectoral initiatives promoted by Food and Agriculture Organization, World Organisation for Animal Health, and Gavi, the Vaccine Alliance aim to mitigate spread in clinical, agricultural, and environmental contexts.