Genomic insights into the emergence, adaptation, and environmental dissemination of Enterococcus faecium as a...

Enterococcus faecium has become a prominent nosocomial pathogen, demonstrating significant multidrug resistance (MDR) and persistence in both hospital and environmental contexts. Genomic analyses indicate a highly adaptable genome characterized by a substantial accessory component enriched in antimicrobial resistance genes (ARGs) and mobile genetic elements (MGEs), including plasmids, transposons, integrative conjugative elements, and prophages. The acquisition and dissemination of resistance determinants, such as vancomycin (vanA, vanB), aminoglycoside, macrolide, tetracycline, and novel oxazolidinone resistance genes (optrA, poxtA), are predominantly facilitated by horizontal gene transfer mediated by these MGEs. Virulence factors, stress response regulators, and biofilm-associated genes augment E. faecium's survival in hospital settings and its colonization potential. Environmental reservoirs, such as wastewater, animal farms, and food products, facilitate interspecies gene exchange, underscoring the pathogen's significance within the broader One Health AMR network. This review brings together what we know about E. faecium's genome, focusing on its evolutionary adaptation, mobilome architecture, clinical and epidemiological importance, and spread in the environment. It gives us a complete picture of what we need to do to keep an eye on and control the disease in the future.