Genomic Insights Into a Hospital-Acquired High-Risk Vancomycin-Resistant Enterococcus faecium Outbreak in Guangdong, China.

A comprehensive molecular epidemiological study was conducted on a vancomycin-resistant Enterococcus faecium (VR-Efm) outbreak in Guangdong, China, with the aim of analyzing transmission routes and antimicrobial resistance patterns, developing specific diagnostic tools for early detection, and elucidating genetic relationships with previously reported strains. Strain identification was performed using matrix-assisted laser desorption/ionization mass spectrometry, whereas whole-genome sequencing was performed for bacterial genomic characterization. Comprehensive bioinformatic analyses, including multilocus sequence typing, phylogenetic tree construction, principal component analysis, minimum spanning tree, and comparative genomic analyses, were performed. Our genomic investigation identified as predominant the sequence type 80 strain of VR-Efm, which exhibited a high level of resistance to a range of antibiotics, particularly vancomycin, amoxicillin, and teicoplanin. Through genome sequencing, we established genetic proximity between the outbreak strain and those previously identified in India and Japan. Furthermore, functional genomic analyses have elucidated genetic variations within critical genes, such as rsmH, which may be associated with the acquisition of antibiotic resistance. The identification of unique molecular markers within the outbreak strain facilitated the development of specific PCR assays, thereby significantly enhancing our capacity for early and precise detection of VR-Efm. Our in-depth genomic analysis of the VR-Efm outbreak in Guangdong, China, identified a predominant ST80 strain that exhibited multidrug resistance, especially to vancomycin. This finding underscores the need for enhanced global public health surveillance to address this emerging threat.