Molecular investigation of an epidemic dissemination of vancomycin-resistant Enterococcus faecium sequence type 80 in Guangdong Province, China

Objectives: The detection rate of vancomycin-resistant Enterococcus faecium (VREfm) displayed a dramatically increase in Guangdong, China from 2021 to 2023, for which the molecular epidemiology and genomic characteristics remain largely unexplored. In this study, we investigated the genetic features and epidemiology of VREfm isolates in Guangdong.

Methods: A total of 54 Guangdong VREfm isolates were collected from three tertiary hospitals in Guangdong. We preformed antimicrobial susceptibility test, whole genome sequencing, risk factor analysis, and bioinformatics analysis to conduct this research.

Results: Our investigation indicated that VREfm isolates were highly clonal and multidrug-resistant ST80 Enterococcus faecium harboring vanA-positive plasmid. The phylogenetic analysis based on single-nucleotide polymorphisms (SNPs) demonstrated that VREfm isolates exhibited minimal genetic similarity to previously reported E. faecium in China, whereas exhibited high genomically similar to an India strain A10290 isolated in 2019 and Hiroshima isolates detected in 2020, indicative of a possible exogeneous import. The genetic environment of cps region showed a novel type of wzy gene cluster involved in capsule polysaccharide (CPS) biosynthesis flanked by ISEf1 and IS16 was identified in VREfm isolates, which displayed a remarkably divergence from the downstream of putative cpsABCD region in other sequence types (STs) E. faecium. Heat map of plasmid-mediated virulence factors suggested several predicted proteins including Cag pathogenetic island proteins existed in VREfm isolates at a high frequency.

Conclusions: This study highlighted the importance of ongoing surveillance to track the dynamic dissemination of multidrug-resistant ST80 VREfm isolates harboring multiple virulence genes in Guangdong province, China.