To analyze the drug resistance phenotypes and genotypes of 2 307 Enterococcus faecium strains collected from 2011 to 2024.

The antimicrobial susceptibility testing of the strains was performed using the broth microdilution method, followed by genomic DNA extraction from the strains and polymerase chain reaction (PCR) amplification for screening of resistance genes.

From 2011 to 2012, the detection rate of vancomycin-resistant Enterococcus faecium was 1.67%, and the detection rate of vanM gene-positive vancomycin-susceptible strains was 0.34%. In contrast, from 2023 to 2024, the detection rate of vancomycin-resistant Enterococcus faecium increased to 5.11%, while the detection rate of vanM gene-positive vancomycin-susceptible strains reached as high as 4.75%. Additionally, 22 Enterococcus faecium strains co-harboring both vanA and vanM resistance genes were identified during the period from 2021 to 2024.

The detection rate of the vanM resistance gene in Enterococcus faecium has increased year by year, and its horizontal transfer may have contributed to the increased prevalence of Enterococcus faecium co-harboring both vanA and vanM resistance genes in recent years.