Novel Vancomycin-Resistance Transposon, Plasmid Replicon Types, and Virulence Factors of Vancomycin-ResistantEnterococciin Zhejiang, China

Abstract

Forty-seven vancomycin-resistant Enterococcus (VRE) strains were isolated from clinical samples in 13 Zhejiang hospitals and fecal samples from ICU patients in a large teaching hospital in China. No VRE isolates were detected in healthy human subjects. CC17 was the main clonal complex in clinical Enterococcus faecium isolates but not in isolates from healthy human subjects. Novel vancomycin-resistance transposons were detected among VRE strains. This is the first report demonstrating insertion of tnpA and fosB genes in the vanRS-vanH intergenic region of Tn1546 leading to coresistance to vancomycin and fosfomycin. The four plasmid replicon types (pRUM, pRE25, pEF418, and pB82) were more common in VRE isolates, suggesting their association with vancomycin resistance and nosocomial transmission. The prevalence rate of vancomycin-resistant Staphylococcus aureus-related Inc18-like plasmid, pIP501, in VRE was 21.3%. The prevalence of the esp gene among VRE isolates was high (76.6%). In several VRE strains, the esp and hyl genes were cotransferred with the vanA gene by conjugation. Although the frequency of VRE is low in Chinese hospitals, its association with virulence determinants, the vancomycin-resistance transposon with other resistance gene insertions or plasmids may lead to multidrug resistance and the evolution of pathogenic VRE.