Molecular characterization of vancomycin-resistant enterococci in a Chinese hospital between 2003 and 2009

From June 2003 to December 2009, 98 isolates of vancomycin-resistant enterococci (VRE) were cultured from clinical specimens taken from patients admitted to a 1,500-bed tertiary-care teaching hospital in Beijing, China. Isolates were characterized by pulsed-field gel electrophoresis and multilocus sequence typing. We investigated the structure of the vanA gene cluster and the distribution of the virulence markers esp, hyl, gelE, asa1, and cylA by polymerase chain reaction. Our results indicate that multilocus sequence typing revealed five novel sequence types and one new allele. VRE faecium (VREfm) isolates were heterogeneous in their vanA cluster types and in the presence of virulence genes. We also observed inconsistency between genotype and phenotype in VREfm isolates. The outbreak with VREfm in our hospital appears polyclonal, whereas VRE faecalis characterization indicated dissemination of a particular clone. After 2007, VRE faecalis was completely replaced by VREfm, which has since been the predominant species in our hospital. VRE appears to be in an evolutionary flux in our hospital.