In July 2010, we identified an outbreak of vancomycin-resistant enterococci (VRE) in our 26-bed neonatal intensive care unit. We performed an epidemiological investigation after clinical cultures of 2 neonates were positive for VRE. Identification, susceptibility testing, and molecular characterization were performed. Cultures of 3 surveillance stool samples of inpatients and 5 environmental samples were positive for VRE. All isolates were identified as Enterococcus faecium containing the vanA gene. Two distinct clones were identified by performing pulsed-field gel electrophoresis. The 2 clones exhibited different pulsotypes, but they represented identical Tn1546 types. Two sequence types, ST18 and ST192, were identified among all of the isolates with multilocus sequence typing. Our investigation determined that the outbreak in the neonatal intensive care unit was caused by 2 genetically different clones. The outbreak may have occurred through clonal spread and horizontal transfer of the van gene.

This study compared the molecular characteristics of vancomycin-resistant Enterococcus faecium (VREF) isolates recovered from 20 non-tertiary-care hospitals (36 isolates) and three tertiary-care hospitals (26 isolates) in diverse geographical areas of Korea from October 2010 to April 2011. All isolates carried the vanA gene only, but 42% and 73% of non-tertiary and tertiary-care isolates expressed the VanB phenotype (teicoplanin minimum inhibitory concentration ⩽16 μg/ml). All isolates harboured insertion sequences, IS1542 and IS1216V, within Tn1546. The isolates from tertiary-care hospitals tended to have reduced Tn1546 lengths by deletion of sequences adjacent to IS elements. Multilocus sequence typing revealed eight sequence types within clonal complex 17 (CC17), but DNA fingerprinting by rep-PCR did not show clonal relatedness between the intra- and inter-hospital isolates. These results suggest that vanA, which has prevailed in tertiary-care hospitals of Korea since the 1990s, had been transferred horizontally to non-tertiary-care hospitals while the genetic rearrangement driven by evolutionary adaptation to adverse environments may have occurred in tertiary-care hospitals.

Background: Asymptomatic vancomycin-resistant enterococci (VRE) colonization precedes infection. VREcolonized patients serve as silent reservoirs of enterococci that go on to colonize other patients. Rapidly identifying colonized patients is crucial to prevent the spread of VRE. The culture-based method of VRE screening is time-consuming. We evaluated the diagnostic performance of a recently developed multiplex real-time PCR for the detection of VRE. Methods: We obtained 105 rectal swabs from patients who were being monitored for carriage of VRE. After 24 hour incubation of swabs in enterococcosel broth (EB) supplemented with 6 μg/mL vancomycin, multiplex real-time PCR was performed using the Anyplex TM VanR Real-time Detection (VanR) kit (Seegene, Inc., Seoul, Korea). The results of multiplex real-time PCR were compared to those of culture. We evaluated the specificity and detection limits of multiplex real-time PCR using VanR for VRE. Results: A total of 96/105 (91.4%) samples were