Background and purpose: In 2007, an outbreak of vancomycin-resistant enterococci (VRE) occurred at Taipei Medical University, Wan Fang Hospital, Taipei, Taiwan. The aim of this study was to characterize the mechanism of glycopeptide resistance and to investigate the genetic relatedness among isolates of VRE.
Methods: Between May and October 2007, bacterial isolates from 16 patients identified as colonized or infected with VRE were collected. Polymerase chain reaction and pulsed-field gel electrophoresis (PFGE) were used to determine resistant genes and molecular typing.
Results: All 16 isolates of VRE presented with the VanA phenotype with the vanA gene except for 1 isolate of Enterococcus faecalis, which had the VanB phenotype with the vanA gene. PFGE analysis revealed a major clone containing 12 isolates, and 4 other distinct clones containing 1 to 2 isolates each. Five patients had VRE colonized in their gastrointestinal tract, the genotype of which was the same as the clinical isolates. Fourteen isolates (87.5%) had the esp gene.
Conclusions: An outbreak of VRE was caused by the simultaneous existence of monoclonal and polyclonal spread. Rigorous infection control, active surveillance, and decreasing pressure of antibiotic use are important for controlling the emergence of VRE.