Thirty-six VanB glycopeptide-resistant Enterococcus faecium isolates were collected from patients in five different hospitals in Taiwan. The vancomycin resistance genes were amplified by the long vanB PCR, which amplifies the 6,373-bp vanB gene cluster including the vanR B2, vanS B2, vanY B2, vanW B2, vanH B2, vanB2, and vanX B2 genes. The deduced amino acid sequences were found to be 95 to 98% homologous to those of the vanB1 gene cluster: VanR B1, 97%; VanS B1, 97%; VanY B1, 96%; VanH B1, 95%; VanB1, 96%; and VanX B1, 98%. Restriction enzyme analysis of the long vanB PCR products revealed that all 36 isolates had the same vanB2-specific pattern. DNA sequence analysis of the vanB2 gene, which is a D-Ala-D-Lac ligase gene, revealed that none of the 36 sequences were identical to the previously published vanB2 sequence. Thirty-one isolates had 1 nucleotide different from the published vanB2 sequence. The sequences of the other five isolates differed from the published vanB2 sequence by 2 or 3 nucleotides. Four isolates with a low or moderate resistance to vancomycin (MIC = 4 to 32 μg/ml) were found to have the same leucine-to-methionine change at amino acid position 308 of the vanB2 gene. The genomic DNAs of all 36 isolates were digested with SmaI and then typed by pulsed-field gel electrophoresis (PFGE). Eight different PFGE types (I to VIII) were observed, and type I was found to be prevalent in all hospitals examined in this study. This result suggests that intra- and interhospital dissemination of this E. faecium strain has occurred in Taiwan.
ASJC Scopus subject areas