Detection and typing of vancomycin-resistance genes of enterococci from clinical and nosocomial surveillance specimens by multiplex PCR

Ninety-three clinical isolates of vancomycin-resistant enterococci (VRE) co llected from nine hospitals in Taiwan were examined for the presence of van A, vanB, vanC1, or vanC2/vanC3 genes by a multiplex PCR. Forty-seven of the se VRE isolates were vanA positive, I contained both vanC1 and vanA, 40 har boured vanB, 2 were vanC1, and 3 were identified to be vanC2/vanC3. Twenty- four vanA isolates were sensitive to teicoplanin and thus did not have a ty pical VanA phenotype. Five isolates with the VanC phenotype harboured vanB. None of the 40 clinically isolated vancomycin-susceptible E. faecium or E. faecalis and the vancomycin-resistant Leuconostoc and Pediococcus isolates were positive for any of the van genes. While performing nosocomial survei llance, VRE were isolated from 47 of 467 rectal swabs by culture. Compared with the conventional culture method, the sensitivity and specificity of th e multiplex PCR for detecting and identifying vancomycin-resistance genes i n enterococci directly from culture-positive broth were 97(.)9% and 100%, r espectively. The results suggest that genotypic characterization of vancomy cin-resistance is necessary for all clinical VRE isolates and that the mult iplex PCR assay can be an alternative method for this purpose.