Enterococci with reduced susceptibility to vancomycin in New Zealand

This study was conducted to determine the prevalence of vancomycin-resistan t enterococci (VRE) in the stools of hospitalized patients with possible an tibiotic-associated diarrhoea. From 176 faecal samples collected during 199 7 and 1998, 66 strains of enterococci were recovered using vancomycin enric hment techniques. Only six of these displayed reduced susceptibility to van comycin (MIC 8-12 mg/L). All VRE were positive for the presence of the vanC gene. Based on motility, pigment production and automated Gram-positive id entification (GPI Vitek card), four of these six VRE isolates were identifi ed as Enterococcus gallinarum. The remaining two isolates were non-motile a nd therefore were considered to be Enterococcus faecium. However, 16S rDNA sequence analysis and positive methyl-alpha-D-glucopyranoside tests indicat ed that they were non-motile species of E. gallinarum. This is consistent w ith the intrinsic, low-level vanC-1-mediated resistance associated with thi s species. Pulsed-field gel electrophoresis analysis comparisons between th e VRE indicated genetic relatedness between some strains. This work confirm s that vancomycin-resistant E. faecium and Enterococcus faecalis are rare i n New Zealand.