Detection of vancomycin variable enterococci (VVE) among clinical isolates of Enterococcus faecium collected across India-first report from the subcontinent

Abstract

Purpose: Emergence of vancomycin variable enterococci (VVE) poses a challenge to empiric vancomycin therapy. Vancomycin-variable enterococci (VVE) are vanA-positive, yet phenotypically vancomycin-susceptible enterococci that can switch to a vancomycin-resistant phenotype when exposed to vancomycin. The aim of the present study was to determine the prevalence of VVE in India.

Methods: Isolates of phenotypically vancomycin susceptible Enterococcus faecium from 20 tertiary care hospitals across India were collected and tested for the presence of vanA, vanR, vanS, vanB and vanC genes by conventional PCR using previously published primers. Isolates positive for vanA gene were considered as VVE.

Results: The prevalence of VVE was 1.5% (5/340). Only one VVE isolate was positive for vanR and vanS, and all the isolates were negative for vanB and vanC.

Conclusions: Although the prevalence is low, our finding emphasizes the importance of routinely screening for van genes in enterococci that are phenotypically susceptible. Silenced vanA able to escape detection and revert to resistance during vancomycin therapy represents a new challenge in clinical settings.

Keywords: Enterococcus faecium; Vancomycin susceptibility; Vancomycin variable enterococci; vanA.