Detection of glycopeptide resistance genotypes and identification to the species level of clinically relevant enterococci by PCR

TLDR

A PCR assay was developed to simultaneously detect glycopeptide resistance genotypes and identify clinically relevant enterococci species. The assay amplifies internal fragments of genes encoding D‑alanine:D‑alanine ligases and related glycopeptide resistance proteins, and its specificity was validated on five resistant and fifteen susceptible strains. The PCR test identified species‑level enterococci in clinical isolates that conventional methods could not, providing a specific and rapid alternative for detecting low‑level vancomycin resistance.

Abstract

A PCR assay that allows simultaneous detection of glycopeptide resistance genotypes and identification to the species level of clinically relevant enterococci (Enterococcus faecium, E. faecalis, E. gallinarum, and E. casseliflavus) was developed. This assay was based on specific amplification of internal fragments of genes encoding D-alanine:D-alanine ligases and related glycopeptide resistance proteins. The specificity of the assay was tested on 5 well-characterized glycopeptide-resistant strains and on 15 susceptible enterococcal type strains. Clinical isolates of enterococci that could not be identified to the species level by conventional methods were identified by the PCR test. This assay offers a specific and rapid alternative to antibiotic susceptibility tests, in particular for detection of low-level vancomycin resistance.