Abstract

Objective: In recent years, there has been a marked increase in multidrug resistance among Enterococcus species, which are among the most common causes of both community- and hospital-acquired infections. The treatment of vancomycin-resistant enterococci (VRE) remains a major challenge. In addition to phenotypic identification based on conventional culture methods, genotypic detection of species and resistance genes by polymerase chain reaction (PCR) has been increasingly used. The multiplex PCR (mPCR) technique, which allows simultaneous amplification of multiple genes in a single reaction, enables faster and more cost-effective identification of species and antibiotic resistance genes. This study aimed to compare the mPCR method and conventional culture tests for the detection of species and vancomycin resistance in Enterococcus isolates.

Methods: A total of 38 Enterococcus isolates collected from various clinical specimens between 2015 and 2019 and preserved after conventional identification were analyzed by the mPCR method to determine their species and vancomycin resistance genotypes.

Results: An 82% concordance was found between culture-based and molecular diagnostic results for species identification and resistance classification (31/38 isolates). The predominant species was Enterococcus faecium carrying the VanA resistance gene. Unusually, one Enterococcus faecalis isolate harbored the vanA gene instead of the typically observed vanB, and one Enterococcus gallinarum isolate carried both vanC-1 and vanA resistance genes.

Conclusion: The study demonstrates the effectiveness of the mPCR method and highlights the genetic diversity of vancomycin-resistant enterococci. The rare occurrence of horizontal gene transfer among clinical isolates has important clinical and epidemiological implications for the spread of resistance. Implementing measures to control the dissemination of VRE is of critical importance.

Keywords: Enterococcus, VRE, vanA, vanB, vanC-1, mPCR