Objective: Enterococci are among the important microorganism group worldwide due to their natural resistance to many antibiotics, especially their acquired resistance mechanisms against glycopeptides (vancomycin, teicoplanin). In this study, vancomycin and teicoplanin resistance were phenotypically determined in Vancomycin-resistant Enterococci strains obtained from various clinical specimens, and the presence of VanA, VanB and VanC was investigated by molecular methods.

Method: A total of 30 VRE strains isolated from various clinical specimens at Microbiology Laboratory of Van Yuzuncu Yil University Faculty of Medicine Hospital between 2015 and 2018 were included in the study. MicroScan WalkAway 96 Plus (Beckman Coulter, USA) automated system was used for the identification of strains and determination of antibiotic resistance. Antimicrobial resistance to vancomycin and teicoplanin were also determined by gradient test method. Resistance genes were investigated by in-house PCR method performed in Inonu University Faculty of Medicine, Molecular Diagnostics Laboratory of The Department of Medical Microbiology using appropriate primers.

Results: Identification tests revealed 29 strains as Enterococcus faecium and 1 as Enterococcus faecalis. While all strains were resistant to vancomycin and teicoplanin in the automated identification system, three isolates tested by gradient test method were found to be susceptible to these antibiotics. Molecular method of these three strains showed that there were no VanA, VanB and VanC genes. While VanA gene was detected in 27 strains, VanB gene was detected in one strain, and VanC gene was not detected. Resistance detection by gradient test and molecular method were found to be 100% compatible in the identification of vancomycinresistance in enterococci isolates.

Conclusion: Gradient test method is reliable in determining glycopeptide resistance of enterococcal isolates in clinical microbiology laboratory.