A novel method “CHROMagar” for screening vancomycin-resistant enterococci (VRE) isolates

Abstract

Infection with vancomycin-resistant enterococci (VRE) is reported to be increasing and becoming a problem especially in health care systems with prolonged survival in the environment. In this study, we compared the performance characteristics of CHROMagar with conventional methods for detection of VRE in clinical urine specimens. A total of 7404 urine samples were entered in the study. All specimens were cultured by routine microbiological method and were simultaneously cultured in prepared CHROMagar plate for growth characteristics with positive and negative controls. Susceptibility tests were performed by disk diffusion method as recommended by Clinical Laboratory Standards Institute. We also used E-test minimum inhibitory concentration (MIC) for confirmation of VRE isolates. Total isolation rate was 22.19% of the tested specimens. Enterococcus faecium and Enterococcus faecalis were isolated in 10 (0.13%) and 72 (0.92%) cases, respectively while six were VRE belonging to admitted patients. Analyzed data of VRE cases revealed the results of all three applied methods. The antimicrobial susceptibility testing, E-test and CHROMagar were in agreement in all the six identified VRE cases. The obtained results in the present study indicate that CHROMagar method is easy to use, and is a cost- and time-effective procedure for the isolation of VRE especially in urine specimens.

Key words: Vancomycin-resistant enterococci (VRE), CHROMagar, admitted patients.