Conventional culture and molecular screening methods for detection of vancomycin-resistant enterococci activity

Abstract

Introduction: Early identification of vancomycin-resistant enterococci (VRE) colonization by screening patients is necessary in terms of preventing spread and development of infection. The purpose of this study was to investigate the presence of VRE using and real time polymerase chain reaction (RT-PCR) and to compare the results and costs. Materials and methods: Patients in the risk group attending our hospital and planned for treatment with hospitalization were included. Two rectal swab specimens were taken. One swab specimen was inoculated into enterococci broth for CCSM. Resistant gene investigation was performed with the other specimen by using RT-PCR. The costs of the two methods were then compared. Results: VRE were detected in 75 (6.63%) of the 1130 patients screened using the two methods. Resistance gene was determined in 69 (6.1%) patients using RT-PCR and 32 (2.8%) with CCSM. RT-PCR results were negative in 6 patients with VRE growth determined using CCSM. VRE was detected with CCSM in all 26 patients in whom vanA genotype VRE were determined using RT-PCR, but no growth was determined with CCSM in any of the 43 patients in whom vanB genotype VRE were detected. Results obtained in 3 days using CCSM and within 4 hours using RT-PCR. Costs were 58 $ with CCSM and 46 $ with RT-PCR. Conclusion: VRE colonization being detected faster with RT-PCR than CCSM. When the costs in isolation of patients until VRE screening test results emerged were compared, VRE screening with RT-PCR was cost-effective. RT-PCR was markedly superior to CCSM in determining VanB type resistance. Due to the late results from CCSM and its failure to detect VanB type resistance, we think that RT-PCR can be an alternative to CCSM or that the two techniques can usefully be combined depending on the hospital conditions.