Karbapenemaz üreten Enterobactericea üyelerinin saptanmasında CHROMagar besiyeri ile RAPIDEC ® CARBA NP testin performansının karşılaştırılması

Objective: Carbapenemase-producing strains of the Enterobacteriaceae family (CPE) are important agents of health-care associated infections in both our country and worldwide but their detection is difficult. The aim of this study was to compare RAPIDEC ® CARBA NP test and new chromogenic media, OXA-48 and CHROMID CARBA medium performances for detecting carbapenemase-resistant Enterobacteriaceae isolates. Material and method: This study was performed in intensive care units (ICU) of a tertiary care training and research hospital. Totally 67 Enterobacteriaceae strains (30 Escherichia coli, 37 Klebsiella pneumoniae) isolated from varies cultures including blood, urine and tracheal aspirate of ICU patients were included to the study. Identification and antibiotic susceptibility tests of the isolates were performed using VITEK 2 automated system as well disc diffusion test. All isolates were inoculated into chromogenic CHROMID CARBA medium and OXA-48 medium simultaneously. They are incubated at 37oC for 24-72 hours. Color changes were evaluated at 24,48 and 72. hours. RAPIDEC ® CARBA NP test was also performed for all isolates according to the recommendations of the manufacturer and then its performance was compared with chromogenic media. When comparing the methods, carbapenem resistance values determined by disc diffusion and VITEK 2 automated system were accepted as reference. Results: Among 67 isolates, 28 (42%) were found carbapenem-sensitive and 39 (58%) carbapenem-resistant by using disc diffusion and VITEK-2 automated systems. When disc diffusion test and VITEK 2 automated systems were accepted as reference, compliance rate between Rapidec CARBA ® NP test and disc diffusion and VITEK-2 automated system was 93% (62/67) while it was 75% (50/67) between chromogenic media (CHROMID CARBA and OXA-48) and disc diffusion and VITEK-2. When chromogenic CHROMID CARBA and OXA-48 medium and RAPIDEC ® CARBA NP test were evaluated together, their compliance rate with disc diffusion and VITEK-2 automated system was 69% (46/67). Conclusions: In this study we found close to %70 compliance between CHROMID CARBA medium, OXA-48 medium and Rapidec ® Carba NP test results. We believe that the studies involving more isolates should be performed on this subject. Moreover, we think that carbapenem resistance should be confirmed by genotypic tests which are the reference method.