Comparison of Classical Methods and Chromogen Media for Detection of Stool Colonisation by Carbapenem-resistant Enterobacteriaceae

Objectives: We aimed to compare classical methods and chromogenic media to detect carbapenem-resistant Enterobacteriaceae (CRE) colonization among hospitalized patients and determine the risk factors causing infection in colonized patients. Methods: Between January and August 2017, 100 patients over the age of 18 who were hospitalized in the Reanimation Intensive Care Unit and the Trauma Emergency Intensive Care Unit of a university hospital were examined. From the first day of intensive care unit (ICU) admission, rectal swabs were collected once every week and were tested for the presence of CRE by using the classical method defined by the Centers for Disease Control and Prevention (CDC), ChromID CARBA chromogenic medium, and direct inoculation into MacConkey agar plates. In addition, MIC values for imipenem, ertapenem, meropenem and colistin were determined by using the Etest. Results: Rectal BDE carriage was detected by at least one method in 46 (46%) of 100 patients included in the study. Sensitivity and specificity values of the CDC classical method, direct MacConkey inoculation, and ChromID CARBA medium in the first 24 hours were found as 78%-42%, 87%-80%, and 91%-98%, respectively. Sensitivity and specificity values of these methods after 72 hours were determined as 78%-100%, 87%-100%, and 91%-100%, respectively. Conclusion: We observed that, although the ChromID CARBA method performed better than classical CDC and direct MacConkey inoculation methods, direct MacConkey inoculation can still be employed, especially in areas with limited resources.