Evaluation of a New Colorimetric Medium for Detection of Extended Spectrum β-lactamases (ESBLs) Producing Isolates of Entrobacteriaceae family

Abstract

Background and Aim: Due to the increased growth of bacteria producing ESBL, among the members of the Enterobacteriaceae family, monitoring and treatment of nosocomial infections are important, especially caused by ESBL-producing clinical isolates belonging to this family. The aim of this study is to evaluate a rapid method, using new colorimetric culture was made at the University of Al-Zahra (Tehran, Iran).The used method to detect ESBLs, according to disk diffusion method based on CLSI on colorimetric culture and the results of it, compared with the Müller-Hinton agar for disk diffusion method. Materials and Methods: In this study, the clinically isolated samples belonged to the Enterobacteriaceae family which was evaluated in both Müller-Hinton agar medium and colorimetric culture using ceftazidime (CAZ), ceftazidime + clavulanate (CZA), cefotaxime + clavulanate (CTC) and Cefotaxime (CTX) discs. Results & Conclusions: Because of the metabolic activity of bacteria, a color change occurred from red to yellow in colorimetric culture after 5-6 hours and red inhibitory zone created around the disc. The obtained results from the colorimetric method are same with the results of Müller-Hinton agar method for disk diffusion after a day.

Keywords

• Colorimetric medium
• ESBLs
• Rapid detections
• Disk diffusion test