Early Detection of ESBL Producers from Clinical Samples Using Macconkey Agar with Ceftazidime

Abstract

Objectives: MacConkey agar with ceftazidime (CMAC) was used for early detection of extended spectrum beta-lactamase(ESBL) for clinical sample received from ICU. Methods: A total of 374 clinical samples were received from ICU in the Dept. of Microbiology. Along with MacConkey agar and Blood agar, the samples were processed on MacConkey agar with ceftazidime (1 mg/L) for provisional detection of ESBL isolates. Lactose -fermenting colonies on MacConkey agar with ceftazidime(CMAC) were provisionally detected as ESBL producing isolates. These isolates were identified by standard methods. Presence of ESBL was determined by CLSI method (cefotaxime and ceftazidime disks with and without clavulinic acid). Results: 128 isolates showed growth on CMAC of which 50 were lactose fermenters. 31 isolates were identified as E.coli and 19 as K.pneumoniae. All the 50 isolates were identified as confirmed ESBL producers. Conclusion: Compared to phenotypic identification of ESBL producers, CMAC helps in early detection ESBLs which can be very useful from treatment point of view. Since in our hospital we have about 60% of ICU patients growing ESBL producers, this early detection helps the intensivist to start anti-ESBL therapy.