Molecular Detection of CTX-M Genes in ESBL Producing Escherischia Coli Isolated from Various Clinical Samples

Author: Kavitha.A, Suneetha.C, Indra Priyadharsini.R

Category: Microbiology

Abstract:

Introduction: There has been an increased emergence of ESBLs serving as a cause of failure of beta lactam therapy leading to increased morbidity and mortality. A study was conducted to identify CTX-M group of ESBLs among Escherichia coli isolated from various clinical samples collected at a tertiary care hospital using multiplex polymerase chain reaction.

Aims & Objectives: Phenotypic detection and confirmation of ESBL E.coli and detection of bla CTX-M gene by Multiplex PCR.

Materials & Methods: During the period from April 2013 to May 2014, clinical isolates of E.coli were collected and Antibiotic Susceptibility Testing (AST) was done according to Clinical Laboratory Standards Institute (CLSI) guidelines. Phenotypic screening and confirmation of ESBL production were done by Double Disc Synergy Test (DDST), Phenotypic Confirmatory Disc Diffusion Test (PCDDT) and E-test. Genotypic confirmation was done by Multiplex PCR for the presence of bla CTX-M genes.

Results: Out of the total 214 isolates, 133 showed resistance to at least one of the third generation cephalosporins. Primary phenotypic tests, DDST revealed 75 isolates and PCDDT revealed 93 isolates to be ESBL producers. 97 isolates were confirmed to be ESBL producers by E test and these 97 isolates were positive for CTX-M group 1 genes by Multiplex PCR.

Conclusion: The study demonstrated that Multiplex PCR is a rapid method for detection of bla CTX-M genes and CTX-M group 1 are the commonest among E.coli isolates in our hospital.

Keywords: ESBL E.coli, Double Disc Synergy, PCDDT, ESBL E-test, Multiplex PCR, CTX-M group 1 genes.