Molecular Epidemiology and Antimicrobial Susceptibility of Extended-Spectrum β-lactamases Produced by Clinical Isolates of Escherichia Coli Collected from ICU Patients in Shiraz, Iran

Background & Objectives: Extended-spectrum β-lactamase (ESBL) producing gram negative bacilli are a growing concern in human medicine today. When producing these enzymes, organisms (mostly E.coli and K.pneumoniae) become highly efficient at inactivating the newer third-generation cephalosporins. The aim of this study was to understand the molecular epidemiology of E.coli ESBL producers and to identify the ESBL genes carried by them. Methods: In this descriptive cross-sectional study, 195 clinical isolates of E.coli collected from ICUs was tested. Invitro susceptibility testing, screening for ESBL production and minimum inhibitory concentration (MIC) was carried by the disk diffusion methods according to the CLSI (Clinical & Laboratory Standard Institute) guideline. All isolates were screened for the resistance genes TEM, CTX-M and SHV by a Multiplex PCR assay using universal primers. Data were analysed using ANOVA, chi-squre or Fisher exact tests. For all tests, p