Determination of CTX-M genes in enterobacteriaceae producing extended-spectrum beta-lactamase using PCR method

Extended-spectrum beta-lactamase of CTX-M-type is considered as an important mechanism resistant to cephalosporin in the gram-negative patogene and is wildly growing. Enterobacteriaceae species are able to produce extended-spectrum beta-lactamases (ESBLs). The aim of this study was to detect the prevalence of CTX-M genes in ESBLs producing enteric bacteria isolated in Shahrekord educational hospitals using Polymerase Chain Reaction method. In this analytical-descriptive study, antibacterial susceptibility patterns of 325 gram negative bacteria to Cefotaxim, Ceftazidim, Cefterixon and Azteronam tested using disk diffusion (Kirby-Buer) method. In addition, confirmatory tests for detecting ESBLs phenotypes were performed using Ceftazidim-clavulanic acid and Cefotaxim- clavulanic acid combination disks (MAST). The presence of CTX-M gene was assessed using PCR. Bacteria strains isolated in this study were Escherichia coli (59.4%), Klebsiella pneumoniae (30.4%), Enterobacter spp. (15.4%) and Proteus spp. (2.2%). Confirmatory phenotypic test showed that 28% of the strains were ESBL positive. The prevalence of CTX-M gene in isolated Enterobacteriaceae was 50.5 %. High frequency of CTX-M gene in ESBL producing isolates indicates that this enzyme plays an important role in resistance to betalactam containing antibiotics.