Genetic properties of blaCTX-M and blaPER β-lactamase genes in clinical isolates of Enterobacteriaceae by polymerase chain reaction

Objective(s):blaCTX-Mand blaPER are two genes that encode class A extended-spectrum β-lactamases (ESBLs) and can be responsible for therapeutic problems. This study was carried out to evaluate the molecular properties of these genes in clinical isolates of Enterobacteriaceae by polymerase chain reaction (PCR), restriction digestion and sequencing. Materials and Methods: During six months, starting from January ۲۰۱۲, one hundred clinical isolates of Enterobacteriaceae were collected from urinary samples. The ESBL-producing isolates were detected by phenotypic confirmation test. After plasmid extraction, blaPER and blaCTX-M genes were detected using PCR by specific primers. The blaCTX-M PCR products were digested with Taq۱, and two of the blaCTX-Mgenes were sequenced. Results: Phenotypic tests showed that ۲۷ (۲۷%) isolates were ESBL producers with the highest frequency for Klebsiella pneumoniae (۴۷.۴%) andEscherichia coli (۱۷.۹%). Twenty six (۲۶%) of Enterobacteriaceae isolates harbored the blaCTX-Mgene, and none of them had blaPER. The restriction analysis of PCR products showed that all blaCTX-M amplified products had the same patterns. Both sequenced bacteria were CTX-M-۱۵ type ESBL carriers.   Conclusion: The results of this study showed the blaCTX-M-۱۵gene in Enterobacteriaceae isolates for the first time in Mashhad, Iran. High degrees of associated resistance to co-trimoxazole and gentamicin were found in ESBL producers. Therefore, an integrated and regular management of antibiotic prescription need to be trained in our society.

Keywords:

CTX-M-۱۵ , Enterobacteriaceae , Extended-spectrum beta-lactamase , PER