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

Abstract

<em>Objective(s):</em><em>bla_CTX-M</em>and <em>bla_PER</em> 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 <em>Enterobacteriaceae</em> by polymerase chain reaction (PCR), restriction digestion and sequencing. <br/><em>Materials and Methods:</em> During six months, starting from January 2012, one hundred clinical isolates of <em>Enterobacteriaceae</em> were collected from urinary samples. The ESBL-producing isolates were detected by phenotypic confirmation test. After plasmid extraction, <em>bla_PER</em> and <em>bla_CTX-M</em> genes were detected using PCR by specific primers. The <em>bla_CTX-M</em> PCR products were digested with Taq1, and two of the <em>bla_CTX-M</em>genes were sequenced. <br/><em>Results:</em> Phenotypic tests showed that 27 (27%) isolates were ESBL producers with the highest frequency for <em>Klebsiella pneumoniae</em> (47.4%) and<em>Escherichia coli</em> (17.9%). Twenty six (26%) of <em>Enterobacteriaceae</em> isolates harbored the <em>bla_CTX-M</em>gene, and none of them had <em>bla_PER</em>. The restriction analysis of PCR products showed that all <em>bla_CTX-M</em> amplified products had the same patterns. Both sequenced bacteria were CTX-M-15 type ESBL carriers. <br/><em>Conclusion:</em> The results of this study showed the <em>bla_CTX-M_-15</em>gene in <em>Enterobacteriaceae</em> 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.