Frequency of Extended-Spectrum Beta-Lactamase-producing Genes associated in gram-negative bacteria isolated from infectious patients in Kermanshah (2019-2020)

Background and Aim: Nosocomial infections caused by antibiotic-resistant bacteria and their rapid spread threaten public health. This study aimed to determine the frequency of genes encoding Extended-Spectrum Beta-Lactamase (ESBL) in gram-negative bacteria in Kermanshah city, west of Iran. Materials and Methods: Identification and antibiotic susceptibility pattern of 165 isolates were performed by biochemical and disk diffusion methods, respectively. Screening and confirming the presence of ESBL genes were performed according to the double disk combination test (DDCT) method. The presence of genes encoding ESBL in each isolate was identified by Polymerase Chain Reaction (PCR) method. Results: Out of 165 isolates, 83 strains were resistant to all antibiotics. The lowest frequency of resistance was observed for Gentamicin, while the highest frequency was observed for Cefotaxime and Cefazolin. Among all strains, 50 (30.30 %) and 80 (48.48%) isolates were phenotypically and genotypically ESBL-positive, respectively. The most prevalent genes encoding ESBL were SHVOS and SHV-1, with a frequency of 20.61 % and 21.82 %, respectively. Conclusion: The frequency of producing ESBL bacteria and the prevalence of blaSHV and blaCTX-M genes in our studied Klebsiella pneumoniae and Escherichia coli isolates were high. However, unlike some previous reports from Kermanshah, the prevalence of ESBL-encoding genes in Pseudomonas aeruginosa was low, and the blaVEB gene was not found.