High Prevalence of CTXM-15 Type Extended-Spectrum Beta-Lactamase Among Clinical Isolates of Klebsiella Pneumoniae

Background: Production of β–lactamases by enterobacteriacea, especially Klebsiella pneumoniae, is one of the emerging health problems in the world. The purpose of this study was to assess the frequency of blaCTX-M15 gene in K. pneumoniae isolates and determine the molecular diversity of CTXM producing isolates. Methods: In this descriptive cross-sectional study, 100 K. pneumoniae strains were tested for susceptibility to cephalosporins category by using disk diffusion method and the prevalence of blaCTX-M-1, blaCTX-M-2, blaCTX-M-9 and blaCTX-M-15 genesin these isolates were determined by PCR method. Eventually, a number of isolates were sequenced and typed using single locus sequence typing (SLST) of blaCTX-M group1 gene. The phylogenetic relatedness of all CTX-M producing isolates was determined using enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR). Results:The rates of resistance to cephalosporins category were in the following order: cefepime(57%), ceftazidime (54%), cefotaxime (36%), cefoxitine (32%), and ceftriaxone (31%). Of all 100 K. pneumoniae isolates, 31 were harboring CTX-M genes, and the blaCTX-M-15 (77.5%) was the most common of the genes investigated. The results of SLST showed that all of the sequenced isolates were divided into two groups. ERIC-PCR method represented ten different genotypes in CTX-M positive isolates. Conclusion: The results of this study showed that one of the most important reasons for resistance to cephalosporins is the presence of blaCTX-M genes. In addition, there was a high genetic variation among blaCTX-M genes positive isolates.