High Prevalence of CTXM-۱۵ 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-M۱۵ gene in K. pneumoniae isolates and determine the molecular diversity of CTXM producing isolates. Methods: In this descriptive cross-sectional study, ۱۰۰ K. pneumoniae strains were tested for susceptibility to cephalosporins category by using disk diffusion method and the prevalence of blaCTX-M-۱, blaCTX-M-۲, blaCTX-M-۹ and blaCTX-M-۱۵ 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 group۱ 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(۵۷%), ceftazidime (۵۴%), cefotaxime (۳۶%), cefoxitine (۳۲%), and ceftriaxone (۳۱%). Of all ۱۰۰ K. pneumoniae isolates, ۳۱ were harboring CTX-M genes, and the blaCTX-M-۱۵ (۷۷.۵%) 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.

Keywords:

Klebsiella pneumoniae , Genetic variation , Polymerase Chain Reaction