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

Production of β–lactamases by enterobacteriacea, especially Klebsiella pneumoniae</em>, is one of the emerging health problems in the world. The purpose of this study was to assess the frequency of bla</em>CTX-M15</sub> gene in K. pneumoniae</em> isolates and determine the molecular diversity of CTXM producing isolates.

In this descriptive cross-sectional study, 100 K. pneumoniae</em> strains were tested for susceptibility to cephalosporins category by using disk diffusion method and the prevalence of bla</em>CTX-M-1, </sub>bla</em>CTX-M-2, </sub>bla</em>CTX-M-9</sub> and bla</em>CTX-M-15</sub> genesin these isolates were determined by PCR method. Eventually, a number of isolates were sequenced and typed using single locus sequence typing (SLST) of bla</em>CTX-M group1</sub> gene. The phylogenetic relatedness of all CTX-M producing isolates was determined using enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR).

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</em> isolates, 31 were harboring CTX-M genes, and the bla</em>CTX-M-15</sub> (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.

The results of this study showed that one of the most important reasons for resistance to cephalosporins is the presence of bla</em>CTX-M</sub> genes. In addition, there was a high genetic variation among bla</em>CTX</sub>-M</sub> genes positive isolates.