Prevalence of blaTEM, blaSHV, and blaCTX-M genes among extended spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae of clinical origin

Objective: To determine the prevalence of blaTEM, blaSHV, and blaCTX-M genes among extended spectrum betalactamase-producing Escherichia coli and Klebsiella pneumoniae of clinical origin. Methods: Exactly 276 isolates were obtained from patients who met the definition of wound and urinary tract infection between December 2016 and November 2017. In vitro antibiotic susceptibility test was performed using Kirby-Bauer disc diffusion method. The phenotypic identification of beta-lactamase and ESBL were confirmed by nitrocefin sticks, DDST and chromogenic brilliant ESBL agar. Phenotypically positive ESBL isolates were molecularly characterized for the presence of blaTEM, blaSHV, and blaCTX-M genes by PCR. The PCR products of 16S rRNA region of the isolates were sequenced. Nucleotide sequences of the isolates were deposited in the GenBank of the NCBI database, assigned accession numbers and phylogenetic tree of the isolates was constructed. Results: The prevalence frequency of ESBL-producing E. coli and K. pneumoniae were 68.2% and 31.8% respectively. In vitro antibiotic susceptibility test showed that most of isolates were highly susceptible to cefepime (85.7%). The frequency of resistance to other antibiotics varied from 23.8% to 82.6%. A total of 89 isolates were beta-lactamase producers while 20 isolates [15 (75%) E. coli and 5 (25%) K. pneumonia] harboured ESBL genes. The prevalence of blaTEM, blaSHV and blaCTX-M genotypes was identified to be 55%, 35% and 45% respectively. Isolates were also observed to harbour ESBL genes. Conclusion: ESBL-producing isolates in our study were molecularly confirmed to harbour multiple ESBL genes. Furthermore, continuous surveillance and routine clinical detection of ESBL-producing organisms are necessary to curtail public health problems in clinical settings.