Genomic Analysis of Highly Virulent blaCTX-M, blaSHV and blaTEM Genes in Resistant Strains of E.coli and Klebsiella: an emerging threat

Abstract

Background: The term antimicrobial resistance refers to the ability to resists the effects of drugs formally used to treat them and this term relates only to bacteria becoming resistant. Microorganisms that are resistant to multiple drugs are known as multidrug-resistant bacteria. Aim: To investigate the prevalence of SHV, TEM and CTXm genes from E.coli and Klebsiella isolated from patients of Lahore, Pakistan. Methods: Patients with prolonged hospital stay were enrolled in this cross-sectional study with 60 samples comprising Klebsiella pneumoniae and Escherichia coli (Ctx, Cro, Caz resistant) were identified in clinical specimens. To assess susceptibility, the disc diffusion method was applied with eight antibiotic panel of cephalosporin 3rd generation. A Double disc, combined disc test was used to identify the ESBL-producing bacteria. By real - time PCR, The presence of the genes encoding blaTEM, blaSHV, and blaCTXm was tested in ESBL positive isolates as well as additional isolates with MICs of less than 4g/mL for ceftazidime, cefotaxime, ceftriaxone, and aztreonam (PCR). Results: The frequency of E. coli and Klebsiella bacteria was found in 59% and 41% of the 60 samples, respectively. According to the data, 23 isolates (16.37%) were multidrug resistant, and 7(6.89%) were ESBL-positive. At least one of the antibiotics ceftazidime, ceftriaxone, or cefotaxime was resistant to 30(25.86%) of the isolates. The ESBL genes were sequenced to corroborate the PCR result. Conclusions: Among E. coli and Klebsiella bacteria obtained from patients, blaTEM-116 was the most frequently isolated ESBL gene, followed by Shv and Ctxm. Keywords: Antibiotic Resistance, Beta- Lactamases, E. coli, Klebsiella pneumonia