Characterization of Extended Spectrum Beta Lactamase Producing Escherichia coli from Calves

Background: Cephalosporins are major antimicrobials used to treat serious infections. However, their effectiveness is being compromised by the emergence of extended spectrum beta lactamases (ESBL). The present study was aimed to characterize ESBL producing Escherichia coli from healthy and diarrheic cattle calves. Methods: A total of 52 rectal swabs were collected from healthy and diarrheic cattle calves between August 2019 to March 2020. Phenotypically E. coli were characterized based on morphology, microscopy and biochemical tests. Extended Spectrum Beta Lactamases (ESBL) E. coli initial screening was performed by using cefpodoxime, ceftazidime, cefepime and aztreonam antibiotics. The confirmation of the ESBL producing strains was conducted through ESBL phenotypic identification kit and double disc diffusion test (DDDT). Molecular characterization of ESBL E. coli was conducted by PCR amplification of blaCTX-M, bla TEM and bla AmpC genes. Plasmid profiling of the ESBL E. coli isolates was carried out.<br /> Result: Phenotypically, out of the 51 E. coli isolated, 05 (9.8%) E. coli isolates were confirmed as ESBL strains. PCR amplification revealed 01 (20%), 04 (80%) and 03 (60%) isolates positive for blaCTX-M, bla TEM and bla AmpC genes, respectively. Plasmid profiling of the isolates showed that 60% isolates were harboring plasmids of varying size and number. The plasmid number among the isolates ranged from 0-4 plasmids per isolate and plasmid size varied from 900 bp to >10 kb. The relatively high rates of ESBL producers in diarrheic calves were found than healthy calves. The study highlights the existence of ESBL producing E. coli isolates with certain strains carrying mobile genetic elements in livestock and probable disseminators of resistance, thus imposing public health threat.