Antibiotypes and genetic characteristics of fluoroquinolone- and beta-lactam-resistant Escherichia coli isolated from food-producing animals

Abstract

Background and Aim: Farm animals, including cattle, have been implicated as antimicrobial-resistant bacterial pathogen reservoirs. This study aimed to determine the antimicrobial resistance profiles and genetic characteristics of cattle colonized by fluoroquinolone-resistant and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in Ebonyi state, Nigeria. Materials and Methods: We randomly collected 100 fresh fecal samples from 100 cattle in major abattoirs and analyzed the samples using standard microbiological methods. Isolates were further characterized by polymerase chain reaction (PCR) using 16S rRNA sequence primers. Phenotypic detection of ESBL production was performed using the double disk synergy test. Antimicrobial susceptibility profiles of ESBL-producing Escherichia coli were determined using the disk diffusion method, whereas molecular characterization of ESBL- and fluoroquinolone-resistant genes was performed by PCR using specific primers. Results: A total of 20 (20%) ESBL-producing E. coli were isolated from 100 animal fecal samples. Isolates were generally multidrug-resistant (MDR) with a resistance rate of 100% to 45% to trimethoprim-sulfamethoxazole, tetracycline, amoxicillin, cephalosporins, and ciprofloxacin. The average multiple antibiotic resistance index values of the isolates ranged from 0.5 to 0.8. BlaTEM (75%), followed by blaCTX-M (20%) and blaSHV (5.0%) was the most predominant ESBL gene among the isolates. The Aac-lb-6-cr fluoroquinolone-resistant gene was harbored by 90% of the isolates, whereas Qnr was absent. Conclusion: This study showed a high frequency of MDR ESBL-producing E. coli harboring ESBL and fluoroquinolone-resistant genes in fecal samples of cattle with serious public health consequences if not adequately addressed. Keywords: Escherichia coli, extended-spectrum beta-lactamase genes, fluoroquinolone resistance genes, cattle, multidrug-resistance.