Genetic Determinants of Carbapenem and Fluoroquinolone Resistance in Escherichia coli Isolates of Clinical Origin.

Abstract

Background: Antimicrobial resistance has emerged as a global public health challenge, leading to higher mortality rates from infections that were once treatable with antibiotics. In this study, we assessed the susceptibility of Escherichia coli strains isolated from clinical samples to carbapenems and fluoroquinolones and screened for genetic determinants mediating resistance.

Materials and methods: This retrospective study included 46 E. coli isolates retrieved from the stock culture collection at the Molecular Biology and Biotechnology Department of the Nigerian Institute of Medical Research. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disc diffusion method, and molecular techniques were employed to detect genetic determinants of antimicrobial resistance.

Results: The E. coli isolates exhibited high resistance to fluoroquinolones, with 72% resistant to ciprofloxacin and 52% to levofloxacin. Resistance to carbapenems was relatively low, with 4% resistant to imipenem and 11% to meropenem. The prevalence of the genetic determinants gyrA, gyrB, and parC, which mediate fluoroquinolone resistance, was 26%, 24%, and 15%, respectively. bla_OXA-48 and bla_NDM, which mediate carbapenem resistance, were detected in only two isolates. Some isolates harbored plasmids ranging from 5 kb to 16 kb; however, no plasmid-mediated genetic determinants conferring fluoroquinolone resistance were identified.

Conclusion: This study revealed a high level of resistance to fluoroquinolones, emphasizing the need for judicious use of antibiotics, particularly those with low resistance rates. Continuous surveillance is essential to monitor emerging trends in resistance among bacterial pathogens.