Occurrence and characterization of genetic determinants of β-lactam-resistance in Escherichia coli clinical isolates

beta-lactamase mediated resistance in Escherichia coli is a significant problem that requires immediate attention. Herein, we aim to characterize and understand the dynamics of the genetic determinants of beta-lactam resistance (i.e. ESBL, AmpC, and MBL) in E. coli. Out of 203 E. coli isolates, genetic determinants of beta-lactam resistance were identified in 50% (n = 101) of isolates. ESBL, AmpC, and MBL resistance determinants were detected in 78%, 40%, and 18% of isolates, respectively with bla(CTX-M group 4) (48%), bla(CMY) (40%), and bla(SIM) (33%) as the most prevalent beta-lactam resistance genes. Among these isolates, 45% harbored plasmid replicon types, with L/M (40%) and Y (33%) as the most dominant replicon types. Integrons were detected in 40% of such isolates, with Class-1 and Class-3 representing 62% and 55%, respectively. Overall, we observed high rate of genetic determinants of beta-lactam-resistance in E. coli isolates recovered from patients in clinical settings. The co-occurrence of antimicrobial resistance genes and mobile genetic elements in a high percentage of isolates is a major concern and relates to complex resistance mechanisms. To combat the serious threat of antimicrobial resistance, it is imperative to develop strategies for robust surveillance and understand the molecular basis of resistance acquisition and transmission.

Automated summary

This study aimed to characterize and understand the genetic determinants of beta-lactam resistance in Escherichia coli, and found that approximately 50% of the isolates contained these genetic determinants. ESBL, AmpC, and MBL resistance determinants were detected in 78%, 40%, and 18% of the isolates, respectively, with bla(CTX-M group 4), bla(CMY), and bla(SIM) being the most prevalent resistance genes. The study also observed a high percentage of isolates with co-occurrence of antimicrobial resistance genes and mobile genetic elements.