Molecular Detection of qnr Genes in Multidrug-Resistant E. coli from Punjab, Pakistan: A Rising Threat of Quinolone Resistance

Abstract

Escherichia coli is a primary causative agent of urinary tract infections (UTIs) and has shown rising multidrug resistance (MDR) worldwide. Prevalence and molecular characteristics of plasmid-mediated quinolone resistance (PMQR) in 43 collected MDR clinical isolates of E. coli have been studied. Using the E-test, antimicrobial susceptibility testing was performed to determine the minimum inhibitory concentrations (MICs) of Ciprofloxacin, Levofloxacin, and Ofloxacin. Among 30 quinolone-resistant isolates, resistance rates were 73% for Ofloxacin, 75% for Levofloxacin, and 83% for Ciprofloxacin. Molecular characterization using polymerase chain reaction (PCR) revealed a high prevalence of the qnrB gene (76.7%), followed by qnrS (6.97%) and qnrA (4.7%). Notably, 11.2% of resistant isolates lacked detectable qnrA, qnrB, or qnrS, suggesting the possible presence of lesser-known qnrC or qnrD genes. These findings emphasize the growing challenge of PMQR in the region and highlight the need for regular molecular surveillance to guide public health strategies and antibiotic stewardship.