Fluoroquinolones remain one of the most successful and widely exploited classes of antimicrobial agents, but recent times, widespread use of fluoroquinolones in human and veterinary medicine, as well as their presence in the water, soil, and the environment, has led to a high and escalating emergence of antimicrobial resistance to members of the class. The acquisition of plasmid-mediated quinolone resistance (PMQR) genes, such as qnrA, qnrB, and related genes. confers on bacteria such as coliforms resistance to fluoroquinolones by protecting DNA gyrase and topoisomerase IV. This study was aimed at detecting QnrA and QnrB genes in quinolone-resistant coliforms recovered from herbal remedies. Antimicrobial susceptibility testing was performed using fresh colonies of pre-isolated coliform strains using the disc diffusion method. The identified multi-resistant coliform isolates were subjected to molecular analysis for phylogenetic identification and detection of the quinolone-resistance genes QnrA and QnrB. The cumulative results for the five quinolone antimicrobial agents tested indicated a resistance of 35.0% among the coliform strains. The least number of strains were resistant to Ciprofloxacin (25.0%,), followed by levofloxacin (30.4%), pefloxacin (35.7%), ofloxacin (37.5%), and norfloxacin (46.4%) The Multidrug Resistance patterns indicate that 25% were nonMDR, 75% were MDR; 47.6% were found to be extensively multidrug resistant, 2.6% was pan-drug resistant, while the remaining 50% were MDR. Among 47 Klebsiella pneumoniae strains, 10 (21.3%) were non-MDR, 37 (78.7%); 18 (48.6%) of the 37 MDR strains were XDR, 2.7% was PDR, while the remaining 48.6% were simply MDR. The Agarose gel electrophoresis of the 16S rRNA gene of the MDR coliforms revealed presence of QnrA genes in Pantoea dispersa and Enterobacter hormaechei but none in Klebsiella pneumoniae; QnrB was detected only in Pantoea dispersa.
Ndukwu et al. (Mon,) studied this question.