Plasmid - Mediated Quinolone Resistance (PMQR) determinants in multidrug-resistant, non - ESBL- producing, non-typhoidal Salmonella species isolated from commercial laying chickens

Cloacal swab samples were collected from 350 apparently healthy commercial layers in Oyo and Osun states, Nigeria. Nine fluoroquinolone-resistant Salmonella species belonging to serovar Infantis (n=4), Heidelberg (n=3), and Saintpaul (n=2) were isolated from the sampled birds. The isolates were multidrug resistant with Multiple Antibiotic Resistance Index (MAR) ranging from 0.15 to 0.54. There was high resistance to fluoroquinolones, with 88.9% resistance to pefloxacin and ofloxacin, 77.8% to nalidixic acid and ciprofloxacin. None of the isolates were ESBL positive. All the nine isolates did not carry qnrA gene; 11.1%, 22.2% and 88.9% possessed qnrB, qnrD and qnrS, respectively. This study isolated plasmid mediated fluoroquinolone resistant rare Salmonella serovars from commercial layers in Nigeria. © 2023 Informa UK Limited, trading as Taylor & Francis Group.