The rate of frequent co-existence of plasmid-mediated quinolone resistance (PMQR) and extended-spectrum β-lactamase (ESBL) genes in Escherichia coli isolates from retail raw chicken in South Korea.

Since plasmid-encoded antibiotic resistance facilitates the emergence of antibiotic-resistant bacteria, the increasing prevalence of Escherichia coli harboring plasmid-mediated quinolone resistance (PMQR) and extended-spectrum β-lactamase (ESBL) genes is a public health concern. The objective of this study is to investigate the co-existence of PMQR and ESBL genes in E. coli isolates from retail raw chicken in South Korea. Among 67 ESBL-producing E. coli isolates from 40 retail raw chicken, more than half of them carried PMQR genes, including qnrS , aac ( 6 ') -Ib-cr , and oqxAB . The qnrS was predominantly (91.4%) detected in E. coli isolates carrying both PMQR and ESBL. The aac ( 6 ') -Ib-cr was detected in seven ESBL-producing E. coli strains, and 85.7% of the aac ( 6 ') -Ib-cr -positive strains also carried qnrS . Moreover, the strains co-harboring qnrS and aac ( 6 ') -Ib-cr exhibited increased resistance to ciprofloxacin and kanamycin. These results demonstrate that PMQR genes are frequently detected in ESBL-producing E. coli isolates from retail raw chicken in South Korea.