title: Prevalence and dissemination of oqxAB in Escherichia coli isolates from animals, farmworkers, and the environment.
abstract: OqxAB has recently been identified as one of the mechanisms of plasmid-mediated quinolone resistance (PMQR). Compared to what is observed for other PMQR determinants, there is a paucity of data with regard to the prevalence and epidemiology of OqxAB and its contribution to resistance to different antimicrobials. In this study, the prevalence and dissemination of oqxAB and other PMQR genes in Escherichia coli isolates from animals, farmworkers, and the environment in 2002 in China were investigated. Of the 172 E. coli isolates, 39.0% carried oqxA, while only 4.1%, 2.9%, and 0.6% carried qnr (1 qnrB6 isolate, 5 qnrS1 isolates, and 1 qnrD isolate), qepA, and aac(6')-Ib-cr, respectively. Among the 33 isolates from farmworkers, 10 (30.3%) were positive for oqxA. oqxAB was associated with IS26 and was carried on the 43- to 115-kb IncF transferable plasmid. Transconjugants carrying oqxAB showed 4- to 16-fold increases in the MICs of quinolones, 16- to 64-fold increases in the MICs of quinoxalines, 8- to 32-fold increases in the MICs of chloramphenicol and trimethoprim-sulfamethoxazole, and 4- to 8-fold increases in the MICs of florfenicol compared to the levels for the recipient. The pulsed-field gel electrophoresis (PFGE) analysis showed that the high levels of prevalence and dissemination of oqxAB in E. coli in animal farms were primarily due to the transmission of plasmids carrying oqxAB, although clonal transmission between human and swine E. coli isolates was observed. It is concluded that oqxAB was widespread in animal farms in China, which may be due to the overuse of quinoxalines in animals. This study warrants the prudent use of quinoxalines in food animals.
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues SCAU, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zhao
authors.forename: Zhangliu
authors.initials: Z
authors.lastname: Chen
authors.forename: Sheng
authors.initials: S
authors.lastname: Chen
authors.forename: Yuting
authors.initials: Y
authors.lastname: Deng
authors.forename: Yahong
authors.initials: Y
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Tian
authors.forename: Xianhui
authors.initials: X
authors.lastname: Huang
authors.forename: Congming
authors.initials: C
authors.lastname: Wu
authors.forename: Yongxu
authors.initials: Y
authors.lastname: Sun
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Zhenling
authors.initials: Z
authors.lastname: Zeng
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Liu
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D015363:Quinolones / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D015363:Quinolones