title: Detection of mutations in the gyrA and parC genes in Escherichia coli isolates carrying plasmid-mediated quinolone resistance genes from diseased food-producing animals.
abstract: In this study, the prevalence of plasmid-mediated quinolone resistance (PMQR) was investigated in 495 Escherichia coli isolates from diseased food-producing animals in Guangdong province, China. The quinolone resistance-determining regions (QRDRs) of the gyrA and parC genes were analysed for mutations in 55 isolates harbouring only oqxAB and all isolates harbouring other PMQR genes. Overall, 282 (57.0 %) E. coli isolates had at least one PMQR gene. oqxAB was detected in 215 isolates and predominated the PMQR genes, followed by qnrS (63 isolates), aac(6')-Ib-cr (56 isolates), qnrB (39 isolates) and qepA (18 isolates). qnrA, qnrC and qnrD were not found in any of the isolates. The rates of resistance to ciprofloxacin, enrofloxacin, levofloxacin and nalidixic acid were 75.2, 81.0, 70.5 and 97.4 %, respectively, among the 495 isolates. Eight types of mutation in gyrA were detected in 154 PMQR-positive isolates, and 147 isolates were found to have mutations in parC. PFGE analysis indicated that the PMQR-positive E. coli isolates were genetically diverse. This study demonstrated that the number of mutations in QRDRs of gyrA and/or parC was significantly associated with the MICs of quinolones (P<0.01). The rates of resistance to ciprofloxacin, enrofloxacin and nalidixic acid in PMQR-positive isolates were significantly higher than those in PMQR-negative isolates (P<0.05). In addition, the prevalence of oqxAB had significant Spearman correlation coefficients in relation to the MICs of all four tested quinolones (P<0.01).
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Bao-Tao
authors.initials: BT
authors.lastname: Liu
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Liao
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Shou-Shen
authors.initials: SS
authors.lastname: Yang
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Xiu-Mei
authors.initials: XM
authors.lastname: Wang
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Lu-Lu
authors.initials: LL
authors.lastname: Li
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Yu-Rong
authors.initials: YR
authors.lastname: Yang
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Liang-Xing
authors.initials: LX
authors.lastname: Fang
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Dong-Hao
authors.initials: DH
authors.lastname: Zhao
authors.affiliation: College of Veterinary Medicine, National Reference Laboratory of Veterinary Drug Residues, South China Agricultural University, Guangzhou 510642, PR China.
authors.forename: Ya-Hong
authors.initials: YH
authors.lastname: Liu
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002645:Chickens; D002681:China / Q000453:epidemiology; D027081:DNA Gyrase / Q000235:genetics* / Q000378:metabolism; D027101:DNA Topoisomerase IV / Q000235:genetics* / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004372:Ducks; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005516:Food Microbiology; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D009154:Mutation; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology; D015363:Quinolones / Q000494:pharmacology*; D011815:R Factors / Q000235:genetics*; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D015363:Quinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase