title: Development of quinoxaline 1, 4-dioxides resistance in Escherichia coli and molecular change under resistance selection.
abstract: Quinoxaline 1, 4-dioxides (QdNOs) has been used in animals as antimicrobial agents and growth promoters for decades. However, the resistance to QdNOs in pathogenic bacteria raises worldwide concern but it is barely known. To explore the molecular mechanism involved in development of QdNOs resistance in Escherichia coli, 6 strains selected by QdNOs in vitro and 21 strains isolated from QdNOs-used swine farm were subjected to MIC determination and PCR amplification of oqxA gene. A conjugative transfer was carried out to evaluate the transfer risk of QdNOs resistant determinant. Furthermore, the transcriptional profile of a QdNOs-resistant E. coli (79O4-2) selected in vitro with its parent strain 79-161 was assayed with a prokaryotic suppression subtractive hybridization (SSH) PCR cDNA subtraction. The result showed that more than 95% (20/21) clinical isolates were oqxA positive, while all the 6 induced QdNOs-resistant strains carried no oqxA gene and exhibited low frequency of conjugation. 44 fragments were identified by SSH PCR subtraction in the QdNOs-resistant strain 79O4-2. 18 cDNAs were involved in biosynthesis of Fe-S cluster (narH), protein (rpoA, trmD, truA, glyS, ileS, rplFCX, rpsH, fusA), lipoate (lipA), lipid A (lpxC), trehalose (otsA), CTP(pyrG) and others molecular. The 11 cDNAs were related to metabolism or degradation of glycolysis (gpmA and pgi) and proteins (clpX, clpA, pepN and fkpB). The atpADG and ubiB genes were associated with ATP biosynthesis and electron transport chain. The pathway of the functional genes revealed that E. coli may adapt the stress generated by QdNOs or develop specific QdNOs-resistance by activation of antioxidative agents biosynthesis (lipoate and trehalose), protein biosynthesis, glycolysis and oxidative phosphorylation. This study initially reveals the possible molecular mechanism involved in the development of QdNOs-resistance in E. coli, providing with novel insights in prediction and assessment of the emergency and horizontal transfer of QdNOs-resistance in E. coli.
authors.affiliation: National Reference Laboratory of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, Hubei, People's Republic of China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Guo
authors.forename: Haihong
authors.initials: H
authors.lastname: Hao
authors.forename: Menghong
authors.initials: M
authors.lastname: Dai
authors.forename: Yulian
authors.initials: Y
authors.lastname: Wang
authors.forename: Lingli
authors.initials: L
authors.lastname: Huang
authors.forename: Dapeng
authors.initials: D
authors.lastname: Peng
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.forename: Hailan
authors.initials: H
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Yawei
authors.initials: Y
authors.lastname: Sun
authors.forename: Zhenli
authors.initials: Z
authors.lastname: Liu
authors.forename: Zonghui
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics; D006019:Glycolysis; D008826:Microbial Sensitivity Tests / Q000379:methods; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010087:Oxides / Q000494:pharmacology*; D010641:Phenotype; D010766:Phosphorylation; D016133:Polymerase Chain Reaction / Q000379:methods; D011810:Quinoxalines / Q000737:chemistry* / Q000494:pharmacology; D013552:Swine
chemical_list: D000900:Anti-Bacterial Agents; D017931:DNA Primers; D018076:DNA, Complementary; D029968:Escherichia coli Proteins; D010087:Oxides; D011810:Quinoxalines; C020728:cyadox; C013168:olaquindox