title: Characterization of florfenicol resistance among calf pathogenic Escherichia coli.
abstract: Three floR genes were cloned from calf pathogenic Escherichia coli strains, and the efflux-mediated accumulation of florfenicol in the floR gene-JM109 E. coli system was determined by HPLC. The floR genes resulted in a 1356-bp fragment covering the ORF in region 66-1280 coding for 404 amino acids. The common motifs of 12-transmembrane segments efflux pumps family were conserved in the deduced floR amino acid sequences. HPLC results indicated a significant difference in florfenicol accumulation between florfenicol-resistant strains and the susceptible strains, which was almost reversed by the addition of a proton motive force blocker. These results suggest that the florfenicol resistance mediated by the floR gene involves active efflux of florfenicol.
authors.affiliation: Department of Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing 100094, PR China.
authors.forename: Xiangdang
authors.initials: X
authors.lastname: Du
authors.forename: Chun
authors.initials: C
authors.lastname: Xia
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Shen
authors.forename: Beibei
authors.initials: B
authors.lastname: Wu
authors.forename: Zhangqi
authors.initials: Z
authors.lastname: Shen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D001693:Biological Transport, Active; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D003967:Diarrhea / Q000382:microbiology / Q000662:veterinary; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D021382:Protein Sorting Signals; D054328:Proton Pump Inhibitors; D018892:Proton-Motive Force / Q000187:drug effects; D017422:Sequence Analysis, DNA; D013839:Thiamphenicol / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D021382:Protein Sorting Signals; D054328:Proton Pump Inhibitors; D014475:Uncoupling Agents; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; C035534:florfenicol; D013839:Thiamphenicol