title: Absence of mutations in marRAB or soxRS in acrB-overexpressing fluoroquinolone-resistant clinical and veterinary isolates of Escherichia coli.
abstract: The amount of acrB, marA, and soxS mRNA was determined in 36 fluoroquinolone-resistant E. coli from humans and animals, 27 of which displayed a multiple-resistance phenotype. acrB mRNA was elevated in 11 of 36 strains. A mutation at codon 45 (Arg-->Cys) in acrR was found in 6 of these 11 strains. Ten of the 36 isolates appeared to overexpress soxS, and five appeared to overexpress marA. A number of mutations were found in the marR and soxR repressor genes, correlating with greater amounts of marA and soxS mRNA, respectively.
authors: Antimicrobial Agents Research Group, Division of Immunity and Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom.
authors: M A
authors: MA
authors: Webber
authors: L J
authors: LJ
authors: Piddock
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D029968:Escherichia coli Proteins; D024841:Fluoroquinolones; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D024841:Fluoroquinolones; C080002:MarA protein, E coli; C080004:MarR protein, E coli; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C080003:multiple antibiotic resistance protein B; C070724:SoxR protein, Bacteria; C070725:SoxS protein, E coli