Quinolone resistance due to reduced target enzyme expression.

  title={Quinolone resistance due to reduced target enzyme expression.},
  author={Dilek Ince and David C. Hooper},
  journal={Journal of bacteriology},
  volume={185 23},
We report for the first time low-level quinolone resistance mediated by decreased expression of topoisomerase IV in Staphylococcus aureus. A single-step mutant of wild-type S. aureus strain ISP794, P18 selected by using twice the MIC of premafloxacin, had four- and four- to eightfold greater MICs of premafloxacin and ciprofloxacin, respectively, than the wild type. Sequencing of parEC and gyrBA with their promoter regions revealed a point mutation (G-->A) 13 bp upstream of the start codon of… CONTINUE READING