title: [Investigating the fluoroquinolone molecular resistant mechanism of Stenotrophomonas maltophilia].
abstract: OBJECTIVE
  To research DNA gyrase and topoisomerase IV quinolone resistance-determining regions (QRDRs) in Stenotrophomonas maltophilia clinical isolates with different resistant levels of quinolone susceptibility.
  
  
  METHODS
  We selected five strains for which the MIC of ciprofloxacin were higher than 2 mg/L and were negative for efflux mechanism; then we amplified their QRDRs of gyrA and parE, purified the fragment, and analyzed the nucleotide sequences.
  
  
  RESULTS
  In Stenotrophomonas maltophilia DNA gyrA, the changes at positions 83 and 87 commonly involved in quinolones resistance in gram-negative bacteria were absent, and there was Gln but not Ser or Thr. Of the five strains, one strain showed a ParE amino acid change in position 402, the other was in position 432, but the mutations were not associated with FQNS resistance.
  
  
  CONCLUSIONS
  FQNS resistance in Stenotrophomonas maltophilia is related to active efflux pump and may be correlated with a low level of permeability. But it is not clear whether the resistance is related to the mutants in DNA gyrase and topoisomerase N.
authors.affiliation: Division of Clinical Microbiology, Department of Laboratory Medicine, West China Hospital, Sichuan University, Chengdu 610041, China.
authors.forename: Chuan-Min
authors.initials: CM
authors.lastname: Tao
authors.forename: Xiao-Ju
authors.initials: XJ
authors.lastname: Lü
authors.forename: Ping
authors.initials: P
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology; D001483:Base Sequence; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D024841:Fluoroquinolones / Q000494:pharmacology*; D008969:Molecular Sequence Data; D020615:Stenotrophomonas maltophilia / Q000187:drug effects*
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase