title: Molecular characterization of fluoroquinolone resistant Streptococcus pneumoniae clinical isolates obtained from across Canada.
abstract: There is little published data detailing fluoroquinolone resistance in clinical isolates of S. pneumoniae. The purpose of this study was to characterize the resistance mechanisms of 34 fluoroquinolone-resistant S. pneumoniae clinical isolates obtained from medical centers in 8 of 10 Canadian provinces between 1997 and 2000. The quinolone resistance determining regions of gyrA, parC, and parE from the isolates were sequenced. The isolates were evaluated for reserpine-sensitive efflux of ciprofloxacin and the new fluoroquinolones: gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin. The isolates were typed using pulsed field gel electrophoresis. The majority of the isolates were genetically unrelated. Lower level fluoroquinolone resistance (ciprofloxacin MIC 4-8 microg/ml) was associated with amino acid substitutions in ParC, while higher level resistance (ciprofloxacin MIC > or = 16 microg/ml) was associated with amino acid substitutions in both ParC and GyrA. ParE substitutions were not associated with clinical resistance. Twelve of 34 (35%) isolates demonstrated reserpine-sensitive efflux of ciprofloxacin. Efflux alone conferred low level ciprofloxacin resistance in 3 isolates. Significant reserpine-sensitive efflux of the new fluoroquinolones was not observed.
authors.affiliation: Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada. ggzhanel@pcs.mb.ca
authors.forename: George G
authors.initials: GG
authors.lastname: Zhanel
authors.forename: Andrew
authors.initials: A
authors.lastname: Walkty
authors.forename: Kim
authors.initials: K
authors.lastname: Nichol
authors.forename: Heather
authors.initials: H
authors.lastname: Smith
authors.forename: Ayman
authors.initials: A
authors.lastname: Noreddin
authors.forename: Daryl J
authors.initials: DJ
authors.lastname: Hoban
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002170:Canada / Q000453:epidemiology; D004352:Drug Resistance, Microbial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D010597:Pharmacogenetics; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D015363:Quinolones / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D015363:Quinolones