title: Trends in antibiotic resistance over time among pathogens from Canadian hospitals: results of the CANWARD study 2007-11.
abstract: OBJECTIVE
  Antimicrobial resistance patterns change over time and longitudinal surveillance studies provide insight into these trends. We sought to describe the important trends in antimicrobial resistance in key pathogens across Canada to provide useful information to clinicians, policy makers and industry, to assist in optimizing antimicrobial therapy, formulary choices and drug development.
  
  
  METHODS
  We analysed longitudinal data from the CANWARD study using a multivariate regression model to control for possible effects of patient demographics on resistance, in order to assess the impact of time on antimicrobial resistance independent of other measured variables.
  
  
  RESULTS
  We identified several key trends in common pathogens. In particular, we observed a statistically significant increase in the proportion of Escherichia coli isolates that were resistant to extended-spectrum cephalosporins and fluoroquinolones, an increase in the proportion of Klebsiella pneumoniae isolates that were resistant to extended-spectrum cephalosporins, a reduction in the proportion of Staphylococcus aureus that were methicillin, clindamycin and trimethoprim/sulfamethoxazole resistant, and a reduction in the proportion of Pseudomonas aeruginosa that were fluoroquinolone and gentamicin resistant.
  
  
  CONCLUSIONS
  Although some of these trends, such as the dramatic increase in fluoroquinolone and cephalosporin resistance in E. coli, can be attributed to the emergence and global spread of resistant clones (e.g. ST131 E. coli), others remain unexplained. However, recognizing these trends remains important to guide changes in empirical antimicrobial therapy and drug development.
authors.affiliation: Department of Microbiology, St Boniface General Hospital/Diagnostic Services of Manitoba, Winnipeg, Manitoba, Canada R2H 2A6. plagacewiens@dsmanitoba.ca
authors.forename: Philippe R S
authors.initials: PR
authors.lastname: Lagacé-Wiens
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Adam
authors.forename: Donald E
authors.initials: DE
authors.lastname: Low
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Blondeau
authors.forename: Melanie R
authors.initials: MR
authors.lastname: Baxter
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Denisuik
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Nichol
authors.forename: Andrew
authors.initials: A
authors.lastname: Walkty
authors.forename: James A
authors.initials: JA
authors.lastname: Karlowsky
authors.forename: Michael R
authors.initials: MR
authors.lastname: Mulvey
authors.forename: Daryl J
authors.initials: DJ
authors.lastname: Hoban
authors.forename: George G
authors.initials: GG
authors.lastname: Zhanel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D001419:Bacteria / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D001424:Bacterial Infections / Q000188:drug therapy; D002170:Canada / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology* / Q000266:history / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D004352:Drug Resistance, Microbial; D005260:Female; D049674:History, 21st Century; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents