title: Antibiotic susceptibility and molecular analysis of invasive Haemophilus influenzae in Canada, 2007 to 2014.
abstract: Previously we studied the antibiotic susceptibility of invasive Haemophilus influenzae collected in Canada from 1990 to 2006 and characterized isolates by serotype, MLST and ftsI gene sequencing for significant PBP3 mutations.
  
  
  
  To provide an update based on isolates collected from 2007 to 2014.
  
  
  
  A total of 882 case isolates were characterized by serotype using slide agglutination and PCR. MLST was carried out to determine ST. Isolates were tested for β-lactamase production, presence of significant PBP3 mutations and antibiotic susceptibility by disc diffusion against 14 antibiotics. MIC values of three antibiotics were determined for 316 isolates using microbroth dilution.
  
  
  
  Non-typeable H. influenzae accounted for 54.6% of the isolates and 45.4% were serotypeable, predominantly type a (23.1%), type b (8.3%) and type f (10.8%). The overall rate of ampicillin resistance due to β-lactamase production was 16.4% and increased from 13.5% in 2007-10 to 19% in 2011-14. Significant PBP3 mutations were identified in 129 isolates (14.6%) with 23 (2.6%) also producing β-lactamase. MLST identified related STs (ST-136, ST-14 and ST-367) associated exclusively with genetically β-lactamase-negative, ampicillin-resistant isolates and confirmed previously reported associations between significant PBP3 mutations and ST.
  
  
  
  A significant increase in β-lactamase-producing isolates was observed from 2007 to 2014; the rate of significant PBP3 mutations has increased since previously reported and 52.5% of non-typeable H. influenzae now show resistance markers. Resistance to trimethoprim/sulfamethoxazole was common and no resistance to fluoroquinolones or third-generation cephalosporins was found.
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
authors.forename: Raymond S W
authors.initials: RSW
authors.lastname: Tsang
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: Shuel
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Whyte
authors.affiliation: BC Public Health Microbiology and Reference Laboratory, Vancouver, British Columbia, Canada.
authors.forename: Linda
authors.initials: L
authors.lastname: Hoang
authors.affiliation: Provincial Laboratory for Public Health, Edmonton, Alberta, Canada.
authors.forename: Gregory
authors.initials: G
authors.lastname: Tyrrell
authors.affiliation: Saskatchewan Disease Control Laboratory, Regina, Saskatchewan, Canada.
authors.forename: Greg
authors.initials: G
authors.lastname: Horsman
authors.affiliation: Cadham Provincial Laboratory, Winnipeg, Manitoba, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Wylie
authors.affiliation: Public Health Ontario, Toronto, Ontario, Canada.|Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Frances
authors.initials: F
authors.lastname: Jamieson
authors.affiliation: Laboratoire de santé publique du Québec, Institut National de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Lefebvre
authors.affiliation: Nova Scotia Health Authority, Halifax, Nova Scotia, Canada.|Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Haldane
authors.affiliation: Communicable Disease Control Unit, Department of Health, Government of New Brunswick, Fredericton, New Brunswick, Canada.
authors.forename: Rita R
authors.initials: RR
authors.lastname: Gad
authors.affiliation: Department of Health, Government of Prince Edward Island, Charlottetown, Prince Edward Island, Canada.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: German
authors.affiliation: Public Health Laboratory and Microbiology, Eastern Health, St John's, Newfoundland and Labrador, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Needle
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002170:Canada / Q000453:epidemiology; D004269:DNA, Bacterial / Q000235:genetics; D005838:Genotype; D006192:Haemophilus Infections / Q000453:epidemiology / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D016133:Polymerase Chain Reaction; D065288:Serogroup; D012703:Serotyping; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D000667:Ampicillin; D001618:beta-Lactamases