title: Mass Spectrometry-Based Escherichia coli H Antigen/Flagella Typing: Validation and Comparison with Traditional Serotyping.
abstract: BACKGROUND
  Escherichia coli H antigen typing with antisera, a useful method for flagella clinical identification and classification, is a time-consuming process because of the need to induce flagella growth and the occurrence of undetermined strains. We developed an alternative rapid and analytically sensitive mass spectrometry (MS) method, termed MS-based H antigen typing (MS-H), and applied it at the protein sequence level for H antigen typing. We also performed a comparison with traditional serotyping on reference strains and clinical isolates.
  
  
  METHODS
  On the basis of international guidelines, the analytical selectivity and sensitivity, imprecision, correlation, repeatability, and reproducibility of the MS-H platform was evaluated using reference strains. Comparison of MS-H typing and serotyping was performed using 302 clinical isolates from 5 Canadian provinces, and discrepant results between the 2 platforms were resolved through whole genome sequencing.
  
  
  RESULTS
  Repeated tests on reference strain EDL933 demonstrated a lower limit of the measuring interval at the subsingle colony (16.97 μg or 1.465 × 10(7) cells) level and close correlation (r(2) > 0.99) between cell culture biomass and sequence coverage. The CV was <10.0% among multiple repeats with 4 reference strains. Intra- and interlaboratory tests demonstrated that the MS-H method was robust and reproducible under various sample preparation and instrumentation conditions. Using discrepancy analysis via whole genome sequencing, performed on isolates with discrepant results, MS-H accurately identified 12.3% more isolates than conventional serotyping.
  
  
  CONCLUSIONS
  MS-H typing of E. coli is useful for fast and accurate flagella typing and could be very useful during E. coli outbreaks.
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada; Department of Human Anatomy and Cell Sciences, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada; Keding.Cheng@phac-aspc.gc.ca.
authors.forename: Keding
authors.initials: K
authors.lastname: Cheng
authors.affiliation: Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, China;
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: She
authors.affiliation: Henan Centre of Disease Control and Prevention, Henan Province, China;
authors.forename: Huixia
authors.initials: H
authors.lastname: Chui
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada;
authors.forename: Larissa
authors.initials: L
authors.lastname: Domish
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada;
authors.forename: Angela
authors.initials: A
authors.lastname: Sloan
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada;
authors.forename: Drexler
authors.initials: D
authors.lastname: Hernandez
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada;
authors.forename: Stuart
authors.initials: S
authors.lastname: McCorrister
authors.affiliation: Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, China;
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: Henan Centre of Disease Control and Prevention, Henan Province, China;
authors.forename: Bianli
authors.initials: B
authors.lastname: Xu
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada;
authors.forename: Aleisha
authors.initials: A
authors.lastname: Reimer
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada; Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: J David
authors.initials: JD
authors.lastname: Knox
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada;
authors.forename: Gehua
authors.initials: G
authors.lastname: Wang
mesh_terms: D000942:Antigens, Bacterial / Q000032:analysis* / Q000737:chemistry* / Q000276:immunology; D002170:Canada; D004926:Escherichia coli / Q000737:chemistry* / Q000276:immunology / Q000302:isolation & purification; D005407:Flagella / Q000737:chemistry* / Q000276:immunology; D013058:Mass Spectrometry / Q000379:methods*; D012680:Sensitivity and Specificity; D012703:Serotyping / Q000379:methods* / Q000592:standards*
chemical_list: D000942:Antigens, Bacterial; C022863:H antigen