title: Rapid, Sensitive, and Specific Escherichia coli H Antigen Typing by Matrix-Assisted Laser Desorption Ionization-Time of Flight-Based Peptide Mass Fingerprinting.
abstract: Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has gained popularity in recent years for rapid bacterial identification, mostly at the genus or species level. In this study, a rapid method to identify the Escherichia coli flagellar antigen (H antigen) at the subspecies level was developed using a MALDI-TOF MS platform with high specificity and sensitivity. Flagella were trapped on a filter membrane, and on-filter trypsin digestion was performed. The tryptic digests of each flagellin then were collected and analyzed by MALDI-TOF MS through peptide mass fingerprinting. Sixty-one reference strains containing all 53 H types and 85 clinical strains were tested and compared to serotyping designations. Whole-genome sequencing was used to resolve conflicting results between the two methods. It was found that DHB (2,5-dihydroxybenzoic acid) worked better than CHCA (α-cyano-4-hydroxycinnamic acid) as the matrix for MALDI-TOF MS, with higher confidence during protein identification. After method optimization, reference strains representing all 53 E. coli H types were identified correctly by MALDI-TOF MS. A custom E. coli flagellar/H antigen database was crucial for clearly identifying the E. coli H antigens. Of 85 clinical isolates tested by MALDI-TOF MS-H, 75 identified MS-H types (88.2%) matched results obtained from traditional serotyping. Among 10 isolates where the results of MALDI-TOF MS-H and serotyping did not agree, 60% of H types characterized by whole-genome sequencing agreed with those identified by MALDI-TOF MS-H, compared to only 20% by serotyping. This MALDI-TOF MS-H platform can be used for rapid and cost-effective E. coli H antigen identification, especially during E. coli outbreaks.
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada 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, MB, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Chan
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
authors.forename: Drexler
authors.initials: D
authors.lastname: Hernandez
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Chong
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
authors.forename: Stuart
authors.initials: S
authors.lastname: McCorrister
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
authors.forename: Alyssia
authors.initials: A
authors.lastname: Robinson
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
authors.forename: Matthew
authors.initials: M
authors.lastname: Walker
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
authors.forename: Lorea A M
authors.initials: LA
authors.lastname: Peterson
authors.affiliation: Newfoundland and Labrador Public Health Laboratory, St. John's, NL, Canada.
authors.forename: Sam
authors.initials: S
authors.lastname: Ratnam
authors.affiliation: Nova Scotia Provincial Public Health Laboratory Network, Halifax, NS, Canada.
authors.forename: David J M
authors.initials: DJ
authors.lastname: Haldane
authors.affiliation: Laboratoire de Santé Publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada.
authors.forename: Sadjia
authors.initials: S
authors.lastname: Bekal
authors.affiliation: Cadham Provincial Laboratory, Winnipeg, MB, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Wylie
authors.affiliation: Provincial Laboratory for Public Health, University of Alberta Hospital, Edmonton, AB, Canada.
authors.forename: Linda
authors.initials: L
authors.lastname: Chui
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada.
authors.forename: Garrett
authors.initials: G
authors.lastname: Westmacott
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, MB, Canada Department of Medical Microbiology, College of Medicine, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Mike
authors.initials: M
authors.lastname: Drebot
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada Department of Medical Microbiology, College of Medicine, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: Celine
authors.initials: C
authors.lastname: Nadon
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada Department of Medical Microbiology, College of Medicine, University of Manitoba, Winnipeg, MB, Canada.
authors.forename: J David
authors.initials: JD
authors.lastname: Knox
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada Gehua.Wang@phac-aspc.gc.ca Keding.Cheng@phac-aspc.gc.ca.
authors.forename: Gehua
authors.initials: G
authors.lastname: Wang
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada Department of Human Anatomy and Cell Sciences, College of Medicine, University of Manitoba, Winnipeg, MB, Canada Gehua.Wang@phac-aspc.gc.ca Keding.Cheng@phac-aspc.gc.ca.
authors.forename: Keding
authors.initials: K
authors.lastname: Cheng
mesh_terms: D000942:Antigens, Bacterial / Q000032:analysis*; D015373:Bacterial Typing Techniques / Q000379:methods*; D004926:Escherichia coli / Q000737:chemistry* / Q000145:classification*; D006801:Humans; D012680:Sensitivity and Specificity; D012703:Serotyping / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013997:Time Factors
chemical_list: D000942:Antigens, Bacterial; C022863:H antigen