title: Discrimination of Escherichia coli O157, O26 and O111 from other serovars by MALDI-TOF MS based on the S10-GERMS method.
abstract: Enterohemorrhagic Escherichia coli (EHEC), causes a potentially life-threatening infection in humans worldwide. Serovar O157:H7, and to a lesser extent serovars O26 and O111, are the most commonly reported EHEC serovars responsible for a large number of outbreaks. We have established a rapid discrimination method for E. coli serovars O157, O26 and O111 from other E. coli serovars, based on the pattern matching of mass spectrometry (MS) differences and the presence/absence of biomarker proteins detected in matrix-assisted laser desorption/ionization time-of-flight MS (MALDI-TOF MS). Three biomarkers, ribosomal proteins S15 and L25, and acid stress chaperone HdeB, with MS m/z peaks at 10138.6/10166.6, 10676.4/10694.4 and 9066.2, respectively, were identified as effective biomarkers for O157 discrimination. To distinguish serovars O26 and O111 from the others, DNA-binding protein H-NS, with an MS peak at m/z 15409.4/15425.4 was identified. Sequence analysis of the O157 biomarkers revealed that amino acid changes: Q80R in S15, M50I in L25 and one mutation within the start codon ATG to ATA in the encoded HdeB protein, contributed to the specific peak pattern in O157. We demonstrated semi-automated pattern matching using these biomarkers and successfully discriminated total 57 O157 strains, 20 O26 strains and 6 O111 strains with 100% reliability by conventional MALDI-TOF MS analysis, regardless of the sample conditions. Our simple strategy, based on the S10-spc-alpha operon gene-encoded ribosomal protein mass spectrum (S10-GERMS) method, therefore allows for the rapid and reliable detection of this pathogen and may prove to be an invaluable tool both clinically and in the food industry.
authors.affiliation: Hub of Knowledge Aichi, Aichi Science and Technology Foundation, Yakusa, Toyota, Aichi, Japan.
authors.forename: Teruyo
authors.initials: T
authors.lastname: Ojima-Kato
authors.affiliation: School of Agriculture, Meijo University, Shiogamaguchi, Tenpaku-ku, Nagoya, Aichi, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: School of Agriculture, Meijo University, Shiogamaguchi, Tenpaku-ku, Nagoya, Aichi, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Japan Food Research Laboratories, Osu, Naka-ku, Nagoya, Aichi, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Fukunaga
authors.affiliation: School of Agriculture, Meijo University, Shiogamaguchi, Tenpaku-ku, Nagoya, Aichi, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Tamura
mesh_terms: D015415:Biomarkers / Q000032:analysis; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000032:analysis; D030562:Databases, Protein; D054324:Enterohemorrhagic Escherichia coli / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D019453:Escherichia coli O157 / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000032:analysis*; D036781:Fimbriae Proteins / Q000032:analysis; D008970:Molecular Weight; D010802:Phylogeny; D012269:Ribosomal Proteins / Q000032:analysis; D017422:Sequence Analysis, DNA; D065288:Serogroup; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D015415:Biomarkers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C529458:FimG protein, E coli; D012269:Ribosomal Proteins; C084502:hdeB protein, E coli; C031127:ribosomal protein L25; D036781:Fimbriae Proteins