title: Genetic diversity of Shiga toxin-producing Escherichia coli O157 : H7 recovered from human and food sources.
abstract: The aim of this study was to identify an epidemiological association between Shiga toxin-producing Escherichia coli O157 : H7 strains associated with human infection and with food sources. Frequency distributions of different genetic markers of E. coli O157 : H7 strains recovered from human and food sources were compared using molecular assays to identify E. coli O157 : H7 genotypes associated with variation in pathogenic potential and host specificity. Genotypic characterization included: lineage-specific polymorphism assay (LSPA-6), clade typing, tir (A255T) polymorphism, Shiga toxin-encoding bacteriophage insertion site analysis and variant analysis of Shiga toxin 2 gene (stx2a and stx2c) and antiterminator Q genes (Q933 and Q21). The intermediate lineage (LI/II) dominated among both food and human strains. Compared to other clades, clades 7 and 8 were more frequent among food and human strains, respectively. The tir (255T) polymorphism occurred more frequently among human strains than food strains. Q21 and Q933 + Q21 were found at significantly higher frequencies among food and human strains, respectively. Moreover, stx2a and stx2a+c were detected at significantly higher frequencies among human strains compared to food strains. Bivariate analysis revealed significant concordance (P<0.05) between the LSPA-6 assay and the other typing methods. Multivariable regression analysis suggested that tir (255T) was the most distinctive genotype that can be used to detect bacterial clones with potential risk for human illness from food sources. This study supported previous reports of the existence of diversity in genetic markers among different isolation sources by including E. coli O157 : H7 strains from both food and human sources. This might enable tracking genotypes with potential risk for human illness from food sources.
authors.affiliation: Department of Bacteriology, Mycology and Immunology, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Elhadidy
authors.affiliation: Department of Pharmacy Practice, School of Pharmacy, Hampton University, Kittrell Hall Hampton, VA 23668, USA.|Department of Microbiology & Immunology, Faculty of Pharmacy, Ain Shams University, African Union Organization St Abbassia, Cairo 11566, Egypt.
authors.forename: Walid F
authors.initials: WF
authors.lastname: Elkhatib
authors.affiliation: Department of Animal Husbandry and Development of Animal Wealth, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt.
authors.forename: Eman A Abo
authors.initials: EAA
authors.lastname: Elfadl
authors.affiliation: Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
authors.forename: Karen
authors.initials: K
authors.lastname: Verstraete
authors.affiliation: Foodborne Pathogens, Scientific Institute of Public Health, Juliette Wytsmanstraat 14, 1050 Brussels, Belgium.
authors.forename: Sarah
authors.initials: S
authors.lastname: Denayer
authors.affiliation: Foodborne Pathogens, Scientific Institute of Public Health, Juliette Wytsmanstraat 14, 1050 Brussels, Belgium.
authors.forename: Elodie
authors.initials: E
authors.lastname: Barbau-Piednoir
authors.affiliation: Department of Veterinary Public Health and Food Safety, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: De Zutter
authors.affiliation: Department of Veterinary Public Health and Food Safety, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium.|Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
authors.forename: Bavo
authors.initials: B
authors.lastname: Verhaegen
authors.affiliation: UZ Brussels, Department of Microbiology, Belgian VTEC Reference Lab, Laarbeeklaan 101 - 1090 Brussels, Belgium.
authors.forename: Klara
authors.initials: K
authors.lastname: De Rauw
authors.affiliation: UZ Brussels, Department of Microbiology, Belgian VTEC Reference Lab, Laarbeeklaan 101 - 1090 Brussels, Belgium.
authors.forename: Denis
authors.initials: D
authors.lastname: Piérard
authors.affiliation: Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: De Reu
authors.affiliation: Department of Pathology, Bacteriology and Poultry Diseases, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium.|Technology and Food Science Unit, Institute for Agricultural and Fisheries Research (ILVO), Brusselsesteenweg 370, Melle 9090, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Heyndrickx
mesh_terms: D004927:Escherichia coli Infections / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D005516:Food Microbiology; D005798:Genes, Bacterial; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D058885:Multilocus Sequence Typing; D011110:Polymorphism, Genetic; D022621:Shiga Toxin / Q000235:genetics*
chemical_list: D022621:Shiga Toxin