title: Escherichia coli O157:H7 and O157:H(-) strains that do not produce Shiga toxin: phenotypic and genetic characterization of isolates associated with diarrhea and hemolytic-uremic syndrome.
abstract: We have isolated one sorbitol-nonfermenting (SNF) Escherichia coli O157:H7 isolate and five sorbitol-fermenting (SF) E. coli O157:H(-) isolates that do not contain Shiga toxin (Stx) genes (stx). Isolates originated from patients with diarrhea (n = 4) and hemolytic-uremic syndrome (HUS) (n = 2). All isolates harbored a chromosomal eae gene encoding gamma-intimin as well as the plasmid genes E-hly and etp. The E. coli O157:H7 isolate was katP and espP positive. Respective sera obtained from the patient with HUS contained antibodies to the O157 lipopolysaccharide antigen. The stx-negative E. coli O157:H7 isolate is genetically related to stx-positive SNF E. coli O157:H7. All stx-negative SF E. coli O157:H(-) isolates belong to the same genetic cluster and are closely related to stx-positive SF E. coli O157:H(-) isolates. Our data indicate that stx-negative E. coli O157:H7/H(-) variants may occur at a low frequency and cannot be recognized by diagnostic methods that target Stx.
authors.affiliation: Institut für Hygiene und Mikrobiologie der Universität Würzburg, 97080 Würzburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Schmidt
authors.forename: J
authors.initials: J
authors.lastname: Scheef
authors.forename: H I
authors.initials: HI
authors.lastname: Huppertz
authors.forename: M
authors.initials: M
authors.lastname: Frosch
authors.forename: H
authors.initials: H
authors.lastname: Karch
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood; D001427:Bacterial Toxins / Q000096:biosynthesis / Q000235:genetics; D003967:Diarrhea / Q000276:immunology / Q000382:microbiology*; D004927:Escherichia coli Infections / Q000276:immunology / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D005285:Fermentation; D005798:Genes, Bacterial; D006463:Hemolytic-Uremic Syndrome / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D008070:Lipopolysaccharides / Q000276:immunology; D010802:Phylogeny; D022603:Shiga Toxins; D013012:Sorbitol / Q000378:metabolism; D014774:Virulence / Q000235:genetics
chemical_list: D000907:Antibodies, Bacterial; D001427:Bacterial Toxins; D008070:Lipopolysaccharides; D022603:Shiga Toxins; D013012:Sorbitol