title: Clonal relationships among Escherichia coli strains that cause hemorrhagic colitis and infantile diarrhea.
abstract: The genetic relationships among 1,300 isolates of Escherichia coli representing 16 serotypes associated with enteric disease, including O157:H7 strains recovered from patients with hemorrhagic colitis and hemolytic uremic syndrome and O26:H11, O55:H6, O55:H7, O111:H2, and O128:H2 strains, many of which were isolated originally from infants with diarrhea, were estimated from allelic variation among 20 enzyme-encoding genes detected by multilocus enzyme electrophoresis. Multiple electrophoretic types were observed among isolates of each serotype, with isolates of the same O serogroup differing on average at 28% of the enzyme loci. Comparisons of the multilocus enzyme profiles revealed that 72% of the isolates belong to 15 major electrophoretic types, each of which corresponds to a bacterial clone with a wide geographic distribution. Genetically, the O157:H7 clone is most closely related to a clone of O55:H7 strains that has long been associated with worldwide outbreaks of infantile diarrhea. We propose that the new pathogen emerged when an O55:H7-like progenitor, already possessing a mechanism for adherence to intestinal cells, acquired secondary virulence factors (Shiga-like cytotoxins and plasmid-encoded adhesins) via horizontal transfer and recombination.
authors.affiliation: Department of Biology, Pennsylvania State University, University Park 16802.
authors.forename: T S
authors.initials: TS
authors.lastname: Whittam
authors.forename: M L
authors.initials: ML
authors.lastname: Wolfe
authors.forename: I K
authors.initials: IK
authors.lastname: Wachsmuth
authors.forename: F
authors.initials: F
authors.lastname: Orskov
authors.forename: I
authors.initials: I
authors.lastname: Orskov
authors.forename: R A
authors.initials: RA
authors.lastname: Wilson
mesh_terms: D000483:Alleles; D001427:Bacterial Toxins / Q000235:genetics; D001483:Base Sequence; D005075:Biological Evolution; D003092:Colitis / Q000382:microbiology*; D003968:Diarrhea, Infantile / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D005798:Genes, Bacterial; D014644:Genetic Variation; D006463:Hemolytic-Uremic Syndrome / Q000382:microbiology; D006801:Humans; D007223:Infant; D007527:Isoenzymes / Q000032:analysis; D008969:Molecular Sequence Data; D019081:O Antigens; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010802:Phylogeny; D011135:Polysaccharides, Bacterial / Q000032:analysis; D012703:Serotyping; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2
chemical_list: D001427:Bacterial Toxins; D007527:Isoenzymes; D019081:O Antigens; D009838:Oligodeoxyribonucleotides; D011135:Polysaccharides, Bacterial; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2