

@article {8170,
	title = {{Clonal relationships among Escherichia coli strains that cause hemorrhagic colitis and infantile diarrhea}},
	journal = {Infection and Immunity},
	volume = {61},
	number = {5},
	year = {1993},
	pages = {1619{\textendash}1629},
	edition = {1993/05/01},
	abstract = {<p>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.</p>
},
	isbn = {0019-9567 (Print)0019-9567 (Linking)},
	author = {Whittam, T S and Wolfe, M L and Wachsmuth, I K and Orskov, F and Orskov, I and Wilson, R A}
}
