[Genomic analysis of enterohemorrhagic Escherichia coli (EHEC) O157:H7 strains isolated in Saitama City].

To elucidate the origin of infection, we conducted epidemiological and bacteriological studies to clarify the origin of five sporadic outbreaks of enterohemorrhagic Escherichia coli (EHEC) O157:H7 between May and July 2007 in Saitama City and its outskirts. Of the 20 subjects were reported; including 6 patients and 5 infected persons, none of the 9 symptomatic subjects developed hemolytic-uremic syndrome. No association was confirmed between infection and food materials, but 11 organisms showed almost the same chromosomal DNA restriction patterns produced by pulsed-field gel electrophoresis. Our results suggested that these 5 sporadic outbreaks were part of a diffuse outbreak induced by an EHEC O157:H7 strain having a single origin.