LABORATORY INVESTIGATION OF ENTEROAGGREGATIVE ESCHERICHIA-COLI O-UNTYPABLE-H10 ASSOCIATED WITH A MASSIVE OUTBREAK OF GASTROINTESTINAL ILLNESS

A massive outbreak of gastrointestinal illness occurred in Tajimi city , Gifu prefecture, in June of 1993 in which 2,697 children in elementa ry and junior high schools developed severe diarrhea, Stool specimens from 30 children with severe protracted diarrhea were studied, Twenty- seven strains of enteroaggregative Escherichia coli (EAggEC) isolated from 12 of 30 patients all belonged to the same serotype, O untypeable (OUT): H10, and showed the same biochemical characteristics and antib iotic susceptibility pattern, These strains were negative for the viru lence factors of the four standard categories of diarrheagenic E. coli (enterotoxigenic, enteropathogenic, enteroinvasive, and enterohemorrh agic). However, the isolates showed an aggregative pattern of adherenc e to HEp-2 cells and had a 60-MDa plasmid and an astA gene, which enco des heat-stable enterotoxin-l production. These data suggested that th e EAggEC serotype OUT:H10 was associated with this massive outbreak of gastrointestinal illness.