[Enteropathogenic Escherichia coli strains harboring enteroaggregative Escherichia coli (EAggEC) heat-stable enterotoxin-1 gene isolated from a food-borne like outbreak].

A food-poisoning outbreak occurred in G Town in Minami-Akita District, Akita Prefecture on 16 January 1995. As the causative agent of the outbreak, Enteropathogenic Escherichia coli (EPEC) O126:NM were isolated. The isolates showed the same plasmid profile and antibiotic susceptibility patterns suggesting that the EPEC strains originated from same infectious source. The isolates lacked eae and EAF genes which were considered to play a significant role in the diarrheagenic mechanism of EPEC. On the otherhand, the isolates possessed Enteroaggregative E. coli (EAggEC) heat-stable enterotoxin-1 (EAST-1) gene, though they did not possess the agg A gene in which the coded structural subunit of Aggregative adherence fimbriae 1 (AAF/1) has been demonstrated to be involved in the expression of ability for EAggEC to adhere to cultured cells in aggregative pattern, indicating that the EPEC strains apparently differed from EAggEC. These data suggested that EAST-1 showed its enterotoxic activity to human, and that EPEC represented multiple category of E. coli strains with different diarrheagenic mechanism, in which both eae and EAST-1 might be involved.