[Enteroinvasive Escherichia coli O29:H--isolated from travellers' diarrheal cases]

Escherichia coli strains isolated in Tokyo from stool cultures of two sporadic diarrheal cases of travellers returning from South America and Thailand in 1985 and 1987 respectively, were found to be enteroinvasive strains with rare serotype O29:H--. These E. coli O29:H-- strains showed typical biochemical reactions of enteroinvasive E. coli in that they were negative lysine decarboxylase and non-motile. They were positive for Serèny test with guinea pig eye, cell-invasion test with HeLa cells, 140 megadalton virulence plasmid, and the virulence-plasmid encoded outermembrane protein, indicating that these strains were pathogenic and may cause a Shigella-like disease. Although the same serotype strains have been isolated in other countries, this may be the first report of isolation in Japan.