[The eae gene, adherence to HeLa cells and serotypes of Escherichia coli isolated from diarrhea]

We screened for the presence of Escherichia coli eae gene, one of the pathogenic factors of enteropathogenic E. coli (EPEC), by using the PCR method and compared the results with those from localized adherence to HeLa cells, presence of the EAF plasmid and the serotyping. One thousand one hundred and four E. coli strains isolated from diarrhea were examined, 144 (13.0%) possessed the eag gene. Of these eae positive strains, 93 (8.4%) exhibited localized adherence to HeLa cells and carried the EAF plasmid. And of these, 79 (7.2%) belonged to EPEC serotypes and 14 (1.3%) belonged to non-EPEC serotypes. Five (0.5%) with weak adherence, and 46 (4.2%) with no adherence were EAF plasmid negative. Predominant serotypes of EPEC were O55:H-, O86:H34, O111:H2, O119:H6, O128:H2 and main serotype of non-EPEC was O88:H25. Predominant serotypes of E. coli with no adherence to HeLa cells were O26:H-, O55:H-, O101:H-. EPEC and non-EPEC with localized adherence to HeLa cells were associated with diarrhea. Some of the eae positive strains with no adherence to HeLa cells, may have lost the EAF plasmid during storage. Though several variants of eae gene exist, it is necessary to confirm whether the strains possessing the eae gene without localized adherence to HeLa cells can cause diarrhea.