Presence of eaeA sequences in pathogenic and nonpathogenic Escherichia coli strains isolated from weaned rabbits.

Seventy-one Escherichia coli strains isolated from diarrhoeic weaned rabbits from different areas of France were tested for the presence of DNA sequences specific for the EPEC, EHEC, DAEC and EAggEC strains and 16 of them were tested for pathogenicity in animal experiments. High pathogenicity was observed only with strains unable to ferment rhamnose. DNA from all 55 rhamnose-negative O103, O26 and rough strains hybridised with the eaeA probe. Similar hybridisation was obtained with six non-pathogenic rhamnose-positive strains belonging to serogroups O128 and O132. No hybridisation was observed with the other probes. This is the first report of the presence of eaeA sequences in genomic DNA of non-pathogenic strains.