Production of cytolethal distending toxin and other virulence characteristics of Escherichia coli strains of serogroup O86

Genetic and phenotypic virulence markers of different categories of diarrho eagenic Escherichia coli were investigated in 106 strains of enteropathogen ic E. coli (EPEC) serogroup O86. The most frequent serotype found was O86:H 34 (86%). Strains of this serotype and the non motile ones behaved as EPEC i.e.. carried eae, bfpA and EAF DNA sequences and presented localised adher ence to Hel;a cells. Serotypes O86:H2, O86.H6, O86:H10, O86:H18, O86:H27 an d O86:H non determined, belonged to other categories. The majority of the s trains of serotype O86:H34 and non motile strains produced cytolethal-diste nding toxin (CDT). The ribotyping analysis showed a correlation among ribot ypes, virulence markers and serotypes, thus suggesting that CDT production might be a property associated with a universal clone represented by the O8 6.H34 serotype.