Cluster 2 typical EPEC accounted for serotypes that were more rarely associated with outbreaks, except for EPEC O119:H6, the latter was frequently associated with infantile diarrhoea in Brazil [38, 39]. On the basis of these findings, Lazertinib in vitro a seropathotype classification for typical EPEC similar to those described for STEC [4, 24] can be established. Typical EPEC strains associated with outbreaks and high mortality are gathered in Cluster 1 which is mainly characterized by the presence of OI-122 associated genes ent/espL2, nleB, nleE. These findings are supported by two clinical studies showing that the presence of OI-122 encoded genes

was BIX 1294 solubility dmso significantly associated with diarrhoea in patients infected with atypical EPEC [40, 41]. The function of nle-genes in pathogenesis of EHEC and EPEC infection is only partially known [30, 42, 43]. Further work is needed to explore the contribution of

OI-122 effectors to the high infectivity and virulence of EPEC and EHEC strains resulting in outbreaks and severe disease in humans. It has been shown previously that the evolution of typical and atypical EPEC has occurred from LEE positive ancestor strains and divergent phylogenetic groups of EPEC (EPEC1 to EPEC4) and EHEC (EHEC1 and EHEC2) were established [1, 6, 37]. Virulence genes harboured by EAF-plasmids, EHEC-plasmids and stx-phages were found in phylogenetically unrelated strains indicating that these were acquired several times during evolution [1]. Their horizontal spread to unrelated strains and the frequent loss of plasmid and bacteriophage inherited determinants AC220 in vitro makes these less suitable for

identifying clones associated with high infectivity and virulence in humans. The OI-122 inherited nle-genes were found to be significantly associated with highly virulent Cluster 1 strains of EHEC and EPEC. They appear to be more stably inherited than plasmid and phage associated genes and could thus serve as an additional diagnostic tool for the reliable identification of EHEC and EPEC infections in humans, animals and EHEC contamination of food sources and the environment. Conclusion Our results indicate that the OI-122 pathogenicity island is a common attribute that Oxaprozin is significantly associated with highly virulent EHEC and EPEC strains. Of the OI-122 encoded genes, nleB was found as most conserved and thus presents a suitable marker for genetic screening for human virulent EHEC and EPEC strains. Horizontally transferred genetic elements such as the virulence-plasmids and phages were less significantly associated with the highly virulent clones of EHEC and EPEC strains. Methods Bacteria A total of 445 E. coli strains from the collection of the National Reference Laboratory for Escherichia coli (NRL-E.coli) were investigated. These originated from humans (n = 286), domestic animals (n = 84) and food (n = 70). Five strains were of unknown origin. The 445 strains were grouped into apathogenic E.