Molecular characterization of uropathogenic and diarrheagenic Escherichia coli pathotypes.

In this study diarrheagenic and uropathogenic Escherichia coli (UPEC) strains were comparatively characterized according to serotype, hemolytic activity, protein polymorphism among housekeeping enzymes, phylogenetic group and urovirulence genes. Intra-serogroup/serotype variations were observed. Hemolytic activity was detected in 100%, 93%, 67% and 39% of UPEC, EAEC, EPEC and ETEC strains, respectively. The alpha-hemolytic phenotype was observed in all pathogenic groups while beta-hemolytic phenotype was less frequent. PCR phylotyping revealed higher prevalence of diarrheagenic E. coli in groups A and D while uropathogenic strains were mainly found in subgroup B2. Amplification assays revealed that 74%, 45% and 22% of UPEC, EAEC and EPEC strains, respectively, carried at least one of the urovirulence sequences. The molecular typing system revealed a pathotype-specific clonal group distribution and showed a closer relationship between the EAEC and UPEC. Additionally, the occurrence of urovirulence traits, especially those related to iron acquisition, was more frequent among EAEC and UPEC than among the other E. coli pathotypes. This observation is of special value considering that the EAEC pathotype constitutes an emerging group of enteropathogens, particularly, in developing countries, and information on their pathogenic and phylogenetic characteristics is still scarce.