Fondecyt Grant 1160426 -Bacterial microbiota strains associated with diarrheogenic E. coli infection promotes fimbrial-mediated adherence and inflammation induction of Enteroaggregative and Shiga Toxin-producing E. coli to intestinal cells

Background. Diarrheagenic Escherichia coli (DEC) remain a major cause of diarrhea in children under 5 years of age worldwide. DEC pathogenicity relies on the interaction of the bacteria with environmental factors including the gut resident microbiota. Previous reports have shown changes in gut microbiota composition in diarrhea episodes that might potentiate the pathogenicity of DEC strains. Considering the clinical relevance of DEC infections, the search of gut resident strains specifically associated to these infections is warranted, in order to define their role in DEC pathogenicity. Aim. To identify resident indicative taxa for DEC-positive in diarrhea stool samples of Chilean children between 1 and 5 years of age. Methods. 63 diarrheal stool samples obtained from children aged between 1 and 5 years old, were analyzed by FilmArray GI® and grouped whether they were positive exclusively for DEC pathotypes (D-group, 32 samples) or enteric virus (V-group, 31 samples). In addition, 30 stool samples from healthy children negative for enteric pathogens were included (C-group). In all samples, 16S ribosomal gene was amplified and sequenced using 454 pyrosequencing. Sequences were clustered in operational taxonomic units (OTUs) at 99% identity and their representatives used for a phylogenetic inference approach to circumscribe the operational phylogenetic units (OPUs).