Diarrhea is a major public health problem worldwide, accounting for more than two million deaths each year, especially among children under five years of age. It is known that several microbial agents can be involved in the diarrhea disease, and that enteric bacteria and viruses comprise the most commonly agents involved in this process. Escherichia coli associated with intestinal infections in both children and adults are known as diarrheagenic E. coli and are classified into six distinct pathotypes, considering their virulence mechanisms, the clinical syndromes, serotypes (O:H), the epidemiological aspects and type of interaction with cell lines cultured in vitro. The diarrheagenic E. coli pathotypes are: enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), enteroaggregative E. coli (EAEC), enterohemorrhagic E. coli (EHEC) and diffusely adherent E. coli (DAEC). Currently, EPEC have been divided into typical and atypical based on the presence of pEAF (with the bfp operon expression) in typical EPEC and its absence in atypical EPEC. Epidemiological studies conducted in different geographical regions of Brazil, on the etiology of diarrheal disease, have demonstrated that atypical EPEC and EAEC pathotypes are among the most frequent agents. Previous studies conducted in Botucatu in the late 90s, also pointed to a high prevalence of EAEC among diarrheal children. However, EAEC and atypical EPEC have been isolated in equal frequency from children with and without diarrhea making the association of these pathotypes of diarrheagenic E. coli as infectious agents of the gastrointestinal tract difficult. The role of atypical EPEC as an important causative agent of gastrointestinal infections can be supported by the involvement of these bacteria in outbreaks of acute diarrhea, affecting not only children but also adults. The main objective of this project includes investigating the prevalence and association of different pathotypes of diarrheagenic E. coli among children under 5 years of age in Botucatu with diarrheal disease, as well as to characterize of the isolates of diarrheagenic E. coli, especially atypical EPEC currently considered an emerging pathotype both in developed and in developing countries.
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