Phenotypic and molecular characterization of typical and atypical Enteroaggregative Escherichia coli (EAEC) isolated from sporadic cases and outbreaks of diarrhea in Brazil

• Grant number: 14/17286-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2015
• End date: December 31, 2015
• Field of knowledge: Health Sciences - Collective Health - Public Health
• Principal Investigator: Rodrigo Tavanelli Hernandes
• Grantee: Bruna Cardoso dos Santos
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Enteroaggregative Escherichia coli (EAEC), one of the six pathotypes of diarrheagenic E. coli (DEC), is defined based on the establishment of the aggregative adherence (AA) pattern in cultured epithelial cells in vitro. The presence or absence of the aggR gene, located in the EAEC virulence plasmid, separates the EAEC in typical and atypical, respectively. Although EAEC was initially described as a cause of acute diarrhea, its epidemiological association with this pathology is still controversial. Furthermore, in developing countries, EAEC has also been implicated as a cause of persistent diarrhea. Several potential virulence factors have been described in the EAEC; however the pathogenesis of the diarrhea caused by this DEC pathotype has not been fully understood. Many of the major virulence factors associated with EAEC are encoded by genes located on virulence plasmids, and detecting of these genes has been routinely used in the diagnosis of this pathotype. Recent studies have identified a pathogenicity island (PAI) inserted close the locus encoding the tRNA for phenylalanine (pheU), in the EAEC 042 prototype chromosome. This PAI presents 117 kb and encodes a type VI secretion system through the aai operon. The main objective of this study comprises to characterize EAEC strains isolated between 2010 and 2013, from sporadic cases and outbreaks of diarrhea in Brazil, regarding its ability to adhere to epithelial cells (HeLa), presence of virulence markers associated with the EAEC pathotype (fimbrial adhesins, toxin and the dispersin), evaluate the presence of genes from the aai operon, and to discuss the applicability of employing chromosomal genes in typical and atypical EAEC identification. (AU)