Abstract
Diarrheagenic Escherichia coli (DEC) is an important group of pathogens associated with enteric diseases. Diffusely adherent Escherichia coli (DAEC) strains are currently considered to constitute a sixth group of DEC. Although recent epidemiological studies have shown a high prevalence of DAEC strains among strains isolated from infant diarrheal stools, their involvement remains a matter of debate. Both commensal and pathogenic strains can be classified as Afa/Dr DAEC isolates since DAEC strains have been identified based on their diffuse adherence (DA) to cultured epithelial cells and on the detection of afa/dra/daa related operons encoding the DA phenotype. Measuring diffuse adhesion alone is insufficient to evaluate the diarrheagenicity of strains and other distinguishing characteristics are needed. In order to elucidate the pathophysiological processes by which Afa/Dr DAEC strains induce diarrhea, the present review focuses on the Afa/Dr adhesin and the various cell signaling events that occur after epithelial cells have been infected by Afa/Dr DAEC.
