Diffusely Adherent Escherichia coli

Abstract

Diffusely adherent Escherichia coli (DAEC) were the last diarrheagenic E. coli pathogroup (DEC) to be recognized. DAEC pathogroup encompasses a heterogeneous group of E. coli strains, harboring genes encoding for Afa/Dr adhesins that are capable of causing diarrhea illness in otherwise healthy individuals. Afa/Dr family includes Afa, Dr, and F1845 adhesins that are encoded by the afa/dra/daa operons, respectively. Afa/Dr adhesins bind to cell receptors human decay-accelerating factor (hDAF) and carcinoembryonic antigen cell adhesion molecules (hCEACAMs), inducing receptor clustering and finger-like cell projections, resulting in bacteria embedding without complete internalization. DAEC infection also causes damages on epithelial cells, including loss of microvilli structure, impaired enzyme activities of functional brush border-associated proteins, and loss of adherens junctions, in an Afa/Dr-dependent fashion. Diarrhea prevalence studies among Latin American children have confirmed that DAEC diarrhea illness susceptibility is age-related and DAEC-diarrhea risk increases with children’s age. DAEC was the most prevalent DEC identified from children with acute diarrhea attending a hospital rehydration unit and an Emergency Room service in Mexico and US, respectively. In adults, DAEC was identified in travelers’ diarrhea patients who visited Latin America and from HIV-positive patients with diarrhea from Peru. Recently, DAEC strains carrying virulence genes associated with pathogenesis, M cell translocation, angiogenesis, and genotoxicity were isolated from patients with inflammatory bowel disease and colorectal cancer. DAEC is a bacterial pathogen that induces unique alterations on epithelial cells, resulting in diarrhea illness and epithelia damage that may also contribute to the development of other intestinal diseases.