Adherence patterns of Escherichia coli in the intestine and its role in pathogenesis

Gut microbiota plays an important role in maintaining a healthy intestine. Escherichia coli (E.coli) is a commensal bacteria colonizes the mucous membranes of the gut, intestine, and urinary tract. However, these strains incorporate genetic elements to become pathotype and affected in hundreds of millions of people worldwide. Seven pathotypes have been categorized such as Entero-Hemorrhagic E.coli (EHEC), Entero-Aggregative E.coli (EAEC), Entero-Pathogenic E.coli (EPEC), Entero-Toxigenic E.coli (ETEC), Diffusely Adherent E.coli (DAEC), Entero-Invasive E.coli (EIEC) and Adherent-Invasive E.coli (AIEC), and each pathotype possess distinct virulence mechanism and virulence factors to disrupt the host intestinal epithelial cells that cause diarrhea and other intestinal inflammation. This review highlights the various fimbrial and afimbrial adherence mechanisms of E.coli pathovars, and how it competes with commensal bacteria in achieving pathogenicity in the host. Such adherence mechanisms are mediated by virulence proteins that have a significant impact on the outcome of intestinal inflammation.