Stages of pathogenesis of EAEC. Numbers in circles show the progression of EAEC pathogenesis. (1) Agglutination of planktonic EAEC bacteria. (2) Adherence to the intestinal epithelium and colonization of the gut. (3) Formation of biofilm. (4) Release of bacterial toxins, inducing damage to the epithelium and increased secretion. (5) Establishment of additional biofilm.