The E. coli bacterium is one obligate inhabitants of the colon. However, some tribes possess virulence factors. These strains can cause severe and fatal diarrhea. Of particular importance is the K 99 capsule antigen, which allows E. coli to adhere to the epithelial cells of the villi. It comes to the increased secretion of enterocytes and consequently diarrhea. The E. coli bacteria also produce so-called Enerotoxine. In severe cases, an E. coli infection can lead to septicemia as well as toxemia with corresponding organ damage.