Escherichia coli
E. coli normally grow in soil and in the large intestines of many mammals, including humans. Most strains of E. coli do not cause disease, but instead help animals get vitamins and digest food. Some strains of E. coli cause sickness in people. E. coli are not usually in food or water. When food has not been prepared with clean equipment, E. coli can grow in the food. When E. coli are found in water, this may mean that the water has touched sewage.