Please explain what happens when you get e coli?

Bad E coli: Most E. coli bacteria are harmless,are part of the normal bacteria in bowels, and can benefit humans by producing vitamin K, but some can be bad, and be responsible for food poisoning or food contamination. Most healthy adults recover, but bad E. coli Infection, called type O157:H7 can also cause blood and kidney complications in susceptible people, such as babies and elderly.