Gram-negative bacteria such as E. coli species are responsible for digestion and essential for the life of all animals and humans. Infection frequently occurs when the symbiotic bacteria pass through the intestinal wall. Regardless of the bacterial resistance to antibiotics, colonized-only hosts are without symptoms but infected patients must be treated quickly. Most difficult-to-treat hospital infections are endogenous, i.e., they are caused by the patient’s own intestinal multiresistant bacteria. Patrick's success story shows what measures can be taken.