About two million people in Europe suffer from chronic inflammatory bowel diseases, which are characterized by progressive tissue destruction and that often necessitate removal of sections of the intestine. The exact causes of Crohn's disease and ulcerative colitis, the most common forms of these diseases, are still largely unknown. In addition to genetic and environmental as well as lifestyle factors, a disturbed intestinal microbiota is responsible for triggering the disease. Complete recovery is often not possible. "If drug therapies fail, removal of parts of the inflamed intestine is currently the last treatment option," said Walter Reinisch, a gastroenterologist at the University Clinic for Internal Medicine III, Medical University of Vienna, and initiator of the study.