Purpose of review: To summarize recent evidence on the role of intestinal bacteria in inflammatory bowel diseases, and of antibiotics and probiotics in their treatment. The implications connected with the use of antibiotics are also examined.
Recent findings: The hypothesis that Mycobacterium paratuberculosis could be a causative agent of Crohn's disease has not been confirmed by a large trial on symptomatic patients treated by a combination of antibiotics active against this bacterium. An increased number of adherent-invasive Escherichia coli have been found in the intestinal tissue of patients with Crohn's disease, but their role in the pathogenesis of this condition remains to be defined. The combination of metronidazole and azathioprine, associating the effects of a reduced bacterial load with immunosuppression, appears to be a therapeutic option to decrease the recurrence of postoperative Crohn's disease in high-risk patients. However, concerns are raised by the possibility that antibiotics may induce disease relapse due to Clostridium difficile infection.
Summary: Recent literature provides increasing support for the use of antibiotics in Crohn's disease, although the side effects limit their long-term use. The efficacy of antibiotics in ulcerative colitis is not confirmed by the available literature, except in severe colitis. More trials are needed to support the use of probiotics as therapy in inflammatory bowel disease.