Role of the intestinal microbiota and fecal transplantation in inflammatory bowel diseases.

Ulcerative colitis and Crohn's disease are the two major types of inflammatory bowel disease (IBD). Despite intensive study, it is still challenging because the precise etiology and pathogenesis remains unclear. Studies have shown that IBD is associated with changes in the composition of intestinal microbiota, as either a cause or a consequence of abnormal host immune response in genetic susceptible population. Two specific microorganisms (Mycobacterium avium subsp. paratuberculosis and Escherichia coli) get more widely studied, but till now no single microorganism has been identified as the only pathogen. Genetic susceptibility data also suggest impaired handling of bacteria as well as an improper immune response to potential pathogens. The microbiota provides new therapeutic methods, and fecal microbiota transplantation may restore the balance of intestinal flora to supplement or optimize the current therapies.