Update on Fecal Microbiota Transplantation 2015: Indications, Methodologies, Mechanisms, and Outlook.

The community of microorganisms within the human gut (or microbiota) is critical to health and functions with a level of complexity comparable to that of an organ system. Alterations of this ecology (or dysbiosis) have been implicated in a number of disease states, and the prototypical example is Clostridium difficile infection (CDI). Fecal microbiota transplantation (FMT) has been demonstrated to durably alter the gut microbiota of the recipient and has shown efficacy in the treatment of patients with recurrent CDI. There is hope that FMT may eventually prove beneficial for the treatment of other diseases associated with alterations in gut microbiota, such as inflammatory bowel disease, irritable bowel syndrome, and metabolic syndrome, to name a few. Although the basic principles that underlie the mechanisms by which FMT shows therapeutic efficacy in CDI are becoming apparent, further research is needed to understand the possible role of FMT in these other conditions. Although relatively simple to perform, questions regarding both short-term and long-term safety as well as the complex and rapidly evolving regulatory landscape has limited widespread use. Future work will focus on establishing best practices and more robust safety data than exist currently, as well as refining FMT beyond current "whole-stool" transplants to increase safety and tolerability. Encapsulated formulations, full-spectrum stool-based products, and defined microbial consortia are all in the immediate future.