Fecal microbiota transplantation - something more than merely a therapeutic curiosity

Abstract

Intestinal microbiota likely represents the most complex organ in our body. It is estimated to include approximately 10 14 independent living organisms comprising bacteria, archaea, fungi, and acellular forms such as viruses. In a healthy adult microbiota accounts for approximately one kilogram in weight, and plays a role in multiple homeostatic and physiological functions. These include energy and intermediary metabolism, normal immune responses, and even appropriate bowel development and nervous system functioning. Several bacterial patterns (so-called "enterotypes") exist that have been associated with appropriate, healthy intestinal functioning. The therapeutic manipulation of intestinal microbiota may seem innovative. However, early (rudimentary) examples date back to remote times such as ancient Imperial China, and have been documented across time and geography ever since.As stated, we have increasingly more evidence available suggesting a key role of intestinal microbiota in human health and disease. Hence, its manipulation, and more specifically fecal microbiota transplantation (FMT), is currently becoming increasingly interesting because of its proven effectiveness and the myriad of possibilities it offers (1). Some of these possibilities are now fairly well established whereas others remain under study.The primary indication of FMT is Clostridium difficile infection. Many clinical series have been reported in major publications (2,3). Recently, Rossen and colleagues performed a systematic review of FMT cases thus far reported (4). After reviewing 33 series of cases and two clinical trials, they corroborated the procedure's high efficacy rate, with resolution of diarrhea by C. difficile in up to 90% of patients. All studies reviewed showed efficacy above 50%, even in immunosuppressed or elderly individuals, or in patients with severe conditions; furthermore, no differences in results were seen according to fecal infusion route (using colonoscopy or a nasojejunal feeding tube). Three clinical trials have been reported thus far on FMT for recurrent C. difficile colitis. The first one, of poor methodological quality, showed a symptom resolution rate of 81% (5). The second study, on a sample of 20 patients, compared several infusion routes with no control group, and found a cure rate of 70%, no differences being observed according to administration approach (6). The third study, with no control group and using capsules for FMT administration, found a success rate of 70% with a single dose, and up to 90% after a second dose (7). In the setting of refractory C. difficile colitis fewer -though highly successful-reports and no clinical trials are available. Notably, in the light of available evidence the procedure seems very safe. But for anecdotal evidence, no adverse effects have been reported, to which thorough donor assessment surely contributes. From all the above, the procedure's effectiveness in this setting is beyond doubt, which is reflected by the inclusion of FMT in the therapeutic guidelines issued ...