Allogeneic Microbiota-reconstitution (AMR) in Diarrhea-predominant Irritable Bowel Syndrome (IBS-D)

The investigators will perform a multicenter, 2:1 randomized, double-blinded, placebo-controlled trial of AMR in patients with diarrhea predominant-IBS (IBS-D) diagnosed according to Rome III criteria and the IBS-QOL questionnaire. Central supply and quality control of donor material will be used to control bias. Primary endpoint is improvement of IBS-SSS (Severity Score System) compared to baseline. Secondary endpoints include changes in IBS-QOL, short term safety and one year follow up to control long term effects, safety and changes in and acceptance of donor microbiome after AMR using16S rDNA sequencing and quantitative diversity analysis.