Faecal Microbiota Transplantation in Irritable Bowel Syndrome

Inclusion Criteria: * Diarrhea Predominant Irritable Bowel Syndrome (IBS-D) or Irritable Bowel Syndrome with mixed bowel habits (IBS-M) according to the Rome IV criteria Exclusion Criteria: * The use of antibiotics within one month prior to faecal microbiota transplantation * The use of probiotics within one month prior to faecal microbiota transplantation * History of inflammatory bowel disease or gastrointestinal malignancy, systemic autoimmune diseases (ongoing or in history) * Previous abdominal surgery (other than appendectomy or cholecystectomy or hernioplasty or cesarean section) * HIV infection or other active infection * Renal or hepatic disease (both defined by biochemistry workup) * Diabetes mellitus, abnormal thyroid functions not controlled by thyroid medications * Bipolar disorder or schizophrenia (ongoing or history thereof), moderately severe depression defined by Patient Health Questionnaire-9 (PHQ-9) score \> 15 * Anxiety defined by a Generalised Anxiety Disorder 7 (GAD7) score \> 10 * Current pregnancy and lactation