Fecal Microbiota Transplantation to Relieve Symptoms of Irritable Bowel Syndrome Without Constipation

Inclusion Criteria: * Ability to express and give informed consent * Age ≥ 18 years * Diagnosis of diarrhoea-predominant or unclassified IBS, according to the Rome IV criteria * Have performed a colonoscopy within the last 5 years that has ruled out intestinal diseases Exclusion Criteria: * Taking antibiotics or probiotics within the 8 weeks before the baseline visit * Patients with chronic inflammatory bowel disease (Crohn's disease, ulcerative colitis, indeterminate colitis or eosinophilic gastroenteritis), malignant neoplasms of the gastroenteric tract, celiac disease, diverticular disease * Uncontrolled heart failure or severe heart disease with EF \< 30% * Severe respiratory failure * Serious psychiatric conditions or psychological instability according to the clinician * Contraindication to fecal microbiota transplantation (high risk of complications related to colonoscopy) * Previous abdominal surgery on the gastroenteric tract (except cholecystectomy, appendectomy and other types of surgery not involving the digestive tract) * Patients with cutaneous enterostomy * Pregnancy or lactation * Concurrent enrollment in other interventional experimental protocols * Personality unstable or unable to adhere to protocol procedures * Any clinical condition which, in the opinion of the investigators, may contraindicate enrollment in the study