Inclusion Criteria:  Patients who belong to one of the following sub-groups:  Newly diagnosed (<1 years), therapy naïve IBD and pouchitis patients IBD patients in complete remission (treated or untreated with biologics) Patients (with and without IBD) scheduled to commence a biological therapy  Exclusion Criteria:  Age≤18 years Inability to sign an informed consent Abdominal surgery during the previous 3 months Systemic antibiotic therapy in the previous 4 weeks Severe systemic disease such as kidney, liver, neurologic, cardio-vascular disease Primary sclerosing cholangitis Pregnancy at recruitment Cancer within the previous 5 years excluding local NMSC