Oral Fecal Microbiota Transplantation in Pediatric Ulcerative Colitis

Inclusion Criteria for patients: * Patient aged 8 to 17 years old * Ulcerative colitis (UC), whatever the extent, except isolated proctitis (\<5 cm), diagnosed for more than 3 months according to the usual clinical, biological and endoscopic criteria * Moderate active UC defined by a PUCAI score \> 35 and responding to corticosteroid treatment with a PUCAI score \<10 at enrollment * Treatment of UC (5-ASA, immunosuppressants, biotherapies) stable for more than 3 months * Patient able to swallow test capsules * For girls of childbearing age: * To have a negative blood (or urine) pregnancy test * To agree to use a reliable contraceptive method from visit 1 until the end of the research * Patient with health insurance * Informed written consent form signed by both parents or by the person (s) with parental authority Exclusion Criteria for patients: * isolated proctitis (\<5 cm) * Being on enteral nutrition * Have received antibiotic or antifungal treatment in the 4 weeks prior to enrollment * Having a Clostridioides difficile infection in the 4 weeks prior to enrollment; * Being pregnant or breastfeeding, or have a positive pregnancy test; * Have a contraindication to colonoscopy or general anaesthesia