GM-CSF, Fosfomycin and Metronidazole for Pouchitis in Ulcerative Colitis Patients After Restorative IPAA Surgery

Inclusion Criteria: * Of any gender * Over 18 years of age * Have a previous diagnosis of ulcerative colitis * Have had IPAA surgery, and * Have been diagnosed with pouchitis * Be able to understand and complete study procedures as determined by the investigator * Be able to speak either Danish or English * Be able to comply with study procedures for the length of the study * Use a highly effective contraception method for the duration of the trial (until day 30 in Phase I and until day 37 in Phase II), such as implants, injectables, oral contraceptives, IUD (intrauterine device), sexual abstinence or vasectomized partner. Exclusion Criteria: * Patients with a previous allergic reaction to GM-CSF, metronidazole or fosfomycin * Patients who are currently under antibiotic treatment or have received antibiotic treatment within the past 30 days * Patients currently pregnant or breastfeeding * Patients with ASA IV classification (American Society of Anesthesiologists physical status classification) * Patients with severe pulmonary disease * Patients with autoimmune thrombocytopenia * Patients with severe renal impairment (eGFR \< 40 ml/min) * Patients with alcohol use disorder or history of drug abuse * Patients currently in treatment for any malignant or hematological disease * Patients with a previous history of cancer will be excluded from the study (except for patients with well-treated and stabile cancer after a control period of more than two years). * Patients with antic…