This is a Single-center, Prospective, Single-arm Clinical Study Designed to Evaluate the Efficacy and Safety of Oral Aeromonas sp. MTB Phage Therapy for Pouchitis in Patients With Ulcerative Colitis (UC).

The goal of this single-arm, prospective clinical trial is to assess the clinical efficacy and safety of oral Aeromonas sp. MTB-specific phage therapy in adult participants aged 18-70 years with pouchitis following ileal pouch-anal anastomosis (IPAA) for ulcerative colitis, who are positive for stool MTB bacteria or aerolysin. The main questions it aims to answer are: * Does 2-week oral MTB phage treatment lead to mPDAI-defined pouchitis remission at Week 14? * What is the safety profile of oral MTB phage intervention in this patient population? No external control group is utilised; baseline data of each participant serves as self-control. Participants will: * Receive once-daily oral MTB phage (one bottle, 30 minutes post-meal) for 14 consecutive days. * Complete mPDAI symptom questionnaires and IBDQ quality-of-life assessments at baseline and follow-up time-points (Weeks 2, 8, 14, 24, 34). * Provide stool specimens for measurement of faecal phage titre, MTB bacterial load and aerolysin level at 24-48 hours post-initial phage administration, Weeks 2, 8, 14, 24 and 34. * Undergo pouch endoscopy for mPDAI endoscopic scoring at baseline, Week 14 and Week 34. * Complete scheduled follow-up up to Week 34, with continuous monitoring of vital signs, laboratory parameters and all adverse events throughout the study period.