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.

Inclusion Criteria: 1. Male and female subjects aged 18-70 years; 2. Confirmed diagnosis of ulcerative colitis (UC) prior to IPAA, with pouch takedown completed for at least 3 months; 3. Patients with pouchitis and an mPDAI score ≥ 5 points; 4. Positive stool test for MTB bacteria or Aeromonas aerolysin; 5. Subjects who agree to participate in this clinical study and have provided written informed consent. Exclusion Criteria: 1. Patients with pre-operative diagnosis of familial polyposis, Crohn's disease, or indeterminate colitis; 2. Subjects who underwent temporary or permanent ileostomy without pouch construction; 3. Active cardiovascular and cerebrovascular diseases including coronary heart disease, hypertension, cerebral infarction; 4. Patients suffering from other systemic diseases, autoimmune diseases, malignant tumors, or other severe chronic illnesses; 5. History of psychotropic substance abuse; 6. Pregnant or lactating women; 7. Recent use of probiotic therapy; 8. Patients who have received antibiotics within the past three months; 9. Subjects deemed unsuitable for participation in this study at the investigator's discretion.