The Bacteriology of Pouchitis A Molecular Phylogenetic Analysis Using 16S rRNA Gene Cloning and Sequencing

Objective: To identify, compare, and contrast the microbiota in patients with and without pouchitis after restorative proctocolectomy (RPC) for ulcerative colitis (UC) and familial adenomatous polyposis (FAP). Summary Background Data: Pouchitis is the most common complication following RPC. An abnormal host-microbial interaction has been implicated. We investigated the pouch microbiota in patients with and without pouchitis undergoing restorative proctocolectomy for UC and FAP. Methods: Mucosal pouch biopsies, taken from 16 UC (pouchitis 8) and 8 FAP (pouchitis 3) patients were analyzed to the species (or phylotype) level by cloning and sequencing of 3184 full-length bacterial 16S rRNA genes. Results: There was a significant increase in Proteobacteria (P = 0.019) and a significant decrease in Bacteroidetes (P = 0.001) and Faecalibacterium prausnitzii (P = 0.029) in the total UC compared with the total FAP cohort, but only limited differences were found between the UC nonpouchitis and pouchitis groups and the FAP pouchitis and nonpouchitis groups. Bacterial diversity in the FAP nonpouchitis group was significantly greater than in UC nonpouchitis (P = 0.019) and significantly greater in UC nonpouchitis compared with UC pouchitis (P = 0.009). No individual species or phylotype specifically associated with either UC or FAP pouchitis was found. Conclusions: UC pouch patients have a different, less diverse, gut microbiota than FAP patients. A further reduction in bacterial diversity but no significant dysbiosis occurs in those with pouchitis. The study suggests that a dysbiosis occurs in the ileal pouch of UC RPC patients which predisposes to, but may not directly cause, pouchitis.