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* = Presenting author

P751 Low enteric microbial diversity in patients with ulcerative colitis after pouch surgery having a mature normal ileal pouch may be predictive of pouchitis

N. Maharshak*1, N.A. Cohen1, L. Reshef2, H. Tulchinsky3, U. Gophna2, I. Dotan4

1Tel Aviv Medical Centre, IBD Centre, Department of Gastroenterology and Liver Diseases, Tel Aviv, Israel, 2Tel Aviv University, Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv, Israel, 3Tel Aviv Sourasky Medical Centre, affiliated to Sackler Faculty of Medicine, Tel Aviv University, Proctology Unit, Department of Surgery, Tel Aviv, Israel, 4Tel Aviv Medical Centre, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Department of Gastroenterology and Liver Diseases, Tel Aviv, Israel

Background

Pouchitis is a common complication in patients with ulcerative colitis (UC) undergoing proctocolectomy with an ileal pouch-anal anastomosis (pouch surgery). Pouchitis occurs frequently during the first year after ileostomy closure; however, acute pouchitis episodes may develop in patients with a mature pouch. We aimed to examine whether the characteristics of faecal microbiota in patients with a normal pouch >1 year post ileostomy closure (‘mature’) can predict pouch inflammation.

Methods

Patients undergoing pouch surgery were prospectively recruited. Normal pouch (NP) was defined using stringent criteria of pouchitis disease activity index (PDAI) ≤ 5. Faecal samples were collected, and microbiota analysis was performed by 16S rRNA gene pyrosequencing. Patients with pouchitis or a history of antibiotic treatment within 3 months before faecal sampling were excluded. Disease activity was assessed at 2 time points (T1 & T2) during a longitudinal follow-up of at least 1 year. All patients had NP at baseline (T1), and were classified into a NP group if they did not experience further pouchitis or into a Pre-Pouchitis group if they further experienced pouchitis during the first year of follow-up.

Results

In total, 20 patients were recruited (age 53.6 ± 13.1 years; male 11; pouch age [time from ileostomy closure] 8.1 ± 5.1 [range 2–19] years). Seven patients developing pouchitis during follow-up (within 263 ± 90 days) were categorised into the Pre-Pouchitis group at T1. These patients had a decreased microbial diversity at T1 compared with NP patients (n = 13) using the Shannon diversity index Pre-Pouchitis = 3.4 vs NP = 4.23 (p = 0.011). These differences were not apparent at the ‘order’ or higher phylogenetic levels, supporting a non-specific decrease in microbial diversity in Pre-Pouchitis patients. The genus Ruminococcus was significantly decreased in Pre-Pouchitis compared with NP patients (0.19% vs 0.78%, FDR = 0.05). Linear Discriminant Analysis with Effect Size estimation algorithm (LEfSe) revealed that Lachnospira (0.6% vs 1.95%) and Coprococcus (2.1% vs 4%) genera were also decreased amongst pre-pouchitis patients.

Conclusion

UC patients after pouch surgery may be predisposed to pouchitis as faecal microbial diversity and certain microbial groups are decreased. These findings might aid in risk stratification of patients with a NP and might explain why patients develop pouchitis during the first year post pouch surgery. Therapeutic strategies to increase microbial diversity, such as probiotics/faecal microbial transplantation, should be examined as a preventive therapy in this group of patients.