eP651 - Relationship Between Gut Mucosal Microbiome and Anastomotic Leak in Ileocolic Anastomoses: A Case-Control Study

Purpose/Background: Anastomotic leak is a serious complication that can occur after an ileocolic anastomosis and can lead to worse clinical outcomes. Despite improvements in technology and technique, the incidence of ileocolic anastomotic leaks varies between 1.5% and 12%. Recent research indicates that the gut microbiome is essential for anastomotic healing. The presence of certain pathogenic bacteria and microbial diversity plays a critical role in anastomotic health. This study aims to compare the microbial diversity and the prevalence of specific bacterial populations in patients with anastomotic leaks after ileocolic anastomosis and those without.Methods/Interventions: This case-control study was conducted between Nov 2020 and July 2022 at the colorectal unit of a tertiary care teaching hospital. The institutional ethics committee approved the study. Consecutive consenting patients undergoing ileocolic anastomosis had mucosal specimens from the ileum and the colon at the site of anastomosis frozen and stored. Fifteen patients who developed an anastomotic leak and 15 age, sex and disease-matched controls were included, and the stored specimens from these patients were processed. 16s Ribosomal metagenomic sequencing was performed to isolate the microbiome from the ileal and colonic ends. The bacterial diversity, individual species, and family of bacteria were compared between cases and controls, both for the colonic and ileal mucosa.Results/Outcomes: Fifteen cases and 15 controls were included. The mean age of the patients was 52.8 (SD 13.2) years. The cases and controls were well-matched for baseline characteristics. The postoperative stay was significantly longer for the cases compared to the controls (18.5 vs 9.9 days p=0.002).The bacterial population of cases and controls differed significantly at the family and genus levels. There were significantly more Enterobacteriaceae found in patients with an anastomotic leak (both colonic and ileal mucosa) than in patients who did not leak. The Shannon Diversity Index revealed lower microbial diversity among patients with an anastomotic leak (both ileal and colonic mucosa) than patients without a leak.Conclusion/

Discussion: The microbiome of patients with anastomotic leak differs from that of patients who do not develop anastomotic leak with a lower microbial diversity and higher specific bacteria. Further research can increase clarity and provide a potential therapeutic intervention to reduce ileocolic anastomotic leaks.