eP588 - The Role of Gut Microbiome in the Development of Anastomotic Leaks in Colorectal Surgery, a Systematic Review

Purpose/Background: Anastomotic leaks are a dreaded complication of colorectal surgery, occurring in up to 30% of cases depending on the site and indication for surgical resection and anastomosis. Despite the frequency of anastomotic leaks, the etiology remains unclear and is believed to be multifactorial. Recent research investigated the role of the gut microbiome in anastomotic leak pathogenesis. However, numerous questions and inconsistencies persist, such as the sample collection method and microorganism profile identified. The aim of this study is to conduct a systematic review of the existing body of literature concerning the intricate interplay between the gut microbiome and the development of anastomotic leaks.Methods/Interventions: A systematic review was performed with searches undertaken on Medline, Pubmed, and Scopus databases without language or date restrictions. The MeSH terms used were “microbiome OR anastomotic leak”, “gastrointestinal microbiome OR anastomotic leak”, “microbiome AND anastomotic leak”, and “gastrointestinal microbiome AND anastomotic leak”. Three authors independently screened the articles to identify those that were relevant. Studies including pediatric ( < 18 years old), reviews, duplicate or animal studies, those that did not identify specific organisms, and those not available in English language were excluded.Results/Outcomes: In total, 87 articles were identified and eight studies were selected for final review. All the studies were observational studies published between 2013 and 2023. A total of 671 patients undergoing colorectal surgery were identified, with the vast majority of procedures done for colon resection secondary to colorectal cancer. 119 (17.7%) patients developed anastomotic leaks. The methods for collecting samples for microbial sequencing included fecal sample (n=4), tissue sample from the donut (n=2), and tissue sample from colon resection just proximal and distal to the anastomosis (n=3). One study collected both fecal and surgical margin tissue samples and found surgical samples to be the preferred method of collection. The microorganisms identified varied between the anastomotic leak groups and non-anastomotic leak groups; however, they also varied greatly between studies, with very few of the same bacteria being identified in more than one study. Bacteria that had antagonistic properties included collagenase- and protease-producing Enterococcus, Fusobacterium nucleatum, Bacteroidaceae, and Lachnospiracea, and many others. Those that were possibly protective included Parabacteroides, Lactobacillus, Comamonas, and others.Conclusion/

Discussion: This systematic review suggests that while a number of studies have investigated the relationship between the gut microbiome and the development of anastomotic leaks, there are several aspects that still need to be further elucidated. Notably, the methodology of sample collection, as well as the timing of sampling, warrants deeper exploration into whether fecal sampling versus tissue biopsy yields more accurate and reproducible data. Additionally, the heterogeneity of microorganisms isolated underscores the complex nature of the gut microbiome’s influence, surpassing current comprehension. With more clarity and reproducibility, further studies may yield invaluable insights into this complex relationship.