Microbiome Diversity in Pancreatic Surgery: Associations with Preoperative Stenting and Postoperative Outcomes

Carcinomas of the pancreas and bile duct remain highly lethal malignancies, with surgical resection representing the only potentially curative treatment. Despite improvements in perioperative mortality, postoperative complications remain frequent and negatively affect long-term outcomes. Recent evidence suggests that the pancreas and bile ducts harbor distinct microbial communities, challenging the traditional concept of sterility in these environments. However, their composition and clinical relevance remain incompletely understood. This study aimed to characterize microbiome profiles across different anatomical sites in patients undergoing pancreatic surgery, evaluate the impact of preoperative biliary stenting, and assess associations between prevalent bacterial species and postoperative outcomes. A total of 224 samples (bile, pancreatic fluid, duodenal tissue, tumor tissue, and healthy pancreatic tissue) from 58 patients with pancreatic cancer, bile duct cancer, chronic pancreatitis, or healthy pancreas were analyzed using 16S rRNA gene sequencing. Microbial diversity was assessed using the Shannon index for alpha diversity and nMDS with PERMANOVA for beta diversity. Distinct microbial profiles were identified across body sites, with significant beta-diversity differences between duodenal, bile, and pancreatic fluid samples and between duodenal and pancreatic fluid samples from the same patient. Preoperative biliary stenting significantly influenced microbial composition. Enterococcus faecalis was associated with a reduced risk of severe postoperative complications (Clavien-Dindo ≥ III). Overall, microbial composition varies across anatomical sites and disease entities, and specific bacteria may influence surgical outcomes, warranting further investigation in larger cohorts.