Enterococcus spp. have higher fitness for survival, in a pH-dependent manner, in pancreatic juice among duodenal bacterial flora

Objectives Bacterial infection is involved in the progression of many gastrointestinal diseases, including cancer; however, how and which bacteria colonize in pancreatic juice and tissue have yet to be elucidated. Recently, we reported that Enterococcus faecalis exists in the pancreatic juice and tissues of patients with chronic pancreatic disease. Here, we investigated the survival of E. faecalis in duodenal juice with different pH conditions. Methods Pancreatic juice samples from 62 patients with cancers of the duodeno-pancreato-biliary region were evaluated for the presence of E. faecalis . 16S ribosomal RNA PCR and 16S-based metagenome analyses were performed to determine the bacterial composition. The survival of E. faecalis in various pancreatic juice conditions was evaluated. Results Of 62 samples, 27% (17/62) were positive for Enterococcus spp., among which 71% (12/17) contained E. faecalis. Enterococcus spp. showed the highest fitness for survival in alkaline pancreatic juice among various bacterial species. The microbiome of pancreatic juice from patients with pancreatic and bile duct cancer showed diversity, but Enterococcus spp. were enriched among duodenal tumors and intraductal papillary mucinous neoplasms. Conclusions Alkalinity is important for the selective survival of E. faecalis among microbiota. E. faecalis may induce pancreatic inflammation with changes in pancreatic juice conditions.