Differences in the Biliary Microbiome Between Biliary Tract Cancer and Benign Biliary Disease

Bile contains many bacteria that can contribute to various diseases. Therefore, identifying bile microbiome differences between benign and malignant conditions is essential. In this study, bile samples were collected aseptically from 141 patients with biliary tract cancer (BTC) or benign biliary diseases (BBDs) who underwent endoscopic retrograde cholangiopancreatography or biliary tract surgery. Quality control PCR was performed to amplify the V3–V4 region of the bacterial 16S rRNA gene. Metagenomic sequencing of bile was successfully performed in 35 of 56 samples collected from patients with BTC and 24 of 85 samples from patients with BBD. The mean alpha diversity values comprised 2.788 ± 2.833 and 2.319 ± 1.355 in the BBD and BTC groups, respectively (p = 0.399). The bacterial species (4.7%) were shared between groups, whereas 12.3% and 83% were indicated to patients with BTC and BBD, respectively. Bacteroides coprocola, Prevotella copri, and Bacteroides plebeius were more frequently identified in the bile of patients with BTC, whereas Bacteroides vulgatus and Bacteroides uniformis were more abundant in the bile of patients with BBD. Distinct patterns of microorganism abundance between the two groups of patients suggest association of bile microbiome with disease status, so its diagnostic potential should be validated in further studies.