Dysbiosis of the Fecal and Biliary Microbiota in Biliary Tract Cancer

Simple Summary There is no reliable data on the dysbiosis of fecal microbiota in biliary tract cancer. We present a metagenomic study to simultaneously analyze the microbiota in bile and feces and found that patients with biliary tract cancer had more Enterobacteriaceae and less Clostridia, including butyrate-producing bacteria such as Faecalibacterium and Coprococcus. Furthermore, metagenomic analysis revealed that the strains isolated from bile harbored genes encoding carcinogenic bacterial colipolyketide synthases (pks). The biliary microbiota is heavily influenced by the colonic flora, and carcinogenic bacteria may be a new risk factor for biliary tract cancer. Characteristic bile duct and gut microbiota have been identified in patients with chronic biliary tract disease. This study aimed to characterize the fecal and bile microbiota in biliary tract cancer (BTC) patients and their relationship. Patients with BTC (n = 30) and benign biliary disease (BBD) without cholangitis (n = 11) were included. Ten healthy, age-matched subjects were also recruited for fecal microbiota comparison. The fecal and bile duct microbiotas were analyzed by sequencing the 16S rRNA gene V3-V4 region. Live bacteria were obtained in the bile from three BTC patients by culture, and metagenomics-based identification was performed. Linear discriminant analysis effect size showed a higher Enterobacteriaceae abundance and a lower Clostridia abundance, including that of Faecalibacterium and Coprococcus, in the BTC patients than in the other subjects. Ten of 17 operational taxonomic units (OTUs) assigned to Enterobacteriaceae in the bile were matched with the OTUs found in the BTC subject fecal samples. Furthermore, a bile-isolated strain possessed the carcinogenic bacterial colipolyketide synthase-encoding gene. Enterobacteriaceae was enriched in the BTC feces, and more than half of Enterobacteriaceae in the bile matched that in the feces at the OTU level. Our data suggests that fecal microbiota dysbiosis may contribute to BTC onset.