Transmission of oral microbiota to the biliary tract during endoscopic retrograde cholangiography

BACKGROUND: Endoscopic retrograde cholangiography (ERC) possesses a translocation risk of microbes to the biliary system. We studied bile contamination during ERC and its impact on patients’ outcome in a real-life-situation. METHODS: Ninety-nine ERCs were analyzed and microbial samples were taken from the throat before and from bile during ERC and from irrigation fluid of the duodenoscope before and after ERC. RESULTS: 91.2% of cholangitis patients had detectable microbes in the bile (sensitivity 91%), but the same was true for 86.2% in the non-cholangitis group. Bacteroides fragilis (p=0.015) was significantly associated with cholangitis. In 41.7% of ERCs with contaminated endoscopes these microbes were found in the bile after the procedure. Analysis of duodenoscopes’ irrigation liquid after ERC matched the microbial bile analysis of these patients in 78.8%. Identical microbial species were in throat and in bile samples of the same ERC in 33% of all cases and in 45% in the non-cholangitis group. Transmission of microbes to the biliary tract did not result in more frequent cholangitis, longer hospital stays, or worse outcome. CONCLUSIONS: During ERC bile samples are regularly contaminated with microbes of the oral cavity but it did not affect clinical outcome. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12876-023-02721-7.