Distribution Characteristics, Antimicrobial Resistance, and Variation Trends of Biliary Microbiome in Acute Cholangitis patients : A 7-Year Retrospective Study in a Tertiary Hospital in Northwest China

Abstract Background With the increase in bacterial resistance worldwide, the bacterial characteristics of the biliary tract may have changed. Bile specimens for microbiological analysis are obtained primarily during endoscopic retrograde cholangiopancreatography, with a few from percutaneous transhepatic cholangial drainage. However, in some regions of China, patients still undergo laparoscopic T-tube drainage. The lack of data from this subset may lead to an incomplete understanding of the characteristics of the biliary microbiome. Method 1094 hospitalized patients diagnosed acute cholangitis from January 1, 2017 to December 31, 2023, who underwent biliary drainage procedures with bile specimen collection in our hospital were selected.Collect and analyse their general information, results of biliary culture, antimicrobial susceptibility and potential reasons for changes over 7 years. Results Among the 1,094 patients with acute cholangitis, 875 specimens (79.91%) yielded positive bile cultures, facilitating the detection of 1,026 strains belonging to 24 genera and 75 species of pathogens..Gram-negative bacteria were predominant,accounting for 63.65%(653/1,026) of the isolates, followed by gram-positive bacteria at 31.97%(328/1,026) and fungi at 4.39%(45/1,026). The main genera were Escherichia (249, 24.27%), Enterococcus (197, 19.20%), Klebsiella (170, 16.57%). Over the years, there has been a fluctuating upward trend in the diversity of pathogens. From 2017 to 2021, the proportion of gram-negative bacilli gradually decreased while gram-positive cocci increased, although the difference was not statistically significant. However, from 2022 to 2023, the proportion of gram-negative bacilli significantly increased compared to the previous five years.There was an increasing trend in the resistance rates of Escherichia coli and Klebsiella pneumoniae to various antibiotics.They were more sensitive to piperacillin/sulbactam sodium than to cefoperazone/sulbactam sodium. Conclusion The proportion of gram-positive bacteria increased annually in patients without differences in the history of Oddi sphincter incision. Incision of the Oddi sphincter increased the proportion of gram-negative bacteria but did not increase the proportion of major bacterial species and had no significant effect on the distribution of Enterococcus. The detection rates of resistant bacteria increased significantly. The resistance rates of Escherichia coli and Klebsiella pneumoniae to antibiotics showed an overall increasing trend.