Abstract
INTRODUCTION: A biliary microbiome comprising flora within normal gallbladders was recently uncovered through analyses targeting the bacterial 16S ribosomal RNA (16S rRNA) gene, despite the gallbladder previously being regarded as a sterile environment. In the present study, we subjected bile samples from patients with acute cholecystitis to gene analysis targeting bacterial flora. METHODS: We targeted patients diagnosed as having Grade I or Grade II acute cholecystitis (in accordance with the Tokyo Guidelines 2018 established by the Japanese Society of Hepato-Biliary-Pancreatic Surgery) who underwent laparoscopic cholecystectomy within 24 h of diagnosis at Juntendo University Urayasu Hospital between July 2021 and January 2024 for evaluation. We drew bile sample from the gallbladder of each patient to confirm the presence of biliary bacterial flora, using both standard bacteriology (culture test) and 16S rRNA gene sequence. RESULTS: Of the 29 samples, 15 yielded cultures positive for bacterial flora, and gene analysis revealed the presence of bacterial biliary flora in all 14 samples that had tested negative in standard bacteriology. Considering the bacterial flora of a normal gallbladder without lesions as "normal flora," bacteria other than normal flora-Propionibacterium spp., Coprococcus spp., Prevotella spp., Sediminibacterium spp., and Collinesella spp.-were detected in 25 of the 29 cases (86 %). CONCLUSIONS: Bacteria not detected in non-inflammatory gallbladders such as Propiobacterium spp., Coprococcus spp., Prevotella spp., Sediminibacterium spp., and Collinesella spp. may play a role in the mechanism underlying development of acute cholecystitis.