Identification of Helicobacter pylori in Gallstone, Bile, and Other Hepatobiliary Tissues of Patients with Cholecystitis

ABSTRACT

BACKGROUND/AIMS: Bacterial infection is accepted as a precipitating factor in cholesterol gallstone formation, and recent studies have revealed the presence of Helicobacter species in the hepatobiliary system. We utilized the polymerase chain reaction (PCR) to establish the presence of bacterial DNA, including from Helicobacter species, in gallstones, bile juice, and gallbladder mucosa from patients with gallstones. METHODS: At cholecystectomy, 58 gallstones, 48 bile samples, and 46 gallbladder mucosa specimens were obtained and subjected to nested PCR using specific 16S rRNA primers of H. pylori and other bacteria. Bacterial species were identified by DNA sequencing analysis. Bacterial 16S rRNA was detected in 25 out of 36 mixed-cholesterol gallstones, 1 out of 10 pure-cholesterol gallstones, and 9 out of 12 pigmented stones. Furthermore, 16S rDNA sequencing identified Escherichia coli, Pseudomonas, Citrobacter, Klebsiella, and Helicobacter species. RESULTS: Helicobacter DNA was detected in 4 out of 58 gallstones, 6 out of 48 bile samples, and 5 out of 46 gallbladder specimens. Direct sequencing of Helicobacter amplicons confirmed strains of H. pylori in all four gallstones, five out of six bile samples, and three out of five gallbladder specimens. Almost all mixed-cholesterol gallstones appear to harbor bacterial DNA, predominantly E. coli. CONCLUSIONS: H. pylori was also found in the biliary system, suggesting that these bacteria are of etiological importance in gallstone formation.