Amplification and sequence analysis of partial bacterial 16S ribosomal RNAgene in gallbladder bile from patients with primary biliary cirrhosis

Background/Aims: The etiopathogenesis of bile duct lesion in primary biliar y cirrhosis is unknown, though the participation of bacteria and/or their c omponents and products is suspected, In this study, we tried to detect and identify bacteria in the bile of patients with primary biliary cirrhosis by polymerase chain reaction using universal bacterial primers of the 16S rib osomal RNA gene, Methods: Gallbladder bile samples from 15 patients with primary biliary cir rhosis, 5 with primary sclerosing cholangitis, 5 with hepatitis C virus-rel ated liver cirrhosis, 11 with cholecystolithiasis, sand from 12 normal adul t gallbladders were used. In addition to the culture study, partial bacteri al 16S ribosomal RNA gene was amplified by polymerase chain reaction (PCR) taking advantage of universal primers that can amplify the gene of almost a ll bacterial species, and the amplicons were cloned and sequenced, Sequence homology with specific bacterial species was analyzed by database research . Bacterial contamination at every step of the bile sampling, DNA extractio n and PCR studs was avoided. Furthermore, to confirm whether bacterial DNA is detectable in liver explants, the same analysis was performed using 10 l iver explants of patients with primary biliary cirrhosis. Results: In primary biliary cirrhosis, 75% (p<0.0001) of 100 clones were id entified as so-called Gram-positive cocci while these cocci were positive i n only 5% in cholecystolithiasis (p<0.0001). In cholecystolithiasis Gram-ne gative rods were predominant instead, One bacterial species detected in a n ormal adult was not related to those detected in primary biliary cirrhosis and cholecystolithiasis patients, No bacterial DNA was detected by PCR ampl ification in 10 liver explants of patients with primary biliary cirrhosis. Conclusions: The present results raise several possible roles of Gram-posit ive bacteria in bile in the etiopathogenesis of primary biliary cirrhosis. However, these results could also reflect an epiphenomenon due to decreased bile flow in the patients with primary biliary cirrhosis at an advanced st age.