Bacteria and gallstones. Etiological significance

Two hundred consecutive gallstone cases have been subjected to bacteriological study employing improved anaerobic culture techniques. In addition to Clostridia species, species of anaerobes such as Bacteroides fragilis, Peptococcus, Veillonella, and Eubacterium are found to be present, some of which possessed beta-glucuronidase activity. This finding has a certain bearing on the etiology of bile pigment calcium stones. In addition to Escherichia coli, Bacteroides and Clostridium often found in the biliary tract may contribute to the formation of bile pigment calcium stones by producing beta-glucuronidase and thus deconjugating bilirubin diglucuronide to form free unconjugated bilirubin which in turn combines with calcium, leading to stone formation. In contrast, very low bacterial incidence was associated with cholesterol stones and so-called black stones--sometimes called pure pigment stones--and thus bacteria play little role, if any, in their formation. Therefore, bile pigment calcium stones and so-called black stones, which are often classified as pigment stones indiscriminately, should be differentiated not only because of their difference in their appearance and composition but also in their etiological background. Regardless of the kind of stones present in the common duct, the incidence of bacteria was found to be increased.