Proliferative activity of bile duct epithelium after bacterial infection in dogs

To clarify the relationship between proliferative activity in bile duct epithelia and bacterial infection in the dog, we induced obstructive cholestasis with a bacterial infection in two lobes of the liver. The bile duct branch draining the left lateral lobes of the liver was cannulated in all mongrel dogs. The dogs were divided into three groups and treated as follows: in group 1 the cannula was clamped after the injection of 10(7) Escherichia coli (aerobic bacteria) and 10(7) Bacteroides fragilis (anaerobic bacteria) cells; in group 2 the cannula was clamped after the injection of 10(7) E. coli cells; and in group 3 the cannula was clamped without the injection of any bacteria. Three months and 9 months later dogs from each group were killed, and their livers were examined. In the group 1 dogs papillary hyperplasia and severe dysplasia were noted in association with chronic cholangitis at 3 months and 9 months, respectively, after operation. In the group 2 dogs periductal fibrosis was severe, but epithelial papillary hyperplasia was less pronounced than in the group 1 dogs at each period. In the group 3 dogs no periductal fibrosis or epithelial papillary hyperplasia was seen at either 3 or 9 months postoperatively. These findings suggest that papillary hyperplasia and/or severe dysplasia of the bile duct epithelium may be caused by aerobic and anaerobic bacterial infection of the biliary tract in combination with bile stasis.