Roles of bile and bacteria in biliary peritonitis

Bile is known to have an adverse effect in peritonitis but the mechanism(s) and site of action of bile are unknown, as are the relative roles of bile and bacteria. The present study was designed to answer some of these questions. Experiments in which rats were injected intraperitoneally and intravenously with bile, Escherichia coli or saline showed that bile had no systemic toxicity and that it increased the mortality rate only when introduced into the peritoneal cavity together with bacteria. Measurements of peritoneal fluid volumes and blood pressure did not confirm the theory that the increased mortality rate was a consequence of loss of plasma volume into the peritoneal cavity. The number of intraperitoneal bacteria decreased continuously in animals receiving intraperitoneal E. coli alone. When bile was added by intraperitoneal injection, the number of intraperitoneal bacteria started to rise at 2 h and then increased steadily with a consequent bacteraemia at 10 h. The number of bacteria per peritoneal phagocyte was significantly lower after intraperitoneal injection of E. coli and bile, when compared with injection of E. coli alone. It is concluded that bile exerts its detrimental effect within the peritoneal cavity in the presence of bacteria. Bile impairs local host defence in a way that remains unknown and may be related to the detergent-lytic effects of bile salts.