EXPERIMENTAL CHOLANGITIS FOLLOWING BILIARY OBSTRUCTION

A rat model for sepsis in chronic biliary obstruction

The effect of retrograde intrabiliary (RI) injection of E. coli was studied in Sprague-Dawley rats with and without chronic biliary obstruction. The challenge dose of E. coli was standardized by the use of frozen (-80 degrees C) aliquots of bacteria. Injection of 10(2), 10(5) or 10(8) colony-forming units (CFU), respectively, into three groups of 8 normal rats, immediately after occlusion of the common bile duct (CBD), did not kill any of the animals. In contrast, 5 of 8 animals with chronic biliary obstruction died from E. coli sepsis after RI injection of 10(2) bacteria (p less than 0.05). Furthermore, all of 4 obstructed animals died after challenge with 10(5) CFU (p less than 0.01), as compared to the 8 normal rats surviving this dose. Intraperitoneal injection of 10(5) E. coli did not kill any of 6 animals with 3 weeks biliary obstruction. It is concluded that chronic biliary obstruction and RI injection are prerequisites for the occurrence of lethal septicemia in the animals. The model might be suitable for the study of biliary sepsis in chronic biliary obstruction.

Impaired liver clearance of bacteria in rats with chronic biliary obstruction

125I-labeled E. coli was injected into the biliary tree of normal rats and rats with 3 weeks' obstruction of the common bile duct to investigate the liver clearance capacity for bacteria. Bile was collected during 15 min, immediately, 1 h, 4 h, or 24 h after the injection. Tissue specimens from the liver, lungs, spleen and kidneys, and blood and urine specimens were collected simultaneously. In normal rats, 40% of the bacteria was recovered in the bile immediately after the injection, whereas 30% was already trapped in the liver. Incubation of the bacteria in the bile duct for 1h, 4h, and 24h resulted in liver retentions of 43%, 15%, and 4%, respectively. The recovery in the bile was 13% after 1-h incubation, and further prolongation of the incubation did not result in a significant decrease. In contrast to these findings, 70% of the injected bacteria was retained in the biliary tree in rats with chronic biliary obstruction (P less than 0.05) as compared to normal rats) and only 1% was trapped in the liver (P less than 0.005) 15 min after injection. One-hour incubation of bacteria in the bile duct decreased the retention in the bile to 30%, but the retention in the liver increased only slightly in these animals. Four and 24 h after injection less than 30% of the bacteria was retained in the hepato-biliary system. Most of these animals showed almost no radioactivity exceeding the background count in the blood, urine, spleen, lungs, and kidneys 15 min after injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Biliary obstruction and susceptibility to biliary sepsis in rats

The effect of retrograde intrabiliary (RI) injection of E. coli was studied in Sprague-Dawley rats with biliary obstruction of different duration (3 days; 2, 4, and 6 weeks). By the injection of 10(5) colony-forming units (CFU) immediately after occlusion of the common bile duct (CBD), 15 of 18 normal rats survived without clinical signs of infection. In contrast, six of 11 animals in 3-day obstruction (P = 0.04), seven of 12 in 2-week obstruction (P = 0.02), ten of 12 in both 4-week and 6-week obstruction (P = 0.0004) died of E. coli sepsis after injection of the same amount of bacteria. Animals with longstanding jaundice (4 and 6 weeks) were more susceptible than those with a shorter duration of jaundice (3 days and 2 weeks, P = 0.04). The results warrant the early decompression of the biliary tract in biliary obstruction.