A 50-year-old female presents with intermittent right upper quadrant discomfort. The physician suspects she is suffering from biliary colic and recommends surgery. Following surgery, brown stones are removed from the gallbladder specimen. What is the most likely cause of the gallstone coloring?
1.E.coli infection ; beta-glucoronidase release
2.Shigella infection ; HMG-CoA reductase release
3.Shigella infection; beta-glucoronidase release
4.Bile supersaturated with cholesterol;beta glucoronidase release
5.Ascaris lumbricoides infection ;bile supersaturated with cholesterol
Summary
Pigmented gallstones, especially brown stones, are typically the result of bacterial infection-mediated release of beta-glucoronidase. This release of beta-glucoronidase leads to the formation of bilirubin glucoronides; unconjugated bilirubin levels rise and result in the brown pigment of the stones.
Cholesterol stones range in color from yellow to dark green and are mainly due to the supersaturation of bile with cholesterol. Brown stones are associated with infected bile and can often be found outside of the gallbladder in the intrahepatic or extrahepatic ducts. Pigmented stones are associated with gallbladder infection (especially with E. Coli and Klebsiella).
Illustration A is a figure from another paper by Stewart et al. denoting the incidence of bacterial presence by gallstone morphology. Note the high incidence of bacteria in pigmented gallstones compared to cholesterol stones.