The role of bacteria in the blockage of biliary stents.

Recurrent jaundice and cholangitis due to stent occlusion by biliary sludge is a major complication of endoscopic stenting for malignant obstructive jaundice. Scanning electron microscopy study of the blocked stents revealed the sludge to consist of a mixture of bacteria and amorphous material. In vitro study using scanning electron microscopy demonstrated the attachment of bacteria to a segment of stent perfused with infected bile containing live bacteria. Associated with the microcolonies of bacteria was a collection of amorphous material forming a dense concretion on the surface of the stent. This phenomenon was not observed in experiments using sterile bile or with infected bile sterilized by formalin treatment or autoclaving. It was concluded that live bacteria are necessary for the initiation of biliary sludge formation which leads to subsequent stent blockage.