Abstract Acute cholangitis is commonly caused by biliary obstruction due to gallstones blocking the bile ducts and to malignancies of the biliary and pancreatic system. The pathogenesis of brown pigment gallstones, blockage of biliary stents, and biliary parasitic infestation are related to the formation of bacterial biofilms. Biliary pathogens, such as Escherichia coli and other enteric organisms, attach themselves to the surface of an ulcerated biliary mucosa or implanted biomaterial to form a bacterial biofilm. Some of these bacteria produce enzymes (β-glucuronidase and phospholipid A 1 ) and glycocalyx material that aid colonization and infestation. Crystals of calcium bilirubinate and other biliary sediments accumulate around the bacterial microcolonies and glycoproteins, forming adherent bacterial biofilms. The thick and often calcified biofilms obstruct the normal bile flow and lead to cholangitis.