Bacterial and parasitic cholangitis.

Bacterial cholangitis is a clinically defined syndrome caused by the regurgitation of infected bile into the circulation. The pathogenic mechanism is unclear, and systemic sepsis may not occur. Prerequisite conditions are the presence of microorganisms in the bile and increased biliary pressure. Bacteria that commonly cause cholangitis are Escherichia coli, Klebsiella, Enterococcus, Enterobacter, Pseudomonas, and anaerobes. Although most infections are polymicrobial, this situation may not always prevail. Successful treatment depends on relieving biliary obstruction and administering antibiotics effective against bacteria in the circulation and the bile. The causes of biliary obstruction that predispose to bacterial cholangitis are myriad. Common conditions include biliary stones and benign strictures. In many parts of the world, biliary parasites are an important factor. Biliary parasites cause necrosis, inflammation, fibrosis, strictures, and cholangiectasis of the bile ducts by several mechanisms: (1) as a direct result of the irritating chemical composition of the parasite, parasitic secretions, or eggs; (2) physical obstruction of the bile ducts; (3) induction of formation of biliary stones; and (4) introduction of bacteria into the biliary system during migration from the duodenum. Therefore, bacterial cholangitis has an important and frequently dominant role in the pathogenesis and clinical course of biliary disease due to these parasitic infestations. Common biliary parasites include the nematode Ascaris lumbricoides, the trematodes Opisthorchis viverrini and felineus, Clonorchis sinensis, and Fasciola hepatica, and the cestodes Echinococcus granulosus and multilocularis. The epidemiologic, pathologic, and clinical manifestations of these parasitic infestations are reviewed.