Biliary tract: most commonly identified cause (24–60%)
Choledocholithiasis
Hepatic artery (∼ 10%)
Bacteremia or sepsis, e.g., due to infective endocarditis or IV line infection
Portal vein (∼ 7%)
Inflammatory bowel disease, most commonly Crohn disease
Common pathogens
Often polymicrobial
Most commonly isolated organisms
E. coli
Staphylococcus aureus
As S. aureus is a skin commensal, it can cause infection in IV drug users, after percutaneous chemoembolization of hepatocellular carcinoma, or after penetrating hepatic injury.