Microbial Profile of Cholangitis in Patients Undergoing Biliary Intervention

Under physiological conditions, bile is sterile. Major factors maintaining sterility of bile are a competent sphincter of Oddi and antegrade flow of bile. Other factors are bile salts in the bile duct, Kupffer cells and tight junctions between the hepatocytes that guard against bacteria getting in from the portal circulation. Any break in these physiological barriers leads to infection of the bile. The main source of infection in most cases is the duodenum. Hematogenous spread through the portal venous flow is another route. In addition, bile duct obstruction e.g., stone, is associated with bacterial colonization within the stagnant bile and with increasing biliary pressure, bacteria may translocate into the circulation causing a systemic infection .

In patients without stone disease, previous biliary intervention is associated with high rates of infection. Bacteremia as a complication of biliary intervention tends to occur in patients with obstructed bile flow, especially those who have previously undergone orthotopic liver transplantation (OLT), surgery to the biliary tree, sphincterotomy, or placement of a biliary stent. The risk of systemic infection is high when adequate biliary drainage has not been achieved after intervention, which typically involves endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography (PTC).

Acute cholangitis is acute inflammation and infection in the bile duct. It is diagnosed in 6-9% of patients with gallstone disease and 1-3% after ERCP. It can progress from a local biliary infection to advanced systemic disease with sepsis and multiple organ dysfunctions with significant mortality rates (10%).

Microbial infection causing acute cholangitis is mainly bacteria and fungi. Despite blood cultures provide an opportunity to detect the causative organism, they remain negative in more than half of the cases with cholangitis. The growth is often mono-microbial organism, predominantly Gram-negative organisms. However, bile cultures often have a poly-microbial growth especially in patients with an indwelling biliary stent where, Gram-negative bacteria, in particular Escherichia coli, are the most common pathogens isolated from infected bile.

The fungal infection of the biliary tract increase in the last years and can lead to biliary obstruction. The most common fungal infection in biliary tract is candidiasis.