Bacterial liver abscess

Infectious diseases of the liver encompass a wide range of conditions. Those of surgical relevance primarily include liver abscesses (commonly pyogenic liver abscess and amebic liver abscess), in addition to certain specific infections such as hepatic tuberculosis, which are now relatively rare. These diseases mainly arise when liver infections are not managed promptly, and are clinically secondary in nature. Pyogenic liver abscess refers to an intraparenchymal suppurative infection of the liver caused by invasion of pyogenic bacteria. This condition may originate from biliary tract disease (accounting for 16%–40%), portal venous hematogenous infection (8%–24%), with direct infection being less common. Reports on hepatic artery hematogenous infection vary, with the highest being 45%, and cryptogenic infection accounting for approximately 10%–15%. Gram-negative bacteria are the most common pathogens, of which two-thirds are Escherichia coli, followed by Streptococcus faecalis and Proteus; among Gram-positive bacteria, Staphylococcus aureus is the most common, and infections are often mixed. Approximately 70%–83% of pyogenic liver abscesses occur in the right hepatic lobe, which is related to the branching pattern of the portal vein. About 10%–16% occur in the left lobe; abscesses in both lobes account for approximately 6%–14%. Abscesses are usually single and large, while multiple abscesses are less common and smaller. In a minority of patients with pyogenic liver abscess, small abscesses may also be present in the lungs, kidneys, brain, and spleen. The main clinical manifestations include chills, high fever, right upper quadrant pain, hepatomegaly, and tenderness. With the advancement of imaging modalities and the development of various comprehensive treatment approaches, the diagnosis and treatment of this disease have improved significantly. Pyogenic liver abscess is mostly a secondary lesion, and its clinical manifestations are influenced by the underlying primary disease. Typically, during the course of the primary disease, there is a sudden onset of chills, high fever, and profuse sweating, along with right upper quadrant or liver area pain, accompanied by anorexia, fatigue, and weight loss. Symptoms are most severe in multiple liver abscesses, whereas those with a single abscess present more insidiously. In severe cases, jaundice and ascites may develop due to extensive hepatic damage. Pyogenic liver abscess is a serious condition that requires early diagnosis and early treatment.