ABC of diseases of liver, pancreas, and biliary system: Liver abscesses and hydatid disease

Liver abscesses are caused by bacterial, parasitic, or fungal infection. Pyogenic abscesses account for three quarters of hepatic abscess in developed countries. Elsewhere, amoebic abscesses are more common, and, worldwide, amoebae are the commonest cause. AetiologyMost pyogenic liver abscesses are secondary to infection originating in the abdomen. Cholangitis due to stones or strictures is the commonest cause, followed by abdominal infection due to diverticulitis or appendicitis. In 15% of cases no cause can be found (cryptogenic abscesses). Compromised host defences have been implicated in the development of cryptogenic abscess and may have a role in the aetiology of most hepatic abscesses. Diabetes mellitus has been noted in 15% of adults with liver abscesses. Typical features of pyogenic liver abscess Origins and causes of pyogenic liver abscess MicrobiologyMost patients presenting with pyogenic liver abscesses have a polymicrobial infection usually with Gram negative aerobic and anaerobic organisms. Most organisms are of bowel origin, with Escherichia coli, Klebsiella pneumoniae , bacteroides, enterococci, anaerobic streptococci, and microaerophilic streptococci being most common. Staphylococci, haemolytic streptococci, and Streptococcus milleri are usually present if the primary infection is bacterial endocarditis or dental sepsis. Immunosuppression as a result of AIDS, intensive chemotherapy, and transplantation has increased the number of abscesses due to fungal or opportunistic organisms. Clinical featuresThe classic presentation is with abdominal pain, swinging fever, and nocturnal sweating, vomiting, anorexia, malaise, and weight loss. The onset may be insidious or occult in elderly people, and patients may present …