Pyogenic liver abscess (PLA), a suppurating infection of the hepatic parenchyma, remains a mortality associated condition and nowadays develops as a complication of biliary tract diseases for about 40% of cases. Recently, the etiologies of PLA have shifted from intra-abdominal infections such as acute appendicitis and trauma to pathologic conditions of the biliary tract; however, up to 60% of patients with PLA have no clear risk factors and these cases are called cryptogenic.

The incidence of PLA varies from 8 to 22 patients per 1,000,000 people belonging to a geographical area with substantially higher rates having been reported in Taiwan. Early diagnosis and treatment is a crucial step in the management of these patients, since the presentation may be subtle and not specific (abdominal pain, fever, nausea, and vomiting), so currently constitutes a challenge for physicians: a high index of suspicion is the cornerstone of prevention for misdiagnosis and improvement of prognosis.

In recent decades, combined antibiotic therapy and percutaneous drainage have become the first-line treatment in most cases and has greatly improved patients’ prognosis: the mortality rate has dropped from 70% to 5%. In terms of causative pathogens, bacteria most frequently associated with PLA are Escherichia coli, Enterobacteriaceae, anaerobes, and other members of the gastrointestinal flora. Over the past 2 decades Klebsiella pneumoniae has been emerging as the predominant pathogen responsible for 50% to 90% of PLA in the Asian population and it has been reported with increasing frequency in South Africa, Europe, and the United States.

Because such experiences have not yet been reported in Maranhão, we reviewed the cases of PLA seen at our institution and the present study is a retrospective analysis of demographic characteristics, etiological factors, presentation patterns, microbiological etiology, and the treatment of PLA cases which were presented in an Brazilian hospital over a 25-year-period.