Bacterial brain abscess: microbiological features, epidemiological trends and therapeutic outcomes

Background: Despite the advent of modern neurosurgical techniques, new antibiotics, and powerful imaging technologies, brain abscess remains a potentially fatal central nervous system infection. Aim: To determine the epidemiological trends, prognostic factors, and outcomes of bacterial brain abscess, to improve the therapeutic strategy for this disease. Design: Retrospective hospital- based epidemiology study. Methods: Over a period of 15 years (1986- 2000), 123 patients were retrospectively identified as having brain abscesses at Kaohsiung Chang Gung Memorial Hospital. To compare changes over time, the appearance of disease among our patients was divided into two time periods: 1986- 1993 and 1994- 2000. Results: The prevalence rate of brain abscesses caused by Gram- negative organisms significantly increased in the second study period. Viridans streptococci and Klebsiella pneumoniae were the two prevalent pathogens associated with haematogenous spread. Metastatic septic abscess, a devastating complication of K. pneumoniae septicaemia, frequently occurs in diabetic patients, with a high mortality rate. Viridans streptococci were the most prevalent pathogens from infection in paranasal sinusitis, but no fatality occurred. In recent years, head trauma and/ or post- neurosurgical states have become important predisposing factors, and nosocomial infections also play an important role. Discussion: Despite the availability of new antibiotics and the development of better neurosurgical techniques, therapeutic outcomes of brain abscess showed no significant change when comparing the two study periods, and only the presence of septic shock influenced outcome.