Microbiology and epidemiology of brain abscess and subdural empyema in a medical center: A 10-year experience

Background and purpose: Brain abscess and subdural empyema are the 2 most common forms of intracranial pyogenic infections. Predisposing factors and etiological agents may change with time. This study examined the epidemiological features of these conditions. Methods: The medical records of all inpatients with a diagnosis of brain abscess or subdural empyema from 1998 to 2007 were reviewed. The diagnosis was confirmed by imaging study or operative findings. Results: 151 episodes of brain abscess were diagnosed in 150 patients, and 10 patients had subdural empyema. The incidence of brain abscess fluctuated over time, while that of subdural empyema remained stable. The mean ± standard deviation age of patients with brain abscess was significantly greater than that of patients with subdural empyema (48.5 ±19 years vs 25.4 ± 24 years; p = 0.004). The number of patients with hematogenous brain abscess increased from 7 in 1998 to 2002 to 19 in 2003 to 2007, while that of those with infection related to operation decreased from 10 to 5. Most subdural empyema was related to bacterial meningitis (4 of 10). Etiological agents were identified in 53% of brain abscesses. Including Enterobacteriaceae spp. (21.3%), Streptococcus spp. (20%), and mixed pathogens (17.5%). Klebsiella pneumoniae was the most common enteric bacteria isolated (15.3%), especially in patients with diabetes mellitus, but was not observed in children younger than 18 years. Conclusions: In contrast to western countries, K. pneumoniae plays an important role in intracranial pyogenic infections in Taiwan. The pathogens and routes of infection are different between children and adults. ? 2009 Journal of Microbiology, Immunology and Infection.