Clinical characteristics and outcome of primary brain abscess: a retrospective analysis

Background Patients with primary brain abscess often present with atypical symptoms, and the outcome varies. We investigated the demographic, laboratory, and neuroimaging features of patients with brain abscess at our hospital and identified factors associated with their outcomes. Methods We retrospectively collected the data of patients diagnosed with primary brain abscess at our hospital between January 2011 and December 2020. Their clinical characteristics, predisposing factors, laboratory and neuroimaging findings, treatment, and outcome were analyzed. Results Of the 57 patients diagnosed with primary abscess, 51 (89.47%) were older than 40 years, and 42 (73.68%) were male. Only eight patients (14.04%) showed the classical triad of headache, fever, and focal neurological deficit. Fifteen patients (26.31%) had comorbidities, of which diabetes mellitus was the most common. Positive intracranial purulent material cultures were obtained in 46.15% of the patients, and gram-negative enteric bacteria were found in 33.33% of them, with Klebsiella pneumoniae being the most frequently observed. Surgical treatment, most commonly in the form of stereotactic drainage, was received by 54.39% of the patients. Good outcomes were achieved in 75.44% of the patients. Multivariate logistic regression analysis showed that patients with headaches were more likely to have a poor outcome (odds ratio 6.010, 95% confidence interval 1.114-32.407, p = 0.037). Conclusions Male patients and those older than 40 years were more susceptible to brain abscess than female patients and those younger than 40 years, respectively. Only a few patients showed the classical triad of clinical symptoms. Diabetes mellitus was the most common comorbidity. Positive intracranial specimens' culture results were uncommon, with gram-negative enteric bacteria, especially Klebsiella pneumoniae, being the main organisms found. Most patients had a good outcome, and the presence of headache may influence the outcome.