Epidemiology of brain abscess: A retrospective cohort from a neurosurgical tertiary referral centre in England

Background Brain abscess is a serious infection with substantial morbidity and mortality. Current data on the aetiology, management and outcomes are limited. This study describes the epidemiology of brain abscess in a large patient-cohort. Methods This is a retrospective, observational study of brain abscess at a tertiary referral centre. Patients were selected using hospital coding. Demographic, clinical, neurosurgical and microbiological data were analysed. Results We identified 174 patients with brain abscess admitted between 2012 and 2023 (32 paediatric, 142 adults, 66.7% male). Subdural empyema and parenchymal abscess were the most common abscess-types in the paediatric and adult cohorts respectively. A microbiological diagnosis was made in 74.1% of cases. Staphylococcus aureus was the commonest cause of post-surgical brain abscess, causing 27.8% of these cases. Streptococcus anginosus caused 42.8% of community-acquired brain abscesses. Microbiological samples were sent for 16S rRNA gene PCR testing in 33 cases (19.0%). A new microbiological diagnosis was made in 14 of these 33 cases (42.4%). In-hospital mortality was 13.4%. Increasing age and poor admission GCS were significantly associated with mortality. A trend towards decreasing mortality was seen with S. anginosus. Conclusions Our data reinforce the importance of early diagnosis and multidisciplinary management, particularly in older patients. Molecular diagnostics, including 16S rRNA gene PCR, may play an increasing role in guiding treatment in the future.