Clinical features and outcomes of Staphylococcus aureus brain abscess in Denmark and the Netherlands: a multicentre cohort study

BACKGROUND: Staphylococcus aureus is the second most common cause of brain abscesses, but only few studies describe the disease characteristics.

OBJECTIVES: This study aimed to characterise the clinical features and outcomes of S. aureus brain abscess.

METHODS: We identified all adults with a brain abscess caused by S. aureus in Denmark between 2007 and 2024, and at the Amsterdam UMC from 2016 to 2024. Unfavourable outcome was defined as Glasgow Outcome Scale scores of 1-4. Modified Poisson regression was used to assess relative risks (RR) with 95% confidence intervals (CI) for an unfavourable outcome.

RESULTS: A total of 56 patients were identified with a median age of 59 years (interquartile range [IQR] 39-70), and 31/56 (55%) were male. Abscesses were mainly located in the frontal lobes (35/56, [63%]) and were due to head trauma or neurosurgery in 27/56 (48%). Patients with non-traumatic abscesses had predisposing otitis media or sinusitis in 9/29 (31%), whereas another 9/29 (31%) had endocarditis. Polymicrobial brain abscesses (Streptococcal species, anaerobic, and skin-colonising bacteria) were observed in 14/56 (25%) among whom 5/14 (36%) were post-traumatic and 9/14 (64%) were non-traumatic. Mortality at six months after discharge was 5/56 (9%), and 20/47 (43%) had an unfavourable outcome. The adjusted RR of an unfavourable outcome was 2.6 (95% CI 1.3-5.1) for post-traumatic abscess compared with non-traumatic S. aureus brain abscess.

CONCLUSIONS: Staphylococcus aureus brain abscess frequently involved the frontal lobes and a quarter were polymicrobial. Poor outcomes were common, especially among patients with post-traumatic abscesses.