Outcomes of adults with community-acquired bacterial meningitis in the Netherlands: a prospective nationwide cohort study

Background: Bacterial meningitis is associated with high rates of unfavourable outcome. We conducted a nationwide prospective study in the Netherlands to evaluate outcome in adults with bacterial meningitis, focusing on pathogen-specific differences, risk factors for unfavourable outcomes, and neurological sequelae. Methods: Adult patients with community-acquired bacterial meningitis confirmed by lumbar puncture were identified through the database of the Netherlands Reference Laboratory for Bacterial Meningitis and prospectively included. Neurological examinations were performed on admission and discharge by the treating physician, and outcome was assessed using the Glasgow Outcome Scale, with scores of 1–4 classified as unfavourable. Logistic regression was used to evaluate the association between potential predictors and outcome. Findings: Between January 1, 2006 and January 1, 2024, 2974 patients were included. Streptococcus pneumoniae was the most common pathogen (2029/2974; 68%), followed by Neisseria meningitidis (329/2974; 11%), Listeria monocytogenes (182/2974; 6%), Haemophilus influenzae (119/2974; 4%) and Streptococcus pyogenes (83/2974; 3%). Overall mortality was 17% (516/2974) and remained stable over 18 years (odds ratio per admission year 0·99 [95% CI 0·97–1·01]). Mortality was highest for L. monocytogenes (58/182; 32%), S. pyogenes (16/83; 19%), and S. pneumoniae (365/2029; 18%). Unfavourable outcome occurred in 1161/2974 patients (39%; 95% CI 37–41), and key predictors included advanced age, prolonged symptom duration, systemic or cerebral compromise, low CSF white-cell counts, and absence of adjunctive dexamethasone. Among survivors, neurological sequelae occurred in 1146/2088 patients (55%), including hearing impairment (692/2197; 31%) and cognitive impairment (481/2108; 23%), with highest rates following S. pneumoniae (881/1419; 62%), and S. pyogenes (44/59; 75%). Interpretation: Mortality and morbidity from bacterial meningitis remain high, especially in L. monocytogenes, S. pyogenes, and S. pneumoniae infections. These findings highlight an urgent need for enhanced vaccination strategies, timely recognition, and improved therapies. Funding: Netherlands Organization for Health Research and Development (ZonMW).