Adjunctive dexamethasone treatment in adults with listeria monocytogenes meningitis: a prospective nationwide cohort study

Background: A French cohort study described a detrimental effect of adjunctive dexamethasone treatment in listeria meningitis. Based on these results guidelines recommend not to use dexamethasone if L. monocytogenes is suspected or stop dexamethasone when the pathogen is detected. We studied clinical characteristics, treatment regimens and outcome of adults with Listeria monocytogenes meningitis in a nationwide cohort study on bacterial meningitis. Methods: We prospectively assessed adults with community-acquired L. monocytogenes meningitis in the Netherlands between Jan 1, 2006, and July 1, 2022. We identified independent predictors for an unfavourable outcome (Glasgow Outcome Scale score 1 to 4) and mortality by logistic regression. Findings: 162 out of 2664 episodes (6%) of community-acquired bacterial meningitis episode were caused by L. monocytogenes in 162 patients. Adjunctive dexamethasone 10 mg QID was started with the first dose of antibiotics in 93 of 161 patients (58%) and continued for the full four days in 83 (52%) patients. Different doses, duration or timing of dexamethasone were recorded in 11 patients (7%) and 57 patients (35%) did not receive dexamethasone. The case fatality rate was 51 of 162 (31%) and an unfavourable outcome occurred in 91 of 162 patients (56%). Age and the standard regimen of adjunctive dexamethasone were independent predictors for an unfavourable outcome and mortality. The adjusted odds ratio of dexamethasone treatment for unfavourable outcome was 0.40 (95% confidence interval 0.19–0.81). Interpretation: Adjunctive dexamethasone is associated with an improved outcome in patients with L. monocytogenes meningitis and should not be withheld if L. monocytogenes is suspected or detected as causative pathogen.