Community-acquired bacterial meningitis in patients of 80 years and older

Background: Advanced age is a risk factor for unfavorable outcome in community-acquired bacterial meningitis, but clinical characteristics and outcome in meningitis patients of 80 years or older have not been defined. Methods: We compared clinical characteristics and outcome of community-acquired bacterial meningitis patients aged 80 years or older and adults under 80 years old within a prospective nationwide cohort study. Results: Out of 2140 episodes identified between March 2006 and July 2018, 149 occurred in patients aged 80 years or older (7%). Common predisposing factors other than age were diabetes mellitus (25 of 148 [17%]), otitis or sinusitis (30 of 136 [22%]), and pneumonia (23 of 141 [16%]). The triad of fever, neck stiffness and altered consciousness was present in 60 of 139 (43%). The most common causative pathogen was Streptococcus pneumoniae (99 of 149 [66%]). Atypical causative pathogens, such as Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli, occurred more often compared to younger patients (49 of 149 [33%] vs 362 of 1991 [18%]; p < 0.001). Patients of 80 years and older had high case fatality rate (75 of 149 [50%]), but 45 of 149 (30%) had a favorable outcome. Characteristics associated with an unfavorable outcome were absence of otitis or sinusitis, presence of aphasia, mono- or hemiparesis, a lower score on the Glasgow Coma Scale, a higher heart rate, a higher blood C-reactive protein concentration and CSF leukocytes <100 per mm³. Conclusions: Bacterial meningitis in patients of 80 years of older is associated with high rates of unfavorable outcome and death. Atypical causative pathogens such as L. monocytogenes, S. aureus, and E. coli occur commonly and should be considered when starting empirical antimicrobial therapy in this age group.