Shift from Streptococcus pneumoniae to Klebsiella pneumoniae: a 15-year nationwide study of bacterial meningitis in Korea.

BACKGROUND: Bacterial meningitis is a medical emergency with high mortality and neurologic sequelae. Its epidemiology is changing with vaccination and evolving pathogens. We investigated current etiologic patterns of adult community-acquired bacterial meningitis in Korea and outcome determinants. METHODS: In this 15-year (2009-2023) retrospective study of 17 hospitals, 247 cases were analyzed for causative organisms, and 224 for 30-day outcomes. Risk factors for mortality and neurologic sequelae were determined. RESULTS: Streptococcus pneumoniae declined from 36.4% in 2009-2013 to 19.4% in 2019-2023 (P = 0.060). Meanwhile, Klebsiella pneumoniae increased significantly (6.8% to 29.2%; P = 0.001), becoming the most common cause. K. pneumoniae meningitis showed a tendency toward higher attributable mortality (35.7%) at 30 days compared to S. pneumoniae (19.7%). Independent predictors of 30-day mortality were older age, seizure at presentation, and septic shock, whereas hypertension was associated with a lower mortality risk. Neurologic sequelae occurred in 29% and were associated with pre-existing cerebrovascular disease, headache, and stuporous consciousness. CONCLUSIONS: Over 15 years in Korea, the declining incidence of S. pneumoniae meningitis coincided with widespread pneumococcal vaccination, while K. pneumoniae has become the leading cause. Given its association with poor outcomes, K. pneumoniae meningitis requires increased awareness.