Pneumococcal Meningitis in Children and Adults Before and After Implementation of PCV13 Into National Pediatric Immunization Program: A Cohort Study in Taiwan

Background Streptococcus pneumoniae remains a leading cause of bacterial meningitis worldwide. Although pneumococcal conjugate vaccines (PCVs) have markedly reduced vaccine serotypes (VTs) invasive pneumococcal disease, the emergence of non-vaccine serotypes (NVTs) has become an increasing concern. Data describing the clinical and microbiological characteristics of pneumococcal meningitis after the introduction of PCV13 remain limited. Methods We conducted a retrospective study of culture-confirmed pneumococcal meningitis at Chang Gung Memorial Hospital, Taiwan, from 2009 to 2025. Clinical characteristics, antimicrobial susceptibility profiles, outcomes, and serotype distributions were reviewed and compared between pediatric and adult patients with pneumococcal meningitis. Results A total of 23 patients with pneumococcal meningitis were identified between 2009 and 2025, including 11 pediatric and 12 adult patients. In children, the mean age was 4.8 years. Majority of the isolates are NVTs (35B, 23 A, and 15B). Two patients had meningitis caused by VTs; however, neither of them received PCV13. Clinical characteristics at admission included fever, productive cough, headache, and decreased consciousness (mean Glasgow Coma Scale:11). Susceptibility to antibiotics were similar, with most of the isolates being resistant to penicillin and ceftriaxone but susceptible to vancomycin. The in-hospital mortality rate was 18% (2/11). Most survivors suffered from complications, including empyema and multiple infarctions following vasculitis. In adults, the mean age was 48.6 years old, and majority of the serotypes were NVTs. Most had comorbidities, and the complications following meningitis were diverse. Overall, 37.5% of the patients (6/16) had meningitis attributed to VTs; all were non-immunized and occurred before 2015. Conclusions This study demonstrated a clear serotype replacement pattern in pneumococcal meningitis in Taiwan following PCV13 implementation in children. The emergence of multidrug-resistant NVTs underscores the importance of continuous surveillance and supports the use of higher-valency pneumococcal conjugate vaccines.