Pneumococcal Meningitis in a Region of Northern Spain, 1993–2023: Incidence Trends, Clinical Features, Recurrences, and Antibiotic Resistance

Background: Streptococcus pneumoniae is currently the leading cause of acute bacterial meningitis. This study assessed the impact of pneumococcal conjugate vaccines (PCVs) on pneumococcal meningitis in Gipuzkoa, north of Spain, between 1993 and 2023. Methods: All cases were serotyped and tested for antimicrobial susceptibility, with medical records reviewed since 2013. Overall, 193 patients were diagnosed (178 patients), averaging 6.2 cases annually. Results: Pneumococcal meningitis annual incidence decreased significantly after PCVs introduction, from 1.99 cases per 100,000 inhabitants in 1993–2001 (before PCV7) to 1.64 in 2002–2010 (PCV7 period) and further to 1.13 in 2011–2023 (PCV13 period). This decline was observed in all age groups except for adults aged ≥65 years, in whom the reduction was observed only after PCV13 introduction. The greatest reduction was observed in children under five. The incidence of meningitis caused by vaccine serotypes decreased following the progressive introduction of PCVs, but non-PCV serotypes increased from 0.70 to 0.95 cases per 100,000 between 1993–2001 and 2011–2023. Otitis media was the most common source of infection, followed by CSF fistula. Most cases (85%) required ICU admission; 67.5% showed sequels at discharge, mainly sensorineural hearing loss, and the 30-day mortality rate was 11.1%. Recurrent pneumococcal meningitis represented 7.8% of cases, associated with head trauma, with favorable outcomes and no mortality. Between 1993–2001 and 2002–2010, penicillin and cefotaxime resistance decreased from 25.4% to 13.3% (47.6% reduction) and from 19.7% to 5% (74.6% reduction), respectively. In 2011–2023, cefotaxime resistance stabilized, but penicillin resistance rose to 32.3%, mainly due to non-PCV13 serotypes. Conclusions: The use of PCV reduced the incidence of pneumococcal meningitis in the region, but penicillin resistance has increased in recent years, due to the rise in non-PCV13 serotypes.