Pneumococcal meningitis in Mexico. Serotype distribution and antimicrobial resistance before and after the introduction of pneumococcal conjugate vaccines in pediatric patients. Results from the GIVEBPVac group.

BACKGROUND

Streptococcus pneumoniae remains a leading cause of bacterial meningitis in children, despite widespread use of pneumococcal conjugate vaccines (PCVs). This study evaluates changes in serotype distribution and antimicrobial resistance (AMR) in pediatric pneumococcal meningitis in Mexico, before and after PCV introduction.

METHODS

We conducted a prospective analysis of pneumococcal isolates collected from children aged 0-17 years diagnosed with meningitis between 1993 and 2024 through the GIVEBPVac surveillance network. Serotyping was performed using the Neufeld-Quellung reaction, and AMR profiles were determined by broth microdilution following CLSI guidelines. Temporal trends were assessed by Poisson regression and stratified by vaccination period (pre-PCV, PCV7/PCV10, and PCV13).

RESULTS

A total of 575 pneumococcal meningitis isolates were analyzed. The proportion of PCV13 serotypes declined from 77.2 % in the pre-PCV period to 33.3 % in the PCV13 period, while non-vaccine serotypes rose to 66.7 %. Serotypes 14, 6B, 19 F, and 23 F were predominant before PCV introduction. In the PCV13 era, serotypes 19 A and 15B increased in frequency, while 23B and 6 C emerged among non-vaccine serotypes. Resistance to cefotaxime increased from 22.8 % in the pre-PCV to 30.4 % during the PCV13 period. The overall case fatality rate was 8 %.

CONCLUSION

PCVs significantly reduced the burden of pneumococcal meningitis in Mexican children. However, the emergence of non-vaccine serotypes and the persistence of serotype 19 A highlights the need for continued surveillance and evaluation of higher-valent vaccines to inform future immunization strategies.