Background: Streptococcus pneumoniae (S. pneumoniae) remains a leading cause of morbidity and mortality, particularly among vulnerable populations. This study investigates the epidemiology of pneumococcal serotypes associated with invasive pneumococcal disease (IPD) in the Comunidad Valenciana (CV) region, Spain, analysing 1587 isolates collected from 2014 to 2023. Methods: Serotyping and antimicrobial susceptibility testing were performed, and whole-genome sequencing was conducted on 104 isolates to explore their clonal relationships. Results: The most prevalent serotype was serotype 8 (17.5%), followed by serotype 3 (14.7%), with a notable increase in serotype 8 cases from 2019 onwards and a decline in serotype 19A being observed. Age distribution played a role, as serotype 8 was more frequent in individuals over ten years old. The overall recovery rate was 72%, while serotypes 3 and 15A exhibited the highest mortality rates. The vaccination coverage was highest among children under five, underscoring the need for continued surveillance to evaluate vaccine effectiveness. The antimicrobial resistance was most pronounced for erythromycin (20%) and clindamycin (16%), with serotypes 19A and 6C displaying the highest resistance levels. Whole-genome sequencing identified sequence type (ST) 53 and ST180 as the predominant STs for serotypes 8 and 3, respectively, mirroring global trends. Conclusions: These findings emphasize the necessity of continuous monitoring to inform vaccination policies and antimicrobial strategies, to ensure effective disease control and improved patient outcomes.

Background/Objectives: This study analyzes the epidemiology of invasive pneumococcal disease (IPD) and the dynamics of Streptococcus pneumoniae serotypes in the Comunidad Valenciana (CV), Spain, over a 10-year period (2014–2024), with particular focus on vaccine coverage and effectiveness of PCV13 compared to the newer PCV20 and PCV21 formulations. Methods: A total of 2,014 isolates were collected from sterile clinical samples and characterized by serotype, patient demographics, and vaccination status. Results: Overall vaccination coverage was low (22.6%), with the highest rates observed in children under 10 years (78%) compared to only 16% in those aged 10–64 years and 22% in those over 64. Serotype distribution revealed 120 distinct serotypes, with serotype 8 (17.6%) and serotype 3 (14.7%) being the most frequent. Serotype 8 predominated among unvaccinated individuals, while serotype 3 remained highly prevalent despite inclusion in PCV13, reflecting limited vaccine effectiveness. Other relevant serotypes included 22F, 9N, 19A, 6C, and 23A. Temporal analysis showed increases in serotypes 8, 3, and 23A in recent years, while 9N, 19A, 15A, and 11A significantly declined. Among serotypes with <2% incidence, some such as 4, 12F, 16F, and 24F showed upward trends. Conclusions: The findings suggest that PCV20 currently provides broad coverage of dominant serotypes, but PCV21 may offer advantages should serotypes like 23A, 9N, or 15A increase further due to serotype replacement. Continuous epidemiological surveillance is essential to guide evidence-based vaccine policy and anticipate future vaccine reformulations.

Pneumococcus is a significant pathogen due to its high morbidity and mortality rates, especially among vulnerable populations. This study investigates the epidemiology of Streptococcus pneumoniae serotypes causing invasive pneumococcal disease in the Region of Comunidad Valenciana, analyzing data from 1587 isolates collected between 2014 and 2023. Serotyping and antimicrobial sensitivity were assessed, and whole genome sequencing was conducted on 104 isolates to examine clonal relationships. The study found that serotype 8 was the most common (17.5%), followed by serotype 3 (14.7%). There were significant variations in serotype distribution over the years, with serotype 8 increasing notably from 2019 onwards, while serotype 19A has decreased. Age was a significant factor, with serotype 8 being more prevalent in individuals older than 10 years. The overall patient recovery rate was 72%, with the higher mortality observed in serotypes 3 and 15A. Vaccination rates were higher among children under five, and the study highlighted the necessity for continuous monitoring of vaccine efficacy. Antimicrobial resistance was most significant for erythromycin (20%) and clindamycin (16%), with serotypes 19A and 6C showing the highest resistance rates. Whole genome sequencing revealed that ST53 and ST180 were the predominant sequence types for serotypes 8 and 3, respectively, reflecting global trend. The study underscores the importance of ongoing surveillance to adapt vaccination strategies and antimicrobial treatments, given the dynamic nature of pneumococcal epidemiology and resistance patterns. The findings also emphasize the need for targeted interventions to manage high-risk serotypes and improve patient outcomes.