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: Vancomycin-resistant Enterococcus faecium (VREfm) is a WHO priority pathogen. In the Comunitat Valenciana (CV), Spain, VREfm prevalence has increased since 2022. We characterized the population structure, transmission patterns and resistance determinants of VREfm across eight hospitals (2021-2024). Methods: Eight hospitals reported 870 VREfm cases during 2021–2024. We sequenced 254 VREfm isolates using WGS (Illumina) and inferred relatedness by MLST, cgMLST, and core-genome SNP analyses. Acquired antimicrobial resistance (AMR) genes, bacteriocins, plasmid replicases and putative virulence markers (PVMs) were identified in silico . Thirty-eight representatives underwent Nanopore long-read sequencing and hybrid assembly to resolve plasmids. Results: The predominant vancomycin-resistance genotype was vanB (62%; six hospitals), followed by vanA (19%; five hospitals) and vanA + vanB (17%; five hospitals). Eight sequence types (ST) and 15 clonal complexes (CT) were identified, grouped into seven main phylogenetic clades with close relatedness to publicly available genomes from other regions of Spain and Europe. A single lineage, ST117-CT7799, accounted for 198/254 (78%) isolates, persisted during 2022-2024 across seven hospitals and was enriched in the bacteriocin gene bac43 (or T8) (84%). Linezolid-resistance genes optrA and cfr (D) were present in 34% of isolates, most of which also carried vanA (32%). Hybrid assemblies revealed a diverse plasmidome including RepA_N megaplasmids with PVMs and AMR genes, and small Rep3-like plasmids harbouring bacteriocins ( bac43 , bac51 , bacAS9 ); a 6 kb repA_pB82 plasmid was bac43 -positive in 37/38 (97%) fully resolved carriers. Eight strains across four hospitals carried identical linear plasmids co-harbouring vanA , optrA , cfrD genes within a widespread repUS78_pZY2 background, consistent with inter-lineage plasmid transmission. Conclusions: This first comprehensive genomic analysis of VREfm in CV indicates extensive inter-hospital spread dominated by expansion of ST117-CT7799 and highlights plasmid-mediated convergence of vancomycin and linezolid resistance via linear plasmids. Strengthened infection prevention and genomic surveillance, including long-read sequencing to track linear plasmids, are warranted.

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.