[Serotype distribution of prevalent Streptococcus pneumoniae strains in China from 2021 to 2025]

Objective: To analyze the serotype distribution of prevalent Streptococcus pneumoniae isolates in China from 2021 to 2025. Methods: The study data were sourced from the pneumococcal genome database jointly established by the National Pathogen Identification Network, the Bacterial Vaccine Preventable Diseases Laboratory Network, and the Institute for Communicable Disease Control and Prevention of the Chinese Center for Disease Control and Prevention from January 2021 to June 2025. A total of 2 134 pneumococcal genomes of S. pneumoniae isolates or genomic data were included in the study. Serotyping was performed using a capsular polysaccharide gene cluster-based prediction method. Isolates were grouped by geographical region, specimen source, and patient age. Differences in categorical data were analyzed using the Chi-square test or Fisher's exact test. Results: Of the 2 134 genomes, 2 055 (96.30%) were successfully typed into 44 serotypes/groups. The top 10 prevalent serotypes/groups were 19F (676/2 055, 32.90%), 6A/6B/6C/6D (261/2 055, 12.70%), 3 (223/2 055, 10.85%), 23F (142/2 055, 6.91%), 19A (101/2 055, 4.91%), 15A (87/2 055, 4.23%), 15B/15C (69/2 055, 3.36%), 34 (69/2 055, 3.36%), 14 (60/2 055, 2.92%), and 6E (58/2 055, 2.85%). Serotype distribution differed significantly across regions, specimen sources, and age groups (all P<0.001). Significant differences were observed in the proportions of serotypes 19F, 14, 37, 18C/18B, and 7C among isolates from different samples (P<0.05), with serotype 14 being significantly more frequent in sterile-site isolates than non-sterile-site isolates (P<0.001). The proportions of serotype 19F, serotype 3, and serogroup 6A/6B/6C/6D also varied significantly across age groups (P<0.001). Conclusion: The serotype profile of S.pneumoniae in China shifts between 2021 and 2025. While 19F remains dominant, non-PCV13 serotypes (15A, 15B/15C, 34, and 6E) increase in prevalence, highlighting the importance of continuous surveillance.