Molecular characterization based on whole-genome sequencing and antimicrobial susceptibility of Streptococcus pneumoniae in Sichuan Province, China in 2023

Streptococcus pneumoniae is a major cause of pneumonia, meningitis and other invasive diseases resulting in high mortality and morbidity among children. In recent years, the issue of drug resistance in Streptococcus pneumoniae has become increasingly prominent, posing challenges to clinical treatment. Besides, the typing of Streptococcus pneumoniae is important information for evaluating the value of pneumococcal vaccines and developing immunization strategies. A total of 105 Streptococcus pneumoniae isolates were collected from ten cities in Sichuan Province in 2023. The leading serotypes were 19F (34.29%), 19A (10.48%), 3 (7.62%) and 6E (7.62%), with CC271 and GPSC1 being the predominant types. The overall coverage rates of 7-, 10-, 13-valent pneumococcal conjugate vaccines (PCV7, PCV10, PCV13) and 23-valent pneumococcal polysaccharide vaccine (PPV23) were 45.71%, 45.71%, 64.78% and 69.52%, respectively. The antimicrobial susceptibility test of Streptococcus pneumoniae showed that most strains were resistant to erythromycin (ERY), clindamycin (CLI), tetracycline (TCY), and trimethoprim/sulfamethoxazole (SXT), with a multidrug resistance rate of 85.71%, and CLI/EY/TCY was the main resistance mode. The resistance rate of strains isolated from the children's group and the elderly group to SXT was higher than that of the adult group, and the difference was statistically significant (χ 2 = 12.143, p = 0.002). In summary, continuous monitoring of the antibiotic resistance of Streptococcus pneumoniae is crucial for controlling and preventing the development of antibiotic resistance in pneumococcal bacteria. Our research is beneficial for understanding the type distribution of Streptococcus pneumoniae in Sichuan province and guiding the rational use of drugs and adjustment of vaccination strategies in clinical practice.