Serotypes, antibiotic susceptibility and whole-genome characterization of Streptococcus pneumoniae in Sichuan Province, China in 2023

<b>Introduction</b>. <i>Streptococcus pneumoniae</i> is a leading cause of pneumonia, meningitis and other invasive diseases. The increasing prevalence of antibiotic resistance in <i>S. pneumoniae</i> has become a major public health concern, complicating clinical treatment and highlighting the need for continuous surveillance.<b>Gap Statement</b>. Although previous studies have reported the antimicrobial resistance, serotype distribution and molecular characteristics of <i>S. pneumoniae</i> in some regions of China, systematic and whole-genome sequencing-based epidemiological data for Sichuan Province remain limited. Currently, there is a lack of comprehensive understanding regarding the predominant serotypes, resistance profiles, virulence gene carriage and their relationship with global clonal complexes in this region. In particular, data supporting the assessment of vaccine-covered serotypes and the transmission risk of multidrug-resistant strains are insufficient.<b>Aim</b>. This study aimed to investigate the prevalence, serotype distribution, antimicrobial resistance and molecular characteristics of <i>S. pneumoniae</i> isolates in Sichuan Province, providing genomic evidence to support rational antibiotic use and optimize immunization strategies.<b>Methodology</b>. A total of 105 clinical <i>S. pneumoniae</i> strains were collected in 2023 through the China Pathogen Identification Net. The serotypes, molecular types and antibiotic resistance of the strains were determined by whole-genome sequencing, sequence analysis and antimicrobial susceptibility test.<b>Results</b>. The leading serotypes were 19F (34.29%), 19A (10.48%), 3(7.62%) and 6E (7.62%). The dominant sequence types (STs) were ST271 (30.48%) and ST320 (10.48%), with CC271 and GPSC1 being the predominant groups. Vaccine coverage rates were 45.71% for PCV7/PCV10, 64.76% for PCV13, 69.52% for PCV20 and 70.48% for PPV23. All isolates were susceptible to linezolid and vancomycin, but high resistance was observed to erythromycin (92.38%), clindamycin (82.86%), tetracycline (86.87%) and trimethoprim/sulfamethoxazole (60.95%). The multidrug resistance (MDR) rate was 85.71%. Nine resistance genes were identified, with <i>erm(B</i>) and <i>tet(M</i>) being the most prevalent.<b>Conclusion</b>. Our study provides reliable information, including the prevalence, molecular characterization and antimicrobial resistance of <i>S. pneumoniae</i> isolates in Sichuan Province of China in 2023. The high MDR rate and predominance of vaccine-covered serotypes highlight the urgent need for enhanced surveillance, rational antibiotic use and broader implementation of pneumococcal vaccines, including the potential introduction of PCV20.