Regional Features of the Serotype Composition of Streptococcus pneumoniae isolated from Bacterial Carriers of Preschool Age in the Republic of Tatarstan

Relevance. Vaccination of the child population against pneumococcal infection (PI) has been carried out in Republic Tatarstan according to national calendar preventive vaccinations since 2014. The vaccination scheme includes with PCV-13 conjugated vaccine. Aim. Study frequency bacterial transmission and serotype landscape S. pneumoniae isolated from healthy children- carriers preschool age (RT). Materials methods. During period 2016 2022, 1,426 children Kazan districts were examined. Examination nasopharyngeal smears was by classical bacteriological method. Serotyping performed using molecular genetic methods (PCR). Results. detection rate among varied different years 29.5 63%, averaging 38.5%. In urban children, incidence significantly higher than rural (p<0.01). Also, when analyzing landscape, mixed colonization several serotypes observed. As January 1, 2021, immune layer pathogen PI 81.7%. Monitoring S.pneumoniae strains circulating RT showed dominance vaccine (67.2%), which 44.4% are PCV13 serotypes. proportion non–vaccinated is 26%, untyped - 6.8%. Unvaccinated 35B (21.3%) 23A (13.6%) dominated vaccinated as well not included PKV-13 cocktail, but PPSV-23 polysaccharide used for namely 11AD (15.3%) 9LN (9.6%). unvaccinated on contrary, prevailed: 6ABCD (17.3%), 19F (20.9%), 11AD, 9LN, 35B, detected lower 11,8%, 10,0%, 4,2%, 7,3% accordingly. Conclusion. Data regional features can be basis expanding cocktail due dominant serotypes: 9LN,11 AD, 23A.