Serotype composition of Streptococcus pneumoniae in children with respiratory infections, optimization of molecular assessment methods

The paper presents optimized methods for PCR and sequence typing of Streptococcus pneumoniae. The serotype composition of pneumococci isolated from children under 5 years of age with infections of the upper respiratory tract was analyzed using optimized methods. Between 2016 and 2021, there was a decrease in the frequency of serotypes included in the pneumococcal 13-valent conjugate vaccine (PCV13) from 94.1 to 25.8%, mainly due to the 6ABCD serogroup and the 19F serotype. The coverage of serotypes circulating in children with PCV15 and PCV20 vaccines was 28.1% and 41.6% in 2021, respectively. During the study period, the number of non-vaccine serogroups 11AD and 15AF, as well as serotypes that are not detected under this capsular PCR typing protocol, increased most significantly.