Antibiotic resistance of Streptococcus pneumoniae isolated from children in Moscow before and after the introduction of 13-valent pneumococcal conjugate vaccination

Abstract

Introduction. The formation and spread of antibiotic-resistant Streptococcus pneumoniae isolates is a concern. After the thirteen-valent pneumococcal conjugate vaccine (PCV13) was added to the children’s immunization program in Russia in 2014, an important task is to monitor the resistance level to antimicrobials and the spectrum of circulating antibiotic-resistant pneumococcal serotypes. Materials and methods. The study included 708 nasopharyngeal pneumococcal isolates from children patients under 5 years who recovered from 2010 to 2018, received inpatient and outpatient care at the National Medical Research Center for Children’s Health (Moscow). The determination of sensitivity to antimicrobials was performed by the disk diffusion method. The MICs of penicillin, amoxicillin, and erythromycin were determined using the E-test method. Evaluation of the results was carried out according to the EUCAST-2019 criteria. Results. In total, 33 different serotypes were identified in the S. pneumoniae collection. Six predominant serotypes accounted for 68.6% of the total distribution and included serotypes: 19F, 6B, 23F, 14, 15B/C, 6A. In general, antimicrobial resistance ranged from 3.5% to chloramphenicol to 54.8% to tetracycline. The level of resistance to oxacillin, erythromycin, and clindamycin increased by 15-20% between 2010 and 2018. However, since 2016, there has established a prevalence level of 40-46%, this process is offset by an increase in the proportion of non-vaccine pneumococcal serotypes. Conclusion. A high level of resistance to penicillin and erythromycin remains. Monitoring the resistance level to antibiotics and the epidemiology of serotypes, clarifying the laws of formation of resistance, and its spread in a dynamically changing pneumococcal population is an important area of microbiology.