Streptococcus pneumoniae Serotype Epidemiology among PCV-10 Vaccinated and Unvaccinated Children at Gertrude’s Children’s Hospital, Nairobi County: A Cross-Sectional Study

Abstract

Background: Serotype replacement and emergence of multidrug resistantS. pneumoniaehas exacerbated the need for continuous regional serotype surveillance especially in the developing world. We investigatedS. pneumoniaeserotypes circulating among vaccinated and unvaccinated children ≤5 years in Nairobi County post PCV10 era.Methods: A total of 206 vaccinated and unvaccinated children attending Gertrude’s Children’s Hospital (GCH) were recruited for this study. Nasopharyngeal swabs collected using Copan Flocked Swabs were the main study specimen. Culturing and isolation ofS. pneumoniaewas done on BA with gentamicin and BA plates respectively at the GCH main laboratory. Serotyping was done using the Quellung reaction at the KEMRI-Wellcome Trust, Kilifi. Results: Out of the 206 subjects sampled, 20.39% (42) were found to be carriers ofS. pneumoniae. About 52% (n=22) of theS. pneumoniaecarriers had received the recommended dose of PCV-10, while 48% (n=20) of the carriers had not. Almost all (n=41; 19.90% of subjects) isolates contained non-vaccine typeS. pneumoniaeserotypes, while n=1 of the serotypes (in 0.49% of subjects) were untypeable. Serotypes 28F, 6A, 11A, 3 and 7C were prevalent in both vaccinated and unvaccinated children, whereas serotypes 23A, 17F, 35F, 48, 13 and 35B, and 23B, 20, 19B, 21, untypeable, 15B and 39 were found among unvaccinated and vaccinated groups, respectively.Conclusions: AllS. pneumoniaeserotypes isolated from the subjects sampled were non PCV-10 vaccine type. These results therefore highlight the importance of monitoring and evaluation to provide epidemiological information to determine the effectiveness of PCV10 in Kenya’s Public health services.