Streptococcus pneumoniae serotype epidemiology among PCV-10 vaccinated and unvaccinated children at Gertrude's Children's Hospital, Nairobi County: a cross-sectional study.

Michael Walekhwa,Beatrice Kabera,Margaret Muturi,Eucharia Kenya,Revathi Gunturu

doi:10.12688/f1000research.14387.1

Michael Walekhwa, Beatrice Kabera + Show 3 more

Open Access

https://doi.org/10.12688/f1000research.14387.1

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Abstract

Background:Streptococcus pneumoniae (SP n) serotype replacement and emergence of multidrug resistant SP n has exacerbated the need for continuous regional serotype surveillance. We investigated SP n serotypes circulating among children ≤5 years in Nairobi County. Methods:Streptococcus pneumoniae stocks stored at -70°C in brain heart infusion medium were thawed at room temperature for 30 minutes. In total, 10 µl of the stored SP n cells were suspended in 50 µl PBS and gently vortexed. About 10 µl of the suspended cells were added on to a glass slide and mixed with 10 µl pooled antisera. The glass slide was swirled gently while observing for any reaction. The process was repeated with individual groups under various antisera pools. Those serotypes that did not belong to any pool were typed directly until a positive agglutination reaction was observed. The cells/PBS/serotype-specific antisera mixture on the glass slide were covered with a coverslip and observed under a phase contrast microscope at ×100 objective lens with oil emulsion. Results: Out of the 206 subjects sampled, 20.39% (n=42) were found to be carriers of SP n. About 52% (n=22) of the SP n carriers 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 type SP n serotypes, 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: All SP n serotypes isolated from the subjects sampled were non PCV-10 vaccine type. Therefore Kenyan children receiving PCV-10 vaccine are not protected.

Highlights

Streptococcus pneumoniae (SPn) is a highly invasive, Grampositive, extracellular bacterial pathogen (Mitchell & Mitchell, 2010)
Given the high burden of under-five mortality associated with pneumonia, control efforts are critical to achieving Sustainable Development Goal 3 (Colglazier, 2015)
Subjects were clinically assessed by a physician and those who presented with pneumococcal disease symptoms recommended to the study nurse for recruitment

Summary

Introduction

Streptococcus pneumoniae (SPn) is a highly invasive, Grampositive, extracellular bacterial pathogen (Mitchell & Mitchell, 2010). It is a major cause of morbidity and mortality globally, causing more deaths than any other infectious disease (Jones et al, 2010). The process was repeated with individual groups under various antisera pools Those serotypes that did not belong to any pool were typed directly until a positive agglutination reaction was observed. The cells/PBS/serotype-specific antisera mixture on the glass slide were covered with a coverslip and observed under a phase contrast microscope at ×100 objective lens with oil emulsion. It needs to be indicated that circulating SPn serotypes are being investigated after the introduction of 10-valent pneumococcal conjugate vaccine (PCV10) in 2011.

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