|dc.description.abstract||Background: Streptococcus pneumoniae (SPn) serotype replacement and
emergence of multidrug resistant SPn has exacerbated the need for continuous
regional serotype surveillance. We investigated SPn 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 SPn 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 SPn. About 52% (n=22) of the SPn 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 SPn
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 SPn serotypes isolated from the subjects sampled were non
PCV-10 vaccine type. Therefore Kenyan children receiving PCV-10 vaccine are