RESUMEN
BACKGROUND: We investigated the pathogenesis of pneumococcal pneumonia using clinical specimens collected for pneumonia surveillance in The Gambia. METHODS: Lung aspirates and nasopharyngeal swabs from 31 patients were examined by culture, quantitative polymerase chain reaction (qPCR), whole genome sequencing, serotyping, and reverse-transcription qPCR. RESULTS: Five lung aspirates cultured pneumococci, with a matching strain identified in the nasopharynx. Three virulence genes including ply (pneumolysin) were upregulatedâ >20-fold in the lung compared with the nasopharynx. Nasopharyngeal pneumococcal density was higher in pediatric pneumonia patients compared with controls (Pâ <â .0001). CONCLUSIONS: Findings suggest that changes in pneumococcal gene expression occurring in the lung environment may be important in pathogenesis.