FIG 1.

Proportion of carriage-positive volunteers detected by bacterial culture or quantitative PCR (qPCR) over time. For detection by culture, nasal wash samples were plated on blood agar with gentamicin. For qPCR detection, nasal wash was added to RNAprotect and frozen until DNA extraction. A volunteer was considered to be positive by culture (white bar) if Gram-positive, α-haemolytic, optochin-sensitive colonies were detected after 48 h. Serotype was confirmed by latex agglutination. The target gene for qPCR was lytA. Samples with a Ct value of <40 were considered to be qPCR-positive (black bar). The number of samples analysed is indicated above each time-point. *Statistical significance (p ≤0.05)