ACQUISITION AND INVASIVENESS OF DIFFERENT SEROTYPES OF STREPTOCOCCUS-PNEUMONIAE IN YOUNG-CHILDREN

Rates of acquisition and mean duration of nasal carriage of different serotypes of Streptococcus pneumoniae have been estimated by fitting a stochastic model to longitudinal carriage data in children from Papua New Guinea. Immunogenicity and two indices of relative invasiveness w ere determined for each serotype. Immunogenic serotypes were less freq uently acquired and were carried for shorter periods, but no relations hip between immunogenicity and invasiveness was apparent using either index of invasiveness. Frequent invasion was associated with a high ac quisition rate and high frequency and prolonged duration of carriage. Carriage studies can provide a broad indication of which serotypes cau se invasive disease but not the proportion of disease due to individua l serotypes; some serotypes which cause invasive disease (e.g. serotyp e 46) are not found even in extensive carriage studies. The antibiotic resistance of carriage organisms, however, does approximate the resis tance patterns of invasive organisms and thus may be used to monitor c hanging patterns of antimicrobial susceptibility in the community.