SAMSAM

Respiratory tract infections (RTI) are a major cause of morbidity in young children in high-income countries and the major cause of mortality in developing countries. The aetiology of lower RTI (LRTI) is often polymicrobial, involving well-known viral or bacterial pathogens or combinations of both. LRTI pathogens all originate in the nasopharynx. Usually these bacteria are regular residents of the nasopharynx of asymptomatic individuals and live there together with other presumed harmless commensals, without causing disease. Together they are a complex bacterial community, called the nasopharyngeal (NP) bacterial microbiome. In addition to bacteria, viruses are also found in the nasopharynx during respiratory tract infection and in asymptomatic individuals. These infections are important for transmission, intermediate step to disease and boost immune responses. Such infections are extremely dynamic, but very few studies have been able to characterize them due to the discomfort related to classical sampling methods, such as nasopharyngeal swabs (NPS). We recently validated the use of minimally-invasive nasal sampling methods that can be done at home for the study of host and microbial parameters in adults and children. In this study we will focus on the daily microbial and immunological composition of the nasopharynx during health in relation to symptoms.

Our hypothesis is that children who become colonized with Streptococcus pneumoniae have low levels of PS-specific memory B cells at the time of exposure.

Daily sampling for 28 consecutive days