Urine Pneumococcal Antigen Project

Background: Pneumonia caused by the bacteria Streptococcus pneumoniae is a leading cause of death among children under five years of age, especially in sub-Saharan Africa. Accurate diagnosis remains challenging due to the need for invasive procedures to obtain samples for culture-based diagnostic tests, which are not very sensitive for detecting S.pneumoniae, particularly after antibiotic use. Serotype-specific urinary antigen detection (ssUAD) assays are a promising, non-invasive alternative for the surveillance and diagnosis of pneumococcal disease. Importantly, they can identify different serotypes of S.pneumoniae, which is crucial for monitoring vaccine impact. However, the ability of the ssUAD to identify invasive disease due to S.pneumoniae has not been studied in children in sub-Saharan Africa, where high rates of asymptomatic carriage may affect diagnostic accuracy. Aim: The overall aim of this study is to evaluate the performance of the ssUAD test to detect pneumococcal carriage, and distinguish it from invasive disease, among children under five years old in Blantyre, Malawi. Methods: This study will test 350 existing urine samples that have already been collected from children as part of the NP Resistome study (LSTM reference 24-076), including healthy children in the community, children with pneumonia in the community, and children hospitalised with pneumonia. Participants of the NP Resistome study will be recruited from Ndirande Health Centre (NHC), Gateway Primary Care Centre (GPCC) and Queen Elizabeth Central Hospital (QECH) in Blantyre, Malawi. Aliquots from each urine sample will be tested using the ssUAD in the UK, as the assay is not currently available in Malawi. Urinary detection of pneumococcal serotypes will be compared with both culture-based and metagenomic sequencing results from nasopharyngeal swab samples taken as part of the main study.