A decade of lower respiratory sampling in paediatric PCD

<bold>Background:</bold> Lower respiratory tract (LRT) sampling forms an integral part of our clinical assessment process as recognised by the BEAT PCD ERS statement for infection prevention & control. <bold>Aims:</bold> To evaluate the quality, frequency, & microbiological yield of LRT sampling in a paediatric PCD population. <bold>Methods:</bold> A single centre retrospective cohort study of all LRT samples collected between April 2013 & April 2023. <bold>Results:</bold> 1197 samples were evaluated from 68 pts. 53% of which were sputum/induced sputum/tracheal samples. Haem I. was the most common bacteria isolated by 60% of pts at some point in the 10yr study period, followed by Pseud A. (20%) and Staph A. (15%). Pathogens were more commonly seen in pts with lower lung function, complex disease & those with increasing age. The percentage of pts achieving the target frequency of sampling ranged from 46-80% (2019-20=80%, 2020-21=46%) & we observed a rising trend of more frequent sampling over the study duration. Increasing numbers of sputum samples were sent for mycobacterial culture over time (0% in 2013-14, 71% in 2022-23). No pt had a positive mycobacterial culture result. Sub-group analysis of paired samples (sputum & cough swab/plates collected at the same clinic visit, n=91) demonstrated superiority of sputum samples in providing a positive microbiological yield. <bold>Conclusions:</bold>LTR sampling in paediatric PCD remains challenging particularly in non-expectorating pts, where induced sputum should be considered. Microbiological surveillance through frequent LTR sampling is essential for infection control, prevention & management of pulmonary exacerbations. Further studies characterising longitudinal microbiological trends & their link with outcomes in PCD are needed.