Do lower airway infections occur concomitant or subsequent to upper airway infections in children with primary ciliary dyskinesia (PCD)?

Abstract

<b>Introduction:</b> PCD&nbsp;is characterised by recurrent upper(UA) and lower airway(LA) infections. While concomitant UA and LA infections have been described, it is not currently known whether UA infections predict LA infection. <b>Aim:</b> To investigate&nbsp;temporal relationships between UA and LA infections in a longitudinal cohort of children with PCD. <b>Method:</b> We analysed microbiological surveillance data from UA samples (sinus rinse, nasal rinse, nose swab) and LA samples (sputum, cough swab, BAL) in children followed up by the Central England PCD management service from 2014 to 2021. An identical LA isolate simultaneous to an UA isolate was termed concomitant infection while subsequent infection was defined as&nbsp;isolation from LA within a 6 month period. The frequency of concomitant and subsequent infections were statistically compared to baseline frequency. <b>Results:</b> We analysed 827 LA samples and 342 UA samples from 58 children (age 0.7 - 18.3 y). Concomitant infections of UA and LA was significantly higher than baseline frequency whereas subsequent LA infections were similar to baseline (table) <b>Table</b>-Frequency (%) of pathogen isolates *p&lt;0.001 <b>Conclusion:</b> We did not find evidence of subsequent infections of LA, therefore there was no evidence of seeding from UA to LA. However, concomitant infections were very frequent, which is important in children where LA samples can often be of poor quality.