81 The concordance between the microbiome of the upper and lower respiratory tract is investigated in infants with cystic fibrosis

Abstract

Background Nasopharyngeal (NP) and oropharyngeal samples (OP) are commonly used to direct therapy for lower respiratory tract (LRT) infections in non-expectorating infants with Cystic Fibrosis (CF). The level of concordance between microbiota of the upper respiratory tract (URT) and LRT in young children is, however, largely unknown. Objective To examine the concordance between URT and LRT microbiota in infants with CF. Methods Paired bronchoalveolar lavage fluid (BAL), NP and OP samples were longitudinally collected from 17 CF patients at the age of 3 and 12 months. We studied the concordance between the URT and LRT microbial communities by 16S-rRNA-based sequencing. Results Bacterial diversity is lower in NP compared to the OP and BAL samples. On group level, OP microbiota profiles showed more similarity with BAL microbiota compared to NP microbiota. However, potential pathogens like staphylococci , Moraxella and Haemophilus influenzae were almost exclusively observed in the NP but not in OP. Moreover, intraindividual concordance between both NP and OP microbiota profiles and paired BAL microbiota was limited. Conclusion At a population level, OP microbiota profiles resemble lung microbiota more closely than NP microbiota, however, potential respiratory pathogens are often detected in NP but not in OP samples. More importantly, within-individual concordance between the URT and LRT microbiome in CF patients is limited, restricting the diagnostic value of URT sampling during LRT infections in infancy. Whether microbiota profiling of BAL samples will indeed more reliably guide treatment of infections in CF infants compared to conventional culture remains to be studied.