Characteristics of healthy sinonasal microbiome - single-centre study in the Czech Republic.

Introduction: The human nasal cavity and paranasal sinuses host a complex and dynamic microbiome which has a crucial role in mucosal immunity. A comprehensive profile of the healthy sinonasal microbiome remains limited. The purpose of our study was to characterize the healthy sinonasal microbiome in adults using 16S rRNA long-read sequencing to enable species-level resolution, and to assess its associations with demographical and clinical factors such as smoking, allergy history, and olfactory function.

Study design: We performed a prospective, single-centre study analysing middle meatus samples from 27 healthy individuals undergoing septoplasty in the age range from 21 to 57 years, excluding those with antibiotic and corticosteroid use and those with signs of acute or chronic rhinosinusitis.

Results: A high interindividual variability in the composition of healthy sinonasal microbiome was observed. At the phylum level, it was dominated by Firmicutes (48.96%), Actinobacteria (34.83%), and Proteobacteria (13.85%), while Firmicutes and Actinobacteria were consistently present in all samples. At the genus level, Staphylococcus spp. (32.32%), Cutibacterium (28.04%), and Corynebacterium (4.66%) were most abundant. We observed trend level correlations between phyla and some clinical factors (e.g., smoking and olfactory dysfunction) and selected phyla. However, none remained significant after false discovery rate (FDR) correction across taxa.

Conclusion: The study proposes Staphylococcus spp., Corynebacterium spp., and Cutibacterium spp. to be a core taxa in the healthy sinonasal microbiome. Amid the interindividual diversity in our cohort, there was evidence of a stable core microbiome potentially influenced by environmental and host factors. Our findings suggest a baseline reference for distinguishing a dysbiosis in upper respiratory disease.