The Nasal microbiome in a large series of chronic rhinosinusitis patients: analyzing the effect of atopy and bacterial pathways of invasion. human nasopharyngeal metagenome

Introduction: Chronic rhinosinusitis (CRS) is a chronic debilitating disease that is the result of complex, interrelated, infectious and inflammatory mechanisms. Therefore, understanding why and how the bacterial community (the microbiome) contributes to this disease is of the utmost importance. Currently, there is a significant lack of consistency with regard to nasal microbiome results in CRS and control patients, which has been attributed to the diversity in methodology of these previous studies as well as their small sample sizes.Methods: In this study we enrolled a large number of CRS patients and controls, and used a unified method for sampling the middle meatus to analyze the bacterial communities. Microbiomes of CRS patients and controls were compared. The effects of multiple CRS-related and comorbid conditions on the microbiome were assessed. Furthermore, we used a novel statistical model to group and compare the nasal microbiome in CRS patients and controls based on a PICRUSt approach to molecular pathways of metabolism and invasion.Results: We studied 111 CRS patients and 21 healthy control subjects. Diversity and abundance of the bacterial community were similar for CRS and control groups. Analyses of different operational taxonomic units (OTUs) showed that CRS patients have, compared to control subjects, significantly lower relative abundance of Actinobacteria (at the phylum level), Corynebacterium and Peptoniphilus (at the genus level). Allergic rhinitis, eczema and asthma were associated with changes in the nasal microbiome. PICRUSt analyses showed that the bacterial community in CRS has a significantly increased abundance of bacteria with the capability of invading the epithelium and higher lipopolysaccharide biosynthesis proteins. Among CRS cases, patients with allergic rhinitis had greater abundance of bacteria with high lipopolysaccharide biosynthesis proteins compared to non-allergic patients.Conclusion: Atopic diseases are linked to changes in the nasal microbiome in CRS at both taxonomic and functional levels.