176. THE COMPOSITION OF THE HUMAN NASAL MICROBIOME IN GRANULOMATOSIS WITH POLYANGIITIS: A PILOT STUDY

Abstract

Background: Granulomatosis with polyangiitis (GPA, formerly Wegener's granulomatosis) is a multi-system disease predominantly affecting the ear, nose and throat (ENT) tract, the lower respiratory tract and the kidneys. A role for Staphylococcus aureus nasal colonization in GPA has been proposed and thus we undertook a study to determine the role of the nasal microbiome in GPA. Method(s): We investigated the nasal microbiome by culture, bacterial 16S rRNA profiling, and shotgun metagenomic sequencing in patients with either active or inactive GPA, disease controls (microscopic polyangiitis or eosinophilic GPA), healthy healthcare professionals and healthy household controls. Result(s): Presence of S. aureus as assessed by nasal culture could be detected in eight out of 12 active GPA patients (66.7%), which was more frequent compared to inactive patients (34.1%). Beta-diversity analysis revealed significant differences in the abundance of staphylococcal species between active GPA and healthy controls (p=0.0007) and disease controls (p=0.0023), while a correlation between S. aureus and active disease (p=0.0075) could be observed by Spearman correlation analysis. The presence of Staphylococcus epidermidis was associated with healthy controls (p=0.042). Staphylococcus pseudintermedius, generally assumed to be a dog-and cat-pathogen, showed an abundance of 13.01% among Staphylococci. Conclusion(s): Our study offered new insights into the complex nasal microbiome of patients with GPA. We observed an association between active disease and S. aureus. Longitudinal studies are necessary to investigate the potential relationship of microbiome changes on the relapse rate of patients with GPA.