House dust microbiota in relation to adult asthma and atopy in a US farming population.

BACKGROUND: Bacterial exposure from house dust has been associated with asthma and atopy in children but whether these relationships are present in adults remains unclear. OBJECTIVE: We sought to examine associations of house dust microbiota with adult asthma, atopy, and hay fever. METHODS: Vacuumed bedroom dust samples from the homes of 879 participants (average age, 62 years) in the Agricultural Lung Health Study, a case-control study of asthma nested within a farming cohort, were subjected to 16S rRNA amplicon sequencing to characterize bacterial communities. We defined current asthma and hay fever using questionnaires and current atopy by blood specific IgE level > 0.70 IU/mL to 1 or more of 10 common allergens. We used linear regression to examine whether overall within-sample bacterial diversity differed by outcome, microbiome regression-based kernel association test to evaluate whether between-sample bacterial community compositions differed by outcome, and analysis of composition of microbiomes to identify differentially abundant bacterial taxa. RESULTS: Overall diversity of bacterial communities in house dust was similar by asthma status but was lower (P < .05) with atopy or hay fever. Many individual bacterial taxa were differentially abundant (false-discovery rate, <0.05) by asthma, atopy, or hay fever. Several taxa from Cyanobacteria, Bacteroidetes, and Fusobacteria were more abundant with asthma, atopy, or hay fever. In contrast, several taxa from Firmicutes were more abundant in homes of individuals with adequately controlled asthma (vs inadequately controlled asthma), individuals without atopy, or individuals without hay fever. CONCLUSIONS: Microbial composition of house dust may influence allergic outcomes in adults.