Classroom Microbiome Signatures of Pest Management Associate with Reduced Asthma Symptoms.

BACKGROUND: Integrated pest management (IPM) is thought to improve asthma symptoms through reduced mouse allergen exposure. Whether IPM acts through changes in mouse-associated microbes remains unknown. OBJECTIVES: To examine the effects of school-based IPM on the classroom microbiome, and to determine the association between intervention microbiome signatures and student asthma morbidity. METHODS: In this ancillary study based on a randomized placebo-controlled clinical trial of school IPM and classroom high efficiency air purifiers (ClinicalTrials.gov NCT02291302), we performed deep metagenomics sequencing of longitudinally collected dust samples from 208 classrooms in 41 schools of 236 children with active, physician-diagnosed asthma with prospective follow-up of asthma severity during the school year. We assessed the effect of the interventions on classroom microbial communities in intention-to-treat analyses. Sparse Partial Least Squares models were used to identify microbial signatures of the interventions and the association between these microbial signatures and asthma morbidity was assessed using mixed effects models, controlling for covariates including mouse allergen exposure. RESULTS: IPM significantly altered classroom bacterial and phage community structure and increased bacterial, archaeal, and fungal diversity. A classroom microbiome signature of IPM was identified (AUC=0.84) and was associated with lower odds of any asthma symptom days in the past two weeks (OR 0.47, 95% CI [0.22, 0.97], p=0.043) and lower Composite Asthma Severity Index (β -0.92, 95% CI [-1.51, -0.33], p=0.002), adjusting for mouse allergen levels and student characteristics. CONCLUSION: IPM-associated changes in the classroom microbiome are associated with lower asthma morbidity independent of mouse allergen exposure.