Decrease in Diversity of Nasal Microbiota during Wheezing Episodes in Preschool Children

T U E S D A Y 890 Decrease in Diversity of Nasal Microbiota during Wheezing Episodes in Preschool Children Gorka Alkorta-Aranburu, PhD, Catherine Igartua, Emily R. Davenport, Katherine Naughton, So Watanabe, MD, PhD, Yoav Gilad, PhD, Robert F. Lemanske, Jr, MD, FAAAAI, David M. Mauger, PhD, Carole Ober, PhD, Daniel J. Jackson, MD, Jayant M. Pinto, MD; The University of Chicago, Showa University, Toyko, Japan, University of Chicago, University of Wisconsin School of Medicine and Public Health, Madison, WI, Penn State University College of Medicine, Hershey, PA, University of Chicago, Chicago, IL, Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, WI, The University of Chicago, Chicago, IL. RATIONALE: Wheezing episodes are responsible for significant morbidity in children and are closely associated with respiratory tract infections (RTIs).We hypothesized that the composition of airway bacteria would be altered during these illnesses. METHODS: Using DNA from nasal lavage samples prospectively collected in the Maintenance and Intermittent Inhaled Corticosteroids in Wheezing Toddlers (MIST) clinical trial, we sequenced the 16S rRNA gene (V4 region) to analyze the bacterial microbiome of 33 children at baseline and during RTI. 160,000 sequence reads per sample were subsampled at random and classified using Mothur (RDP database) in order to generate standard ecologic metrics and identify the abundance of specific bacteria. RESULTS: Among the 18 males and 15 females (mean age 36 months), a majority had allergic sensitization (51.5%) or a parent with asthma (57.6%). Microbial diversity was significantly decreased during RTIs (Shannon Index 1.17 vs. 0.71, P50.018), particularly episodes severe enough to be treated with oral corticosteroids. The relative abundance of the phyla Bacteroidetes and Fusobacteria were lower during RTIs (Bonferroni P 0.01). CONCLUSIONS: Severe RTIs are associated with decreased bacterial diversity in the upper airway, indicating that the composition of nasal microbiota may influence wheezing episodes. Future studies should define the role of specific bacterial populations in these episodes. The nose is an accessible site to assess these relationships.