METHODS: Induced whole sputum of 20 healthy adult subjects and 86 adult asthmatics were obtained. The V3-4 hypervariable region of the bacterial 16S rRNA gene was amplified. Bacterial DNA library data were prepared by sequencing amplicons with the MiSeq v3 platform (Illumina®). Data sets were cleaned and analyzed using QIIME and Ezbiocloud 16S database. Cluster dendrogram was constructed using weighted UniFrac distance data. Chi-square test or Kruskal-Wallis rank sum test was used for analyzing categorical or continuous variables, respectively.
RESULTS: When clustering into two groups (1 and 2) based on UniFrac method, the proportion of several clinical variables were significantly different between groups; high dose inhaled corticosteroid (ICS) (41.2% vs 20.8%, p = 0.043), antibiotics use within six months (35.3% vs 8.3%, p = 0.002), chronic rhinosinusitis (CRS) (55.9% vs 20.8%, p = 0.0007), nasal polyps (17.6% vs 1.4%, p = 0.006). While group 1 had dominancy of Streptococcus, group 2 showed abundant Prevotella. Group 2 showed relatively longer duration of asthma (11.15 years vs. 6.38 years, p = 0.002) and lower asthma control test score (16.5 vs. 19.9, p = 0.045).
CONCLUSIONS: Clinical variables such as the use of high dose ICS, antibiotics use, CRS, duration of asthma, and asthma control seems to be related with characteristics of airway microbiota.