Methods: We enrolled children from the emergency department with asthma exacerbations and children with cold symptoms (controls). We obtained nasal pharyngeal swabs, Asthma Control Tests (ACT), and modified Jackson criteria (MJC). To identify viral infections, we used targeted RNA hybridization-based genome detection methods that included 34 respiratory viruses. We sequenced the variable regions 4-6 of 16S ribosomal RNA gene. Clinical data was compared between viral-induced asthma, asthma, viral-induced colds, and colds. Microbiome data was used to determine if specific bacteria or diversity were associated with viral-induced wheezing.
Results: ACT scores were lower in asthmatics with virus compared to asthmatics without virus (med=17 vs. 20, respectively; p<0.05). Viral-induced asthmatics had worse lower respiratory symptoms by MJC than viral-induced colds control (med=8 and 4, respectively; p<0.05). We identified five microbiome profiles classified by dominant genus, Moraxella, Corynebacterium, Staphylococcus, Haemophilus, and Diverse. Controls were Moraxella-dominant in 52.9% and Diverse in 17.6%. Asthmatics were 27.6% Moraxella-dominant and 37.9% Diverse. The microbiome of asthmatics with respiratory syncytial virus (RSV) infection trended towards a greater number of species than the microbiome from subjects with other viruses (mean 362 (RSV) vs. 276 (Other viruses); p=0.055).
Conclusions: Viral-induced asthma exacerbations are more likely to occur in children with less overall asthma control. Lower respiratory symptoms are more pronounced in asthmatics with viruses than in controls. Asthmatics tend to have a more diverse nasopharyngeal microbiota.