LAUSR

Background Changes in the gut microbiome can affect the incidence of wheeze and bronchiolitis. There is little evidence in regard to the association between enteric viral populations and their potential effects on respiratory health. Methods In a prospective cased-controlled study we recruited over two bronchiolitis seasons (2016–2019) children (0–10years) admitted to a tertiary hospital with a diagnosis of bronchiolitis (<1year old) or viral induced wheeze along with healthy age-matched control patients, excluding those with acute/chronic gastrointestinal conditions. Assays for 15 different viruses (Entero, Parecho, FluA/B, RSV, Adeno, Myco, PFlu1/2/3, MPV, Rhino, Nora, Rota, Boca) were performed by real-time PCR on nucleic acid extracted from stool samples during the illness. Results Stool samples from 43 children with wheeze, 64 with bronchiolitis, and 87 controls were analysed. Viruses were detected significantly more frequent in stool of children with wheeze (7.1% wheeze, 3.7% controls, p<0.005) and bronchiolitis patients compared to controls (66.3% bronchiolitis, 33.7% controls, p<0.001). Rhinovirus was the most prevalent virus in both patient groups reaching significance in those with wheeze compared to controls (32.6% wheeze, 11.8% controls, p=0.02). Influenza A was detected significantly more frequently in the stool in the control compared with the bronchiolitis group (0% bronchiolitis, 16.7% controls, p<0.005). Discussion Respiratory viruses can be identified in the GI tract of patients during acute paediatric respiratory illnesses such a bronchiolitis and exacerbation of wheeze. Although this may represent gut seeding from the respiratory tract there were significant differences between the cohorts included in this study. Disease severity and outcome may be influenced by ‘gut priming’ of the immune system by viruses, and further exploration by deep genome sequencing analysis is indicated to enhance our knowledge of the gut-lung-axis.