A study to define the microbiome of the asthmatic airway

Background: Asthma is generally well controlled but there is a subpopulation that remains uncontrolled. Recent research has shown that the airway is no longer sterile and has its own microbiome. The aim of our study was to characterise the lower airway microbiota in a cohort of well-defined asthmatics of varying disease severity and by doing so potentially identify alternate therapy strategies. Methods: We recruited 76 patients, stratified by asthma severity to our study (36% GINA 1 and 2; 22% GINA 3 and 42% GINA 4,5). All patients had a detailed clinical evaluation including ACQ-7, spirometry, and eosinophil levels prior to proceeding to bronchoscopy with bronchoalveolar lavage (BAL). Cell differential was performed on BAL, which was further evaluated for the presence of microbes using quantitative polymerase chain reaction (qPCR). Results: Microscopic evaluation of patient BAL demonstrated BAL macrophages (95%) containing numerous microbial species. qPCR demonstrated the presence of bacterial DNA in 71.8% of patients. Analysis found a significant difference between 16sDNA when patients were categorized as having BAL neutrophilia (>3%), (p Conclusions: Our results suggest that BAL neutrophilia is associated with the presence of microbes as well as markers of inflammation. These findings may prove a useful tool in future therapeutic strategies.