Viruses are commonly identified in the exhaled breath of adults with stable bronchiectasis

Introduction: Bronchiectasis is characterised by bacterial airway colonisation. The role of viruses in the aetiology of bronchiectasis, progression of airway inflammation and exacerbations is less clear. Exacerbations are strongly associated with symptom burden, disease progression and loss of lung function. Aim: This study aimed to investigate how frequently, common respiratory viruses could be identified in patients with stable non CF-bronchiectasis. Methods: Adult patients (n=13) diagnosed with clinically stable bronchiectasis were recruited, alongside healthy controls (n=10) who completed spirometry and provided a nasal washing or sputum sample. We looked for four common viruses (human rhinovirus, respiratory syncytial virus, influenza A and influenza B) in respiratory secretions and exhaled breath collected in filters from spirometry mouthpieces, using RT-PCR. Results: 92% (12/13) of patients with bronchiectasis, compared with 70% (7/10) of healthy controls had detectable virus in either exhaled breath or nasal washing/sputum samples. The bronchiectasis group had significantly higher detection rates of rhinovirus and influenza A compared with controls (p<0.05). Two or more viruses were detected concurrently in 78% of patients with bronchiectasis compared to 10% of healthy controls. Discussion: In this cross–sectional study we found asymptomatic viral infections occur frequently in patients with bronchiectasis. We speculate that chronic infection may be the result of a dysfunctional innate immune response in bronchiectasis.