The Roles of Bacteria and Viruses in Bronchiectasis Exacerbation: A Prospective Study.

BACKGROUND: Exacerbations are crucial events during bronchiectasis progression. OBJECTIVES: To explore the associations between bacterial, viral, and bacterial plus viral isolations and bronchiectasis exacerbations. METHODS: In this prospective study, we enrolled 108 patients who were followed up every 3-6 months and at onset of exacerbations between March 2017 and November 2018. Spontaneous sputum was split for detection of bacteria (routine culture) and viruses (quantitative polymerase chain reaction). Symptoms and lung function were assessed during exacerbations. RESULTS: The median exacerbation rate was 2.0 (interquartile range: 1.0-2.5) per patient-year. At any visit, viral isolations (V+) occurred more frequently during onset of exacerbations [odds ratio (OR): 3.28, 95% confidence interval (95%CI): 1.76-6.12], as did isolation of new bacteria (NB+) (OR: 2.52, 95%CI: 1.35-4.71) and bacterial plus viral isolations (OR: 2.24, 95%CI: 1.11-4.55). Whilst coryza appeared more common in exacerbations with V+ than in exacerbations with no pathogen isolations and those with NB+, lower airway symptoms were more severe in exacerbations with NB+ (P<.05). Sputum interleukin-1ß levels were higher in exacerbations with NB+ than in exacerbations with no pathogen isolations and those with V+ (both P<.05). Significantly more coryza symptoms correlated with bacterial plus viral isolations at exacerbations (P=.019). Compared with V+ alone, bacterial with and without viral isolations tended to yield more severe lower airway symptoms, but not sputum cytokine levels at exacerbations. CONCLUSIONS: Viral isolations, isolation of new bacteria and bacterial plus viral isolation are associated with bronchiectasis exacerbations. Symptoms at exacerbations might inform clinicians the possible culprit pathogens.