Relationship between COPD characteristics and airway bacterial load measured using 16S qPCR

Introduction: Quantitative PCR of the bacterial 16S rRNA gene provides accurate quantification of the airway microbiome. The relationship between this and disease characteristics have not been fully described in COPD. Aim: To examine the associations of total airway bacterial load with disease characteristics and inflammation in patients with stable COPD. Method: Patients with stable COPD and FEV1 Results: 71 patients were included for analysis; overall mean(SD) bacterial load was 9.22(0.77) log 10 copies/g sputum. There was no relationship to clinical characteristics including smoking status, FEV 1 disease severity and exacerbation frequency. There was a significant correlation between bacterial load and airway inflammation (IL-1β; r=0.311, p=0.009 [Figure 1]). When stepwise multivariate regression was used to fit a model for airway bacterial load, only increasing IL-1β emerged as an independent predictor. Conclusion: Total airway bacterial load is significantly related to airway inflammation but not to clinical measures of disease severity. The relationship with the detailed composition of the airway microbiome requires further investigation.