Bronchial and Systemic Relationships of Haemophilus in Chronic Obstructive Pulmonary Disease

The aim of the study was to assess the microbial composition of bronchial secretions in chronic obstructive pulmonary disease (COPD), focusing on the impact of the exacerbation patterns on the common components of the respiratory flora and their relationship with inflammatory proteins. A total of 72 clinically stable COPD patients provided sputum and blood samples for 16S rRNA gene amplification and peripheral biomarkers. Beta-diversity analyses of the bronchial microbiome showed significant differences between infrequent and frequent (≥2) exacerbators (p = 0.001). Haemophilus was underrepresented in frequent exacerbators (relative abundance [RA] 0.07 [0.003-0.31] vs. 0.24 [0.06-2.36], p = 0.02) while the presence of Pseudomonas was increased (7.70 [0.66-11.68] vs. 1.11 [0.37-2.88], p = 0.01). Eight common taxa, Prevotella, Moryella, Atopobium, Megasphaera, Parvimonas, Veillonella, Bulleidia and Selenomonas, showed significant decreases in their RAs when exacerbations required hospitalization. RAs of Haemophilus and eight common taxa were positively correlated (p < 0.01). Among them, Porphyromonas, Leptotrichia and Selenomonas showed a negative correlation with blood interleukin-8 (IL-8) (p < 0.01) and an equivalent correlation was found for Haemophilus parainfluenzae. Frequent exacerbations cause a decrease in the RA of Haemophilus and have a more extensive impact when hospitalization is required. The RAs of common bronchial bacteria were closely related and some of them were inversely associated with blood IL-8 levels.