Pragman AA, et al. - Among patients with chronic obstructive pulmonary disease (COPD), researchers focused on the main characteristics that distinguish the oral and sputum microbiota of frequent exacerbators (FEs) from the microbiota of infrequent exacerbators (IEs) during periods of clinical stability. This study included 11 FE and 11 IE. The participants had not consumed antibiotics or systemic corticosteroids in the last 1 month. In the sputum samples from FE vs those from IE, more Haemophilus and Moraxella were present, because of dominance of these COPD-related taxa in three FE sputum samples. Findings revealed less diverse oral and sputum microbiota in FE than IE. In IE sputum, significantly more abundance of Actinomyces was seen, compared with FE sputum. The oral and sputum microbiota of COPD individuals cluster based on multiple clinical factors, including exacerbation phenotype. Decreased alpha diversity, beta-diversity clustering, and shifts in taxonomic abundance were reported in relation to the frequent exacerbator phenotype, even during periods of clinical stability.