Association between exacerbation history and airway microbiota assessed by extended bacterial culture and metagenomic approaches in stable COPD

Background. Chronic obstructive pulmonary disease (COPD) is a heterogeneous lung condition characterized by chronic respiratory symptoms due to abnormalities of the airways and/or alveoli that cause airflow obstruction. It is a leading cause of death worldwide. While alterations in airway microbiota have been linked to exacerbation frequency, the underlying mechanisms remain unclear. Methods. This study investigated the associations between airway microbiota composition in stable COPD patients and exacerbation history. Sixty-two stable COPD patients were enrolled and categorized into two groups based on their exacerbation history: low risk (LR) and high risk (HR) of exacerbation. Sputum samples were collected and analyzed using both bacterial extended culture and 16S rRNA metagenomics. The combination of these approaches provided complementary insights, enabling a more comprehensive characterization of the microbiota. Results. Microbial composition analysis revealed a loss of α-diversity in HR patients. This group also exhibited increased abundances of Pseudomonadota and Bacteroidota, alongside a marked decrease in the proportions of Lactobacillus and Streptococcus. Notably, significant reductions were observed at the species level for Streptococcus salivarius and Streptococcus mutans. A comparison of the two methods underlined that 16S rRNA metagenomics identified five additional phyla and 84 genera not detected by culture, notably strict anaerobes. However, extended culture demonstrated robust sensitivity in detecting Enterobacterales and the pathogenic Moraxella and Pseudomonas. Conclusion. This study revealed microbiological characteristics linked to exacerbation history in stable COPD patients, highlighting the need for future functional and longitudinal research to validate these airway microbiota features and develop targeted preventive strategies.