Bacterial Pathogens and Biomarkers in Chronic Obstructive Pulmonary Disease (COPD): A Comprehensive Review

Abstract

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide, characterized by persistent airflow limitation and a chronic inflammatory response in the airways and lungs. While the primary etiological factor is exposure to cigarette smoke, the role of bacterial pathogens and the resident lung microbiome in the pathogenesis, progression, and acute exacerbations of COPD is increasingly recognized. This review synthesizes current knowledge on the most prevalent bacterial species implicated in COPD, including Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, and Pseudomonas aeruginosa. It explores how changes in the lung microbiome contribute to a pro-inflammatory state and discusses the clinical utility of key biomarkers, such as C-reactive protein (CRP), procalcitonin (PCT), and various inflammatory cytokines. We review the evidence supporting the use of these biomarkers for guiding antibiotic therapy, differentiating infectious from non-infectious exacerbations, and predicting patient outcomes. Finally, this article highlights the challenges and future directions in this field, emphasizing the need for a deeper understanding of host-pathogen interactions to facilitate the development of personalized, precision medicine approaches for COPD management.