Narrative Review of the Bacterial Profile Involved in Severe COPD Exacerbations Complicated by Pneumonia in Patients Admitted to the Intensive Care Unit

Chronic obstructive pulmonary disease (COPD) is a chronic progressive respiratory disease characterized by respiratory symptoms and airflow limitation and is one of the leading causes of morbidity and mortality worldwide. The evolution of the disease is associated with episodes of acute exacerbations (AECOPD), characterized by worsening symptoms and accelerated deterioration of lung function. Acute exacerbations of COPD have different severity, being mild, moderate or severe depending on how aggravated the patients’ symptoms are, but they also depend on pulmonary functional and biological changes. Around 70% of AECOPD cases are infectious in nature, through upper or lower respiratory tract infections. Often, exacerbations associated with lower respiratory tract infections are more severe and have a higher risk of unfavorable outcome compared to AECOPD associated with upper respiratory tract infections. Severe exacerbations require hospital management, with most of them being treated in the intensive care unit (ICU). In this narrative review, we evaluated the frequency of different bacterial pathogens involved in severe COPD exacerbations associated with lower respiratory tract infections and the need for treatment in the ICU. Identifying patients with exacerbated COPD at high risk of respiratory infections, especially with Gram-negative bacilli, is extremely important to choose the optimal treatment, thus reducing the risk of death.