Lung Microbiota in Acute Respiratory Failure and Acute Respiratory Distress Syndrome

Purpose of the Review: To provide an overview of the physiology and pathophysiology of low respiratory tract microbiota. Recent Findings: Low respiratory tract microbiota results from the interplay between the host and the environment, with dysbiosis being frequently reported in the context of acute severe respiratory diseases. Summary: Acute respiratory failure and acute respiratory distress syndrome are life threatening conditions, that are mainly induced by low tract respiratory infections and require invasive mechanical ventilation in the most severe forms. Over the last decades, the advent of culture-independent genomics techniques performed on low respiratory tract specimens have revealed the physiologic existence of microbial communities, the lung microbiota. In this context, dysbiosis refers to any alteration of microbiota composition characterised by concurrent loss of α-diversity and increase of β-diversity, and this condition has been observed to occur during pneumonia and acute respiratory distress syndrome. However, this findings do not imply causation, and remains hypothesis-generating to inform future research. Further investigations are urgently warranted to clarify the potential of low respiratory tract microbiota as a diagnostic tool, and a clinical target for preventive and therapeutic interventions, aiming to improve patient related clinical outcomes.