Could lung bacterial dysbiosis predict ICU mortality in patients with extra-pulmonary sepsis? A proof-of-concept study

Sepsis is a major cause of mortality worldwide. However, prognosis in these critically ill patients is based on severity scores, in combination with plasma biomarkers, which have shown a limited power to predict patient severity; thus, novel and more accurate biomarkers are needed. Alterations of the microbial diversity (commonly known as dysbiosis) have been linked to sepsis development and severity. Interestingly, enrichment of gut bacteria in the lung microbiome has been found in patients with sepsis and acute respiratory distress syndrome (ARDS), likely by translocation of intestinal microbes.

However, although it is known that the lung microbiome is severely altered in critically ill patients, a specific association of the lung dysbiosis with sepsis mortality remains to be determined. Here we performed a prospective study to assess the lung dysbiosis in a cohort of 36 mechanically ventilated adult patients diagnosed with extrapulmonary sepsis (avoiding the potential confounder effects of pneumonia in the lung dysbiosis).