Lung Microbiota Can Predict ICU Outcomes

A new study demonstrates for the first time that variation in the lung microbiota of clinically ill patients can predict clinical outcomes. The paper was published on January 24, 2020 in the American Journal of Respiratory and Clinical Care Medicine.

Researchers sampled the lung microbiota of 91 critically ill patients receiving mechanical ventilation within 24 hours of their admittance to the intensive care unit (ICU). Using digital droplet PCR and bacterial 16S rRNA gene sequencing, the researchers analyzed bacterial burden, community diversity, and community composition of the lung microbiota in each sample. 

After 28 days, the researchers assessed the number of ventilator-free days for each patient. They found that, even after controlling for pneumonia and illness severity, patients with increased bacterial lung burden at the start of the study experienced significantly fewer ventilator-free days. They also determined that the presence of the gut-associated family of bacteria Lachnospiraceae in patient samples predicted worse ICU outcomes. The presence of another gut-associated bacterial family, Enterobacteriaceae, was significantly associated with the onset of acute respiratory distress syndrome.

This study points to the lung microbiome as a major source of heterogeneity among critically ill patients that has been understudied. The results could provide a novel target for the prevention and treatment of acute respiratory failure, according to the researchers.