Respiratory Microbiome Disruption and Risk for Ventilator-Associated Lower Respiratory Tract Infection

Area of Science:

• Critical Care Medicine
• Infectious Diseases
• Microbiome Research

Background:

• Ventilator-associated lower respiratory tract infection (VA-LRTI) is a significant complication in critically ill patients, increasing morbidity and mortality.
• Microbiome disruption indices (MDIs) predict VA-LRTI risk in acute illness, but their role in prolonged mechanical ventilation is unclear.

Purpose of the Study:

• To investigate changes in respiratory microbiome disruption indices (MDIs) during prolonged mechanical ventilation.
• To determine if these MDIs remain associated with VA-LRTI risk over time.

Main Methods:

• A cohort of 83 subjects on prolonged mechanical ventilation was studied.
• Longitudinal lower respiratory tract samples were collected and analyzed using 16S rRNA sequencing and qPCR.
• Microbiome disruption indices (MDIs) were calculated, including Shannon diversity and bacterial abundance.

Main Results:

• Cross-sectional MDIs showed weak associations with VA-LRTI risk.
• Persistent lower respiratory microbiome disruption, defined by consecutive days with low Shannon diversity (<2.0), robustly predicted VA-LRTI risk (OR 1.36 per day).
• The association was consistent across different VA-LRTI definitions.

Conclusions:

• Cross-sectional MDIs have limited utility for predicting VA-LRTI risk in prolonged mechanical ventilation.
• Persistent lower respiratory tract microbiome disruption, particularly low Shannon diversity over consecutive days, identifies patients at high risk for VA-LRTI.
• This understanding can inform targeted infection prevention interventions.