Characterization of lung microbiota in pneumonia: a pilot study in ICU and non-ICU patients

Objective: To identify potential differences in lung microbiota according to clinical severity, age, and gender in pneumonia patients compared to controls. Design: Pilot study. Setting: Single center (Azienda Ospedaliera Universitaria Dulbecco, Catanzaro, Italy). Patients: Thirty-three individuals-11 ICU patients requiring invasive mechanical ventilation, 11 non-ICU patients, and 11 cadaver controls without lung disease. Interventions: Bronchoalveolar lavage sample collection and analysis via microbiological cultures and metagenomic sequencing. Measurements and main results: Bacteroidota and Verrucomicrobiota phyla were more abundant in older (≥65 years) ICU and non-ICU patients versus controls. Massilia timonae showed a significantly lower relative abundance at the group level in cases compared to controls, potentially increasing infection susceptibility. Higher microbiota diversity was observed in older patients. Conclusions: Alterations in lung microbiota composition were observed in pneumonia patients, with differences that appeared more evident in older patients. Microbiota phenotyping may offer novel insights into pneumonia pathophysiology and pulmonary dysbiosis.