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 pneu- monia 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 abun- dance at the group level in cases compared to controls, potentially increasing infection susceptibility. Higher micro- biota 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.