Pulmonary Microbiome of Patients Receiving Mechanical Ventilation: Changes Over Time.

BACKGROUND: Interest in the pulmonary microbiome is growing, particularly in patients undergoing mechanical ventilation. OBJECTIVES: To explore the pulmonary microbiome over time in patients undergoing prolonged mechanical ventilation and to evaluate the effect of an oral suctioning intervention on the microbiome. METHODS: This descriptive subanalysis from a clinical trial involved a random sample of 16 participants (7 intervention, 9 control) who received mechanical ventilation for at least 5 days. Five paired oral and tracheal specimens were evaluated for each participant over time. Bacterial DNA from the paired specimens was evaluated using 16S rRNA gene sequencing. Bacterial taxonomy composition, α-diversity (Shannon index), and ß-diversity (Morisita-Horn index) were calculated and compared within and between participants. RESULTS: Participants were predominantly male (69%) and White (63%), with a mean age of 58 years, and underwent mechanical ventilation for a mean of 9.36 days. Abundant bacterial taxa included Prevotella, Staphylococcus, Streptococcus, Stenotrophomonas, and Veillonella. Mean tracheal α-diversity decreased over time for the total group (P = .002) and the control group (P = .02). ß-Diversity was lower (P = .04) in the control group (1.905) than in the intervention group (2.607). CONCLUSIONS: Prolonged mechanical ventilation was associated with changes in the pulmonary microbiome, with the control group having less diversity. The oral suctioning intervention may have reduced oral-tracheal bacterial transmission.