Oral and Gut Microbiota Dysbiosis in Patients With Ventilator‐Associated Pneumonia

Background Ventilator‐associated pneumonia (VAP) is a serious complication in critically ill patients. This study aimed to explore the association between alterations in the composition and diversity of oral and gut microbiota and VAP onset. Methods This prospective observational pilot study enrolled adult patients undergoing mechanical ventilation in an intensive care unit. Saliva and fecal samples were collected for 16S rRNA sequencing of oral and gut microbiota, and baseline clinical information and laboratory results were obtained from all enrolled patients. Results The VAP status was associated with advanced age, alcohol consumption, and high BUN levels. Dysbiosis of the oral microbiome, with a high abundance of Pseudomonadaceae, was associated with the onset of VAP. VAP‐patient‐specific shifts in gut microbial composition and elevated heterogeneity, including specific pathogens such as Enterobacteriaceae , Klebsiella , and Moraxellaceae belonging to the phylum Proteobacteria , are potential biomarkers for VAP onset. We observed no ectopic colonization of oral bacteria in the intestine. Conclusion Our findings suggest that reduced diversity in the intestinal microbiota contributes to the development of VAP, highlighting a promising direction for future research.