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Lower respiratory tract microbial composition was diversified in Pseudomonas aeruginosa ventilator-associated
Xiaoling Qi1, Hongping Qu1, Dandan Yang2
1Department of Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Background:
Probiotics could prevent Pseudomonas aeruginosa colonization in lower respiratory tract (LRT) and reduced P. aeruginosa ventilator-associated pneumonia (VAP) rate. Recent studies also suggested that probiotics could improve lung inflammation in mice infected with P. aeruginosa. It seems that microbiota regulation may be a potential therapy for P. aeruginosa VAP patients. However, we know less about the LRT microbial composition and its correlation with prognosis in P. aeruginosa VAP patients. This study aimed to characterize LRT microbiota in P. aeruginosa VAP patients and explore the relationship between microbiota and patient prognosis.
Methods:
Deep endotracheal secretions were sampled from subjects via intubation. Communities were identified by 16S ribosomal RNA gene sequencing. The relationship between microbiota and the prognosis of P. aeruginosa VAP patients were evaluated. Clinical pulmonary infection score and the survival of intensive care unit were both the indicators of patient prognosis.
Results:
In this study, the LRT microbial composition of P. aeruginosa VAP patients was significantly different from non-infected intubation patients, and showed significant individual differences, forming two clusters. According to the predominant phylum of each cluster, these two clusters were named Pro cluster and Fir-Bac cluster respectively. Patients from Pro cluster were dominated by Proteobacteria (adj.P < 0.001), while those from Fir-Bac cluster were dominated by Firmicutes, and Bacteroidetes (both adj.P < 0.001). These two varied clusters (Pro and Fir-Bac cluster) were associated with the patients' primary disease (χ2-test, P < 0.0001). The primary disease of the Pro cluster mainly included gastrointestinal disease (63%), and the Fir-Bac cluster was predominantly respiratory disease (89%). During the two-week dynamic observation period, despite the use of antibiotics, the dominant genera and Shannon diversity of the LRT microbiota did not change significantly in patients with P. aeruginosa VAP. In prognostic analysis, we found a significant negative correlation between Lactobacillus and clinical pulmonary infection score on the day of diagnosis (P = 0.014); but we found no significant difference of microbial composition between survivors and non-survivors.
Conclusions:
LRT microbial composition was diversified among P. aeruginosa VAP patients, forming two clusters which were associated with the primary diseases of the patients.
Insights
Pseudomonas aeruginosa ventilator-associated pneumonia (VAP) patients exhibit diverse lower respiratory tract (LRT) microbiota, forming two distinct clusters linked to primary diseases. Lactobacillus levels correlated with infection severity, but overall microbiota did not predict survival.
Area of Science:
- Microbiology
- Pulmonary Medicine
- Critical Care
Background:
- Probiotics show potential in preventing Pseudomonas aeruginosa colonization and reducing ventilator-associated pneumonia (VAP).
- Existing research suggests probiotics may mitigate lung inflammation in P. aeruginosa infections.
- Understanding the lower respiratory tract (LRT) microbial composition in P. aeruginosa VAP patients is crucial for potential microbiota-based therapies.
Purpose of the Study:
- To characterize the LRT microbial composition in patients with P. aeruginosa VAP.
- To investigate the correlation between LRT microbiota and patient prognosis in P. aeruginosa VAP.
Main Methods:
- Deep endotracheal secretions were collected from intubated patients.
- Microbial communities were identified using 16S ribosomal RNA gene sequencing.
- Prognosis was assessed using the clinical pulmonary infection score and intensive care unit survival rates.
Main Results:
- LRT microbial composition in P. aeruginosa VAP patients differed significantly from non-infected controls, forming two distinct clusters (Pro and Fir-Bac) associated with primary diseases (gastrointestinal vs. respiratory).
- The Pro cluster was dominated by Proteobacteria, while the Fir-Bac cluster was dominated by Firmicutes and Bacteroidetes.
- Despite antibiotic treatment, LRT microbiota composition and diversity remained stable over two weeks; a negative correlation was observed between Lactobacillus and the clinical pulmonary infection score, but no significant differences were found between survivors and non-survivors.
Conclusions:
- LRT microbial composition in P. aeruginosa VAP patients is diverse and can be categorized into distinct clusters based on predominant phyla.
- These microbial clusters are associated with the patients' underlying primary conditions.
- While specific bacterial correlations exist, the overall LRT microbiota composition did not significantly predict survival in P. aeruginosa VAP patients.
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