Runze Wang, Yiru Shao, Lin Zhang, Chen Zhang, Meili Shen, Weichun Mo, Feng Zhang, Jie Shen
AP was associated with higher alpha diversity. Selected oral-associated taxonomic patterns and their immune-cell percentages correlations were exploratory and were not confirmed after multiple-testing correction. The association between Gemella detection and mortality was imprecise and sensitive to sparse data and model specification, requiring validation in larger prospective studies.
BACKGROUND: Aspiration pneumonia (AP) is a common and severe infection among critically ill older adults, but its lower respiratory tract microbiota and clinical associations remain incompletely characterized.
METHODS: This single-center retrospective exploratory study included 72 intensive care unit patients, comprising 49 patients with AP and 23 with community-acquired pneumonia (CAP). Bronchoalveolar lavage fluid (BALF) microbiota were profiled using metagenomic next-generation sequencing (mNGS). Alpha and beta diversity, taxonomic composition, differential abundance, and associations between bacterial taxa and clinical or peripheral immune markers were analyzed. Within the AP cohort, the association between Gemella detection and in-hospital mortality was evaluated using Firth's penalized logistic regression.
RESULTS: AP patients had higher Shannon and Simpson diversity than CAP patients. Overall community composition did not differ significantly between the groups based on Bray-Curtis dissimilarity and PERMANOVA (R2=0.022, P=0.066). Streptococcus and Rothia showed nominally higher relative abundances in AP, whereas Acinetobacter and Stenotrophomonas showed nominally lower relative abundances. Only Acinetobacter remained more abundant in CAP after FDR correction (FDR-adjusted P=0.032). Nominal correlations between bacterial taxa and clinical or immune variables were not significant after FDR correction. Gemella was detected in 9 AP patients, including 8 of 26 non-survivors and 1 of 23 survivors (P=0.026). In the unadjusted Firth model, Gemella detection was associated with mortality (OR=6.892, 95% CI 1.360-69.062; P=0.018), but the association was attenuated and non-significant after adjustment for APACHE II score (OR=4.708, 95% CI 0.859-48.395; P=0.076).
CONCLUSION: AP was associated with higher alpha diversity. Selected oral-associated taxonomic patterns and their immune-cell percentages correlations were exploratory and were not confirmed after multiple-testing correction. The association between Gemella detection and mortality was imprecise and sensitive to sparse data and model specification, requiring validation in larger prospective studies.