吸入性肺炎危重患者支气管肺泡灌洗微生物组研究：与社区获得性肺炎的探索性比较及Gemella菌检测与死亡率分析

Abstract

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 corr