Relationship between the oral microbiome and post-surgery aspiration pneumonia in oral squamous cell carcinoma patients

Previous studies have linked the oral microbiome to pneumonia; however, its association with postoperative aspiration pneumonia in patients with OSCC remains poorly characterized. We investigate the association between the oral microbiome and the development of aspiration pneumonia in patients with OSCC, using microbial sequencing and causal inference approaches. Oral rinse samples from 203 OSCC patients at Chang Gung Memorial Hospital were analyzed. Associations were assessed by controlling for confounders and examining diversity, relative abundance, and functional predictions of the oral microbiome. Alpha and beta diversity analyses revealed significant differences between the aspiration pneumonia and non-aspiration pneumonia groups, even after adjusting for confounders such as gender, age, and clinical stage. Differential abundance analysis identified 16 genera with significant differences before adjustment and 17 genera after adjustment, out of 105 genera analyzed. For functional prediction, among 97 metabolic pathways, stratified analysis revealed significant differences in atrazine degradation and GPI-anchor biosynthesis. Both pathways were significantly higher in the non-aspiration pneumonia group, regardless of stage. The composition and functional potential of the oral microbiome are significantly associated with the development of aspiration pneumonia in patients with OSCC. By integrating causal inference principles and stratified analyses, we identified specific genera - such as Parvimonas and Veillonella - and microbial pathways - such as atrazine degradation and GPI-anchor biosynthesis - that differ between patients with and without aspiration pneumonia. These findings suggest that certain oral microbes may be associated with susceptibility to respiratory complications, highlighting the potential for microbiome-informed strategies to reduce postoperative risks and improve patient outcomes.