Detection of Oral Bacterial DNA in Abdominal Aortic Aneurysm and Its Microbial Associations

Abdominal aortic aneurysm (AAA) is a life-threatening disease for which no definitive medical therapy has been established, partly because its underlying mechanisms remain incompletely understood. Given accumulating evidence suggesting microbial involvement in vascular inflammation, we conducted a detection-based investigation to identify bacterial DNA in aneurysmal tissues. We performed 16S ribosomal RNA (rRNA) gene sequencing of the aneurysmal wall, intraluminal thrombus, feces, saliva, and dental plaque collected from 32 patients undergoing open surgical repair of non-infectious AAA. Based on the sequencing data, diversity analyses were performed for each sample to characterize bacterial composition, and exploratory statistical analyses were conducted to examine associations between patient characteristics and the relative abundance of bacterial taxa. Oral-associated genera were frequently detected in aneurysm-derived samples, including Prevotella in 78%, Leptotrichia in 81%, and Capnocytophaga in 38% of aneurysmal wall or thrombus samples, whereas their detection in fecal samples was limited. Beta diversity analysis demonstrated significant compositional differences between fecal and oral samples (permutational multivariate analysis of variance [PERMANOVA], p < 0.01). These findings demonstrate the presence of bacterial DNA in aneurysmal tissues and provide descriptive evidence of microbial signatures in AAA.