Fusobacterium in oral bacterial flora relates with asymptomatic brain lesions

Background: Specific bacterial species in the oral cavity contribute to cerebral hemorrhage and microbleeds. The relationship between oral bacterial flora and asymptomatic brain lesions (ABL) remains unclear. This study aimed to investigate this relationship in a healthy Japanese cohort. Methods: This cross-sectional study included participants who underwent health examinations at our Brain Dock facility between October 2020 and March 2021. The oral microbiomes of participants with and without ABL were compared using magnetic resonance imaging. To extensively assess the oral bacterial flora, the differences in genes and species compositions between the ABL and noBL (without brain lesions) groups were statistically evaluated via extensive analysis using 16S rRNA gene-based cloning. Results: Among 143 patients, 48.3 % had ABL. In the univariate analyses, Fusobacterium and Leptotrichia were associated with ABL (P = 0.017 and P < 0.001, respectively). In the adjusted models, Fusobacterium was associated with ABL (P = 0.006). In an intergroup comparison of seven Fusobacterium species, F. nucleatum, F. naviforme, and F. canifelinum were associated with ABL (P < 0.001, P = 0.002, P < 0.001). Conclusions: The elevation of Fusobacterium in the ABL indicates the importance of the microbiome in the oral cavity as a factor in inducing cerebral small-vessel disease in healthy individuals, whose preventive approach might have an impact on therapeutic applications.