Salivary microbiome and periodontopathogen/denitrifying bacteria associated with gingivitis and periodontitis in...

Despite diabetes mellitus and periodontal diseases are mutually exclusive, little is known about particular types of bacteria that may have exacerbated the development of diabetics' periodontal inflammation. The purpose of this study was to descriptively characterize and explore the differences in the salivary microbiomes of individuals with type 2 diabetes (20-40 years old) who had gingivitis or periodontitis to those who did not. Additionally, we evaluated the descriptive relationship between the relative abundance of periodontopathogens and nitrate-reducing bacteria in their salivary microbiome.

Saliva was collected from all participants. Genomic DNA was isolated and pooled in equimolar quantities from all individuals within each group to create three pooled libraries: type 2 diabetes (T2DM) patients without periodontal disease (G1), T2DM patients with gingivitis (G2), and T2DM patients with periodontitis (G3). Sequencing was performed using Oxford Nanopore MinION Technology. The relative abundance and bacterial diversity were measured using bioinformatic methods, and all analyses of sequencing data were strictly descriptive and exploratory. Salivary nitrite/nitrate concentrations were measured on individual, un-pooled samples.

The salivary microbiota among people with type 2 diabetes and periodontal disease (G2; G3) was observed to have greater bacterial diversity and abundance than that of patients without periodontal disease (G1), according to descriptive alpha-diversity analysis. The G3 group exhibited the largest relative abundance of Porphyromonas gingivalis, a key periodontopathogen. Descriptive analysis also suggested that periodontopathic bacteria and nitrate-reducing bacteria have different community structures across the groups. Furthermore, comparison of individual salivary samples showed that nitrite/nitrate concentration was significantly lower in the G3 group compared to the G1 group (p< 0.05). Results reveal that the inverse interaction between increased P. gingivalis and decreased nitrate-reducing bacteria serves as a descriptive hallmark for periodontal disease progression in the T2DM population.

Results of this exploratory study suggest that the relationship between periodontopathic and denitrifying bacteria in the salivary microbiome varies among those with type 2 diabetes mellitus who also have gingivitis or periodontitis. These distinct microbial features observed may be microbiological characteristics associated with the progression of periodontal disease in this population, warranting further validation as potential indicators for early management.