Correlation Between Fungal and Bacterial Populations in Periodontitis Through Targeted Sequencing: A Pilot Study

Background and Objective: The oral microbiome plays an important role in oral health and disease, including periodontitis, which affects about 40% of the adult population in the United States. Bacterial pathogens have been well studied and documented in their relationship with periodontitis; however, the role of fungi in periodontitis is still unclear. The purpose of this study is to determine the relationship of specific fungal species with periodontal pathogenic bacteria in healthy, mild periodontitis, and severe periodontitis patients. Methods: In this study, human participants were recruited, and saliva samples were collected. Twelve participants representing periodontal health (n = 2), mild periodontitis (n = 3), and severe periodontitis (n = 7) were included. Salivary samples were sequenced for analysis of their mycobiome (ITS sequencing) and microbiome (16s RNA sequencing). Results: A total of 375 species of bacteria and 39 species of fungi were identified among all samples. Clustering was observed for bacteria in healthy and mild periodontitis, but more variability was observed in the severe periodontal disease group. Variability was observed for fungi among all samples and groups. Red complex bacteria were negatively correlated with Candida species for the disease groups, although the correlation was not statistically significant. A significant correlation was observed between red-complex bacteria in the severe periodontal disease group. Additionally, a significant correlation was observed among Candida species in all groups. Conclusions: This pilot study simultaneously processed saliva samples for microbiome and mycobiome sequencing and found a trend towards negative correlation between Candida species and red complex bacteria.