Oral microbial taxa associated with risk for SARS-CoV-2 infection

Abstract

Hypothesis and objective: The oral and digestive tract microbial ecosystem has sparked interest because of its impact on various systemic diseases and conditions. The oral cavity serves not only as a reservoir for many potentially virulent microbiota but also as an important entry point and portal to the human body system. This is especially significant in the transmissibility of the virulent current pandemic virus SARS-CoV-2. The oral and digestive microbiome influences the inflammatory burden and effectiveness of the immune system and serves as a marker of activity of these host processes. The host immune response plays a role in infection susceptibility, including SARS-CoV-2. The purpose of this study is to investigate the role of specific salivary oral microbiome in susceptibility to SARS-CoV-2 infection.

Methods and results: One hundred six subjects of known medical and dental history who consented to provide saliva samples between January 2017 and December 2019 were included in this study. Sixteen had become COVID-19 positive based on the PCR test by 3/01/2021. A comparison of oral microbiome bacteria taxa profiles based on 16S rRNA sequencing revealed differences between the two groups in this pilot study.

Conclusions: These bacteria taxa may be markers of increased susceptibility to SARS-CoV-2 infection in the unvaccinated population.

Keywords: 16S rRNA (16S rDNA); COVID-19 risk; Neisseria elongata; bacteria; oral microbiota.

Figure 1

Phylogenetic diversity of saliva from subjects that self-report as being COVID-19 positive and those that did not. A box plot of Comparison of Shannon Diversity indices shows insignificant differences in taxa richness in the two groups, p < 0.543 and [t-test] statistic: −0.616. Comparison of taxa richness based on the CHAO1 indices reveals the same, p < 0.2510, (t-test) statistic: −1.19.

Figure 2

Principal coordinate analysis (PCoA) of saliva microbiome profiles of both groups based on Bray-Curtis Distances.

Figure 3

Significant associations (FDR < 0.25) between bacterial taxa and clinical variables detected by MaAsLin2-based multiple variable analysis. Each association such as future COVID-19 status and salivary taxa were adjusted for the remaining factors, such as subject's tobacco usage, age, and the number of medications prescribed to the subject.