Dissecting Probiotic Modulation of Oral Microbiota in Healthy Individuals

Targeting human microbiota, in particular those of the gastrointestinal tract, by means of prebiotics, probiotics, symbiotics or antibiotics has gained interest for its potential in the management of human health. Oral bacterial communities have been extensively studied over the last decade both in normal and pathological states; however, little data are available on the possibility to modify microbiota composition in a controlled and 'non-aggressive' manner by using probiotics, in order to improve oral health.

Saliva contains microorganisms attached to exfoliated human cells and released from oral biofilms; its microbiota is most similar (proportionally) to those of the dorsal and lateral tongue. In addition, bacteria belonging to genera Porphyromonas, Tannerella and Treponema, which contain species associated with periodontitis, are consistently identified in saliva. Salivary microbial communities are relatively stable and thus potentially interesting as an indicator of oral and general health. Indeed, it has been suggested that interventions aimed at improving oral health should target mucosal microbiota (to which saliva is most similar) in addition to dental microbial communities. Whole saliva also constitutes an alternative to gingival crevicular fluid when analysing analytes present in periodontal pockets. It has been suggested that saliva reflects a consensus inflammatory status of the whole mouth with potentially significant clinical relevance.

Strain K12 of Streptococcus salivarius is available internationally as a food supplement, notably for oral hygiene. Several studies investigated the effectiveness of S. salivarius as a probiotic in the context of pharyngeal infections, halitosis, plaque formation and caries. Our study will focus on the effects of supplementation with this commercially available oral probiotic on the resident microbiota and inflammatory markers in order to identify signatures associated with resistance/susceptibility to colonization by probiotic strains.