Characterization of the Interaction between Candida albicans and Streptococcus mutans

The oral microbial communities are some of the most complex microbial floras in the human body. Occurrence of oral disease results from disturbance of the equilibrium of this ecosystem. Dental caries or tooth decay is the most common oral disease particularly in children characterized by irreversible destruction of the tooth mediated by demineralization of dental surfaces. These processes are the result of interactions between the various microbial species embedded in the biofilm formed on tooth surface known as dental plaque. These complex interactions between metabolically active microbial species cause fluctuations in pH ultimately resulting in dissolution of the dental hard tissues and formation of carious lesions. The bacterial species Streptococcus mutans has long been considered the etiologic agent of caries, however recent in vitro evidence seem to indicate a role for the fungal species Candida albicans in mediating cariogenic development via its physical and metabolic interactions with S. mutans. However, in depth investigations are required to determine mechanistically precise details of adhesion and signaling under conditions of co-existence. To that end, the goal of this proposal is to characterize the interaction between C. albicans and S. mutans using biologically relevant in vitro model systems. Specifically, we aim to demonstrate that the strong co-adherence of these diverse oral pathogens to each other and to oral surfaces results in the formation of mature biofilms, a pre-requisite for the development of dental caries. Importantly, as design of effective therapies to treat caries has been a challenge, this project also aimed to develop a novel antimicrobial bioadhesive hydrogel formulation for use as oral topical agent with targeted action geared towards blocking microbial adhesion to surfaces and in turn prevention and eradication of biofilms. The accomplishment of the work proposed in this project will provide crucial insights into the potential role of C. albicans in the development of dental caries, an area of research that is yet to be explored. The ultimate goal is to contribute to our understanding of the various factors and conditions that play a role in microbial colonization and the progression of colonization to infection. Such crucial information will have important clinical implications as it aids in the identification and the design of novel therapeutic strategies aimed at the prevention and/or treatment of dental caries and oral infections in general. Significantly, the novel findings generated strongly indicate that the presence of C. albicans in the oral environment should be considered as an additional factor in evaluating risks of caries.