Beyond Mucosal Infection: a Role for C. albicans-Streptococcal Interactions in the Pathogenesis of Dental Caries

Abstract

The human body is home to countless microorganisms that can modulate the transition between health and disease. When conditions in the host favor the growth of pathogens, the populations can shift toward their dominance and/or cause disbyosis. In the mouth, commensal organisms are typically most abundant, but when oral hygiene is neglected and sugar is frequently consumed and/or there is a disruption in saliva production/flow, organisms associated with dental caries disease eg, Streptococcus mutans (S. mutans) become more prevalent. These organisms interact with dietary sugars and host saliva to form complex 3-dimensional biofilms on pellicle-coated teeth. The production of exopolysaccharides (eg, via S. mutans-sucrose interactions) modulates the assembly of the biofilm matrix, while acid production (eg, by acidogenic flora) and low pH within the biofilm facilitate the demineralization of the adjacent tooth enamel. During the assembly of cariogenic biofilms, S. mutans likely interacts and competes with other oral microbial species in the mouth. Although it is widely recognized that bacterial-fungal interactions commonly occur on mucosal surfaces, their possible role in dental caries has received limited attention. This review provides evidence that interactions between S. mutans and Candida albicans (C. albicans) may be involved in the pathogenesis of early childhood caries.