Streptococcus mutansis the etiological agent of dental caries and one of the many bacterial species implicated in infective endocarditis. The expression of the collagen-binding protein Cnm byS. mutanshas been associated with extraoral infections, but its relevance for dental caries has only been theorized to date. Due to the collagenous composition of dentinal and root tissues, we hypothesized that Cnm may facilitate the colonization of these surfaces, thereby enhancing the pathogenic potential ofS. mutansin advancing carious lesions. As shown for extraoral endothelial cell lines, Cnm mediates the invasion of oral keratinocytes and fibroblasts byS. mutans. In this study, we show that in the Cnm+native strain, OMZ175, Cnm mediates stringent adhesion to dentinal and root tissues as well as collagen-coated surfaces and promotes both cariogenicity and carriagein vivo. In vitro,ex vivo, andin vivoexperiments revealed that while Cnm is not universally required forS. mutanscariogenicity, it contributes to (i) the invasion of the oral epithelium, (ii) enhanced binding on collagenous surfaces, (iii) implantation of oral biofilms, and (IV) the severity of caries due to a native Cnm+isolate. Taken together, our findings reveal that Cnm is a colonization factor that contributes to the pathogenicity of certainS. mutansstrains in their native habitat, the oral cavity.
The collagen-binding protein of Streptococcus mutans is involved in haemorrhagic stroke
