Mutans streptokokkernes betydning for udvikling af caries
Mutans streptokokkernes virulensfaktorer, bl.a. aciduri og acidogenitet, gør dem til en vigtig ætiolo- gisk faktor i udviklingen af dental caries. Derudover producerer de intra- og ekstracellulære polysakka- rider, der bl.a. gør dem i stand til at adhærere til og multiplicere sig på tandoverflader. MS er en heterogen art, hvor nogle subspecies har større betydning for cariesudvikling end andre. De to mest cariogene subspecies hos mennesket er Strep - tococcus mutans og Streptococcus sobrinus . Sammenhængen mellem forekomsten af mutans streptokokker og udviklingen af caries er ikke givet. Udviklingen af dental caries må jf. »den økologiske plakhypotese«, derfor ses som et sammenspil mellem flere mulige patogene mikroorganismer og økologiske forhold i mundhule og biofilm, der har en varierende grad af indflydelse ved forskellige cariesaktive sites.
Klinisk relevans:
The significance of the mutans streptococci in the development of dental caries: The mutans streptococcus species consist of facultative, Gram-positive, non-motile, catalase-negative, aciduric and acidogenic streptococci. These properties make the mutans streptococci (MS) an important etiological factor in the development of caries. Most important are the aciduric and acidogenous traits of the MS. The low-molecular organic acids produced by the MS cause enamel demineralisation. Their ability to colonise and multiply on the surfaces of the teeth is also of importance. MS are able to do so because of their synthesis of intra- and extracellular polysaccharides. These polysaccharides function as an energy- storage when nutrients are scarce, and they provide texture and increase the porosity of the plaque, thereby making it more cariogenic. The two main human cariogenic members of the MS species are Streptococcus mutans and Streptococcus sobrinus . What part do the MS play in caries development? S. mutans has been considered as the main cause of dental caries for many years, but some findings have shown caries lesions to persist in the absence of S. mutans , while other find ings have shown sound S. mutans infected teeth. This might be explained by »the ecological plaque hypothesis« which states that caries development is due to interactions between several possible pathogenic micro-organisms which have been given a chance to propagate due to a shift in the balance of the plaque microflora.