第67回 薬学セミナー

Many periodontal and dental caries pathogens were detected and described using anaerobic culture studies from The Forsyth Institute. Species recognized from advanced periodontitis included Porphyromonas gingivalis, Prevotella intermedia, Aggregatibacter actinomycetemcomitans, Campylobacter rectus, Eikenella corrodens and Tannerella forsythia. Additional species detected in initial periodontitis included E. saphenum, Filifactor alocis and Selenomonas noxia. Molecular studies found an association of P. gingivalis and T. forsythia with initial periodontitis in young adults.
　Anaerobic culture technique applied to severe (advanced) early childhood caries a revealed new species, Scardovia wiggsiae, in addition to Streptococcus mutans as disease associated. S. wiggsiae is an anaerobic gram positive rod species in the Bifidobacteriaceae family of the Actinobacteria phylum. Scardovia wiggsiae is acidogenic and acid tolerant, cariogenic traits of S. mutans. Cultivation of samples at plaque low pH indicated that only a subset of over 200 species detected was acidogenic and acid-tolerant and thus likely involved in caries-progression. Other species including Bacteroidetes, Selenomonas and Fusobacterium species were not acid tolerant, suggesting that while these taxa can be detected in caries samples they are not likely involved in cavity formation. Cluster and discriminant analyses of the microbiota of severe childhood caries indicated that S. wiggsiae was important in the bacterial complex associated with childhood caries.
　Initial stages of dental caries are recognized as white spot lesions. Some children with fixed orthodontic appliances develop white spot initial carious lesions in addition to gingivitis. Using the HOMIM microarray, a greater proportion of species assayed were associated with gingivitis compared with dental caries. Using quantitative PCR, S. mutans and S. wiggsiae were associated with white spot lesions, whereas bifidobacteria were associated more with gingivitis.
　In both periodontitis and caries, species associated in advanced disease were also found in initial lesions suggesting a continuum of infection from early to late stages of these dental diseases.