THE ROLE OF EUBACTERIUM SPECIES IN PERIODONTAL-DISEASE AND OTHER ORALINFECTIONS

Periodontal disease has been traditionally associated with an anaerobi c gram-negative microbiota. However, improvements in sampling handling and culture media have revealed that gram-positive anaerobes belongin g to the genus Eubacterium can make up around half of the microbiota i n advanced disease. The asaccharolytic species E. brachy, E. nodatum, E. saphenum and E. timidum show significant associations with severe p eriodontal disease, but are only rarely found in oral health. Antibodi es to E. brachy and E. timidium are raised in patients with periodonta l disease compared with healthy controls. Studies of the genus are ham pered by the poor and slow growth of the majority of species and the i ndifferent taxonomy of the group. It is estimated that there are at le ast 20 un-named taxa. 16S ribosomal RNA sequencing has revealed that t he oral asaccharolytic Eubacterium species are closely related to the genera Clostridium and Peptostreptococcus and exhibit three distinct l ines of descent. Virulence factors produced by these organisms are as yet unknown although one unnamed taxon which is strongly associated wi th dento-alveolar abscesses has been established in continuous culture and has been shown to exhibit a wide range of aminopeptidase activity .