STREPTOCOCCUS-ORALIS PREVIOUSLY IDENTIFIED AS UNCOMMON STREPTOCOCCUS-SANGUIS IN BEHCETS-DISEASE

The relation between the biochemical and serological properties of Str eptococcus sanguis' was studied to characterize the strains isolated f rom dental plaque of patients with Behcet's disease and controls. Seve n reference and 100 clinical strains preserved by the Behcet's Disease Research Committee of Japan were identified using established criteri a and differentiated with antisera against Strep. oralis ATCC 10557, S trep. sanguis ATCC 10556 and 'Strep. sanguis' ST7, compatible with the criteria. Uncommon serovars (serotypes) KTH-1 (=ATCC 49298), KTH-2 (= ATCC 49296), KTH-3 (=ATCC 49295), KTH-4 (=ATCC 49297) and B220 (serova r KTH-1) with both IgA1 protease and neuraminidase (sialidase) were id entified as Strep. oralis, whereas common serovars ST3 with IgA1 prote ase alone and ST7 without both enzymes were identified as Strep, sangu is and Strep. gordonii, respectively. Isolates previously ranked as un common serovars were identified as Strep. oralis, whereas the rest ran ked as common serovars were identified as the same species as those of the grouping strains. A soft-agar technique was available for species identification except for Strep. oralis serovar KTH-1 reacting with t he antiserum against Strep. gordonii ST7. The frequency of isolation o f Strep, oralis was higher in Behcet's disease (52%) than in controls (38%), but no difference was observed between the properties of the tw o groups of isolates. Strep. oralis virulence factors may be involved in breach the mucosal barrier in patients with specific reactivity to these antigens and inducing Behcet's disease.