Evaluation of Kanamycin as an aid in the isolation of Bacteroides melaninogenicus from dental plaque.

Dental plaque known to harbour Bacteroides melaninogenicus was removed from the gingival half of selected buccal tooth surfaces. The plaque was dispersed, diluted and cultured on medium containing 0 per cent, 0*05,0* 1 and 0.5 per cent Kanamycin. When the medium contained 0.05 per cent Kanamycin, only B. melaninogenicus were found and the number recovered was about 20 per cent of the B. melaninogenicus colonies isolated on the antibiotic free medium. Apparently certain strains of B. meluninogenicus are resistant to this level of Kanamycin and the addition of this antibiotic to a culture medium would facilitate the primary isolation of this organism from source material.