Increased numbers of black-pigmented Bacteroides in induced periodontitis in monkeys

In four young adult monkeys, periodontitis was experimentally induced by inserting elastic rubber bands around the necks of two teeth on each side of the mandible. On one side the teeth were not cleaned during the experimental period. On the control side, the teeth were cleaned by scaling and polishing weekly. After 8 weeks there were 6 mm deep pockets and great bone loss on the experimental side. Subgingival plaque was collected from experimental and control sides under anaerobic conditions and transported in a reduced transport fluid. The microorganisms were incubated anaerobically for 7 days on four different media: 1) Horse blood agar, 2) Rabbit blood agar, 3) Kanamycin-vancomycin blood agar, 4) Rabbit blood agar with Kanamycin and supernatant of filtrated Propionibacterium acnes culture (BPBSM). All media contained 0.5 microgram/ml menadione and 5.0 micrograms/ml hemin. Colony forming units of black-pigmented Bacteroides were found on all four media from all animals and were increased in numbers in the experimental side. One hundred and fifteen isolates of black-pigmented colonies were identified biochemically. Recovery of black-pigmented Bacteroides on BPBSM was significantly higher than on the other three media.