A microbiological comparison of young adults based on relative amounts of subgingival calculus

This study compared the relative amounts of Actinobacillus actinomycetemcomitans (Aa), Eikenella corrodens (Ec), and black-pigmented anaerobic rods, and the proportions of coccoid forms, nonmotile rods, motile rods, spirochetes, and total motile organisms in subgingival plaque samples from 2 groups of young adults with generalized moderate to severe periodontitis. Two groups of 12 untreated patients were selected based on the relative amounts of subgingival calculus detected. Subgingival plaque samples (2 sites/patient) were taken with a sterile curet, dispersed, and plated under anaerobic conditions on ETSA, ETSA-kanamycin, ETSA-clindamycin, and TSBV agar. Appropriate biochemical tests were performed to confirm suspected microorganisms. Phase-contrast microscopy also was used to count the relative numbers of coccoid forms, nonmotile rods, motile rods, and spirochetes in each of the samples. Patients with no clinically detectable subgingival calculus harbored significantly greater proportions (%) of coccoid forms and Aa and greater amounts (CFU/mg) of Aa than did patients with obvious amounts of subgingival calculus. Subjects with clearly detectable subgingival calculus possessed greater proportions of motile rods, total motile organisms, and black-pigmented anaerobic rods than did subjects with little or no subgingival calculus. Young adult patients with generalized moderate to severe disease and little or no detectable subgingival calculus may possess a subgingival microbiota with relatively higher numbers of Aa and coccoid forms, and a lower percentage of BPB, motile rods, and total motile organisms as compared to similar patients with greater amounts of subgingival calculus.