New findings on the microbial flora associated with adult periodontitis.

The predominant microbial flora associated with adult periodontitis was investigated in 21 patients aged 20-40 years. Microorganisms from samples of subgingival plaque were cultured on selective and non-selective media under aerobic and anaerobic conditions. Ten species or groups out of a total of 31 were found to comprise the predominant cultivable flora: diphtheroids, Porphyromonas asaccharolytica, coagulase-negative staphylococci, 'Streptococcus milleri'-group, Bacteroides ureolyticus, Capnocytophaga ochracea, the Prevotella veroralis/buccalis complex, P. intermedia, P. oralis and unidentified Prevotella spp. Two species previously reported at periodontitis sites, namely P. gingivalis and Fusobacterium nucleatum, were not isolated, whereas Prevotella species accounted for the majority of isolates in this investigation. The large proportion of non-pigmented Prevotella species, P. asaccharolytica and B. ureolyticus that were found have not generally been reported previously. The role of these microorganisms and also coagulase-negative staphylococci, diphtheroids and the 'Streptococcus milleri'-group requires further investigation in adult periodontitis.