Microbial Flora of Bleeding and Non-bleeding Pockets of Variable Depth in Adult Periodontitis

Abstract

The cultivable microbial flora associated with adult periodontitis was investigated according to probing depth and degree of inflammation in each of 21 patients selected for study. At sites which bled upon gentle probing, a greater variety of microbial species was isolated with increasing probing depth. Prevotella intermedia , Bacteroides ureolyticus , Pr. oralis and coagulase-negative staphylococci were major isolates at deep bleeding sites (≥ 6 mm) whereas Porphyromonas asaccharolytica , diphtheroids and Candida species accounted for the greatest proportion of microorganisms at moderate bleeding sites (4 mm). At non-bleeding sites of equal depths, non-pigmented Prevotella species , Neisseria and Capnocytophaga species and gram-positive organisms were isolated in greater proportions than at bleeding sites. Further work is necessary to elucidate the role of non-pigmented species, especially B. ureolyticus and Pr. oralis , and also coagulase-negative staphylococci at deep bleeding sites. A significant proportion of gram-negative anaerobic bacteria could not be identified at species level and further investigation is necessary to classify these species. Preliminary work however shows these are neither P. gingivalis nor Fusobacterium nucleatum , which were not isolated in this study. Keywords: Adult periodontitis; Microbial flora; Probing depth; Degree of inflammation.