Black-pigmented Bacteroides spp. in the human oral cavity

Abstract

Five healthy children under 6 yr of age, 5 healthy adults and 10 adult periodontitis patients were examined for the prevalence and distribution of black-pigmented Bacteroides in the oral cavity. A total of 13 samples was obtained from each individual, including 4 supragingival and 4 subgingival dental plaques, dental occlusal surface, buccal mucosa, dorsal tongue, tonsil and whole saliva. Black-pigmented Bacteroides were recovered from 9 adult periodontitis patients. Healthy adults harbored the organisms in low incidence and proportions; the children exhibited no cultivable black-pigmented Bacteroides. The organisms were isolated in highest proportions from dental plaque, especially subgingival plaque, and from the tonsil area, indicating that these sites constitute the organisms'' primary ecological niche in the oral cavity. The predominant isolate was B. melaninogenicus ssp. intermedius followed by B. gingivalis and B. melaninogenicus ssp. melaninogenicus. B. melaninogenicus ssp. levii constituted low proportions of supragingival microflora of 1 adult periodontitis patient. A positive correlation was demonstrated between the proportion of black-pigmented Bacteroides (mainly B. melaninogenicus ssp. intermedius) and the severity of gingival inflammation and the periodontal pocket depth, suggesting that these organisms may contribute to the pathogenesis of certain forms of periodontal disease.