The prevalence of Bacteroides meianinogenicus and B. intermedius (now belonging to the Prevotella group) and B.gingivalis (Porphyromonas group) in healthy and diseased sites in the oral cavity was studied. The P. melaninogenica, P. intermedia and P. gingivalis were all formerly called black pigmented bacteroides (BPB). Out of the biack pigmented bacteroides, P. intermedia and P. melaninogenica were isolated from 20% and 62% of fifty healthy oral cavities, respectively. No Porphyromonas gingivalis was isolated in this group of subjects. P. gingivalis (25%) and P. intermedia (53.4%) were positively associated with disease in the oral cavity. Their presence in acute necrotizing ulcerative gingivitis (ANUG) was statistically significant. They were also isolated from periodontitis, oral abscesses, infected fractures, infections superimposed on tumors, and suppurating osteomyelitis. There was a non-statistically significant association of these species with periodontitis. It was observed that the older the patient was, the more frequent the isolation rate of P. gingivalis. Some local isolates of P. gingivalis were resistant to ampicillin, tetracycline and cephalothm, produced beta-lactamase and carried cryptic plasmids whose functions were not clear.

Saudi Dental Journal 1993;5(2):57-63.