Prevalence and Gingivalis Pathogenicity of Bacteroides Gingivalts Isolated from Nigerians
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University of Lagos
Plaque samples obtained from 62% and 20% of 50 Nigerians with clinically 'normal' oral cavities were colonized by Bacteroides melaninogenicus and B. intermedius respectively. B. gingivalis was not isolated from these subjects. Pathologic materials obtained from infected sites in 45.6%, 53.3% and 34.9% of 103 patients presenting with a variety of prodental diseases were colonized by B. melanino-genicus, B. intermedius and B. gingivalis respectively. The apparently higher prevalence of B. gingivalis was isolated more frequently with increasing age of patient and most frequently from periodontitis (37.1%). Acute necrotizing ulcerative gingivitis - ANUG (70%), and dento-alveolar abscesses (32%). Clinical isolates of B. gingivalis from Nigerians exhibited several phenotypic similarities with isolates from Americans. Clinically important differences existed however in sensitivity to ampicillin, tetracycline and the production of Beta-lactamase. A reliable simple and rapid scheme for the identification of human black pigmented Bacteroides was developed and evaluated. This scheme utilized microtitration techniques and the hydrolysis of specific chromogenic enzyme substrate for presumptive identification within 4hs. Co-aggregation studies undertaken showed that B. gingivalis exhibited specific affinity to bind in-vitro with members of the Veilonella spp, Capnocytophaga spp and Actinomyces naeslundii but not with any of the oral streptococci. Co-aggregation exhibited by B. gingivalis was lactose reversible. Also, B. gingivalis demonstrated a strong hemagglutinating activity which was enhanced by saliva but weakened when cells are/primed with ethylenediamenetetra acetic acid (EDTA). Salivary enzymes did not interfere with aggregation of human black pigmented Bacteroides species. Cultural filtrates and crude cell extracts of B. gingivalis were cytotoxic to Vero cells and Wi 38 cells in vitro and this activity was related partly to butyrate and propionate metabolic end products. Also a previously unreported heat labile cytotoxin in young cultures of B. gingivalis was reported and related to the activity of a trypsin-like protease by B. gingivalis. An experimental animal model was developed for demonstrating the pathogenicity of mono model B. gingivalis. By utilizing this model B. gingivalis was demonstrated to induced a loculated subcutaneous abscess in hamsters and a spreading subcutaneous infection in mice. Its pathogenicity was not enhanced by reducing agents but was greatly enhanced by haemin. B. gingivalis also produced pneumonitis and lung abscesses in hamsters infected transtracheally, and abscesses in experimentally infected liver, testes and muscles. These studies suggest that B. gingivalis may be involved directly in the pathogenesis of soft tissue abscesses of the oral cavity and respiratory tract.
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Gingivalis Pathogenicity , Bacteroides , Prevalence , Gingivalts Isolated
Eke, I.P, (1988), Prevalence and Gingivalis Pathogenicity of Bacteroides Gingivalts Isolated from Nigerians, University of Lagos School of Postgraduate Studies Phd Thesis and Dissertation Abstracts, 208pp.