Microaerophilic Gram-Negative Rods in Periodontal Disease

Dentistry

Abukhres, Omar Mohamed Omar

University:University of Glasgow

关键词: Dentistry;   

Others  :  http://theses.gla.ac.uk/74918/1/11007838.pdf

来源: University of Glasgow

【 摘 要 】

A.actinomycetemcomitans, H.aphrophilus and Capnocytophaga species are capnophilic Gram-negative rods that have been isolated frequently from dental plaque. They have been studied to varying extents with regard to the role that they may play in the aetiology of human periodontal disease. A.actinomycetemcomitans has been the most extensively studied of the three bacteria and has been implicated in the aetiology of periodontitis, particularly localized juvenile periodontitis. Capnocytophaga species have been implicated in some forms of periodontitis, though the evidence is far from complete and more studies are needed to verify their role. However, few studies have addressed the aetiological role of H.aphrophilus in periodontitis. In the present study a number of A.actinomycetemcomitans. H.aphrophilus and Capnocytophaga strains freshly isolated from subgingival plaque samples, together with type strains of each bacterium, were examined for their ability to produce the following virulence factors. First the ability of each organism to haemagglutinate human erythrocytes was measured. Secondly, their ability to produce a leukotoxin capable of killing HL60 cells and human PMNLs was determined by using two assay systems, the trypan blue exclusion and luminol-dependent chemiluminescence inhibition assays respectively. Thirdly, the ability of human PMNLs to phagocytose strains of A.actinomycetemcomitans. H.aphrophilus and Capnocytophaga species was tested by using a luminol-dependent chemiluminescence assay. Fourthly, the ability of these groups of bacteria to interfere with the proliferation of cultured human skin fibroblasts was examined by using a bio-assay to measure the metabolic activity of cultured fibroblasts. Finally the ability of the organisms to cleave human IgA by production of an IgA protease was investigated by using SDS-PAGE and immunoblotting techniques. The results obtained in the current study indicated that all three groups of bacteria studied are capable of producing virulence factors that may cause ranging degrees of damage to host tissues. The results of this study also indicated that strains of H.aphrophilus are capable of producing virulence factors, though not to the same extent as the other two tested bacteria. To verify the role of H.aphrophilus in periodontitis more studies are clearly required. These should include careful examination of the epidemiology.