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Title: From orthodontic separators to the heart : a laboratory-based study of oral streptococcal blood survival mechanisms
Author: Haworth, Jennifer A.
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2020
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The association between dental procedures, oral bacteria and infective endocarditis (IE) is contentious, particularly following changes in UK guidance on antibiotic prophylaxis in recent years. Although IE in children is rare, the disease carries a high risk of mortality and morbidity, and several cases of orthodontic-induced IE have been reported. Evidence suggests that orthodontic separator placement induces bacteraemia with oral streptococci, potential causative agents in IE. However, a detailed understanding of how such bacteria survive in blood is currently lacking. This study aimed to determine the blood survival mechanisms of oral streptococci commonly implicated in orthodontic separator placement. In particular, the role of bacterial surface determinants and evasion of complement-mediated killing in promoting streptococcal survival in blood were investigated. This work identified that bacterial blood survival rates are species- and straindependent, with a general correlation between IE-associated species and persistence in blood. IE pathogen Streptococcus gordonii surface proteins PadA and Hsa both bound Factor H and vitronectin, indicating two mechanisms by which S. gordonii may evade the host immune system. Better understanding of mechanisms for streptococcal survival in the bloodstream, such as those identified in this project, could identify novel targets for the prevention or treatment of IE in the future.
Supervisor: Nobbs, Angela ; Ireland, Tony Sponsor: Not available
Qualification Name: Thesis (D.D.S.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available