Doctor of Dental Surgery 2014, University of Campinas - Brazil
Project Title: Intracellular Invasion & Carcinogenesis of a Periodontal Pathogen
Research Subject Matter: Oral Microbiology/Oral Cancer
Supervisors: Dr. David H. Edwards, Co-supervisor: Dr. Dorothy (Sam) Crouch
The two most common diseases of the mouth are both precipitated by bacteria. Caries involves the dissolution of the tooth surface by bacterially produced acid, while Periodontal disease is known to involve the action of a wide range of bacteria whose cumulative effect is to promote inflammation and cause direct damage to the gingiva and supporting tissue. For both these diseases a community, or biofilm, of bacteria is key to disease progression. In the case of Caries two species of mutans Streptococci are considered the main bacterial source of acid. In the case of Periodontal disease a group of organisms collectively referred to as Gram negative anaerobic bacteria (GNABs) are the major mediators of disease. One of the best understood GNAB is Porphymonas gingivalis, a major pathogen that can survive intracellularly and encodes a variety of potent virulence factors. The project proposed is aimed at developing specific drugs and improved targeting of existing antibiotics to kill another important Periodontal Pathogen Fusobacterium nucleatum, the earliest colonising and most abundant GNAB in plaque. This microorganism has a unique role in promoting the adhesion of different species of bacteria due to is large surface area; a result of its long filamentous shape (5-25 µMs), and uniquely its ability to coaggregate with all of the oral bacteria so far investigated. This role as a ‘bridging’ organism is key to the accumulation and diversification of bacterial species in dental plaque. ImportantlyF. nucleatum is considered a Periodontal pathogen and the aetiological agent of specific conditions that include Acute Ulcerative Gingivitis. Consequently a method of specifically controlling F. nucleatum offers the opportunity not only to reduce the accumulation of plaque, but also to intervene in destructive oral infections where F. nucleatum is a key mediator of disease.