Oral Microbiology

The Oral Microbiology research group conducts studies into the survival strategies of microorganisms, their colonisation and virulence factors, and the interactions that occur between microbes or between microbe and host, especially in the development of microbial communities (biofilms). These studies impinge on many aspects of both oral and systemic health and disease. Key research areas currently include:

Links between oral microbes and cardiovascular disease:

Oral Streptococcus bacteria are major mediators of a form of cardiovascular disease known as infective endocarditis (IE). This is due to their capacity to activate blood platelets, increasing the risk of thrombotic vegetations forming on heart valves. Ongoing studies aim to reveal new insights into the mechanisms by which oral Streptococcus bacteria interact with platelets and cardiac endothelium to promote unwanted thrombus formation.

Substantial evidence also exists for a causative link between periodontal bacteria and atherosclerosis, a chronic cardiovascular condition associated with hyperinflammation. We are working to determine the mechanisms by which periodontopathogens can trigger this inflammation and so accelerate atherosclerosis, with particular focus on signalling via the Wnt pathway.

These project areas are supported by collaborations with academic staff in the Bristol Heart Institute and Clinical Trials Unit. The mechanistic understanding arising from these studies could ultimately lead to the development of novel therapies for IE and atherosclerosis.

Microbial biofilm community development:

Dental plaque biofilms are polymicrobial communities found on oral surfaces embedded in a matrix of host salivary components and microbial extracellular products. Communication between the microorganisms modulates the structure, composition and pathogenic potential of the biofilms. Oral streptococci are especially important because they are primary colonisers of oral cavity surfaces. Their deposition thus provides attachment sites for colonisation by potentially pathogenic organisms such as the fungus Candida albicans, which is the cause of most yeast infections in humans. Our research aims to identify the molecular basis of bacterial and fungal biofilm formation and of polymicrobial community formation, in terms of both physical interactions (microbe-microbe or microbe-host) and communication/signalling networks. We are also interested in determining the mechanistic basis for high levels of antimicrobial resistance associated with biofilm formation, and developing new strategies to combat biofilm-associated infections. To this end, we have long-standing collaborations with the Oral Nanoscience and bioMEG groups to develop novel antimicrobial biomaterials. These studies have implications for biofilms formed within the oral cavity and at sites throughout the human body.

Streptococcus colonisation and pathogenesis:

Bacteria within the genus Streptococcus are exquisitely adapted to colonisation of humans and other animals. These bacteria predominantly live in harmony with their hosts, but all have capacity to cause disease should prevailing conditions allow. Streptococci express a myriad of colonisation and virulence attributes that promote their survival at a variety of ecological sites. Many of these factors are surface-expressed adhesins that can promote interactions with a multitude of host substrata or can confer pathogenic capabilities associated with immune evasion or host tissue destruction. Given these critical functions, streptococcal adhesins may represent viable targets for combatting streptococcal disease. In collaboration with academic colleagues in the Bristol BioDesign Institute, we seek to determine the structure-function relationships of these bacterial adhesins with regards to streptococcal colonisation and pathogenesis, and to determine their potential to serve as therapeutic targets to combat infection.

Contact

The Oral Microbiology group is led by Dr Angela Nobbs

bacterium under a microscope
TEM image showing ‘fuzzy coat’ of adhesins on Streptococcus cell surface
Streptococcus microbe
Platelet spreading induced by oral bacterium Streptococcus gordonii Image credit: Dr Jennifer Haworth
Biofilm of the microbe streptococcus under a microscope
Biofilm of Candida albicans (red) and Streptococcus gordonii (green) on salivary pellicle Image credit: Dr Lindsay Dutton
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