Antifungal Resistance and Pathogenesis of Candida Albicans Biofilms in Patients with Denture Stomatitis

  • Brent Jason Coco

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


INTRODUCTION: Denture stomatitis is associated with the presence of biofilms on the surface of the denture. Candida albicans is the predominant oral pathogen in this environment, which produces key virulence factors, such as proteases and lipases, which are associated with pathology of the oral mucosa. Therefore, reducing biofilm on the denture and controlling future growth is important in reduction patient morbidity.

METHODS: Intact dentures were removed from denture stomatitis patients, an oral hygiene history obtained and biofilms removed by mild ultrasonicaton. Oral rinses and swabs were also taken. Qualitative and quantitiative microbiology was subsequently
performed or were selected for a study. Biofilm models were used to examine virulence factors expression by biochemical testing and real-time PCR from both single and mixed candidal populations, which was compared to gene expression in vivo. Chemotherapeutic approaches to biofilm disinfection and removal were subsequently evaluated with a range of antifungal products, that were either commerically available, prescriptive or novel.

RESULTS: Candida albicans was the pre dominant pathogen isolated. However, C. glabrata was also isolated in large numbers. These mixed infections correlated with high grades of erythema, but also to poor oral hygiene. Molecular analysis showed that key
protease genes were variably expressed during biofilm growth phases and that virulence gene expression was detectable from in vivo samples. Analysis of mixed C. albicans and C. glabrata population revealed a trend suggestive of increased release of virulence
factors in combination. Candidal biofilms were killed and reduced by denture oral hygiene products and prescriptive antifungal agents to varying extents. Tea tree oil components also demonstrated activity against planktonic and sessile organisms.

Understanding the role of candidal population in the oral cavity will provide important information on how the organism elicits tissue damage. These chronic infections are difficlt to treat with the biofilm growth modality, especially mixed infections. Therefore, new active antifungal agents, such as the tea tree oil components may provide a novel way of reducing oral candidosis by preventing tissue damage.
Date of Award2008
Original languageEnglish
Awarding Institution
  • Glasgow Caledonian University
SupervisorGordon Ramage (Supervisor)

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