Denture-associated stomatitis (DS), a frequent infection in denture-wearers (up to 60%), presents as areas of palatal inflammation and is normally associated with denture biofilms containing Candida albicans. However, the contribution of co-existing bacteria in these biofilms to the infection remains unclear. As current DS management strategies are primarily directed towards Candida, research demonstrating the impact of specific bacteria upon infection prognosis is important to improve treatment regimes. This research evaluated the in vitro impact of bacteria on Candida virulence, and compared bacterial microbiomes at specific oral sites in DS and non-DS patients to determine associations with infection. In vitro biofilm studies assessed expression of C. albicans virulence factors (morphological transformation, adhesins, hydrolytic enzymes) and their impact on pathogenesis in an infection model. In clinical studies, microbiological samples were obtained from the tongue, palate and denture-fitting surface of 19 denture-wearing patients (DS n=8, non-DS n=11). The presence of Candida was ascertained by PCR. Bacterial DNA was extracted and subjected to next generation sequencing using bacterial 16S rRNA gene targets, and differences in the bacterial microbiomes determined. Certain bacterial species in acrylic biofilms significantly (P < 0.05) increased the expression of C. albicans virulence factors, and subsequently, enhanced tissue damage in model systems. Candida was detected in clinical samples of 14 patients (DS n=6, non-DS n=8). Metataxonomic analyses revealed differences in relative abundance of bacterial species, but no significant differences in the bacterial microbiomes of the denture-fitting surface and palate between DS and non-DS patients. Importantly, a significant (P=0.007) increase in the number of bacterial species was evident for the tongue microbiome of non-DS patients. The in vitro modulating capacity of bacteria toward Candida virulence, and the observed species-level differences in bacteria between DS and non-DS patients highlight the need for consideration of the bacterial composition of oral biofilms in the pathogenesis of DS.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:738400 |
| Date | January 2017 |
| Creators | Morse, Daniel |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/110586/ |
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