Avaliação de parâmetros de virulência em leveduras do gênero Candida obtida do dorso lingual e canais radiculares necróticos portadores de periodontite apical primária

Abstract

Yeasts from the genus Candida can be commensal members of the oral microbiota, and can also colonize the endodontic environment. These microorganisms can penetrate the pulp space through dentinal tubules. The ability to adhere to dentinal structures, thigmotropic responses, secretion of proteases, formation of biofilm and pleomorphism is related to this penetration capacity. This study aimed to evaluate this virulence parameters of yeast samples from the tongue dorsum and necrotic root canals. The method for detecting protease in plate was used to indicate enzyme activity. Regardless of the primary isolation site, C. albicans samples were able to degrade the albumincontained in the culture medium, indicating positive protease activity. However, among root canals samples, it was revealed the largest precipitation zones around the colonies. The expression of genes coding for Sap-1, Sap-2 and Sap-4 was identified by RT-PCR. The gene encoding Sap-2 was preferentially expressed by yeasts of the tongue dorsum while for those of the root canals, highlighted the expression of the gene encoding Sap- 4. The results suggest that the concomitant expression of Sap-2 and Sap-4 is necessary for yeast pulpal colonization. Fluorescence microscopy was used to evaluate the microbial adhesion to acrylic and dentin. The highest adhesion means were observed inthe dentin substrate however neither dentin adhesion nor acrylic adhesion showed correlation with the microbial hidrophobicity. Biofilm formation was measured according to the intensity of XTT reaction. Factors such as pH, carbohydrate availability, presence of saliva and other microbial groups present some influence on biofilm formation. Using an in vitro dentin infection model, it was observed that thedirection of hyphal tip did not change in according with tubular nature of the dentin. In this view, only the pleomorfism has a determinant role for the fungal colonization of human dentin.