Association of farnesol to antimicrobial photodynamic therapy for the control of Enterococcus faecalis

Abstract

E. Faecalis has great importance in persistent endodontic infections. Photodynamic therapy (PDT) has demonstrated the ability to reduce the growth of E. faecalis within the root canals, presenting potential to be used as a supporting endodontic conventional treatment. Aiming to increase the effectiveness of photodynamic therapy for the complete elimination of E. Faecalis, this work aims to evaluate the Farnesol as possible enhancer of this therapy. Standard and clinical strains of E. faecalis, previously isolated from root canals of patients with endodontic infections, will be used. Initially, minimum inhibitory concentration (MIC) tests will be carried out by the method of broth microdilution in order to establish the concentration of the Farnesol to be used in the study. Photodynamic therapy will be performed by the Association of Methylene Blue Photosensitizer with low-intensity laser (660 nm). All strains will be subjected to PDT in planktonic cultures, with or without prior treatment with Farnesol. The results will be evaluated by means of the count of colony-forming units (CFU/ML). To investigate the mechanisms by which the Farnesol can impact in PDT, the test will be carried out to determine the permeability of the cellular membrane and quantification of absorption of the photosensitizer by the strains of E. faecalis. The following will be performed in Biofilms, in which the influence of the Farnesol in PDT will be evaluated by the count of viable cells (CFU/ML) and quantification of the total biomass by the method of the Violet crystal. The data obtained will be analyzed for the selection of the most appropriate statistical test for each experiment, with a significance level of 5%.