Antimicrobial activity of metabolites produced by Streptococcus mutans on Candida albicans in in vivo study models

Abstract

"In vitro" studies have shown that Streptococcus mutans can produce metabolites capable of inhibiting Candida albicans, becomming interesting the identification and development of new substances for the treatment of oral candidiasis. The aim of this study is to purify and identify the metabolites produced by S. mutans and evaluate their effects on the pathogenicity of C. albicans and on the immune response in "in vivo" models study. The supernatant metabolites of S. mutans culture will be extracted with ethyl acetate and then fractionated and identified by High-performance Liquid Chromatography - Diode Array Detection (HPLC-DAD). Hereafter, the effects of the metabolites will be assessed on experimental candidiasis in Galleria mellonella and in immunosuppressed mice. In experimental infection model with G. mellonella, the effects of the metabolites will be analyzed by survival curve test, quantitation of CFU/ml of C. albicans in hemolymph, phagocytosis and determining of hemocyte density of G. mellonella larvae. The S. mutans metabolite with greater antimicrobial activity against C. albicans in G. mellonella will be selected for the study of oral candidiasis in mice. In this experimental model, the development of candidosis will be evaluated by recovery tests and determination of CFU/ml of C. albicans from the mice's oral cavity, macroscopic and microscopic examination of the tongue dorsum and quantification of cytokines from the serum of the animals. The results of the survival experiments in G. mellonella will be analyzed by log-rank test (Mantel-Cox). The data obtained in the other tests will be submitted to an exploratory analysis for the selection of the most appropriate statistical test for each experiment. In all tests will be used GraphPad Prism 5.0 program, considering a significance level of 5%.