Although the number of research with biofilms has increased, less is known about the behavior of mixed microbial communities, particularly interactions between fungi and bacteria. To understand the infectious diseases process and develop new drugs and therapeutic strategies, it is necessary in vitro and in vivo models of polymicrobial biofilms. The study will characterize the polymicrobial biofilms, in vitro, formed by Candida albicans, S. aureus, S. epidermidis and P. aeruginosa; assess pathogenicity of the interaction among these microorganisms in the experimental model of invertebrate Galleria mellonella and expression of virulence genes by C. albicans. This study will be divided in five stages. In stage A, the polymicrobial biofilms will be studied and characterized by the following tests: quantification of viable cells and detached cells from the biofilm metabolic activity by the colorimetric XTT assay, analysis of biomass (dry weight), and assay of bacteria adhered to hyphae. In stage B, biofilms will be analyzed microscopically by scanning electron microscopy and confocal laser scanning microscopy. The effects of enzyme lyticase in the integrity of polymicrobial biofilms will be performed in stage C. In vivo study of microbial pathogenicity in experimental model of G. mellonella will be performed in stage D, through the survival curve of this larva and quantification of micro-organisms. The influence of polymicrobial biofilms in the expression of virulence genes by C. albicans will be evaluated in stage E. Statistical analysis of the results obtained in this study will be performed using Minitab software, considering difference statistically significant when p value is less than 0.05.
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