Resumo

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 evaluated the interaction between Candida albicans with Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa in biofilms. Biofilms were grown in vitro in the bottom of a 96-well microtiter plate with microbial suspensions (10⁷ cells/mL) and incubated for 4, 12, 24 or 48 h. After incubation, the numbers colony-forming units per milliliter (CFU/mL; log10) of dispersed cells and cells of the biofilms were determined. The metabolic activity by the colorimetric XTT assay of the biofilms was also performed. 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. This study showed greater biofilm formation by C. albicans when this yeast was cultivated alone. In mixed biofilms, a decrease in number of C. albicans was observed, and this growth was lower in biofilms associated with P. aeruginosa. For periods of incubation, it was observed that the number of CFU/mL increased with the increase of incubation time, however no significant differences between the periods 24 and 48 h were observed. In the XTT assay higher metabolic activity was also observed in biofilms isolates of C. albicans when compared to mixed biofilms. To dispersed cells the counting of CFU/ml was significantly lower than those obtained from biofilms. In conclusion, the interactions with bacteria in mixed biofilms decreased the growth of C. albicans.