The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4–3.3 μg ml⁻¹). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction ∼90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.

The aim of this study was to evaluate the effect of the QS molecule farnesol on single and mixed species biofilms formed by Candida albicans and Streptococcus mutans. The anti-biofilm effect of farnesol was assessed through total biomass quantification, counting of colony forming units (CFUs) and evaluation of metabolic activity. Biofilms were also analyzed by scanning electron microscopy (SEM). It was observed that farnesol reduced the formation of single and mixed biofilms, with significant reductions of 37% to 90% and 64% to 96%, respectively, for total biomass and metabolic activity. Regarding cell viability, farnesol treatment promoted significant log reductions in the number of CFUs, ie 1.3–4.2 log₁₀ and 0.67–5.32 log₁₀, respectively, for single and mixed species biofilms. SEM images confirmed these results, showing decreases in the number of cells in all biofilms. In conclusion, these findings highlight the role of farnesol as an alternative agent with the potential to reduce the formation of pathogenic biofilms.