Abstract
Candida albicans and Staphylococcus aureus specifically often resulted in biofilm-associated diseases, ranging from superficial mucosal to life-threatening systemic infections. Recent studies reported that chelerythrine displayed antimicrobial activities against a few microorganisms, but its effects on mono- and dual-species biofilms of C. albicans and S. aureus have never been reported. The purpose of this study was to evaluate the efficacy of chelerythrine against mono- and dual-species biofilms, and explore its effect on the hyphal growth and the hypha-to-yeast transition of C. albicans. The results showed that minimum inhibitory concentrations (MICs) and minimum biofilm inhibitory concentration (MBIC90S) of chelerythrine against planktonic cells of mono-species were 4 and 2 μg/mL, while the MIC and MBIC90 were 6 and 3 μg/mL for dual-species. Meanwhile, the decrease in three matrix component levels and tolerance to antibiotics of biofilms formed by mono- and dual-species exposed to chelerythrine were confirmed by a confocal laser scanning microscope, in conjugation with five fluorescent dyes and a gatifloxacin diffusion assay. Moreover, C. albicans and S. aureus mono-species showed a 96.4, and 92.3% reduction, respectively, in 24-h preformed biofilm biomass in the presence of 128 µg/mL of chelerythrine. Similarly, preformed (24 h) dual-species biofilm biomass also displayed a significant reduction (90.7%) when treated with 192 μg/mL chelerythrine. Chelerythrine inhibited hyphae formation of C. albicans at 4 μg/mL, and C. albicans in hypha-form can be converted into yeast-form at 8 μg/mL of chelerythrine. Therefore, chelerythrine shows promise as a potential antimicrobial and antibiofilm agent for clinical effective treatments of mono- and mixed-species and/or biofilm-associated infections.
Highlights
Candida accounts for 70% to 90% of all human fungal infections and can be associated with devastating consequences, in intensive care units where mortality rates reach 40% [1,2].Oral candidiasis is one of the observed mostly human opportunistic fungal infections of the oral cavity, caused by an overgrowth of Candida species, the most common being Candida albicans [3]
We further examined the architecture of the biofilms in the presence or absence of chelerythrine cluster composed largely of macrocolonies was present in the untreated C. albicans pure-culture group, by staining with SYTO 9 dyes to detect live cells using a confocal laser scanning microscopy (CLSM)
In dual-species biofilms, mixed-culture biofilms porosity, while the biofilm biomass remarkably decreased in the 1/2 Minimal Inhibitory Concentrations (MICs) group, as compared with the treated with chelerythrine at 1/8 MIC presented a flake-like structure, with a significant increase in porosity, while the biofilm biomass remarkably decreased in the 1/2 MIC group, as compared with the 1/4 MIC group. These results showed chelerythrine at 1/2 MIC could effectively inhibit the biofilms formation C. albicans and S. aureus mono- and dual-species
Summary
Candida accounts for 70% to 90% of all human fungal infections and can be associated with devastating consequences, in intensive care units where mortality rates reach 40% [1,2]. Oral candidiasis is one of the observed mostly human opportunistic fungal infections of the oral cavity, caused by an overgrowth of Candida species, the most common being Candida albicans [3]. C. albicans, a dimorphic fungal organism, is present primarily in the oral cavity in a non-pathogenic yeast state in. J. Fungi 2020, 6, 45; doi:10.3390/jof6020045 www.mdpi.com/journal/jof. A retraction notice was published on 18 April 2020 in Journal of Fungi 2020, 2, 50; doi:10.3390/jof6020050.
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