Photoinactivation of single and mixed biofilms of Candida albicans and non-albicans Candida species using Photodithazine®

Abstract

This study evaluated the effectiveness of antimicrobial photodynamic therapy (aPDT) mediated by Photodithazine (PDZ) formulated in hydrogel, in the inactivation of mono and duo-species biofilms of Candida albicans, Candida glabrata and Candida tropicalis. Standardized suspensions of each strain were prepared and after biofilm formation, mono-species were treated with 150 and 175mg/L of PDZ for 20min (pre-irradiation time), and exposed to LED light at a dose of 37.5J/cm (660nm). The duo-species biofilms (C. albicans+C. glabrata and C. albicans+C. tropicalis) were treated with 150mg/L of PDZ and light. Additional samples were treated with PDZ or light only, and the control did not receive any treatment. Next, microbiological evaluation was performed by spreading the cells on Sabouraud Dextrose Agar and CHROMagar Candida for colony forming units (CFU/mL). Moreover, the total biomass of biofilm was verified using the crystal violet staining assay (CV). The data were submitted to ANOVA and Tukey post-hoc (α=0.05). The use of PDZ 150mg/L promoted a reduction of 1.0, 1.2, 1.5 log in the viability of C. glabrata, C. albicans and C. tropicalis, respectively. The same concentration reduced in 1.0 log the viability of each species grown as duo-species biofilms. The crystal violet assay showed that the use of 150mg/L reduced 24.4%, 39.2% and 43.7% of the total biomass of C. albicans, C. tropicalis and C. glabrata, respectively. aPDT did not reduce the total biomass to the duo-species biofilms. Thus, PDZ-mediated aPDT was more effective in the inactivation of mono-species biofilms of Candida spp. compared with duo-species biofilm.

Antimicrobial sonodynamic and photodynamic therapies againstCandida albicans

“…The application of aPDT mediated by PDZ at 200 mg l −1 reduced the biomass of the biofilm by 30.9%. These results are in agreement with those found in the literature which observed that the combination of 150 mg l −1 of PDZ associated with LED light produced reductions on total biomass equivalent to 24.4, 39.2 and 43.7% for C. albicans, Candida tropicalis and C. glabrata, respectively (Carmello et al 2017). The total biomass of the biofilms treated with SDT mediated by PDZ was similar to the control group.…”

“…In contrast, when PDZ was applied in the absence of light or US, this PS was not able to reduce the suspension viability of C. albicans. The non-toxicity of PDZ has been reported in the literature (Dovigo et al 2013;Carmello et al 2017). Therefore, the effect of the sensitizers on the C. albicans viability depends on the type of the PS evaluated.…”

Synergistic Antifungal Effect of Amphotericin B-Loaded Poly(Lactic-Co-Glycolic Acid) Nanoparticles and Ultrasound against Candida albicans Biofilms

“…After incubation, the OD 490 was measured by a spectrophotometer (UV-2600; Shimadzu, Japan) to quantify biofilm activity. In addition, the total biomass of the biofilm was quantified by using a previously reported CV assay (40,41). After treatment, the supernatant of the biofilm was removed, the biofilm was washed with PBS four times, fixed with 95% methanol, and stained with 500 l of 0.1% CV at 37°C for 10 min in the dark.…”

Hydrogels: soft matters in photomedicine

“…Preliminary studies indicated antimicrobial PDT activity only for each species individually, but there was no reduction in total biomass of dual species biofilms. 371 Further improvements of the PDZ-Natrosol hydrogel formulation against Candida spp. were studied in vitro and in vivo (case study), showing potential for treatment of denture stomatitis.…”