The Effect of Sub-Lethal Successive Applications of Photodynamic Therapy on Candida albicans Biofilm Depends on the Photosensitizer

Abstract

This study aimed to evaluate the potential of successive applications of sub-lethal doses of the antimicrobial photodynamic therapy (aPDT) mediated by Photodithazine® (PDZ) and curcumin (CUR) associated with LED in the viability, reactive oxygen species (ROS) production, and gene expression of Candida albicans. The microbial assays were performed using planktonic cultures and biofilms. Ten successive applications (Apl#) were performed: aPDT (P+L+; C+L+), photosensitizer (P+L−; C+L−), and LED (P−L+; C−L+). Control groups were used (P−L−; C−L−). The viability of C. albicans was determined by cultivating treated cultures on agar plates with or without fluconazole (FLU). In addition, the ROS detection and expression of SOD1, CAP1, and ERG11 genes were determined. For planktonic cultures, no viable colonies were observed after Apl#3 (without FLU) and Apl#2 (with FLU) for either photosensitizer. Biofilm treated with P+L+ resulted in the absence of cell viability after Apl#7, while C+L+ showed ~1.40 log10 increase in cell viability after Apl#2, regardless of FLU. For both photosensitizers, after the last application with viable colonies, the production of ROS was higher in the biofilms than in the planktonic cultures, and SOD1 expression was the highest in P+L+. A reduction of CAP1 and ERG11 expression occurred after P+L+, regardless of FLU. C+L+ had a higher level of ROS, and the treatments were non-significant for gene expression. Sub-lethal doses of aPDT mediated by CUR could induce C. albicans resistance in biofilms, while C. albicans cells in biofilms were susceptible to aPDT mediated by PDZ.

Antibiofilm Activity and Biocompatibility of Temporin-SHa: A Promising Antimicrobial Peptide for Control of Fluconazole-Resistant Candida albicans

“…Standard strains of C. albicans [ATCC 90028 (CaS) [ 20 ] and ATCC 96901 (CaR) [ 20 ] stored at −80 °C were thawed and seeded in petri plates with culture medium Sabouraud dextrose agar (SDA) supplemented with chloramphenicol (0.05 g) and incubated (37 °C/48 h). Then, five colonies were inoculated in 10 mL of yeast nitrogen base (YNB) medium supplemented with 100 mM of glucose and incubated (37 °C/16 h).…”

“…A direct infusion of the sample solution was performed with a flow rate of 5.0 µL/min, and the electrospray source was operated in a positive mode, applying 4.5 kV to the electrospray capillary [21]. [20] and ATCC 96901 (CaR) [20] stored at −80 • C were thawed and seeded in petri plates with culture medium Sabouraud dextrose agar (SDA) supplemented with chloramphenicol (0.05 g) and incubated (37 • C/ 48 h). Then, five colonies were inoculated in 10 mL of yeast nitrogen base (YNB) medium supplemented with 100 mM of glucose and incubated (37 • C/16 h).…”

“…All experiments were performed in quadruplicate on three different occasions (n = 12). [20] and ATCC 96901 (CaR) [20] stored at −80 °C were thawed and seeded in petri plates with culture medium Sabouraud dextrose agar (SDA) supplemented with chloramphenicol (0.05 g) and incubated (37 °C/48 h). Then, five colonies were inoculated in 10 mL of yeast nitrogen base (YNB) medium absence of fungal growth to determine the lowest concentration of AMP to inhibit growth [25,26].…”

“…Considering that the mechanism of protection and survival of C. albicans is related to biofilm, and biofilm is commonplace in the oral cavity, the present study aimed to evaluate the antimicrobial effect of these specific AMPs on susceptible (CaS—90028) [ 20 ] and fluconazole-resistant (CaR—96901) [ 20 ] C. albicans strains. This included cell viability analysis (CFU/mL), survival curve, minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC), quantification of total biomass, and efficacy of AMPs in the inhibition of biofilm formation and against the biofilm formed using biofilm inhibition concentration (BIC-2).…”