Susceptibility of Candida albicans and Candida dubliniensis to erythrosine- and LED-mediated photodynamic therapy

Abstract

The effect of erythrosine- and LED-mediated photodynamic therapy (PDT) on planktonic cultures and biofilms of Candida albicans and Candida dubliniensis was evaluated. Planktonic cultures of standardized suspensions (10(6)cells/mL) of C. albicans and C. dubliniensis were treated with erythrosine concentrations of 0.39-200 μM and LEDs in a 96-well microtiter plate. Biofilms formed by C. albicans and C. dubliniensis in the bottom of a 96-well microtiter plate were treated with 400 μM erythrosine and LEDs. After PDT, the biofilms were analysed by scanning electron microscopy (SEM). The antimicrobial effect of PDT against planktonic cultures and biofilms was verified by counting colony-forming units (CFU/mL), and the data were submitted to analysis of variance and the Tukey test (P<0.05). C. albicans and C. dubliniensis were not detectable after PDT of planktonic cultures with erythrosine concentrations of 3.12 μM or higher. The CFU/mL values obtained from biofilms were reduced 0.74 log(10) for C. albicans and 0.21 log(10) for C. dubliniensis. SEM revealed a decrease in the quantity of yeasts and hyphae in the biofilm after PDT. In conclusion, C. albicans and C. dubliniensis were susceptible to erythrosine- and LED-mediated PDT, but the biofilms of both Candida species were more resistant than their planktonic counterparts.

Fungicidal effect of combined nano TiO2 with erythrosine for mediated photodynamic therapy on Candida albicans: an in vitro study

“…The power density of the LED curing unit in the present study was relatively low; thus, we decided to increase the concentration of erythrosine to obtain enough killing. There have been studies of photodynamic therapy that kills C. albicans by using erythrosine as a photosensitizer, but it was stimulated by green light, which better matches erythrosine absorption (400 μM erythrosine + green LED 42.63 J/ cm 2 led to a reduction of 0.74 log 10 [7]; 400 μM erythrosine + green LED 14.34 J/cm 2 led to a reduction of 0.73 log 10 [8] in the amount of C. albicans present in mouse lesions; and 3000 μM erythrosine + green LED 50 J/cm 2 led to a reduction of C. albicans by 4 log 10 [5]). However, in this study, we used blue light because it has been used routinely in dental clinics.…”

“…It is a photosensitizer that absorbs light at 526 nm [4]. There are studies about erythrosine as a photosensitizer for use in killing Staphylococcus aureus [5], Streptococcus mutans [6], and C. albicans [7,8] when activated by green light. Titanium dioxide is an oxide of titanium that has been widely used in industrial and consumer products [9], whose light-curing unit is blue LED wavelengths of 400-500 nm [10].…”

“…Previous studies have shown the effect of photosensitizers on bactericides and fungicides in solution form [5][6][7][8]. In clinical situations, however, it is difficult to maintain this form in the target area, e.g., deep periodontal pocket.…”

Mixed biofilms formed by C. albicans and non-albicans species: a study of microbial interactions

“…10 The extracellular matrix of the biofilm can protect the cells from phagocytosis, maintain the integrity of the biofilm, and limit the diffusion of substances. 11 It has been estimated that over 60% of microbial infections are involved with biofilm. 1 The high resistance of biofilms to antimicrobials (compared to their planktonic counterparts) is of major clinical relevance.…”

Photodynamic inactivation of biofilm: taking a lightly colored approach to stubborn infection

“…Significant reductions in CFU/ml of 0.74 log 10 and 0.21 log 10 have been observed, respectively [177]. …”