Antimicrobial Photodynamic Therapy: Photodynamic Antimicrobial Effects of Malachite Green on Staphylococcus, Enterobacteriaceae, and Candida

Abstract

Objective: This study investigated in vitro the photodynamic antimicrobial effects of the photosensitizer malachite green on clinical strains of Staphylococcus, Enterobacteriaceae, and Candida. Materials and Methods: Thirtysix microbial strains isolated from the oral cavity of patients undergoing prolonged antibiotic therapy, including 12 Staphylococcus, 12 Enterobacteriaceae, and 12 Candida strains, were studied. The number of cells of each microorganism was standardized to 10 6 cells/mL. Twenty-four assays were carried out for each strain according to the following experimental conditions: gallium-aluminum-arsenide laser and photosensitizer (n ¼ 6, LþPþ), laser and physiologic solution (n ¼ 6, LþPÀ), photosensitizer (n ¼ 6, LÀPþ), and physiologic solution (n ¼ 6, LÀPÀ). Next, cultures were prepared on brain-heart infusion agar for the growth of Staphylococcus and Enterobacteriaceae, and on Sabouraud dextrose agar for the growth of Candida, and incubated for 48 h at 378C. The results are reported as the number of colony-forming units (CFU/mL) and were analyzed with analysis of variance and the Tukey test. Results: The Staphylococcus, enterobacterial, and Candida strains were sensitive to photodynamic therapy with malachite green (LþPþ). A reduction of *7 log 10 for Staphylococcus, 6 log 10 for enterobacteria, and 0.5 log 10 for the genus Candida. Significant statistical differences were observed between the LþPþ groups and the control groups (LÀPÀ). Conclusion: The Staphylococcus, Enterobacteriaceae, and Candida strains studied were sensitive to photodynamic therapy with malachite green.

Photodynamic Antifungal Chemotherapy†

“…Junqueira et al. (32) demonstrated the PDF with malachite green was effective in Candida strains reduction (<1 log 10 ) when irradiated with low doses (26 J cm −2 ) of gallium‐aluminum‐arsenide (GaAlAs) laser. The photoinactivation efficacy of malachite green was also investigated by Souza et al.…”

In vitro reduction of pathogenic sporothrix schenckii fungus by photodynamic therapy

“…Also in this study, photoactivation using methylene blue (0.1 mg/mL), followed by low power GaAlAs laser irradiation at energy densities of 26.31 J/cm², reduced the number of log CFU / ml Sporothrix schenckii complex fungi. In a similar way, it has been shown that the combination of methylene blue and aluminum gallium arsenide (685 nm and 28 J/cm2) caused a reduction of 88.6% of C. albicans, 84.8% of C. dubliniensis, 91.6% of C. krusei, and 82.3% of C. tropicalis 20,21 . In the present experiment, the same laser energy density of Gallium Aluminum Arsenide in J/cm² was used, in addition to the same concentration of methylene blue dye in the samples, in order to evaluate its effect on S. schenckii 2,5,[8][9][10] , because the reduction of Ckefyrse results from the existence of a membrane efflux pump 22,23 .…”

Photodynamic inactivation of Escherichia coli by methylene blue and malachite green under red LED light

“…They observed 99.9% cell viability inhibition using MG 0.01% (w/v) and after 5 minutes of radiation. Junqueira et al (2010) investigated the photodynamic antimicrobial effects of the MG on thirty-six microbial strains, including Gram positive and Gram negative bacteria, and yeasts. The results indicate that Gram positive bacteria were more sensitive to MG-mediated photosensitization, followed by Gram negative species, and the yeast species.…”