Antimicrobial effect of the photodynamic therapy using erythrosine/methylene blue combination on Streptococcus mutans biofilm

Publication date: Available online 12 May 2018
Source:Photodiagnosis and Photodynamic Therapy
Author(s): Laíse Midori Tokubo, Pedro Luiz Rosalen, Janaina de Cássia Orlandi Sardi, Irlan Almeida Freires, Mitsue Fujimaki, Josely Emiko Umeda, Patricia Magalhães Barbosa, Gabriela Ortolan Tecchio, Noboru Hioka, Camila Fabiano de Freitas, Raquel Sano Suga Terada
BackgroundPhotodynamic therapy (PDT) has demonstrated promising results in the treatment of several clinical pathologies through the photochemical reaction caused by the combination of a photosensitizer and a light source. The objective of this study was to evaluate the antimicrobial effect of the combination of the photosensitizers (PSs) erythrosine/methylene blue activated by a white halogen light device on Streptococcus mutans biofilm.MethodsTwo separate experiments were conducted, the first using the PSs at the concentration of 100 μM, and the second 250 μM. The PSs were tested on S. mutans biofilms cultured for 24 hours in isolation, in combination, with and without light activation for 2 minutes fractionated in 4 periods of 30 seconds. After treatment, biofilms were diluted and plated on BHI medium and incubated for 24 hours for colony forming units (CFU) counting. The results (log10) were analyzed with ANOVA followed by Tukey test (p < 0.05).ResultsThe erythrosine/methylene blue combination activated by white halogen light at 100 and 250 μM, and erythrosine at 250 μM, methylene blue at 250 μM presented significantly reduced cell counts (3.2 log10, 5.3 log10, 4.5 log10, 4.3 log10, respectively) when compared to controls (p < 0.05).ConclusionPDT with the combination of erythrosine/methylene blue demonstrated better results that the PSs in isolation regardless of the concentration. The use of this combination at the concentration of 250 μM shows promise as an antibacterial treatment for carious lesions and should be further assessed.



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