Photodynamic  Antimicrobial Chemotherapy (PACT) using Phenothiazines Derivatives Associated with the Red-Orange LED against Staphylococcus aureus

Juliana S. C. Monteiro; Susana C. P. S. Oliveira; Gustavo M. P. Santos; Anderson F. S. Miranda; Fernando J. P. Sampaio; Maria F. M. Gesteira; Fátima A. A. Zainn; Marcos A. V. Santos; Antônio L. B. Pinheiro

doi:10.1117/12.2005591

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5 March 2013 Photodynamic antimicrobial chemotherapy (PACT) using phenothiazines derivatives associated with the red-orange LED against staphylococcus aureus

Juliana S. C. Monteiro, Susana C. P. S. Oliveira, Gustavo M. P. Santos, Anderson F. S. Miranda, Fernando J. P. Sampaio, Maria F. M. Gesteira, Fátima A. A. Zainn, Marcos A. V. Santos, Antônio L. B. Pinheiro

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Proceedings Volume 8569, Mechanisms for Low-Light Therapy VIII; 85690R (2013) https://doi.org/10.1117/12.2005591
Event: SPIE BiOS, 2013, San Francisco, California, United States

Abstract

The objective of this study was to contribute to PDT development by researching alternative light sources using redorange LED light at doses of 2.4 e 4.8 J/cm² to evaluate the bactericidal effect of photodynamic antimicrobial chemotherapy (PACT) using phenothiazinium dye (Toluidine blue O and methylene blue) at a low concentration of 1μg/mL on strain of Staphylococcus aureus (ATCC 23529) in vitro. For this research, tests were performed in triplicate and the samples were distributed into six test groups: (L_-P_-) Negative control (L1₊ P_-) and (L2₊ P_-) bacterial suspensions were irradiated with laser energy 2.4 and 4.8 J/cm² respectively in the absence of photosensitizer; (L1 ₊ P₊) and (L2 ₊ P₊) bacterial suspensions were irradiated with laser in the presence of 1μg/ml of photosensitizer and finally (L_-P₊) bacterial suspensions only in the presence of phenothiazinium dye. Therefore, were analyzed the potential bactericidal PACT by counting of colony-forming units and analyzed statistically (ANOVA, Tukey test, p<0.05). The results demonstrated that comparing the LED group (L2 ₊ P_-) with negative control group, LED group (L1₊ P_-) and photosensitizer group there was a statistically significant (p<0.0001, p<0.01 and p<0.001, respectively) that the group treated only with LED (energy density of 4.8J/cm²) increased the average of CFU counts. The negative control group when compared to the groups submitted to PDT only showed a statistically significant reduction (p<0.01) relative to the group (L2₊P₊) that showed a decrease in the number of CFU. There was no statistically significant difference between the groups submitted to PDT (L1₊P₊ and L2₊P₊). Although the results of this study have shown a reduction in average number of colony forming units by the appropriate LED-dye treatment combination, it needs further investigation.

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Juliana S. C. Monteiro, Susana C. P. S. Oliveira, Gustavo M. P. Santos, Anderson F. S. Miranda, Fernando J. P. Sampaio, Maria F. M. Gesteira, Fátima A. A. Zainn, Marcos A. V. Santos, and Antônio L. B. Pinheiro "Photodynamic antimicrobial chemotherapy (PACT) using phenothiazines derivatives associated with the red-orange LED against staphylococcus aureus", Proc. SPIE 8569, Mechanisms for Low-Light Therapy VIII, 85690R (5 March 2013); https://doi.org/10.1117/12.2005591

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