Photobiomodulation and Antimicrobial Photodynamic Influence of a 650 nm Wavelength on Staphylocoagulase and Viability of Staphylococcus aurous

[摘要] Introduction: Staphylococcus aureus is one of the critical pathological bacteria. This bacterium haddeveloped a variety of genetic mutations that made it resistant to drugs and more harmful to humans.In addition, all attempts to design a specific vaccine against S. aureus have failed. Therefore, thisexperiment was designed as a trial for vaccine production, by using a photodynamic treatment(PDT) through partial biological inhibition. The PDT of bacteria mainly focused on reducing theactivity of staphylocoagulase (SC), which has a protective feature for bacteria. This study aimedto examine the photodynamic effect of combining a specific wavelength of a laser and a certaindilution photosensitizer, methylene blue (MB) dye. The possible PDT effect on the inhibition ofpathogenic enzymatic activity was predicted. This study also aimed to evaluate the inhibitory effectof PDT on the total bacterial account (viability) simultaneously with SC assay.Methods: A 650nm wavelength diode laser was used with 100 mW output power and 2 minutes ofexposure time. Dye dilutions were 50, 100, 150 and 200 μg/mL. The viability of bacteria after andbefore laser treatment was calculated using single plate-serial dilution spotting methods. The activityof SC was detected by using human plasma for 4 hours incubation of crude-substrate interaction.Results: The results revealed a significant decrease in enzyme activity and colony-forming units(CFU) after irradiating bacterialsuspension with 150 g/mL MB, as well as a decline in CFU.However, irradiation with a laser alone showed a significant increase in SC activity and CFU for thesame exposure time.Conclusion: Besides reducing the production of SC activity, PDT significantly inhibited the viabilityof S. aureus. The application of MB photosensitizer at a concentration of 150 g/mL in combinationwith a laser wavelength of 650 nm resulted in a complete decrease in the SC activity value as wellas the viability of bacteria.

[学科分类] 基础医学

[关键词] Photodynamic Therapy;Staphylocoagulase;Laser;Enzyme activity;Methylene blue