Investigating the Effect of Photodynamic Therapy With a ۶۶۰ nm Laser With Methylene Blue and Cold Atmospheric Plasma Therapy on Streptococcus sanguinis Effect of ۶۶۰ nm laser photodynamic therapy and cold plasma therapy on Streptococcus sanguinis

Abstract Introduction: This study was conducted to investigate the effect of photodynamic therapy (PDT) with a ۶۶۰ nm laser along with methylene blue (MB) and cold atmospheric plasma therapy (CAP) on Streptococcus sanguinis. Since S. sanguinis plays a pivotal role in biofilm formation, alongside its ability to survive in the bloodstream, it significantly heightens the risk of infective endocarditis.Methods: In this in-vitro study, the S. sanguinis strain was cultured on a blood agar medium, and the samples were evenly distributed among eight experimental groups using equalization methods with nine repetitions. The experimental groups were ۸ groups. Following the interventions, the samples were cultured using the pour plate method. After ۴۸ hours, the samples were retrieved, and the number of bacterial colonies was counted. The changes in colony numbers, after normaltransformation, were analyzed using the repeated measures ANOVA model, with the between-subject factor considered in the analysis.Results: The highest colony count was observed in the control group. Particularly, in both the PLASMA group and the group treated with PLASMA + PDT using the ۶۶۰ nm laser alone, there was no significant difference from the control group (PLASMA: P > ۰.۰۵; PLASMA + PDT: P > ۰.۰۵). However, the combination of CAP, PDT with the ۶۶۰ nm laser, and MB demonstrateda significant reduction in colony counts compared to the control group (PLASMA + PDT + MB: P = ۰.۰۰۰), making it the most effective intervention in this study.Conclusion: The results demonstrated that the combination of CAP and PDT using a ۶۶۰ nm laser with MB achieved the most significant reduction in S. sanguinis colonies. Keywords: Streptococcus sanguinis; Photodynamic therapy; Cold atmospheric plasma therapy; Methylene blue