Effects on Virulence Factors and Mechanisms Involved in Antimicrobial Sonophotodynamic Therapy Mediated by Curcumin

Due to the progression of antimicrobial resistance, Photodynamic (aPDT) and Sonodynamic (SDT) Therapies arose as promising approaches for microbial control. Recently, the combination of both therapies, called Sonophotodynamic Therapy (SPDT), have shown greater effects than the single treatments. This study evaluated the effects of aPDT, SDT and SPDT mediated by curcumin on the metabolism, adhesion capacity, biofilm formation ability and structural alteration in the Staphylococcus aureus biofilm. Moreover, possible antimicrobial mechanisms involved, such as the production of reactive oxygen species (ROS) and the degradation spectrum of curcumin by light, ultrasound and light+ultrasound, were measured. SPDT was more effective to inactivate the biofilm than aPDT and SDT. All treatments reduced the adhesion ability of the bacteria and it is probably related to the metabolism cell reduction. Regarding to the biofilm formation ability, all treatments reduced the total biomass. One possible mechanism involved in the inactivation is the ROS production observed. Curcumin had a significantly decay in its absorbance with the application of light, and a slighter one caused by the ultrasound. Finally, all treatments impacted the biofilm components and structure, reducing the cells and matrix. In conclusion, SPDT was more effective in the inactivation, and all treatments had the same effect in the virulence factors evaluated.