Antimicrobial Photodynamic Inactivation of Staphylococcus aureus Virulence Factors: In Vitro Study
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Abstract
A therapeutic alternative for the treatment of infectious diseases has arisen from antimicrobial photodynamic inactivation (PDI). The effect of photodynamic therapy (PDT) on Staphylococcus aureus strains was evaluated in this study. The Staphylococcus aureus suspension (108 CFU/mL) was incubated with the dyes Methylene blue (MB), toluidine blue O (TBO) and Rose bengal (RB) for in vitro photodynamic inactivation studies at a concentration of 20 μM using Period of incubation (30 min) and the fluence of light (10 J/cm2 of 635-nm light). The photodynamic inactivation impact on virulence factors i.e catalase, βhemolysis, lipases, thermonuclease, and coagulase of Staphylococcus aureus has been studied. The antimicrobial photodynamic inactivation showed that the reduction of total viable cellsof
Staphylococcus aureus. The study showed that 20μM of MB and TBO both were found good photodynamic action, achieving a reduction of viability of bacterial culture. Photodynamic antimicrobial inactivation suppressed the expression of virulence factors, possibly inactivating virulent strains of Staphylococcus aureus, relative to commonly used antibiotics, meaning that this therapy would become a powerful and efficient alternative to antibiotics to control infections of pathogenic staphylococcus.