Background and objectives: Staphylococcus aureus (S. aureus) are important causes of nosocomial and medical-device-related infections. Photodynamic treatment (PDT) has been proposed as an alternative approach for the inactivation of bacteria. Sinoporphyrin sodium (DVDMS) is a newly identified photosensitizer and has high photo-sensitivity when used in PDT. This study aims to evaluate the antibacterial effect of DVDMS mediated PDT on S. aureus planktonic and biofilm cultures.
Study design/materials and methods: The uptake of DVDMS in S. aureus was evaluated according to photometry after alkali lysis. Then bacteria were incubated with DVDMS and exposed to light treatment. After PDT treatment, counting colony-forming units (CFU) was applied to estimate the bactericidal effect. Intracellular reactive oxygen species (ROS) production was detected by flow cytometry. Scanning electron microscope (SEM) was performed to assess the disruption of biofilm.
Results: With the incubation time increased, the relative fluorescence intensity of DVDMS in bacteria increased and reached peak at 75 minutes. DVDMS alone did not produce significant toxicity compared with the untreated group, while, remarkable survival decrease was observed in PDT groups in a dose-dependent manner. More than 90% of the bacteria were effectively killed by the combined treatment of 2 µM DVDMS with 10 J/cm2 light irradiation, and 4-log reduction in CFU was observed after 5 µM DVDMS treatment followed by 100 J/cm2 light irradiation. Intracellular ROS level was significantly enhanced after PDT treatment. The disruption of biofilm was confirmed by SEM, suggesting DVDMS-PDT effectively damaged the biofilm.
Conclusion: These results indicate DVDMS-PDT presents significant bactericidal activity.
Keywords: antibacterial efficacy; antimicrobial photodynamic inactivation; photodynamic inactivation.
© 2016 Wiley Periodicals, Inc.