Photodynamic antimicrobial chemotherapy for Staphylococcus aureus and multidrug-resistant bacterial burn infection in vitro and in vivo

BACKGROUND AND OBJECTIVES: Antibiotic resistance has emerged as one of the most important determinants of outcome in patients with serious infections, along with the virulence of the underlying pathogen. Photodynamic antimicrobial chemotherapy (PACT) has been proposed as an alternative approach for the inactivation of bacteria. This study aims to evaluate the antibacterial effect of sinoporphyrin sodium (DVDMS)-mediated PACT on Staphylococcus aureus and multidrug resistant S. aureus in vitro and in vivo. MATERIALS AND METHODS: Bacteria were incubated with DVDMS and exposed to treatment with light. After PACT treatment, colony-forming units were counted to estimate the bactericidal effect. Intracellular reactive oxygen-species production was detected by flow cytometry. Flow cytometry and fluorescence-microscopy detection of bacterial cell-membrane permeability. Enzyme-linked immunosorbent assays were used to determine expression of VEGF, TGFβ(1), TNFα, IL6, and bFGF factors in burn infection. RESULTS: DVDMS-PACT effectively killed bacterial proliferation. Intracellular ROS levels were enhanced obviously in the PACT-treatment group. SYTO 9 and propidium iodide staining showed a decrease in the ratio of green:red fluorescence intensity in the PACT-treatment group in comparison to the control group. Enzyme-linked immunosorbent-assay results revealed that in the healing process, the expression of bFGF, TGFβ(1), and VEGF in the treatment group were higher than in the control group, which inhibited inflammation-factor secretion. In addition, skin-tissue bacteria were reduced after treatment. CONCLUSION: These results indicate that DVDMS-PACT presents significant bactericidal activity and promotes wound healing after burn infections.