Infections with pathogens could cause serious health problems, such as septicemia and subsequent death. Some of these deaths are caused by nosocomial, chronic, or burn-related wound infections. Photodynamic therapy (PDT) can be useful for the treatment of these infections. Our aim was to investigate the antibacterial effect of indocyanine green (ICG) and 808-nm laser on a rat abrasion wound model infected with the multidrug resistant Staphylococcus aureus strain. Abrasion wounds were infected with a multidrug resistant clinical isolate of S. aureus. ICG concentrations of 500, 1000, and 2000 μg∕ml were applied with a 450 J∕cm2 energy dose. Temperature change was monitored by a thermocouple system. The remaining bacterial burden was determined by the serial dilution method after each application. Wounds were observed for 11 days posttreatment. The recovery process was assessed macroscopically. Tissue samples were also examined histologically by hematoxylin–eosin staining. Around a 90% reduction in bacterial burden was observed after applications. In positive control groups (ICG-only and laser-only groups), there was no significant reduction. The applied energy dose did not cause any thermal damage to the target tissue or host environment. Results showed that ICG together with a 808-nm laser might be a promising antibacterial method to eliminate infections in animals and accelerate the wound-healing process.
The main purpose in antibacterial photodynamic therapy (PDT) is to kill the micro-organisms that cannot be destroyed by conventional methods. Low-level light and/or low concentration of reactive oxygen species may trigger some biochemical pathways that lead to cell proliferation. Thus, there is a risk of bacterial cell proliferation during PDT. In this study we report that PDT with ICG application can induce biostimulation when laser dose and photosensitizer concentration are not optimized properly. Therefore, optimum dosimetry in PDT possesses great importance in the treatment of wounds infected by antibiotic-resistant bacteria.
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