A novel chlorine derivative ShengTaiBuFen mediated photodynamic therapy on a mouse wound model infected with methicillin-resistant Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) is the most common and difficult-to-treat pathogen in chronic wounds. In this study, a novel derivative of chlorin, ShengTaiBuFen (STBF), was used as a photosensitiser to investigate the effect of STBF mediated photodynamic therapy (STBF-PDT) on MRSA-infected ulcers. Appropriate incubation time and concentration parameters were initially explored to evaluate the anti-MRSA performance of STBF-PDT in vitro. An infected mouse skin ulcer model was further established to assess the antibacterial ability of STBF-PDT on MRSA in ulcers and the ultimate effect on ulcers. Our data showed that the antibacterial activity of STBF-PDT against planktonic MRSA was strongest at 25 µM concentration in a light dose-dependent way, and MRSA strains were completely eliminated at 120 J/cm2. The in vivo study showed the STBF-PDT group had basically healed (96.93 ± 2.21%), while the untreated group (28.83 ± 10.25%), the red light group (36.63 ± 13.08%) and the STBF group (32.95 ± 9.38%) had poor healing. STBF-PDT displayed marked bacteriostatic effect in vivo as opposed to the other three groups. The mean viable bacterial log of wounds subjected to STBF-PDT revealed 6.80 ± 6.98 log cfu/g (a substantial reduction of 99.83% versus the untreated control). STBF was believed to be an advantageous and reliable photosensitizer, and its mediated PDT provided a reliable and safe modality for the clinical treatment of potentially drug-resistant microbial infectious diseases such as chronic wounds.