Abstract
Bacterial resistance to antibiotics has become a worldwide problem. One potential alternative for bacterial control is photodynamic therapy. 5-aminolevulinic acid is a natural precursor of the photosensitizer protoporphyrin IX. Relatively little is known about the antibacterial efficacy of photodynamic therapy using the systemic administration of 5-aminolevulinic acid; a few reports have shown that 5-aminolevulinic acid exerts photodynamic effects on methicillin-resistant Staphylococcus aureus (MRSA) in vitro. In this study, we evaluated the effectiveness of photodynamic therapy using 5-aminolevulinic acid and a 410-nm wavelength light-emitting diode in vitro and in vivo for the treatment of MRSA. We found that 5-aminolevulinic acid photodynamic therapy with the light-emitting diode had an in-vitro bactericidal effect on MRSA. In vivo, protoporphyrin IX successfully accumulated in MRSA on ulcer surfaces after intraperitoneal administration of 5-aminolevulinic acid to mice. Furthermore, 5-aminolevulinic acid photodynamic therapy accelerated wound healing and decreased bacterial counts on ulcer surfaces; in contrast, vancomycin treatment did not accelerate wound healing. Our findings indicate that 5-aminolevulinic acid photodynamic therapy may be a new treatment option for MRSA-infected wounds.
Highlights
Staphylococcus aureus is responsible for severe infections in the hospital and the community
When the irradiation dose was 50 J/cm2, a similar decrease of 5 log10-units was observed at both of these 5-aminolevulinic acid (5-ALA) concentrations. These results indicate that ALA-photodynamic therapy (PDT) with a 410-nm light-emitting diode (LED) exerts an in-vitro antibacterial effect on methicillinresistant S. aureus (MRSA)
The present study showed that ALAmediated PDT (ALA-PDT) with a 410-nm LED exerts an in-vitro antibacterial effect on MRSA
Summary
Staphylococcus aureus is responsible for severe infections in the hospital and the community. Due to the spread of methicillinresistant S. aureus (MRSA), glycopeptide antibiotics such as vancomycin (VCM) and teicoplanin are used to treat severe staphylococcal infections [1]. Extensive use of these antibiotics has led to the appearance of VCM- and methicillinresistant S. aureus [2,3], necessitating alternative approaches against MRSA toward which no resistance can develop. PDT involves the selective photosensitization of target cells using topically or systemically administered agents that can be activated by light to produce an oxygen-dependent cytotoxic reaction [6,7]. PDT is performed with 5-aminolevulinic acid (5-ALA), a natural amino acid that is the precursor of a strong photosensitizer, protoporphyrin IX (PpIX), within cells [8]. PpIX is maximally activated at 410 nm in the Soret
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