A mouse with skin ulcers infected with MRSA
A mouse with skin ulcers infected with MRSA

A research group at Osaka City University succeeded in treating a skin ulcer infected with methicillin-resistant staphylococcus aureus (MRSA) by (1) the systemic administration of natural amino acid (5-aminolevulinic acid: ALA) and (2) a photodynamic therapy (PDT) using LED light.

Because the new method does not cause the emergence of resistant bacteria, it is expected to be used as a new method for the treatment of bacterial infections. The group is developing it in collaboration with SBI Pharmaceuticals Co Ltd, planning to conduct a preclinical test targeted at skin ulcers infected with MRSA.

In recent years, the emergence of bacteria resistant to antibacterial drugs (resistant bacteria) is becoming a global issue. And MRSA is a representative example.

Skin ulcers infected with MRSA are more difficult to cure than those that are not. In some cases, MRSA prevents a wound from curing and causes death. Even MRSA resistant to vancomycin, which is effective in the treatment of MRSA, has already emerged. Under such circumstances, it is necessary to develop a treatment that does not rely on antibacterial drugs and generate new resistant bacteria.

This time, the group formed skin ulcers infected with MRSA on the back of a mouse. Then, it systemically administered ALA as a substance that gives photosensitivity and applied PDT using a blue-violet LED light source with a wavelength of 410nm to them. PDT is a treatment that annihilates target cells (bacteria) with reactive oxygen generated by applying a light with a specific wavelength after concentrating photo-sensitive substances on the target tissues. It does not develop resistant bacteria.

As a result, MRSA was sterilized, and a heating effect equivalent to that of ulcers that are not infected with MRSA was achieved. In other words, the group proved that PDT using ALA can be a new method for the treatment of MRSA infections.

The results of the research was published on the US online journal PLOS ONE under the title "Photodynamic therapy using systemic administration of 5-aminolevulinic acid and 410-nm wavelength light emitting diode for methicillin-resistant Staphylococcus aureus infected ulcers in mice."