A technique that has been around for more than one hundred years is being used in new research as a way of killing methicillin-resistant Staphylococcus aureus (MRSA) using light. The research to be reported today at the British Pharmaceutical Conference in Manchester, is being undertaken by researchers from Queen's University Belfast.
The treatment, called photodynamic antimicrobial therapy (PACT) has the potential to treat MRSA infection in wounds, burns and leg ulcers. PACT uses a combination of visible light and a photosensitising drug to cause destruction of microbial cells via singlet oxygen production. (Singlet oxygen is a high-energy state of oxygen that kills bacteria by damaging their DNA or their cell membrane).
Although photodynamic therapy is groundbreaking in the current age - the process has been around for over a century. Dr Ryan Donnelly, from the Belfast team, explains: "One hundred years ago, people looked at killing bacteria by photosensitising them. The method fell out of favour with the development of antibiotics. But with the present problems of antibiotic resistance, there is interest in alternative antimicrobial therapy."
Dr Donelly says that PACT may be the answer to antiobiotic resistance. "The beauty of PACT is that, because singlet oxygen is a non-specific oxidising agent and is only present during illumination, it is highly unlikely that a population of cells would become resistant."
To test the efficacy of PACT, it was tested on two conditions of MRSA growth: in a method known as 'suspension' and also in 'biofilms'. The latter was a worst-case scenario as biofilms are highly resistant to antibiotics. In both sets of experiments, bacteria were killed by the photodynamic therapy.