Light-activated drug used to tackle MRSA

Sep 7 2008

New treatment using a light-activated drug could revolutionise the fight against hospital "superbug", MRSA (otherwise known as Meticillin resistant staphylococcus aureus) it was revealed at the British Pharmaceutical Conference (BPC) in Manchester.

MRSA can sometimes live on the skin or in the nose and has no harmful effects unless it gets under the skin, for example in wounds, where it can cause infection. If MRSA gets into the bloodstream it can cause serious infections, for example pneumonia, septicaemia, or osteomyelitis (in the bones).

Doctors do not apply antibiotics directly to MRSA-infected wounds as they do not penetrate deep enough into the wound to have an effect, or can irritate the surrounding skin, slowing down wound healing. Worryingly, MRSA is now resistant to most types of standard antibiotics.

Investigations underway by Corona Cassidy and co-workers at the School of Pharmacy, Queen's University of Belfast, move away from the antibiotic approach. The treatment would involve delivering a drug known as a 'photosensitiser' to infected wounds and activating it using a special type of light, triggering it to kill the MRSA. The concept is known as photodynamic antimicrobial chemotherapy or 'PACT'.

In laboratory studies, the team has examined a hydrogel that holds and then releases the light-reacting drug. The system was effective in killing the bacteria when the drug was released from the hydrogel.

Miss Cassidy said: "PACT is an exciting potential treatment of MRSA-infected wounds. More laboratory work must be carried out to optimise our treatment conditions to ensure that all exposed bacteria are killed."