Combined antimicrobial and light therapy effective for treating foot ulcers

By Helen Albert, Senior medwireNews Reporter

Results from a phase II study show that antimicrobial photodynamic therapy (PDT) is significantly more effective than placebo for treating patients with chronic leg ulcers.

Writing in the British Journal of Dermatology, Lesley Rhodes (University of Manchester, UK) and colleagues report that after 3 months, 50.0% of ulcers treated with PDT had healed completely compared with only 12.5% of those in the placebo group.

The patients in the study all had ulcers for over 3 months (16 chronic leg ulcers; 16 diabetic foot ulcers). They were randomly assigned in a blinded fashion to treatment with placebo or PDT (eight chronic leg ulcers and eight diabetic foot ulcers in each group).

The patients had the antimicrobial PPA904 or a placebo lotion applied to their wounds before both groups were exposed to 50 J/cm² of red light. The wounds were swabbed before and after treatment to assess bacterial counts and the antibacterial efficacy of the treatments, and the patients were followed up at 3 months for assessment of wound healing.

There was a significant reduction in the bacterial load of all wounds treated with PDT immediately after treatment (approximately 1 log in magnitude), whereas there was no change in those treated with placebo.

In addition, wound healing was significantly better with antimicrobial and PDT than placebo, although the analysis was restricted to those with chronic leg ulcers, "as there were insufficient data points for the longer times following treatment," for patients with diabetic foot ulcers, say the researchers.

No major adverse events linked to the treatment were observed, notes the team.

"Bacterial colonization of chronic wounds can both delay healing and lead to life threatening clinical infections," write the authors.

They say that the PDT method "appears to be safe and convenient and should be adaptable for use in non-hospital settings, such as local practitioner surgeries or in patient's homes."

However, "further investigation is indicated in larger patient numbers, using optimized drug formulation and light source, and repeat treatments, to attempt to achieve greater, sustained bacterial cell kill and to assess wound healing," they add.

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