Appropriate doses of 405-nm blue light inhibit the growth of S. aureus in vitro. This research does suggest that S. aureus may be capable of developing resistance to blue light irradiation.

Foodborne illness resulting from infectious organisms occurring in vegetables and processed meat is a serious health concern in the United States. Improved and cost‐effective techniques for disinfection are needed. Visible light in the blue range (405 nm) was administered to processed meat that had been inoculated with Escherichia coli. One application of light energy at doses of 10, 30, 60, and 100 J/cm2 was applied, in vitro. In the case of vegetables contaminated with Salmonella (cucumbers), 464 nm light was used at 6, 12, and 18 J/cm2. In both cases, after 20 hours of incubation, colony‐forming units were counted and compared to controls to determine whether the light energy inhibited growth of E. coli or Salmonella. E. coli – 405 nm light at doses of 30, 60, and 100 J/cm2 were all effective inhibitors of the organism. Kill rates of 75.61 – 96.34% were achieved. Salmonella – 464 nm light at doses of 6, 12, and 18 J/cm2 produced significant inactivation of the organism. Kill rates of 80.23–100% were obtained. Blue light, delivered in the wavelength/dose combinations used in this study is an effective inhibitor of both E. coli and Salmonella on actual foodstuffs. Blue light should be considered as a potentially effective tool in the effort to protect humans from foodborne illnesses.

Appropriate doses of 624-nm light from a supraluminous diode array can inhibit the growth of C albicans in vitro. Three, 9, and 30 J/cm(2) are all effective dose levels.

The aim of the study is to confirm the effectiveness of photodynamic therapy (PDT) as a significant inhibitor of Trichophyton rubrum (T. rubrum) and to determine the most appropriate dose and rate of delivery. Trichophyton rubrum is the most common dermatophyte worldwide, responsible for the majority of superficial fungal infections. The traditional treatment of T. rubrum has known adverse effects. An alternative treatment is warranted. Photosensitised T. rubrum specimens were treated with 625-nm light at doses of 3, 12, 24, 40 and 60 J/cm . Colony counts were performed and compared to untreated controls. Doses of 24, 40 and 60 J/cm all produced kill rates of over 94%. A lower rate of delivery (7.80 mW/cm ) was shown to be a greater inhibitor of T. rubrum than a higher rate of delivery (120 mW/cm ). Photodynamic therapy with methylene blue (MB) at 625 nm using a low rate of delivery at doses of 24, 40 and 60 J/cm is an effective inhibitor of T. rubrum. A rate of delivery of 7.80 mW/cm is a significantly greater inhibitor of T. rubrum than a rate of 120 mW/cm when applying 625-nm light in PDT using MB.