OBJECTIVE: To determine whether a blue light (405 nm) could inhibit the growth of Trichopyton mentagrophytes without using a photosensitizing material as part of the treatment protocol.
DESIGN: Basic physiologic randomized trial using laboratory specimens (T mentagrophytes).
INTERVENTIONS/METHODS: Plated on a growth medium, T mentagrophytes were exposed to 3 to 5 administrations of blue light at 20 J/cm2 over 28 hours. Following 7 days of incubation, colony-forming units were counted and compared with nonirradiated controls.
RESULTS: The study found 3, 4, and 5 administrations of blue light produced significant inhibition of T mentagrophytes (P < .05); 4 and 5 applications produced the greatest inhibition of growth (84.7% and 93.6% kill rates, respectively).
CONCLUSIONS: The application of 405-nm light at a dose of 20 J/cm2 is an effective in vitro inhibitor of T mentagrophytes. To give results similar to those seen when a photosensitizing material is included, 3 to 5 applications of this wavelength and dose condition delivered over 28 hours is likely needed.
J. Stephen Guffey, EdD, PT, is Professor of Physical Therapy; William Payne, MS, MT(ASCP), is Assistant Professor of Clinical Laboratory Science; Ben Buchanan, DPT, is Staff Physical Therapist, Visiting Nurse Association of Southeast Missouri, Kennett, Missouri; Jessie Daugherty, DPT, is Staff Physical Therapist, Star Physical Therapy, Clarksville, Missouri; Logan Meurer is a Clinical Laboratory Science Student; and Patricia Hensley, BS, is a Graduate Clinical Laboratory Science Student; Arkansas State University, Jonesboro, Arkansas. Dr Guffey has disclosed that he serves as a paid consultant to Dynatronics. The light device used in this study was manufactured by Dynatronics; however, Dynatronics has neither financial involvement with this research nor any role in the planning, execution, analysis, or reporting of the results. The device used was purchased by Arkansas State University. The remaining coauthors disclose that they have no financial relationships related to this article. Submitted March 3, 2015; accepted in revised form September 10, 2015.