LED to target T. rubrum viability involved photodynamic therapy (the ..... tial of photodynamic therapy (PDT) in treating two clinical cases of .... what's in a word?
Lasers Med Sci DOI 10.1007/s10103-013-1287-4
ORIGINAL ARTICLE
An investigation into the inhibitory effect of ultraviolet radiation on Trichophyton rubrum Leah J. Cronin & Richard P. Mildren & Michelle Moffitt & Antonio Lauto & C. Oliver Morton & Colin M. Stack
Received: 7 August 2012 / Accepted: 8 February 2013 # Springer-Verlag London 2013
Abstract Fungal infection of nails, onychomycosis, is predominantly caused by Trichophyton rubrum. This infection is an important public health concern due to its persistent nature and high recurrence rates. Alternative treatments are urgently required. One such alternative is phototherapy involving the action of photothermal or photochemical processes. The aim of this novel study was to assess which wavelengths within the ultraviolet (UV) spectrum were inhibitory and equally important nail transmissible. Initial irradiations of T. rubrum spore suspensions were carried out using a tunable wavelength lamp system (fluence ≤3.1 J/cm2) at wavelengths between 280 and 400 nm (UVC to UVA) to evaluate which wavelengths prevented fungal growth. Light-emitting diodes (LEDs) of defined wavelengths were subsequently chosen with a view to evaluate and potentially implement this technology as a low-cost “in-home” treatment. Our experiments demonstrated that exposure at 280 nm using an LED with a fluence as low as 0.5 J/cm2 was inhibitory, i.e., no growth following a 2-week incubation (p0.05, n=3; Fig. 3).
way ANOVA, p>0.05)). Our results also show that the inhibitory effect of using an LED with a wavelength of 280 nm was dose dependent. The lower fluences between 0.05 and 0.2 J/cm2 were not inhibitory as regrowth occurred during the 7-day incubation period at 30 °C. Although irradiance with a fluence of 0.2 J/cm2 highlighted a dose-dependent antifungal effect as compared to the controls (39±24 %), this effect was likely fungistatic at best and merely resulted in a slower regrowth. However, irradiations with fluences greater than 0.5 J/cm2 had a profound effect on the viability of T. rubrum with 100 % inhibition of regrowth following a 2-week incubation at 30 °C. These results are summarized in Table 1. Figure 4 demonstrates that significant growth inhibition was achieved between 5 and 30 min irradiance (fluence, 0.5 to 3.2 J/cm2) (n=3; one-way ANOVA, p
