Objective: To determine the in vitro activity of the low-level laser (light) therapy (LLLT) device (Phovia; Vetoquinol) on Malassezia pachydermatis.
Methods: Clinical isolates of M pachydermatis (n = 30) and a commercially available anamorph of M pachydermatis (ATCC strain 14522) were used in this study. Both groups of organisms were plated on potato agar plates and exposed to the LLLT device for 2, 4, 6, and 8 minutes with a 30-second break after every 2 minutes of exposure. The plates were then incubated at 37 °C for 48 hours. Each experiment was run in duplicate. The experiment for the internal control was repeated independently 6 times. Nonirradiated plates served as the viability control (positive control). The number of CFUs between each treatment and the control was analyzed using a repeated-measures ANOVA or a Friedman test followed by a post hoc analysis.
Results: Compared to the control, there was a statistically significant decline in CFUs after a minimum of 4 minutes of exposure to the LLLT device in both groups compared to unexposed controls.
Conclusions: This preliminary in vitro study demonstrated that the LLLT device tested can inhibit the growth of M pachydermatis.
Clinical relevance: This in vitro study offers a novel proof-of-concept approach to treating Malassezia infections in veterinary medicine. Low-level laser (light) therapy has the potential to shorten treatment durations and reduce side effects, making it a promising alternative to standard antifungal therapy, particularly in the context of antifungal resistance.
Keywords: Malassezia pachydermatis; Phovia; dogs; in vitro; low-level light therapy.