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- Author or Editor: Lisa Long x
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Background:
Onychomycosis and tinea pedis (athlete’s foot) are infections of the nails and skin caused by pathogenic fungi collectively known as dermatophytes. These infections are difficult to treat, and patients often relapse; it is thought that a patient’s footwear becomes infected with these fungal organisms and, thus, is an important reservoir for reinfection. Therefore, it is important to find an effective means for killing the dermatophytes that may have colonized the inner surface of the shoes of patients with superficial fungal infections. In this study, we developed an in vitro model for culturing dermatophytes in footwear and used this model to evaluate the effectiveness of a commercial ultraviolet shoe sanitizer in eradicating the fungal elements residing in shoes.
Methods:
Leather and athletic shoes (24 pairs) were inoculated with either Trichophyton rubrum or Trichophyton mentagrophytes (107 colony-forming units/mL) strains and were placed at 35°C for 4 to 5 days. Next, we compared the ability of swabbing versus scraping to collect microorganisms from infected shoes. Following the optimized method, shoes were infected and were irradiated with one to three cycles of radiation. The inner surfaces of the shoes were swabbed or scraped, and the specimens were cultured for dermatophyte colony-forming units.
Results:
Leather and canvas shoes were infected to the same extent. Moreover, scraping with a scalpel was overall more effective than was swabbing with a cotton-tipped applicator in recovering viable fungal elements. Irradiation of shoes with one, two, or three cycles resulted in reduction of fungal colonization to the same extent.
Conclusions:
The developed infected shoe model is useful for assessing the effectiveness of ultraviolet shoe sanitizers. Also, ultraviolet treatment of shoes with a commercial ultraviolet C sanitizing device was effective in reducing the fungal burden in shoes. These findings have implications regarding breaking foot infection cycles. (J Am Podiatr Med Assoc 102(4): 309–313, 2012)
Abstract
Background: Recently, an increasing number of resistant-to-terbinafine dermatophytosis cases have been reported. Thus, identifying an alternative antifungal agent that possesses a broad-spectrum activity, including against resistant strains, is needed.
Methods: In this study, we compared the antifungal activity of efinaconazole to fluconazole, itraconazole, and terbinafine against clinical isolates of dermatophyte, Candida, and molds using in vitro assays. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of each antifungal was quantified and compared. Both susceptible and resistant clinical isolates of Trichophyton mentagrophytes (n=16), T. rubrum (n=43), T. tonsurans (n=18), T. violaceum (n=4), Candida albicans (n=55), C. auris (n=30), Fusarium sp., Scedosporium sp., and Scopulariopsis sp. (n=15 for each) were tested.
Results: Our data shows that efinaconazole was the most active antifungal, compared to the other agents tested, against dermatophytes with MIC50 and MIC90 (Concentration that inhibited 50% and 90% of strains tested, respectively) values of 0.002 and 0.03 μg/ml, respectively. Fluconazole, itraconazole and terbinafine showed MIC50 and MIC90 values of 1 and 8 μg/ml, 0.03 and 0.25 μg/ml, and 0.031 and 16 μg/ml, respectively. Against Candida isolates, efinaconazole MIC50 and MIC90 values were 0.016 and 0.25 μg/ml, respectively, whereas fluconazole, itraconazole and terbinafine had MIC50 and the MIC90 values of 1 and 16 μg/ml, 0.25 and 0.5 μg/ml, and 2 and 8 μg/ml, respectively. Against various mold species, efinaconazole MIC values ranged from 0.016 and 2 μg/ml, compared to 0.5 to greater than 64 μg/ml for the comparators.
Conclusions: efinaconazole showed superior potent activity against a broad panel of susceptible and resistant dermatophyte, Candida, and mold isolates.