In vitro Activities of Antifungal Drugs against Clinical Isolates of Trichophyton tonsurans

Genotyping of Trichophyton tonsurans strains isolated between 2016 and 2020, and terbinafine susceptibility of the species in Japan

Trichophyton tonsurans is the most prevalent fungus which causes dermatophytosis among contact sports players in Japan. We previously surveyed the epidemic of T. tonsurans in Japan from early 2000, and determined the genotypes of isolates by analysis of restriction enzyme fragment length polymorphisms in the non-transcription spacer (NTS) region of ribosomal RNA gene, which enabled discrimination of eight genotypes, namely NTS I to NTS VIII. In the present study, we performed genotyping of T. tonsurans isolated between 2016 and 2020, and investigated the trend of the epidemic and resistance of the pathogen to antibiotic terbinafine (TBF). Regardless of which contact sport they played, the genotype of all 123 strains of T. tonsurans isolated from athletes was NTS I. Genotypes NTS II and III, which were isolated in considerable numbers mainly from wrestlers between 2000 and 2015, were conspicuously absent. TBF susceptibility was screened in 237 T. tonsurans strains isolated between 2000 and 2020 with 28 of these further assessed for minimum inhibitory concentration of TBF and squalene epoxidase gene sequences. None of the strains showed TBF resistance. TBF may still be effective to control the epidemic of T. tonsurans.

Tavaborole, Efinaconazole, and Luliconazole: Three New Antimycotic Agents for the Treatment of Dermatophytic Fungi

Fungal diseases of the nail bed (onychomycosis) and epidermis are recurrent illnesses in the elderly and immunocompromised patients, which have few efficacious treatment options. Current treatment options for onychomycosis are limited to topical agents, laser treatment, and oral antifungals. Previous generations of topical agents were not efficacious, owing to poor penetration of the nail bed. Oral antifungal drugs, such as itraconazole, terbinafine, and fluconazole, not only give better response rates but also inhibit a host of CYP450 enzymes. Oral antifungals can exacerbate drug–drug interactions for patients taking other medications concurrently. Newer topical agents might recognize improved efficacy and provide therapeutic alternatives when the use of oral antifungal agents is contraindicated. Recently, the Food and Drug Administration (FDA) approved efinaconazole and tavaborole for the treatment of onychomycosis. Additionally, the FDA approved luliconazole for the treatment of tinea pedis, tinea cruris, and tinea corporis. This review examines the mechanism of action, spectrum of activity, pharmacokinetics, and clinical trials data and considers the place in therapy for these 3 new antimycotic agents.

Importance of Vehicles in Topical Treatment of Fungal Infections

Topical drug therapies are commonly used to manage dermatologic diseases and their manifestations in the skin, hair, nails, and mucous membranes. Compared with systemic treatment, topical drug delivery provides 2 notable benefits in the management of skin diseases. In addition to delivering the active drug, a well-designed vehicle can have supportive effects on the skin, whereas a poorly designed vehicle can have detrimental effects. In many cases, the same active drug is available in several dosage forms, offering the prescriber the ability to tailor treatment to the patient's unique presentation and needs.

Fungistatic effects of optical brightener 220 against Trichophyton tonsurans, Aspergillus fumigatus and Candida albicans

BACKGROUND

Dermatophytes are one of the main causes of dermal infections. Moreover, there are some opportunistic fungi such as Aspergillus fumigatus (mycelial form) and Candida albicans (yeasty form) that in immunosuppressed patients can cause cutaneous disease.

OBJECTIVES

The possible effect of optical brightener 220 (OB-220) on the growth of fungi has been evaluated in this study.

METHODS

Isolates were grown on agar plates containing OB-220 in concentration between 0.06 and 11.68 mg ml(-1). MICs of OB-220, ketoconazole and fluconazole were obtained by the agar dilution method. Hyphae and yeasts grown with OB-220 were compared with controls by fluorescence and transmission electron microscopy. The cell cytotoxicity of OB-220 was also assessed.

RESULTS

The MIC(90) of OB-220 was obtained: 1.17-1.46 mg ml(-1) for A. fumigatus, 0.58-1.17 mg ml(-1) for C. albicans and 0.29 mg ml(-1) for Trichophyton tonsurans. Electron microscopy revealed a thickening and blurred contours of the cell wall by OB-220. OB-220 in concentrations up to 11.68 mg ml(-1) posed no mammalian cell toxicity.

CONCLUSION

OB-220 suppresses the growth of fungi by interfering with the formation of normal chitin.

Comparison of the in vitro activity of terbinafine and lanoconazole against dermatophytes

The objective of this study was to compare the antifungal activity of terbinafine (TERB) with that of lanoconazole (LAN). Test isolates, which were clinical isolates of Japanese origin, included 10 strains each of Trichophyton rubrum, T. mentagrophytes and Epidermophyton floccosum. The minimum inhibitory concentration (MIC) of TERB and LAN against each dermatophyte isolate was determined according to the Clinical and Laboratory Standards Institute microbroth methodology, M38-A2. Minimum fungicidal concentrations were determined by subculturing the contents of each visibly clear well from the MIC assay for colony count. All LAN MICs were <or=0.008 microg ml(-1), while the TERB range was 0.008-0.03 microg ml(-1). Moreover, by standard definition, LAN was fungistatic against most strains, whereas TERB was fungicidal. Both LAN and TERB demonstrated potent antifungal activity against dermatophytes; however, the lack of fungicidal activity by LAN needs to be evaluated in terms of potential clinical efficacy.