A study of In vitro antifungal susceptibility patterns of dermatophytic fungi at a tertiary care center in Western India

Abstract

Background: Recent years have seen an alarming rise in the prevalence of recalcitrant and relapsing dermatophyte infections in India associated with lack of clinical response to standard antifungal regimens. Aims and Objectives: A study was undertaken to identify the antifungal susceptibility patterns of dermatophyte species isolated from lesions of dermatophytoses in patients examined at our center. Materials and Methods: A total of 85 patients with clinically diagnosed dermatophytoses were subjected to skin scrapings for potassium hydroxide mount (microscopic examination) and culture using Sabouraud's agar medium containing chloramphenicol and cycloheximide (incubated at 30°C). Antifungal susceptibilities [minimum inhibitory concentration-90 (MIC-90)] of the identified dermatophytes were tested for seven systemic and topical antifungal agents (terbinafine, griseofulvin, itraconazole, fluconazole, sertaconazole, ketoconazole, and clotrimazole) using Clinical and Laboratory Standards Institute broth microdilution method (M38-A). Results: Trichophyton rubrum (50%) and Trichophyton mentagrophytes complex (47.2%) were the two major species isolated. Isolates of both showed downy and granular forms (61.11%, 38.89% and 32.35%, 67.65%, respectively). The overall in-vitro susceptibility profiles (MIC-90 ranges in μg/mL) of the seven drugs for T. rubrum and T. mentagrophytes complex respectively were as follows: terbinafine (0.008–0256, 0.016–0.256), griseofulvin (0.03-1, 0.06–1), itraconazole (0.125-2, 0.25–2), fluconazole (0.125–1, 0.25–32), sertaconazole (0.03-1, 0.03-1), ketoconazole (0.06–1, 0.125–1), and clotrimazole (0.03–2, 0.06–1). Conclusions: This study indicates a rising proportion of T. mentagrophytes complex with increased proportion of granular form ( T. mentagrophytes var. mentagrophytes ). This study represents the current antifungal susceptibility profile of dermatophytic infections in a tertiary care medical center in western India with rising MICs to terbinafine and itraconazole.

Population differentiation, antifungal susceptibility, and host range of Trichophyton mentagrophytes isolates causing recalcitrant infections in humans and animals

“…Nonetheless, the term “resistance” and the breakpoint of 1 μg/ml for dermatophytes need an appropriate context and the limitation of wide use is the lack of a clear link to clinical failure of treatment. Indira [ 78 ], Bhatia and Sharma [ 79 ], and Poojary [ 80 ] reported that MIC 90 ranges for griseofulvin, itraconazole, and fluconazole were significantly higher against T. mentagrophytes isolates than against T. rubrum . Generally, Tamura et al [ 81 ] suggested that T. mentagrophytes strains were more resistant to azoles than T. rubrum and the MIC ranges of the non-azole agents, i.e.…”

Indian association of dermatologists, venereologists and leprologists (IADVL) task force against recalcitrant tinea (ITART) consensus on the management of glabrous tinea (INTACT)

“…[ 31 ] AFSTs help understand the local drug susceptibility patterns but are possible only in research institutes and reference laboratories. [ 25 26 51 ] There is a dearth of clinically correlated mycological data which impacts the clinical utility of AFST. Histological diagnosis of dermatophytosis is not done routinely but can be useful in diagnosis of unusual clinical presentations like Majocchi granuloma and deep dermatophytosis.…”

The Emerging Terbinafine-Resistant <b><i>Trichophyton</i></b> Epidemic: What Is the Role of Antifungal Susceptibility Testing?

“…However, the revised taxonomy is not yet fully implemented. Hence, the term T. mentagrophytes complex is commonly used, and the specific genotype of T. mentagrophytes which shows alarming resistance to terbinafine (TRB) is often referred to as T. interdigitale [5][6][7][8]. In this context, it is important to appreciate that the names used in this paper are the original published names used in the articles included in the review which may refer to species names used before the new classification was proposed in 2017.…”