Antifungal Resistance, Susceptibility Testing and Treatment of Recalcitrant Dermatophytosis Caused by Trichophyton indotineae: A North American Perspective on Management

Green synthesis of zinc oxide nanoparticles using Cnidium monnieri fruit extract: Prescription optimization, Characterization and antifungal activity

Currently, the drugs employed to treat superficial fungal infections are encountering challenges, particularly the rise of drug resistance. Numerous studies have suggested that zinc oxide nanoparticles (ZnO NPs) show promise in the realm of antifungal treatment. Green synthesis makes the preparation of ZnO NPs more environmentally friendly and economical. In order to prepare antifungal active nanoparticles with low economic cost and stable performance, zinc oxide nanoparticles (CM-ZnONPs) were synthesized for the first time in this study using zinc sulfate heptahydrate (ZnSO4·7H2O) with a Cnidium monnieri (L.) Cuss. (C. monnieri) fruit extract as a reducing agent. In this study, the Box-Behnken design method was used to optimize the manufacturing process of CM-ZnONP. Various techniques, including UV-vis, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Powder Diffraction (XRD) were employed to demonstrate the successful preparation of CM-ZnONPs. The Transmission Electron Microscopy (TEM) analysis indicated that the size of CM-ZnONPs was 53.30 ± 12.89 nm. The dynamic light scattering (DLS) analysis showed the size of 157.7 ± 15.57 nm for CM-ZnONPs, along with an average polydispersity index (PDI) of 0.1791 ± 0.1394. The zone of inhibition of CM-ZnONPs against Candida albicans (C. albicans) was demonstrated to be 17.0 ± 0.8 mm by paper diffusion experiments. The minimum inhibitory concentration (MIC) of CM-ZnONPs against C. albicans was established at 58.59 μg/mL through the microdilution method. In summary, CM-ZnONPs exhibit excellent performance and antifungal activity in various properties. It is expected to be widely produced and used as an effective treatment for superficial fungal infections.

Effect of cannabidiol (CBD), a cannabis plant derivative, against Candida albicans growth and biofilm formation

HIGHLIGHTS

Cannabidiol (CBD) decreases the growth of C. albicans. CBD inhibits the yeast-to-hyphae transition. CBD reduces biofilm formation by C. albicans. CBD induces C. albicans death through necrosis.

Antifungal susceptibility testing: applicability of methods and strategies for improving access in resource-constrained settings

Patients infected with antifungal-resistant fungi often do not respond to therapy, substantially increasing mortality risk. Some fungi are inherently resistant to particular antifungals, underscoring the importance of rapid genus identification or, ideally, rapid species identification. The past decade has seen an increase in variable antifungal resistance rates among human fungal pathogens, necessitating individual isolate testing. Various antifungal susceptibility testing (AFST) methods are most suitable for resource-constrained settings, including agar diffusion, gradient diffusion, broth microdilution, and automated tests, which all differ in speed, reliability, and cost; yet AFST remains largely unavailable in resource-constrained settings. This Personal View explores the feasibility of AFST implementation in resource-constrained settings and addresses broader accessibility concerns. We outline seven steps for implementation of AFST with an initial focus on accurate species identification (to predict intrinsic resistance) of Candida albicans, Candida parapsilosis, Candida glabrata, and Aspergillus fumigatus. New funding, laboratory and clinical training, clear protocols, access to media and reagents, acquisition and maintenance of quality control strains, and regular participation in an external quality assurance programme are all essential for sustainable AFST services. AFST is fundamental for patient care guidance, surveillance data generation, and strengthening antifungal stewardship programmes. Political commitment and international collaborations are crucial for enhanced AFST service delivery.

Tinea pseudoimbricata: a narrative literature review and five new cases

BACKGROUND

Tinea pseudoimbricata is a variant of tinea incognito, with multiple erythematous concentric rings (ring in a ring) and pruritus. Misuse of topical corticosteroids is a major exogenous factor.

OBJECTIVE

We provide an overview of published cases and report the first case series from Romania.

PATIENTS AND METHODS

A narrative review of the literature was conducted in PubMed and amended by ResearchGate. A series of pediatric cases from Romania with clinical suspicion of tinea pseudoimbricata was investigated by clinical examination, KOH preparations of skin scrapings, and mycological culture when possible.

RESULTS

We collected 137 cases of tinea pseudoimbricata from the literature and added a series of 5 pediatric patients from Romania. Oral treatment with fluconazole was effective in all of them. Worldwide, most reports came from India (86%), 3.5% were from other Asian countries, 3.5% were from the Americas, and 7% were from Europe. M. canis and T. mentagrophytes were identified in 2 patients from Romania. T. mentagrophytes, T. rubrum, and T. tonsurans are the dominant species worldwide, but molecular diagnostics were available for only a minor part of cases.

CONCLUSION

Tinea pseudoimbricata is most common in India. This is the first case series on tinea pseudoimbricata from Romania. Tinea pseudoimbricata is an emerging disease in Europe. Identification of fungi has rarely been done by molecular mycology. This may have caused an overestimation of T. mentagrophytes and an underestimation of T. indotineae.

First Reported Cases of Terbinafine-Resistant Trichophyton indotineae Isolates in Israel: Epidemiology, Clinical Characteristics and Response to Treatment

BACKGROUND

Trichophyton indotineae, a newly defined species within the T. mentagrophytes/T. interdigitale complex, has emerged as an epidemiological concern worldwide. However, owing to the limitations of commonly applied fungal identification techniques, T. indotineae remains underreported. In addition, T. indotineae's response to treatment has been described in only a few studies.

OBJECTIVE

To investigate the prevalence, clinical characteristics and treatment outcomes of terbinafine-resistant T. mentagrophytes/T. interdigitale complex infections, as well as to detect T. indotineae cases.

PATIENTS AND METHODS

A retrospective cohort study was conducted on 22 patients with T. mentagrophytes/T. interdigitale complex infections between 2019 and 2023, using either culture or commercial polymerase chain reaction methods. Patient demographics, disease characteristics and treatment responses were recorded. Patients non-responsive to oral terbinafine underwent further analyses, including DNA sequencing of the internal transcribed spacer region for accurate species identification and mutational analysis of the squalene epoxidase (SQLE) gene.

RESULTS

The mean age of the patients was 49.7 years (±18.2), with 54.5% men. Terbinafine-resistant T. mentagrophytes/T. interdigitale complex infections were reported in 46.2% of the cohort (n = 6/13 patients; 9 lost to treatment response follow-up), all of whom exhibited extensive dermatophytosis. Among the terbinafine-resistant T. mentagrophytes/T. interdigitale isolates, all five isolates available for fungal analysis were identified as T. indotineae, harbouring SQLE single-point mutations (Phe397Leu and Leu393Ser). Only three of the terbinafine-resistant cases responded to oral itraconazole 200 mg/day, with two responding only to oral voriconazole and one to oral itraconazole 400 mg/day.

CONCLUSION

All cases of T. mentagrophytes/T. interdigitale assessed in this study were identified as T. indotineae, which exhibits SQLE gene mutations. This underscores the importance of integrating methods to detect T. indotineae in routine clinical practice.

Global Insights and Trends in Research on Dermatophytes and Dermatophytosis: A Bibliometric Analysis

BACKGROUND

Dermatophytosis, caused by dermatophytes, affects up to 25% of people globally, with higher rates observed in Africa and Asia. While these infections are usually superficial, they can become severe in immunocompromised individuals. Despite their high prevalence, scientific research on dermatophytes is limited and the epidemiological data available are insufficient. In addition, diagnostic methods are not standardised and there are challenges with resistance to antifungals.

OBJECTIVES

This study aimed to conduct a bibliometric analysis of scientific publications related to dermatophytes and dermatophytosis to assess research output and trends.

METHODS

A bibliometric analysis of publications from 2000 to 2023 in Web of Science and Scopus examined trends, citation counts, publication types, key journals, top authors and institutions and funding sources.

RESULTS

The analysis revealed a significant increase in dermatophyte-related publications, with 15,868 articles retrieved from the Web of Science and 23,189 from Scopus. Research articles dominated the output, constituting 76.2% in Web of Science and 80% in Scopus. Peak publication years were 2019, 2021 and 2022 in Web of Science, and 2020, 2021 and 2023 in Scopus, with lower output between 2000 and 2002. The United States and India were the leading contributors, followed by Brazil and China, though citation metrics varied. Although there has been a rise in the number of publications, the amount of research conducted on dermatophytes is still very limited in comparison with other types of fungal diseases.

CONCLUSIONS

Dermatophyte-related research has increased over the past 2 decades. However, research gaps remain, particularly compared with other fungal diseases. Advances in diagnostics, antifungal testing and taxonomic classification are urgently needed. The study underscores the need for continued research and global collaboration to address these issues.

Antifungal resistance in dermatophytes - review of the epidemiology, diagnostic challenges and treatment strategies for managing Trichophyton indotineae infections

INTRODUCTION

There is an increasing number of reports of Trichophyton indotineae infections. This species is usually poorly responsive to terbinafine.

AREAS COVERED

A literature search was conducted in May 2024. T.indotineae infections detected outside the Indian subcontinent are generally associated with international travel. Reports of local spread are mounting.As a newly identified dermatophyte species closely related to the T. mentagrophytes complex with limited genetic and phenotypic differences, there is an unmet need to develop molecular diagnosis for T. indotineae. Terbinafine has become less effective as a first-line agent attributed to mutations in the squalene epoxidase gene (Leu393Phe, Phe397Leu). Alternative therapies include itraconazole for a longer time-period or a higher dose (200 mg/day or higher). Generally, fluconazole and griseofulvin are not effective. In some cases, especially when the area of involvement is relatively small, topical non-allylamine antifungals may be an option either as monotherapy or in combination with oral therapy. In instances when the patient relapses after apparent clinical cure then itraconazole may be considered. Good antifungal stewardship should be considered at all times.

EXPERT OPINION

When both terbinafine and itraconazole are ineffective, options include off-label triazoles (voriconazole and posaconazole). We present four patients responding to these newer triazoles.

Trichophyton indotineae, an Emerging Drug-Resistant Dermatophyte: A Review of the Treatment Options

Background: Dermatophytosis is a prevalent superficial infection caused by filamentous fungi, primarily affecting the skin and/or its appendages. In recent years, there has been a notable increase in mycotic strains resistant to standard antifungal therapies, including Trichophyton indotineae, a dermatophyte of the Trichophyton mentagrophytes complex. This review aims to provide a comprehensive overview of the treatment options for T. indotineae, elucidating their effectiveness in managing this challenging mycotic infection. Methods: For this review, a search was conducted in the PubMed, Scopus, Web of Science, Embase, and Google Scholar databases, encompassing all published data until March 2024. English-language articles detailing therapy outcomes for patients confirmed to be affected by T. indotineae, identified through molecular analysis, were included. Results: Itraconazole was shown to be a good therapeutic choice, particularly when administered at a dosage of 200 mg/day for 1-12 weeks. Voriconazole was also demonstrated to be effective, while terbinafine exhibited a reduced response rate. Griseofulvin and fluconazole, on the other hand, were found to be ineffective. Although topical treatments were mostly ineffective when used alone, they showed promising results when used in combination with systemic therapy. Mutational status was associated with different profiles of treatment response, suggesting the need for a more tailored approach. Conclusions: When managing T. indotineae infections, it is necessary to optimize therapy to mitigate resistances and relapse. Combining in vitro antifungal susceptibility testing with mutational analysis could be a promising strategy in refining treatment selection.

Safety and efficacy of new generation azole antifungals in the management of recalcitrant superficial fungal infections and onychomycosis

INTRODUCTION

Terbinafine is considered the gold standard for treating skin fungal infections and onychomycosis. However, recent reports suggest that dermatophytes are developing resistance to terbinafine and the other traditional antifungal agents, itraconazole and fluconazole. When there is resistance to terbinafine, itraconazole or fluconazole, or when these agents cannot used, for example, due to potential drug interactions with the patient's current medications, clinicians may need to consider off-label use of new generation azoles, such as voriconazole, posaconazole, fosravuconazole, or oteseconazole. It is essential to emphasize that we do not advocate the use of newer generation azoles unless traditional agents such as terbinafine, itraconazole, or fluconazole have been thoroughly evaluated as first-line therapies.

AREAS COVERED

This article reviews the clinical evidence, safety, dosage regimens, pharmacokinetics, and management algorithm of new-generation azole antifungals.

EXPERT OPINION

Antifungal stewardship should be the top priority when prescribing new-generation azoles. First-line antifungal therapy is terbinafine and itraconazole. Fluconazole is a consideration but is generally less effective and its use may be off-label in many countries. For difficult-to-treat skin fungal infections and onychomycosis, that have failed terbinafine, itraconazole and fluconazole, we propose consideration of off-label voriconazole or posaconazole.

Mapping the Global Spread of T. indotineae: An Update on Antifungal Resistance, Mutations, and Strategies for Effective Management

INTRODUCTION

The global spread of Trichophyton indotineae presents a pressing challenge in dermatophytosis management. This systematic review explores the current landscape of T. indotineae infections, emphasizing resistance patterns, susceptibility testing, mutational analysis, and management strategies.

METHODS

A literature search was conducted in November 2023 using Embase, PubMed, Scopus, and Web of Science databases. Inclusion criteria covered clinical trials, observational studies, case series, or case reports with T. indotineae diagnosis through molecular methods. Reports on resistance mechanisms, antifungal susceptibility testing, and management were used for data extraction.

RESULTS AND DISCUSSION

A total of 1148 articles were identified through the systematic search process, with 45 meeting the inclusion criteria. The global spread of T. indotineae is evident, with cases reported in numerous new countries in 2023. Tentative epidemiological cut-off values (ECOFFs) suggested by several groups provide insights into the likelihood of clinical resistance. The presence of specific mutations, particularly Phe397Leu, correlate with higher minimum inhibitory concentrations (MICs), indicating potential clinical resistance. Azole resistance has also been reported and investigated in T. indotineae, and is a growing concern. Nevertheless, itraconazole continues to be an alternative therapy. Recommendations for management include oral or combination therapies and individualized approaches based on mutational analysis and susceptibility testing.

CONCLUSION

Trichophyton indotineae poses a complex clinical scenario, necessitating enhanced surveillance, improved diagnostics, and cautious antifungal use. The absence of established clinical breakpoints for dermatophytes underscores the need for further research in this challenging field.

An update on antifungal resistance in dermatophytosis

INTRODUCTION

The reports of resistance to antifungal agents used for treating onychomycosis and other superficial fungal infections are increasing. This rise in antifungal resistance poses a public health challenge that requires attention.

AREAS COVERED

This review explores the prevalence of dermatophytes and the current relationship between dermatophyte species, their minimum inhibitory concentrations (MICs) for terbinafine (an allylamine) and itraconazole (an azole), and various mutations prevalent in these species. The most frequently isolated dermatophyte associated with resistance in patients with onychomycosis and dermatophytosis was T. mentagrophytes. However, T. indotineae emerged as the most prevalent isolate with mutations in the SQLE gene, exhibiting the highest MIC of 8 µg/ml for terbinafine and MICs of 8 µg/ml and ≥ 32 µg/ml for itraconazole.Overall, the most prevalent SQLE mutations were Phe397Leu, Leu393Phe, Ala448Thr, Phe397Leu/Ala448Thr, and Lys276Asn/Leu415Phe (relatively recent).

EXPERT OPINION

Managing dermatophyte infections requires a personalized approach. A detailed history should be obtained including details of travel, home and occupational exposure, and clinical examination of the skin, nails and other body systems. Relevant testing includes mycological examination (traditional and molecular). Additional testing, where available, includes MIC evaluation and detection of SQLE mutations. In case of suspected terbinafine resistance, itraconazole or voriconazole (less commonly) should be considered.

Navigating fungal infections and antifungal stewardship: drug resistance, susceptibility testing, therapeutic drug monitoring and future directions

Antifungal stewardship refers to the rational use of antifungal agents. Historically, in some instances, the misuse or overuse of antifungal agents has predisposed patients to an elevated risk of systemic side-effects and treatment resistance, as well as increased healthcare costs. Superficial mycoses, such as onychomycosis, are sometimes treated without any diagnostic testing and is associated with a high likelihood of self-diagnosis and self-treatment, potentially leading to the emergence of resistance against commonly used antifungals like terbinafine. Practitioners need to ensure that a proper clinical diagnosis is backed up by appropriate testing. This may include the traditional light microscopy and culture; additionally, molecular techniques (such as polymerase chain reaction, terbinafine gene mutational analysis) and antifungal susceptibility testing are considerations as appropriate. The choice of antifungal agent should be guided by what is the standard of care in the location where the clinician practices as well as more broadly state and national prescription patterns. Recently, reports of treatment resistance concerning both superficial and deep fungal infections have added another layer of difficulty to clinical practice. This review aims to explore the phenomenon of antifungal drug resistance, and highlights the importance of adopting antifungal stewardship programs. We provide an overview of treatment resistance and mechanisms of resistance reported thus far in dermatophytes. Challenges of performing antifungal susceptibility testing and therapeutic drug monitoring are discussed, as well as principles, recommendations and future directions of antifungal stewardship programs.

Effectiveness and safety of oral terbinafine for dermatophyte distal subungual onychomycosis

INTRODUCTION

Terbinafine has been a cornerstone in dermatophyte infection treatment. Despite its global efficacy, the emergence of terbinafine resistance raises concerns, requiring ongoing vigilance.

AREAS COVERED

This paper focuses on evaluating the efficacy and safety of terbinafine in treating dermatophyte toenail infections. Continuous and pulse therapies, with a 24-week continuous regimen and a higher dosage of 500 mg/day have demonstrated superior efficacy to the FDA approved regimen of 250 mg/day x 12 weeks. Pulse therapies, though showing comparable effectiveness, present debates with regards to their efficacy as conflicting findings have been reported. Safety concerns encompass hepatotoxicity, gastrointestinal, cutaneous, neurologic, hematologic and immune adverse-effects, and possible drug interactions, suggesting the need for ongoing monitoring.

EXPERT OPINION

Terbinafine efficacy depends on dosage, duration, and resistance patterns. Continuous therapy for 24 weeks and a dosage of 500 mg/day may enhance outcomes, but safety considerations and resistance necessitate individualized approaches. Alternatives, including topical agents and alternative antifungals, are to be considered for resistant cases. Understanding the interplay between treatment parameters, adverse effects, and resistance mechanisms is critical for optimizing therapeutic efficacy while mitigating resistance risks. Patient education and adherence are vital for early detection and management of adverse effects and resistance, contributing to tailored and effective treatments.