Trichophyton indotineae—An Emerging Pathogen Causing Recalcitrant Dermatophytoses in India and Worldwide—A Multidimensional Perspective

High Prevalence of Terbinafine Resistance Among Trichophyton mentagrophytes/T. interdigitale Species Complex, a Cross-Sectional Study from 2021 to 2022 in Northern Parts of Iran

Treatment-resistant dermatophytosis caused by the members of the Trichophyton mentagrophytes/Trichophyton interdigitale species group (TMTISG) is increasing worldwide. We aimed to determine the prevalence of TMTISG in patients with dermatophytosis in two centers from north of Iran and detect the possible mutations in the squalene epoxidase (SQLE) gene in relevant terbinafine (TRB) resistant pathogenic isolates. From November 2021 to December 2022, 1960 patients suspected to dermatophytosis and referred to two mycology referral laboratories in the north of Iran were included in the study. Identification of all dermatophyte isolates was confirmed by RFLP of rDNA internal transcribed spacer (ITS) regions. Antifungal susceptibility testing against five common antifungals using the CLSI-M38-A3 protocol was performed. The TMTISG isolates resistant to TRB, were further analyzed to determine the possible mutations in the SQLE gene. Totally, 647 cases (33%) were positive for dermatophytosis of which 280 cases (43.3%) were identified as members of TMTISG. These were more frequently isolated from tinea corporis 131 (44.56%) and tinea cruris 116 (39.46%). Of 280 TMTISG isolates, 40 (14.3%) were resistant to TRB (MIC ≥ 4 µg/mL), all found to be T. indotineae in ITS sequencing. In SQLE sequencing 34 (85%) of TRB-resistant isolates had coincident mutations of Phe397Leu and Ala448Thr whereas four and two isolates had single mutations of Phe397Leu and Leu393Ser, respectively. Overall, the resistance of Iranian TMTISG isolates to TRB greatly occurred by a mutation of Phe397Leu in the SQLE gene as alone or in combination with Ala448Thr. Nevertheless, for the occurrence of in vitro resistance, only the presence of Phe397Leu mutation seems to be decisive.

Epidemiological trends, antifungal drug susceptibility and SQLE point mutations in etiologic species of human dermatophytosis in Al-Diwaneyah, Iraq

Dermatophytes show a wide geographic distribution and are the main causative agents of skin fungal infections in many regions of the world. Recently, their resistance to antifungal drugs has led to an obstacle to effective treatment. To address the lack of dermatophytosis data in Iraq, this study was designed to investigate the distribution and prevalence of dermatophytes in the human population and single point mutations in squalene epoxidase gene (SQLE) of terbinafine resistant isolates. The identification of 102 dermatophytes isolated from clinical human dermatophytosis was performed through morphological and microscopic characteristics followed by molecular analysis based on ITS and TEF-1α sequencing. Phylogeny was achieved through RAxML analysis. CLSI M38-A2 protocol was used to assess antifungal susceptibility of the isolates to four major antifungal drugs. Additionally, the presence of point mutations in SQLE gene, which are responsible for terbinafine resistance was investigated. Tinea corporis was the most prevalent clinical manifestation accounting for 37.24% of examined cases of dermatophytosis. Based on ITS, T. indotineae (50.98%), T. mentagrophytes (19.61%), and M. canis (29.41%) was identified as an etiologic species. T. indotineae and T. mentagrophytes strains were identified as T. interdigitale based on TEF-1α. Terbinafine showed the highest efficacy among the tested antifungal drugs. T. indotineae and T. mentagrophytes showed the highest resistance to antifungal drugs with MICs of 2-4 and 4 μg/mL, while M. canis was the most susceptible species. Three of T. indotineae isolates showed mutations in SQLE gene Phe397Leu substitution. A non-previously described point mutation, Phe311Leu was identified in T. indotineae and mutations Lys276Asn, Phe397Leu and Leu419Phe were diagnosed in T. mentagrophytes XVII. The results of mutation analysis showed that Phe397Leu was a destabilizing mutation; protein stability has decreased with variations in pH, and point mutations affected the interatomic interaction, resulting in bond disruption. These results could help to control the progression of disease effectively and make decisions regarding the selection of appropriate drugs for dermatophyte infections.

Comprehensive Review of Tinea Capitis in Adults: Epidemiology, Risk Factors, Clinical Presentations, and Management

Tinea capitis is a fungal infection of the scalp and hair caused by dermatophyte molds, that most often affects children and may also affect adults. Previous estimates suggest that between 3% and 11% of all tinea capitis cases worldwide occur in adults, although updated epidemiological studies are needed to reassess the prevalence of tinea capitis in adult populations specifically. Postmenopausal adult women are most often affected by tinea capitis, with African American or Black women particularly at risk. Adults who experience crowded living conditions, who live in close proximity to animals, who are immunosuppressed, and/or who live in households with affected children are at greatest risk of infection. Tinea capitis can be non-inflammatory or inflammatory in nature, and the subtype affects the extent and severity of clinical symptoms. Fungal culture and potassium hydroxide preparations are the most commonly used diagnostic tools. Trichoscopy, defined as dermoscopic imaging of the scalp and hair, is a useful adjunct to the physical examination. The mainstay of therapy is oral antifungal therapy, and topical therapy alone is not recommended. Since tinea capitis infection is uncommon in adults, there are no widely accepted treatment guidelines. Rather, the same medications used for tinea capitis infection among children are recommended for adults at varying doses, including griseofulvin, and terbinafine, and, less commonly, itraconazole and fluconazole. The prognosis for tinea capitis in adults is typically excellent when prompt and adequate treatment is administered; however, delayed diagnosis or inadequate treatment can result in scarring alopecia. Over the past decade, dermatophyte infections resistant to treatment with topical and oral antifungal agents have emerged. While tinea capitis infections resistant to antifungal therapy have been rarely reported to date, antifungal resistance is rising among superficial fungal infections in general, and antifungal stewardship is necessary to ensure that resistance to treatment does not develop among dermatophytes that cause tinea capitis.

Clinical Course, Antifungal Susceptibility, and Genomic Sequencing of Trichophyton indotineae

Importance

Trichophyton indotineae is an emerging dermatophyte causing outbreaks of extensive tinea infections often unresponsive to terbinafine. This species has been detected worldwide and in multiple US states, yet detailed US data on infections with T indotineae are sparse and could improve treatment practices and medical understanding of transmission.

Objective

To correlate clinical features of T indotineae infections with in vitro antifungal susceptibility testing results, squalene epoxidase gene sequence variations, and isolate relatedness using whole-genome sequencing.

Design, Setting, and Participants

This retrospective cohort study of patients with T indotineae infections in New York City spanned May 2022 to May 2023. Patients with confirmed T indotineae infections were recruited from 6 New York City medical centers.

Main Outcome and Measure

Improvement or resolution at the last follow-up assessment.

Results

Among 11 patients with T indotineae (6 male and 5 female patients; median [range] age, 39 [10-65] years), 2 were pregnant; 1 had lymphoma; and the remainder were immunocompetent. Nine patients reported previous travel to Bangladesh. All had widespread lesions with variable scale and inflammation, topical antifungal monotherapy failure, and diagnostic delays (range, 3-42 months). Terbinafine treatment failed in 7 patients at standard doses (250 mg daily) for prolonged duration; these patients also had isolates with amino acid substitutions at positions 393 (L393S) or 397 (F397L) in squalene epoxidase that correlated with elevated terbinafine minimum inhibitory concentrations of 0.5 μg/mL or higher. Patients who were treated with fluconazole and griseofulvin improved in 2 of 4 and 2 of 5 instances, respectively, without correlation between outcomes and antifungal minimum inhibitory concentrations. Furthermore, 5 of 7 patients treated with itraconazole cleared or had improvement at the last follow-up, and 2 of 7 were lost to follow-up or stopped treatment. Based on whole-genome sequencing analysis, US isolates formed a cluster distinct from Indian isolates.

Conclusion and Relevance

The results of this case series suggest that disease severity, diagnostic delays, and lack of response to typically used doses and durations of antifungals for tinea were common in this primarily immunocompetent patient cohort with T indotineae, consistent with published data. Itraconazole was generally effective, and the acquisition of infection was likely in Bangladesh.

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.

Recalcitrant dermatophyte infections: identification and risk factors

INTRODUCTION

Recalcitrant dermatophytosis is an emerging phenomenon that occurs worldwide, and Trichophyton indotineae is currently the prominent cause.

MATERIALS AND METHODS

Skin specimens from patients with tinea infection were obtained by scrubbing and then sectioned into three fragments. Two fragments were subjected to direct microscopic examination and culture, while the third portion was utilized in the PCR method.

RESULTS

Isolates were morphologically identified as Trichophyton mentagrophytes/interdigitale complex (n = 60 [83.33%]), Microsporum canis (n = 8 [11.11%]), Trichophyton rubrum (n = 3 [4.16%]), and Epidermophyton floccosum (n = 1 [1.38%]). Among 60 T. mentagrophytes complex isolates, 53 (88.33%) were classified as T. indotineae and seven as T. interdigitale genotype II. The disease duration was longer in the T. indotineae group (P = 0.035). Both Gradient PCR and skin-sampling methods yield similar results in terms of positive and negative cases (P = 1.0000). The time patients stopped their medication did not impact the positive case numbers (P = 0.803). Gender had no effects on the frequency (P = 0.699). Familial contamination, dermatologic disorder, and other underlying conditions did not differ in the two group infections (P > 0.05). Steroid usage is strongly associated with the emergence of tinea infection (P < 0.04). The duration of antifungal administration had a substantial effect on the emergence of resistant organisms (P = 0.05).

CONCLUSIONS

Steroid usage, T. indotineae involvement, and prolonged exposure to antifungals were the solid and influential factors in recalcitrant involvement. Regarding quick and suitable diagnosis and treatment, which is essential in preventing recalcitrant cases, we suggest that direct skin sample PCR can meet the demands.

Expert Panel Review of Skin and Hair Dermatophytoses in an Era of Antifungal Resistance

Dermatophytoses are fungal infections of the skin, hair, and nails that affect approximately 25% of the global population. Occlusive clothing, living in a hot humid environment, poor hygiene, proximity to animals, and crowded living conditions are important risk factors. Dermatophyte infections are named for the anatomic area they infect, and include tinea corporis, cruris, capitis, barbae, faciei, pedis, and manuum. Tinea incognito describes steroid-modified tinea. In some patients, especially those who are immunosuppressed or who have a history of corticosteroid use, dermatophyte infections may spread to involve extensive skin areas, and, in rare cases, may extend to the dermis and hair follicle. Over the past decade, dermatophytoses cases not responding to standard of care therapy have been increasingly reported. These cases are especially prevalent in the Indian subcontinent, and Trichophyton indotineae has been identified as the causative species, generating concern regarding resistance to available antifungal therapies. Antifungal-resistant dermatophyte infections have been recently recognized in the United States. Antifungal resistance is now a global health concern. When feasible, mycological confirmation before starting treatment is considered best practice. To curb antifungal-resistant infections, it is necessary for physicians to maintain a high index of suspicion for resistant dermatophyte infections coupled with antifungal stewardship efforts. Furthermore, by forging partnerships with federal agencies, state and local public health agencies, professional societies, and academic institutions, dermatologists can lead efforts to prevent the spread of antifungal-resistant dermatophytes.

Clotrimazole-Betamethasone Dipropionate Prescribing for Nonfungal Skin Conditions

This cross-sectional study identifies the common diagnoses and physician encounter types associated with clotrimazole-betamethasone dipropionate prescriptions among Medicare enrollees in 2021.

Atypical and Unpredictable Superficial Mycosis Presentations: A Narrative Review

While typically exhibiting characteristic features, fungal infections can sometimes present in an unusual context, having improbable localization (eyelid, face, or joint); mimicking other skin diseases such as eczema, psoriasis, or mycosis fungoides; and appearing with unexpected color, shape, or distribution. The emergence of such a challenging clinical picture is attributed to the complex interplay of host characteristics (hygiene and aging population), environment (climate change), advances in medical procedures, and agent factors (fungal resistance and species emergence). We aim to provide a better understanding of unusual epidemiological contexts and atypical manifestations of fungal superficial diseases, knowing that there is no pre-established clinical guide for these conditions. Thus, a literature examination was performed to provide a comprehensive analysis on rare and atypical superficial mycosis as well as an update on certain fungal clinical manifestations and their significance. The research and standard data extraction were performed using PubMed, Medline, Scopus, and EMBASE databases, and a total of 222 articles were identified. This review covers published research findings for the past six months.

Clinico-mycological and therapeutic updates on cutaneous dermatophytic infections in the era of Trichophyton indotineae

Trichophyton indotineae has emerged as a novel dermatophyte species resulting in treatment recalcitrant skin infections. While the earliest reports came from India, T. indotineae has now spread to many parts of the world and is rapidly becoming a global health concern. Accurate identification of T. indotineae requires elaborate mycological investigations which is beyond the domain of routine microbiology testing. Extensive, non-inflammatory and atypical presentations are commonly seen with this novel species. T. indotineae shows an alarmingly high rate of mutations in the squalene epoxidase gene leading to lowered in vitro susceptibility to terbinafine. This has also translated into a lowered clinical response and requirement of a higher dose and much longer durations of treatment with the drug. Although the species remains largely susceptible to itraconazole, prolonged treatment durations are required to achieve cure with itraconazole. Fluconazole and griseofulvin do not have satisfactory in vitro or clinical activity. Apart from requirement of prolonged treatment durations, relapse postsuccessful treatment is a distressing and yet unexplained consequence of this "species-shift." Use of third generation azoles and combinations of systemic antifungals is unwarranted as both have not demonstrated clear superiority over itraconazole given alone, and the former is an important class of drugs for invasive mycoses.

Potential Sexual Transmission of Antifungal-Resistant Trichophyton indotineae

We describe a case of tinea genitalis in an immunocompetent woman in Pennsylvania, USA. Infection was caused by Trichophyton indotineae potentially acquired through sexual contact. The fungus was resistant to terbinafine (first-line antifungal) but improved with itraconazole. Clinicians should be aware of T. indotineae as a potential cause of antifungal-resistant genital lesions.

Dermatophytes and skin dermatophytoses in Southeast Asia-First epidemiological survey from Cambodia

BACKGROUND

Dermatomycoses count to the most frequent dermatoses in Cambodia.

OBJECTIVES

The aim of this survey was to investigate the occurrence of dermatophytes in this Southeast Asian country.

METHODS

From June 2017 to July 2018, skin scrapings were taken from 67 patients with superficial dermatophytosis for mycological diagnostics. Identification of dermatophytes was confirmed by sequencing of the 'internal transcribed spacer'-(ITS) region of the rDNA, and the gene of the Translation Elongation Factor (TEF)-1α.

RESULTS

Patients were suffering from tinea corporis and tinea inguinalis/cruris 42/67 (63%), tinea capitis/faciei 14/67 (21%), tinea corporis/capitis/faciei 6/67 (9%), tinea manuum/pedis 2/67 (3%), tinea pedis 2/67 (3%) and tinea manuum 1/67 (1%). Both, by culture and/or PCR, a dermatophyte was detected in 52 (78%) out of 67 samples. Culture positive were 42 (81%) of 52, PCR positive were 50 (96%). The following dermatophytes were found: Trichophyton (T.) rubrum, 36/52 strains (69%, 29 by culture), T. mentagrophytes/T. interdigitale (TM/TI) 9/52 (17%, six by culture) and Microsporum (M.) canis 5/52 strains (10%, by culture). One strain of Nannizzia (N.) incurvata 1/52 (2%) and N. nana 1/52 (2%) was isolated. Based on sequencing, we demonstrated that two T. mentagrophytes strains out of the nine TM/TI represented the new ITS genotype XXV Cambodia. We found one T. mentagrophytes strain genotype VIII (now, reclassified as T. indotineae). This isolate was terbinafine resistant, and it exhibited the amino acid substitution Phe397Leu in the squalene epoxidase. Three strains of T. interdigitale genotype II* were isolated.

CONCLUSION

This is the first survey on epidemiology of dermatophytes in Cambodia. Currently, T. rubrum represents the most frequent species in Cambodia. One Indian strain genotype VIII T. mentagrophytes was found. A highlight was the first description of the new T. mentagrophytes genotype XXV Cambodia.

Emerging Antifungal Resistance in Fungal Pathogens

Purpose of Review

Over recent decades, the number of outbreaks caused by fungi has increased for humans, plants (including important crop species) and animals. Yet this problem is compounded by emerging antifungal drug resistance in pathogenic species. Resistance develops over time when fungi are exposed to drugs either in the patient or in the environment.

Recent Findings

Novel resistant variants of fungal pathogens that were previously susceptible are evolving (such as Aspergillus fumigatus) as well as newly emerging fungal species that are displaying antifungal resistance profiles (e.g. Candida auris and Trichophyton indotineae).

Summary

This review highlights the important topic of emerging antifungal resistance in fungal pathogens and how it evolved, as well as how this relates to a growing public health burden.

Resistance Profile, Terbinafine Resistance Screening and MALDI-TOF MS Identification of the Emerging Pathogen Trichophyton indotineae

The emerging pathogen Trichophyton indotineae, often resistant to terbinafine (TRB), is known to cause severe dermatophytoses such as tinea corporis and tinea cruris. In order to achieve successful treatment for these infections, insight in the resistance profile of T. indotineae strains and rapid, reliable identification is necessary. In this research, a screening medium was tested on T. indotineae strains (n = 20) as an indication tool of TRB resistance. The obtained results were confirmed by antifungal susceptibility testing (AST) for TRB following the in vitro broth microdilution reference method. Additionally, AST was performed for eight other antifungal drugs: fluconazole, itraconazole, voriconazole, ketoconazole, griseofulvin, ciclopirox olamine, naftifine and amorolfine. Forty-five percent of the strains were confirmed to be resistant to terbinafine. The TRB resistant strains showed elevated minimal inhibitory concentration values for naftifine and amorolfine as well. DNA sequencing of the squalene epoxidase-encoding gene showed that TRB resistance was a consequence of missense point mutations in this gene, which led to amino acid substitutions F397L or L393F. MALDI-TOF MS was used as a quick, accurate identification tool for T. indotineae, as it can be challenging to distinguish it from closely related species such as Trichophyton mentagrophytes or Trichophyton interdigitale using morphological characteristics. While MALDI-TOF MS could reliably identify ≥ 95% of the T. indotineae strains (depending on the spectral library), it could not be used to successfully distinguish TRB susceptible from TRB resistant strains.

Time to Think Antifungal Resistance Increased Antifungal Resistance Exacerbates the Burden of Fungal Infections Including Resistant Dermatomycoses

Increased antifungal resistance is exacerbating the burden of invasive fungal infections, as well as potentially contributing to the increase in resistant dermatomycoses. In this commentary, we focus on antifungal drug resistance, in contrast to antibacterial resistance. We provide a brief historical perspective on the emergence of antifungal resistance and propose measures for combating this growing health concern. The increase in the incidence of invasive and cutaneous fungal infections parallels advancements in medical interventions, such as immunosuppressive drugs, to manage cancer and reduce organ rejection following transplant. A disturbing relatively new trend in antifungal resistance is the observation of several fungal species that now exhibit multidrug resistance (eg, Candida auris, Trichophyton indotineae). Increasing awareness of these multidrug-resistant species is paramount. Therefore, increased education regarding potential fungus-associated infections is needed to address awareness in the general healthcare setting, which may result in a more realistic picture of the prevalence of antifungal-resistant infections. In addition to education, increased use of diagnostic tests (eg, micro and macro conventional assays or molecular testing) should be routine for healthcare providers facing an unknown fungal infection. Two critical barriers that affect the low rates for Antifungal Susceptibility Testing (AST) are low (or a lack of) sufficient insurance reimbursement rates and the low number of qualified laboratories with the capacity to perform AST. The ultimate aim is to improve the quality of patient care through fungal identification, diagnosis, and, where appropriate, susceptibility testing. Here we propose an all-encompassing call to action to address this emerging challenge.

Terbinafine resistance in Trichophyton mentagrophytes and Trichophyton rubrum in the Czech Republic: A prospective multicentric study

BACKGROUND

Terbinafine, an allylamine antifungal, is crucial for treating dermatophytosis by inhibiting squalene epoxidase (SQLE) in the ergosterol biosynthetic pathway. However, resistance is emerging, particularly in India and Southeast Asia, but reports of resistance spread worldwide. Despite this, comprehensive studies on terbinafine resistance in Trichophyton are still limited.

OBJECTIVES

This research aimed to determine the prevalence of terbinafine resistance in the Czech Republic, with a focus on Trichophyton rubrum and Trichophyton mentagrophytes, and investigate the underlying molecular mechanisms.

PATIENTS/METHODS

A total of 514 clinical strains of T. rubrum and 240 T. mentagrophytes collected from four Czech clinical institutions were screened for terbinafine resistance. Molecular investigations included DNA sequencing, specifically the ITS rDNA region and SQLE gene, as well as antifungal susceptibility testing following EUCAST guidelines.

RESULTS

While no resistance was observed in T. rubrum, 2.5% of T. mentagrophytes strains exhibited resistance, marked by the F397L mutation in SQLE. Notably, resistance surged from 1.2% in 2019 to 9.3% in 2020 but reverted to 0% in 2021. All resistant strains were identified as T. mentagrophytes var. indotineae. Resistant strains exhibited high MICs for terbinafine (≥4 mg L-1 ) but low MICs to the other seven antifungals tested except for fluconazole.

CONCLUSIONS

This study highlights the emergence of terbinafine-resistant T. mentagrophytes strains in the Czech Republic, with the F397L mutation being pivotal. Due to the relatively low resistance level, the current guidelines for dermatomycosis treatment in the Czech Republic remain effective, but ongoing surveillance is essential for timely adaptations if resistance patterns change.

Whole genome characterization of Trichophyton indotineae isolated in Singapore

Complete genome sequences from two Trichophyton indotineae isolates were obtained from a 23-year-old male presenting with tinea cruris after an overseas recreational water exposure and from a 53-year-old female patient with unknown travel history. Analysis of the squalene epoxidase gene and the cyp51 gene family showed an absence of mutations, correlating with phenotypic drug susceptibility. The Single Nucleotide Polymorphisms (SNPs) distance between both isolates was 92. Within the T. indotineae cluster, SNPs ranged from 7 to 182, suggesting a high genetic relatedness with other South Asian isolates. This study suggests that the prevalence of T. indotineae is under-reported and more widespread than previously thought.

Molecular Verification of Trichophyton in the Brazilian URM Culture Collection

Trichophyton species cause dermatophytosis in humans, with a high, worldwide frequency of reports and important public health relevance. We evaluated 61 Trichophyton strains from different sources deposited in the University Recife Mycology (URM) culture collection of the Universidade Federal de Pernambuco, Brazil. Strains were phenotypically identified and confirmed by sequencing Internal Transcribed Spacers rDNA and partial beta-tubulin 2-exon. Additionally, we evaluated their susceptibility to terbinafine and itraconazole. Physiological analyses included urease activity and growth in casein medium. Phenotypic methods allowed the reliable identification of T. rubrum only, whereas, for other species, molecular methods were mandatory. All Trichophyton species exhibited susceptibility profiles to itraconazole (0.04-5.33 μg/mL) and terbinafine (0.17-3.33 μg/mL). Our analyses revealed a heterogeneous distribution of T. mentagrophytes, which does not support the current distribution within the species complex of T. mentagrophytes and its genotypes.

A Current Diagnostic and Therapeutic Challenge: Tinea Capitis

Tinea capitis is a dermatophyte scalp infection with a marked prevalence among the pediatric population. However, in the last few years, its epidemiology has changed due to increasing population migration worldwide. Host-specific and environmental factors contribute to the pathogenesis of tinea capitis. Clinically, tinea capitis may present as a subtle hair loss accompanied by scalp scaling, alopecia with scaly patches, or alopecia with black dots. A more severe form of tinea capitis is represented by kerion celsi, which clinically presents as a tender plaque covered by pustules and crusts. If left untreated, this dermatophytic infection may resolve with permanent scarring and alopecia. The pathological changes found in tinea capitis are reflected by a spectrum of clinical changes. Zoophilic infections typically prompt an extensive inflammatory reaction, while anthropophilic dermatophytoses often lack inflammation and result in more persistent lesions. Tinea capitis typically requires systemic antifungal therapy. Griseofulvin, terbinafine, itraconazole, and fluconazole are the main antifungal agents used. Currently, the duration of antifungal therapy varies based on the clinical presentation and type of dermatophyte involved. Through the reported cases and literature review, we aim to emphasize the importance of the early recognition of atypical variants of tinea capitis in immunocompetent children for the prompt initiation of systemic antifungal therapy, minimizing the need for prolonged treatment. Additionally, we emphasize the importance of regular laboratory testing during systemic antifungal therapy, particularly liver enzyme tests, to prevent adverse events, especially in cases requiring long-term treatment.

Kerion Celsi in infants and children-A narrative review 2010-2023

Kerion Celsi is an inflammatory, deep fungal infection of the scalp. It is rare in neonates but gets more common in children about 3 years and older. It represents with swelling, boggy lesions, pain, alopecia and purulent secretions. Secondary bacterial infection is not unusual after maceration. Extracutaneous manifestations include regional lymphadenopathy, fever and very rare fungemia. Id-reactions can occur. Diagnosis is based on clinical suspicion, clinical examination and medical history. Diagnosis should be confirmed by microscopy, fungal culture and molecular procedures. The most common isolated fungal species are anthropophilic Trichophyton (T.) tonsurans and zoophilic Microsporum (M.) canis, while geophilic species and moulds rarely cause Kerion Celsi. Treatment is medical with systemic and topical antifungals supplemented by systemic antibiotics when necessary, while surgery needs to be avoided. Early and sufficient treatment prevents scarring alopecia. The most important differential diagnosis is bacterial skin and soft tissue infections.

Prior selection of itraconazole in the treatment of recalcitrant Trichophyton indotineae infection: Real-world results from retrospective analysis

BACKGROUND

The number of terbinafine-resistant Trichophyton indotineae is increasing in recent years while the treatment is still a matter to discuss.

OBJECTIVES

To explore the best therapeutic approach, we present real-world treatment of T. indotineae infection by analysing publicly available data.

METHODS

We have reviewed all published articles, mainly including case reports and case series, on the drug-resistant T. mentagrophytes complex by using the key search terms to search the databases.

RESULTS

We enrolled 25 articles from 14 countries, including 203 times of treatment information for 113 patients. The cure rate of itraconazole 200 mg per day at the fourth, eighth and the twelfth week were 27.27%, 48.48% and 54.55%, respectively, which was significantly higher than terbinafine 250 mg per day (8.77%, 24.56% and 28.07%) and even 500 mg/d terbinafine. Griseofulvin 500-1000 mg for 2-6 months may be effective while fluconazole had no record of successful treatment. Voriconazole and ravuconazole had potential therapeutic efficacy. Topical therapy alone showed limited therapeutic efficacy, but the combination with oral antifungals can be alternative.

CONCLUSION

Oral itraconazole 200 mg per day for 4-8 weeks was the most effective treatment out of these commonly used antifungal drugs, and can be prior selection.

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.

Multi-drug resistance Trichophyton indotineae in a stray dog

A 2.5-year-old stray dog showed signs of hair loss, mild skin crusting, and redness on extremities and trunk. The etiologic agent was confirmed as Trichophyton indotineae by sequencing of ITS region. Using the Clinical and Laboratory Standards Institute (CLSI M38-A3) guideline, antifungal susceptibility testing showed multidrug resistance phenotype against terbinafine (16 μg/mL-1), itraconazole, and some other tested antifungals (minimum inhibitory concentration, MIC≥16 μg/mL-1). However, luliconazole was found to be active in- vitro (0.016 μg/mL-1). Upon further studies, sequencing of SQLE gene showed an amino acids substitution of Phe397Leu and Ala448Thr, which is potentially linked to terbinafine resistance in Trichophyton species.

Trichophyton indotineae and other terbinafine-resistant dermatophytes in North America

Dermatophyte infections (a.k.a. ringworm, tinea) affect an estimated 20%-25% of the world's population. In North America, most dermatophytoses are caused by Trichophyton rubrum or Trichophyton mentagrophytes species complexes. Severe and antifungal-resistant dermatophytoses are a growing global public health problem. A new species of the T. mentagrophytes species complex, Trichophyton indotineae, has recently emerged and is notable for the severe infections it causes, its propensity for antifungal resistance, and its global spread. In this issue of the Journal of Clinical Microbiology, C. F. Cañete-Gibas, J. Mele, H. P. Patterson, et al. (J Clin Microbiol 61:e00562-23, 2023, https://doi.org/10.1128/JCM.00562-23) summarize the results of speciation and AFST performed on North American dermatophyte isolates received at a fungal diagnostic reference laboratory. Within their collection, 18.6% of isolates were resistant to terbinafine (a first-line oral antifungal for dermatophytoses), and similar proportions of T. rubrum and T. indotineae demonstrated terbinafine resistance. The authors also found that T. indotineae has been present in North America since at least 2017. These findings highlight the importance of increased surveillance efforts to monitor trends in severe and antifungal-resistant dermatophytoses and the need for antifungal stewardship efforts, the success of which is contingent upon improving laboratory capacity for dermatophyte speciation and AFST.

The rapid emergence of antifungal-resistant human-pathogenic fungi

During recent decades, the emergence of pathogenic fungi has posed an increasing public health threat, particularly given the limited number of antifungal drugs available to treat invasive infections. In this Review, we discuss the global emergence and spread of three emerging antifungal-resistant fungi: Candida auris, driven by global health-care transmission and possibly facilitated by climate change; azole-resistant Aspergillus fumigatus, driven by the selection facilitated by azole fungicide use in agricultural and other settings; and Trichophyton indotineae, driven by the under-regulated use of over-the-counter high-potency corticosteroid-containing antifungal creams. The diversity of the fungi themselves and the drivers of their emergence make it clear that we cannot predict what might emerge next. Therefore, vigilance is critical to monitoring fungal emergence, as well as the rise in overall antifungal resistance.

Detection of Squalene Epoxidase Mutations in United States Patients with Onychomycosis: Implications for Management

Resistance to oral terbinafine, the most commonly used antifungal to treat dermatophytosis and onychomycosis worldwide, is being increasingly reported. In this study, we aimed to investigate the species distribution and prevalence of squalene epoxidase mutations among toenail dermatophyte isolates. Samples from 15,683 patients suspected of onychomycosis visiting the offices of dermatologists and podiatrists in the United States were analyzed. Clinical information was reviewed, and dermatophyte species with or without squalene epoxidase mutations were detected using multiplex real-time PCRs. The frequency of dermatophytes was 37.6%; of isolates belonging to the Trichophyton genus, 88.3% were the T. rubrum complex, and 11.2% were the T. mentagrophytes complex. Individuals aged >70 years exhibited higher infection rates for the T. mentagrophytes complex. The overall mutation rate among Trichophyton spp. was 3.7%, with a higher mutation rate detected in the T. mentagrophytes complex (4.3 vs. 3.6%). Commonly detected mutations were T1189C/Phe397Leu (34.5%), T1306C/Phe415Ser (16.0%), and C1191A/Phe397Leu (11.0%). Squalene epoxidase gene mutations associated with decreased terbinafine susceptibility have been identified in United States patients with toenail onychomycosis. Physicians should be aware of the risk factors for resistance development and engage in antifungal stewardship practices such as directed diagnosis and treatment of dermatophytosis and onychomycosis.

Long Amplification PCR (LA-PCR) Detection of Azole Resistant Trichophyton indotineae

Trichphyton indotineae, a species newly designated in 2020 independent of T. interdigitale, comprises highly terbinafine (TRF)-resistant dermatophytosis that is epidemic in North India and spreding to worldwide. Some clinical isolates of T. indotineae have been resistance both TRF and azoles that might be caused the treatment failure. To detect the azole resistance strains, we developed a long amplification PCR (LA-PCR) detection method for the tandem repeat of the CYP51B (encoding sterol 14a-demethylase gene) in T. indotineae. Contrasting the drug susceptibility test results with the LA-PCR results confirmed a trend toward low susceptibility to azole antifungal agents in strains with amplifications of 9.5 kbp or greater (3 or more copies of CYP51B). Our results suggest that the method could be detected rapidly of low-susceptibility strains to azole antifungal agents.

Hedgehog Dermatophytosis: Understanding Trichophyton erinacei Infection in Pet Hedgehogs and Its Implications for Human Health

Pet hedgehogs, which are increasingly favoured companions, have garnered attention due to their potential as carriers of zoonotic diseases. These small insectivorous mammals, native to Europe, Asia, and Africa, are commonly kept as pets. The encroachment of humans into hedgehog habitats has brought these animals closer to people, raising concerns about disease transmission. This article reviews the current knowledge regarding zoonotic disease associated with pet hedgehogs, with a particular focus on mycotic infections caused by Trichophyton erinacei. Data from various regions and hedgehog species are synthesised to assess the significance of pet hedgehogs as potential reservoirs and transmitters of zoonotic pathogens. Our study highlights the importance of understanding the health risks associated with pet hedgehogs and underscores the need for continued research to mitigate zoonotic disease transmission from these potentially disease-carrying companions.

Erythroderma combined with deeper dermal dermatophytosis due to Trichophyton rubrum in a patient with myasthenia gravis: first case report and literature review

BACKGROUND

Dermatophytes are the most common causative pathogens of mycoses worldwide and usually cause superficial infections. However, they can enter deep into the dermis lead to invasive dermatophytosis such as deeper dermal dermatophytosis on rare occasions. Erythroderma is a severe dermatological manifestation of various diseases resulting in generalized skin redness, but erythroderma due to fungi infections is barely reported. In this article, we reported the first case of erythroderma combined with deeper dermal dermatophytosis due to Trichophyton rubrum (T. rubrum) in a patient with myasthenia gravis.

CASE PRESENTATION

A 48-year-old man was hospitalized because of erythema with scaling and nodules covering his body for a month. The patient had a history of myasthenia gravis controlled by regularly taking prednisolone for > 10 years and accompanied by onychomycosis and tinea pedis lasting > 8 years. Based on histopathological examinations, fungal cultures, and DNA sequencing results, the patient was finally diagnosed with dermatophyte-induced erythroderma combined with deeper dermal dermatophytosis caused by T. rubrum. After 2 weeks of antifungal treatment, the patient had recovered well.

CONCLUSIONS

This case report shows that immunosuppressed patients with long histories of superficial mycoses tend to have a higher risk of developing invasive dermatophytic infections or disseminated fungal infections. Dermatologists should be alert to this condition and promptly treat the superficial dermatophytosis.

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

There is an ongoing epidemic of chronic, relapsing dermatophytoses caused by Trichophyton indotineae that are unresponsive to one or multiple antifungal agents. Although this new species may have originated from the Indian subcontinent, there has been a notable increase of its reporting in other countries. Based on current literature, antifungal susceptibility testing (AFST) showed a large variation of terbinafine minimum inhibitory concentrations (MICs) (0.04 to ≥ 32 µg/ml). Elevated terbinafine MICs can be attributed to mutations in the squalene epoxidase gene (single mutations: Leu393Phe, Leu393Ser, Phe397Leu, and double mutations: Leu393Phe/Ala448Thr, Phe397Leu/Ala448Thr). Itraconazole MICs had a lower range when compared with that of terbinafine (0.008-16 µg/ml, with most MICs falling between 0.008 µg/ml and < 1 µg/ml). The interpretation of AFST results remains challenging due to protocol variations and a lack of established breakpoints. Adoption of molecular methods for resistance detection, coupled with AFST, may provide a better evaluation of the in vitro resistance status of T. indotineae. There is limited information on treatment options for patients with confirmed T. indotineae infections by molecular diagnosis; preliminary evidence generated from case reports and case series points to itraconazole as an effective treatment modality, while terbinafine and griseofulvin are generally not effective. For physicians working outside of endemic regions, there is currently an unmet need for standardized clinical trials to establish treatment guidelines; in particular, combination therapy of oral and topical agents (e.g., itraconazole and ciclopirox), as well as with other azoles (i.e., fluconazole, voriconazole, ketoconazole), warrants further investigation as multidrug resistance is a possibility for T. indotineae.

Autochthonous case of Trichophyton indotineae in Kuwait

Trichophyton indotineae is an emerging dermatophyte that has remarkable impact on public health worldwide. In addition to producing severe extensive skin lesions, this species is frequently resistant to terbinafine, used as a first line agent. As a result, the infection is often refractory, making treatment very challenging. The current report describes the first case of Trichophyton indotineae infection in Kuwait. The infected woman had no recent travel history. She failed to respond to several courses of antifungals, but finally responded to voriconazole. The report suggests that T. indotineae is under recognised, hence, active surveillance of dermatophytes is warranted.

[Recurrent tinea corporis generalisata due to Terbinafine-resistant Trichophyton rubrum strain : Long-term treatment with super bioavailability itraconazole]

For more than 30 years, an 82-year-old man has been suffering from tinea corporis generalisata in the sense of Trichophyton rubrum syndrome. The patient received long-term treatment with terbinafine. Fluconazole had no effect. There was an increase in liver enzymes with itraconazole. Super bioavailability (SUBA) itraconazole was initially not tolerated. A therapy attempt with voriconazole was successful, but was stopped due to side effects. The Trichophyton (T.) rubrum strain isolated from skin scales was tested for terbinafine resistance using the breakpoint method and found to be (still) sensitive. Sequencing of the squalene epoxidase (SQLE) gene revealed a previously unknown point mutation of the codon for isoleucine ATC→ACC with amino acid substitution I479T (isoleucine479 threonine). Long-term therapy with terbinafine 250 mg had been given every 3 days since 2018. In addition, bifonazole cream, ciclopirox solution, and occasionally terbinafine cream were used. The skin condition was stable until an exacerbation of the dermatophytosis in 2021. There were erythematosquamous, partly atrophic, centrifugal, scaly, confluent plaques on the integument and the extremities. Fingernails and toenails had white to yellow-brown discoloration, and were hyperkeratotic and totally dystrophic. T. rubrum was cultured from skin scales from the integument, from the feet, from nail shavings from the fingernails and also toenails and detected by PCR. In the breakpoint test, the T. rubrum isolates from tinea corporis and nail samples showed a minimum inhibitory concentration (MIC) of 0.5 µg ml-1 (terbinafine resistance in vitro). Sequencing of the SQLE gene of the T. rubrum isolate revealed evidence of a further point mutation that led to amino acid substitution I479V (isoleucine 479 valine). Long-term therapy was started with SUBA itraconazole: 14 days 2 × 1 capsule daily, then twice weekly administration of 2 × 50 mg. During breaks in therapy, the mycosis regularly flared up again. Finally, 50 mg SUBA itraconazole was given 5 days a week, which completely suppressed the dermatophytosis. Topically, ciclopirox and miconazole cream were used alternately. In conclusion, in the case of recurrent and therapy-refractory dermatophytoses caused by T. rubrum, terbinafine resistance must also be considered in individual cases. An in vitro resistance test and point mutation analysis of the squalene epoxidase gene confirms the diagnosis. Itraconazole, also in the form of SUBA itraconazole, is the drug of choice for the oral antifungal treatment of these patients.

A Clinico-Mycological and Histopathological Study of Recurrent Dermatophytosis

Background

A few recent studies have shown fungal elements within the hair follicle epithelium, which may act as a reservoir and responsible for recurrent dermatophytosis.

Objectives

To assess the clinical patterns, mycological profile, and histopathology of recurrent dermatophytosis and to determine the prevalence of fungal hyphae in the hair follicle epithelium and other appendages.

Materials and Methods

One hundred and fifty clinically diagnosed cases of recurrent dermatophytic infection were included. Skin samples were taken for direct microscopy, fungal culture, and histopathological analysis. Haematoxylin and eosin and special staining with periodic acid Schiff (PAS) and Gomori's methenamine silver (GMS) were performed to detect the fungal hyphae in the skin and hair follicle epithelium.

Results

The most common clinical pattern observed was tinea corporis et cruris in 64 patients (42.66%). On direct microscopy and fungal culture, positive results were obtained in 116 cases (77.33%) and 78 (52%) cases, respectively. Presence of fungal hyphae in the stratum corneum, hair follicle, and acrosyringium was seen in 107 patients (71.33%), 47 patients (31.33%), and five patients (3.33%), respectively. Out of the 52 cases with hair follicle and eccrine gland involvement, history of fixed drug combinations (FDC) cream use was present in 42 cases (80.76%) and absent in ten cases (19.24%) (P = 0.000062).

Limitations

Skin samples were taken only from a single skin lesion. Higher incidence of follicular invasion may have been detected if multiple biopsy samples were taken.

Conclusion

Hair follicle/eccrine sweat gland involvement was observed in nearly one-third of the patients, which may act as a reservoir and may be responsible for recurrence and chronicity. Histopathology should be considered as an important adjuvant tool in recurrent dermatophytosis to establish the extent of the infection, which guides the further management.

Trichophyton mentagrophytes Internal Transcribed Spacer Genotype VIII

This case report describes large, annular, scaly, and erythematous plaques in the axillae and legs extending from the groin as well as involvement of the chest surrounding the areola.

Revisiting the pathogenesis of dermatophytosis: A cross-sectional analytic study of serum levels of interleukins-2, 8, 10 and 17

BACKGROUND

Given the current epidemic-like scenario of dermatophyte infections, it is prudent to revisit the immunopathogenesis of dermatophytosis. Comprehending the intricate interactions among interleukins can aid in understanding the recent trends in infection. There is a paucity of literature on the various cytokine levels observed in the serum of patients suffering from various dermatophytoses.

AIM

To study serum cytokine levels of interleukins 2, 8, 10 and 17 in patients with dermatophytosis.

METHODS

A cross-sectional analytic study was conducted on 64 cases of clinical dermatophyte infections (KOH confirmed) and 64 controls. The clinico-epidemiological profile of the cases was studied. By using a solid phase sandwich ELISA (enzyme-linked immunosorbent assay), the serum levels of interleukins 2, 8, 10 and 17 were measured and compared between cases and controls. Serum interleukin-2, 8, 10 and 17 levels were studied among cases based on mode of onset, duration of illness, treatment history, site of infection and multiple other morphological characteristics of the infection.

RESULTS

The cases had statistically higher levels of interleukins-8, 10 and 17 in comparison with controls. The levels of interleukin-8 were significantly lower (p < .05) among those who had received oral antifungals. In cases where the lesion had scaling, the serum levels of interleukin-10 were significantly higher (p < .05). The lesional hyperpigmentation was significantly (p < .05) associated with low levels of interleukin-17. Also, interleukin-17 was significantly (p < .05) elevated in patients with lesions in the abdomen.

CONCLUSION

It is the first time that serum interleukin levels are studied in dermatophytosis. There is an immunological dysfunction specific to dermatophytoses initiated by their infection. Key factor in this dysfunction is the elevation of IL-10, contributing to persistent infection. In turn, causing an increase in IL-17, promoting inflammation and tissue damage. This cycle of elevated IL-10 and IL-17 can further exacerbate the infection and lead to chronicity. The activity of IL-2 and the Th1 immune pathway is reduced by two opposing immune pathways: the Th17 and Th2 axes.

First case report of tinea corporis caused by Trichophyton indotineae in Latin America

A case of tinea corporis by Trichophyton indotineae observed in Argentina is presented. The patient had a history of having spent 18 months in Tulum, Mexico. She was suffering from tinea corporis in the anterior region of both thighs and the gluteal area. A mycological study was performed and T. mentagrophytes complex was isolated. The fungus was later identified as T. indotineae by DNA sequencing and treatment with SUBA-itraconazole was initiated with good clinical response.

Trichophyton: Changing Nomenclature and Practical Implications

Trichophyton interdigitale had been regarded as anthropophilic, mainly causing non-inflammatory tinea unguium and tinea pedis. T. mentagrophytes, thought to be zoophilic, were regarded as responsible for more inflammatory dermatophytosis. Indian terbinafine-resistant strains, identified with ribosomal internal transcribed spacer as 'genotype VIII', have recently been termed Trichophyton indotineae based on clinical and mycological features. Some of these have shown selective azole resistance as well. Phenotypic studies have shown some similarities and some differences between Trichophyton indotineae, T. mentagrophytes, and T. interdigitale, which are optimally distinguished with HMG locus analyses as three main genotypic groups containing the type strains of T. indotineae (CBS 146623), T. interdigitale (CBS 428.63), and T. mentagrophytes (IHEM 4268) and having approximate differences in geographic distribution. Trichophyton interdigitale was prevalently isolated from superficial infections on exposed body sites such as the scalp and face, while also feet and nails. Trichophyton mentagrophytes has a similar predilection but are also often found on the trunk and genitals. Trichophyton indotineae is mostly restricted to the trunk and groin. T. indotineae lesions are generally highly inflammatory, strongly associated with tinea cruris, corporis, and faciei and less commonly with fingernail onychomycosis and tinea pedis. They cause papulosquamous, pustular, pseudo-imbricata (tinea faciei), lichenoid, and pityriasis rosea (tinea corporis of the neck) types of lesions and spread rapidly to multiple sites and cause painful lesions with itching or burning. Lipolytic abilities of T. mentagrophytes and T. interdigitale are very similar and are higher than those of T. indotineae, which is associated with a higher prevalence of T. mentagrophytes on the human scalp, which is relatively rich in lipids. Keratin degradation is significantly larger in T. interdigitale due to location (tinea pedis and tinea unguium). Identification of T. indotineae through culture alone may not be sufficient for effective treatment decision-making; genetic analysis for resistance profiles is needed for optimum treatment selection. In India, steroid-induced suppression of local cellular immunity as well as an altered cutaneous microbiome provided a window of opportunity for the unique, multidrug-resistant species Trichophyton indotineae.

A Terbinafine Sensitive Trichophyton indotineae Strain in Italy: The First Clinical Case of tinea corporis and onychomycosis

Trichophyton indotineae is an emerging dermatophyte species that plays a relevant role in human healthcare. It has been associated with severe chronic skin infections and a high level of terbinafine resistance. T. indotineae is endemic to India, Iran, and Iraq but several cases have been reported in Europe, recently. In this manuscript, the authors report the first clinical description of a tinea corporis and onychomycosis due to T. indotineae. The patient was a 42-year-old female from India that has lived in Umbria (Central Italy) for the last two years. Firstly, a dermatological examination suggested dermatophytosis: mycology isolation from cultures and macro- and microscopical features identified the colonies as belonging to the T. mentagrophytes/T. interdigitale species complex. Subsequently, ITS1/ITS4 end-point PCR and Sanger sequencing identified the strain as T. indotineae. Lastly, a DermaGenius® Resistance Multiplex real-time PCR assay was carried out, targeting the mutations in the SQLE gene to establish terbinafine resistance or susceptibility of the strain. The melting curve observed was compatible with wild-type positive control, identifying the strain as T. indotineae terbinafine-sensitive. An oral terbinafine treatment was associated with a topical ciclopirox nail solution, resulting in remission in its clinical manifestation. On 3 July 2023, the local Prevention Service notified the case to the Ministry of Health that then reported the information at national and international levels.

The in vitro Activity of Echinocandins Against Clinical Trichophyton rubrum Isolates and Review of the Susceptibility of T. rubrum to Echinocandins Worldwide

Introduction

The emergence of resistance in Trichophyton rubrum to azoles and terbinafine has become increasingly evident in recent years, necessitating the development of novel antifungal drugs and the exploration of new indications for existing agents.

Methods

In this study, we retrospectively evaluated the in vitro antifungal activity of 3 echinocandins (anidulafungin, caspofungin, and micafungin) against 73 clinical isolates of T. rubrum collected from a teaching hospital in Shanghai, China, using EUCAST E.DEF 9.3.1 with minor modification. We also reviewed the susceptibility of T. rubrum to echinocandins globally by literature searching.

Results

Our findings revealed that micafungin exhibited the lowest modal minimum effective concentration (MEC) value (0.08 mg/L, n = 28) and the lowest geometric mean (GM) MEC value (0.014 mg/L) among the 73 isolates of T. rubrum tested, followed by anidulafungin with a modal MEC value of 0.016 mg/L (n = 67) and a GM of 0.018 mg/L. Caspofungin displayed a higher modal MEC value of 0.5 mg/L (n = 35) and a GM of 0.308 mg/L. Despite variations in methodologies, similar results were obtained from the review of five relevant studies included in our analysis.

Discussion

Echinocandins exhibited excellent in vitro activity against T. rubrum isolates, with micafungin and anidulafungin demonstrating greater potency than caspofungin. These findings suggest that echinocandins could be considered as potential treatment options for managing recalcitrant dermatophytoses resulting from the emergence of resistance. However, it is important to note that the clinical efficacy of these in vitro findings has yet to be established and warrants further investigation.

The Domestic Isolation of Terbinafine- and Itraconazole-Resistant Trichophyton indotineae in Chinese Mainland

BACKGROUND

Trichophyton indotineae, a new species of dermatophytes, has become a significant concern in treating dermatophytosis due to the high level of terbinafine resistance reported in India and even worldwide.

OBJECTIVES

This study aimed to report the terbinafine- and itraconazole-resistant T. indotineae in Chinese mainland, by identifying the phylogenetic classification of the isolate strain, and detecting the drug resistance, gene mutation and expression.

PATIENTS/METHODS

The skin scales of the patient were cultured on SDA and the isolate was authenticated by DNA sequencing and MALDI-TOF MS. Antifungal susceptibility testing was performed following the M38-A2 CLSI protocol to examine the MICs values of terbinafine, itraconazole, fluconazole, etc. The strain was screened for mutations in the squalene epoxidase (SQLE) gene by Sanger sequencing and detected the expression of CYP51A and CYP51B by qRT-PCR.

RESULTS

A multi-resistant ITS genotype VIII sibling of the T. mentagrophytes complex (T. indotineae) was isolated in Chinese mainland. The strain harbored high terbinafine MIC of > 32 μg/mL and itraconazole MIC of 1.0 μg/mL, which was identified a mutation in the squalene epoxidase gene with amino acid substitution (Phe397Leu, mutation 1191C > A). In addition, overexpression of CYP51A and CYP51B was observed. With multiple relapses, the patient finally achieved clinical cure by itraconazole pulse therapy and topical clotrimazole cream for 5 weeks.

CONCLUSIONS

The first domestic strain of terbinafine- and itraconazole-resistant T. indotineae from a patient in Chinese mainland was isolated. Itraconazole pulse therapy can be an effective method for the treatment of T. indotineae.

Internal Transcribed Spacer Region Typing of Trichophyton interdigitale Isolated from Japanese Patients

Trichophyton interdigitale, an anthropophilic species, is one of the main causative agents of tinea unguium and tinea pedis. T. interdigitale and the zoophilic species T. mentagrophytes are morphologically and physiologically very similar. Isolates of the T. interdigitale/T. mentagrophytes complex from around the world have been classified into more than 10 internal transcribed spacer (ITS) genotypes. In this study, we isolated T. interdigitale from Japanese patients and investigated which ITS type was more common. The ITS regions of 29 clinical isolates of T. interdigitale and one clinical isolate of T. mentagrophytes were sequenced. The phylogenetic analysis of the ITS region sequences revealed that the 29 isolates of T. interdigitale belong to ITS type II of T. interdigitale. The one clinical isolate of T. mentagrophytes was in the same cluster with ITS type II* of T. mentagrophytes. One terbinafine-resistant strain of T. interdigitale also belonged to ITS type II of T. interdigitale.

Towards an Early Clinical and Biological Resistance Detection in Dermatophytosis: About 2 Cases of Trichophyton indotineae

Trichophyton indotineae causes resistant dermatophytosis to terbinafine. The global spread of terbinafine-resistant Trichophyton indotineae strains with mutations in the squalene epoxidase gene is a major issue. This emerging species is now more frequently isolated in Europe and we report here two cases of T. indotineae tinea corporis in Switzerland, one with in vitro resistance to terbinafine and a second with in vitro susceptibility but a clinical resistance. Mycology isolation from cultures and sequencing ITS gene were used to confirm T. indotineae infection. In vitro antifungal susceptibility was tested in a microplate with a colorimetric detection of fungal viability for the determination of the minimal inhibitory concentration (MIC). Facing these emerging resistances and since there are a limited number of antifungal agents available to treat dermatophytosis, the early detection of terbinafine resistance should be a prerequisite in the management of T. indotineae infections.

Sheep serve as a reservoir of Trichophyton mentagrophytes genotype V infection

Human infections by Trichophyton mentagrophytes occur mainly due to contact with diseased animals. In Iran, T. mentagrophytes genotype V is the most prevalent variant of the fungus. We aimed to determine the animal reservoir of T. mentagrophytes genotype V infection. The study was done on a total of 577 dermatophyte strains obtained from animals with signs of dermatophytosis and human patients. The list of extensively sampled animals included sheep, cows, cats and dogs. For human cases, epidemiological data were collected. All dermatophyte isolates from animals along with 70 human isolates morphologically similar to T. verrucosum and T. mentagrophytes genotype V were identified by rDNA internal transcribed spacer region restriction fragment length polymorphism analysis and DNA sequencing. A total of 334 animal dermatophyte strains were identified as Microsporum canis, T. mentagrophytes genotype V, T. verrucosum, Nannizzia gypsea, T. mentagrophytes genotype II*, T. mentagrophytes genotype VII, T. quinckeanum, and N. fulva. All clinical isolates identified as T. mentagrophytes genotype V originated from skin and scalp infections. Almost all veterinary isolates of T. mentagrophytes genotype V were cultured from sheep, but epidemiological data on animal-to-human transmission of T. mentagrophytes genotype V infection were limited and we found evidence in favor of interhuman transmission. In Iran, sheep maintain T. mentagrophytes genotype V population and therefore serve as animal reservoir of respective infections. The role of sheep as the source of human dermatophytosis due to T. mentagrophytes genotype V isolates is yet to be proven.

Cutaneous Fungal Infections Caused by Dermatophytes and Non-Dermatophytes: An Updated Comprehensive Review of Epidemiology, Clinical Presentations, and Diagnostic Testing

Cutaneous fungal infection of the skin and nails poses a significant global public health challenge. Dermatophyte infection, mainly caused by Trichophyton spp., is the primary pathogenic agent responsible for skin, hair, and nail infections worldwide. The epidemiology of these infections varies depending on the geographic location and specific population. However, epidemiological pattern changes have occurred over the past decade. The widespread availability of antimicrobials has led to an increased risk of promoting resistant strains through inappropriate treatment. The escalating prevalence of resistant Trichophyton spp. infections in the past decade has raised serious healthcare concerns on a global scale. Non-dermatophyte infections, on the other hand, present even greater challenges in terms of treatment due to the high failure rate of antifungal therapy. These organisms primarily target the nails, feet, and hands. The diagnosis of cutaneous fungal infections relies on clinical presentation, laboratory investigations, and other ancillary tools available in an outpatient care setting. This review aims to present an updated and comprehensive analysis of the epidemiology, clinical manifestations, and diagnostic testing methods for cutaneous fungal infections caused by dermatophytes and non-dermatophytes. An accurate diagnosis is crucial for effective management and minimizing the risk of antifungal resistance.

Management of Dermatophytosis: Real-World Indian Perspective

Background

In spite of the availability of multiple consensus statements on dermatophytosis management, different treatment approaches have been experienced in India and require more scrutiny to further update guidelines and improve patient care.

Aim

To determine the different approaches in dermatophytosis diagnosis and management among dermatologists in India.

Materials and Methods

A web-based questionnaire was created and validated by five panelists with experience of >15 years in dermatophytosis and then circulated to about 2,000 dermatologists in India in September 2021 for a real-world management scenario.

Results

Out of 2,000 dermatologists, 459 responded. About half of the dermatologists (51%) routinely conduct potassium hydroxide mount (KOH) at the initiation of therapy. Similarly, about 53% of dermatologists initiate the management of dermatophytosis with combination therapy in all types of dermatophytosis for 4-6 weeks depending upon severity. Different types of combinations are being practiced, such as either two systemic and one topical, two topicals and one systemic, but the combination of one systemic and one topical (69%) is the most commonly practiced. Itraconazole (100 mg twice a day) and luliconazole are the most commonly prescribed antifungal medications. In case of non-response to routine dose of systemic anti-fungals, about 72% of dermatologists up dose them. Most of them continue these drugs for additional 1-2 weeks after clearance of the disease. Additionally, keratolytics and moisturizers are commonly prescribed. Additionally, 62% advise liver function tests (LFTs) at the initiation of therapy, whereas 72% advise monitoring adverse effects due to systemic antifungal drugs during treatment.

Conclusion

Combination therapy stood out as the need of the hour in the current menace of dermatophytosis with timely monitoring of laboratory tests for adverse events due to the use of systemic antifungals for a longer duration.

Potential Inhibitory Effect of Miltefosine against Terbinafine-Resistant Trichophyton indotineae

Several prolonged and significant outbreaks of dermatophytosis caused by Trichophyton indotineae, a new emerging terbinafine-resistant species, have been ongoing in India in recent years, and have since spread to various countries outside Asia. Miltefosine, an alkylphosphocholine, is the most recently approved drug for the treatment of both visceral and cutaneous leishmaniasis. Miltefosine in vitro activity against terbinafine-resistant and susceptible T. mentagrophytes/T. interdigitale species complex, including T. indotineae, is limited. The current study aimed to assess miltefosine's in vitro activity against dermatophyte isolates, which are the most common causes of dermatophytosis. Miltefosine, terbinafine, butenafine, tolnaftate, and itraconazole susceptibility testing was performed using Clinical and Laboratory Standards Institute broth microdilution methods (CLSI M38-A3) against 40 terbinafine-resistant T. indotineae isolates and 40 terbinafine-susceptible T. mentagrophytes/T. interdigitale species complex isolates. Miltefosine had MIC ranges of 0.063-0.5 µg/mL and 0.125-0.25 µg/mL against both terbinafine-resistant and susceptible isolates. In terbinafine-resistant isolates, the MIC₅₀ and MIC₉₀ were 0.125 µg/mL and 0.25 µg/mL, respectively, and 0.25 µg/mL in susceptible isolates. Miltefosine had statistically significant differences in MIC results when compared to other antifungal agents (p-value 0.05) in terbinafine-resistant strains. Accordingly, the findings suggest that miltefosine has a potential activity for treating infections caused by terbinafine-resistant T. indotineae. However, further studies are needed to determine how well this in vitro activity translates into in vivo efficacy.

Dermatophytic Biofilms: Characteristics, Significance and Treatment Approaches

Microbes are found in the environment, possibly more often as biofilms than in planktonic forms. Biofilm formation has been described for several important fungal species. The presence of a dermatophytoma in a dermatophytic nail infection was the basis for the proposal that dermatophytes form biofilms as well. This could explain treatment failure and recurrent dermatophytic infections. Several investigators have performed in vitro and ex vivo experiments to study the formation of biofilms by dermatophytes and their properties. The nature of the biofilm structure itself contributes to fungal protection mechanisms against many harmful external agents, including antifungals. Thus, a different approach should be carried out regarding susceptibility testing and treatment. Concerning susceptibility testing, methods to evaluate either the inhibition of biofilm formation, or the ability to eradicate it, have been introduced. As for treatment, in addition to classical antifungal agents, some natural formulations, such as plant extracts or biosurfactants, and alternative approaches, such as photodynamic therapy, have been proposed. Studies that connect the results of the in vitro and ex vivo experimentation with clinical outcomes are required in order to verify the efficacy of these approaches in clinical practice.