Fungal skin infections represent the fourth most prevalent disease globally, predominantly attributed to dermatophyte species such as Trichophyton. Nevertheless, sporadic instances of dermatophytosis may also arise from opportunistic, uncommon fungi. This study documents the association of keratinophilic fungi, Myriodontium keratinophilum and Aphanoascus verrucosus, with cases of dermatophytosis in Kashmir, North India. Internal transcribed spacer region sequencing of 64 isolates obtained from skin, hair, and nail samples of 62 patients identified 61% of isolates (n = 39) as M. keratinophilum, followed by Trichophyton indotineae and A. verrucosus in 20% (n = 13) and 19% (n = 12) cases, respectively. Furthermore, the first hybrid de novo genome assembly of M. keratinophilum is reported in the present study. Genomic analysis of both M. keratinophilum and A. verrucosus species revealed median intra-species single nucleotide polymorphism (SNP) differences of 100 and 27, respectively, suggesting highly related strains in the patient population. De novo functional annotation identified a higher number of coding regions in M. keratinophilum compared to T. indotineae and A. verrucosus, including carbohydrate-active enzymes (CAZymes) exhibiting unique substrate affinities and subtilisin 3 (SUB3) gene, previously implicated as a potential virulence gene in dermatophytes. Notably, in addition to all the multidrug transporters encoded by Trichophyton species, M. keratinophilum genome contains six putative ATP-binding cassette (ABC) transporters showing 40%-70% sequence similarity with the CDR1 gene. M. keratinophilum exhibited reduced susceptibility to multiple antifungals, including high minimum inhibitory concentrations (MICs) (>16 mg/L) against griseofulvin and itraconazole. Importantly, itraconazole is a primary therapeutic agent for terbinafine-resistant T. indotineae infections, underscoring the necessity for early and accurate identification and intervention of dermatophytic infections.IMPORTANCEThe study reports cases of dermatophytosis associated with two rare keratinophilic fungi, i.e., Myriodontium keratinophilum and Aphanoascus verrucosus. The cases mainly presented as tinea corporis and cruris, commonly caused by Trichophyton indotineae in the Indian subcontinent, which may remain undiagnosed due to a lack of molecular identification. Furthermore, the first-ever genome report of M. keratinophilum and its ab initio functional annotation is useful for further studies and management of opportunistic pathogens that exhibit reduced susceptibility towards itraconazole, the first-line drug of treatment for terbinafine-resistant T. indotineae infections. An early correct molecular identification of the etiologic agents of skin infections is warranted to tackle the new agents of dermatophytosis at the earliest stage.

Kerion is an abscess caused by a fungal infection, commonly occurring on the scalp among children and rarely in adults. This report illustrates the case of a 12-year-old boy who presented with multiple plaques with crusty lesions on the scalp for 2 months, associated with purulent discharge and boggy swelling, initially misdiagnosed as seborrheic dermatitis. Following unsuccessful treatment, his condition was correctly diagnosed as kerion based on clinical appearance, history of contact with domestic animals and Wood's lamp examination findings. The diagnosis was delayed for 2 months, leading to a prolonged disease course. Complete resolution of symptoms and lesions was achieved with systemic antifungal treatment, although permanent scarring alopecia remained. The delay in diagnosis and treatment led to prolonged illness and alopecia.

Background. Trichophyton indotineae is an emerging multidrug-resistant dermatophyte that has rapidly spread across continents, posing a serious threat to global public health. Limited genomic data from mainland China hinder a comprehensive understanding of its evolutionary origin, underscoring the urgent need for molecular susceptibility data to guide clinical antifungal therapy. To clarify the evolutionary origin and genome-wide characteristics of three newly identified clinical isolates of T. indotineae from Fujian Province, China, we sequenced these isolates to a mean coverage of 1,300× using the Salus Pro sequencing platform and delineated a comprehensive genomic portrait. Additionally, a linear regression model was constructed between the copy-number variation (CNV) of the CYP51B gene and the minimum inhibitory concentration (MIC) values of four antifungal agents to achieve molecular susceptibility prediction for T. indotineae. Finally, functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were employed to identify virulence-associated genes and pathways. Three T. indotineae isolates recovered in Xiamen, Fujian Province, China, fell into two distinct phylogenetic clades (Group II and Group IV). Notably, genome-wide scanning identified CYP51B CNV and the SQLE p.Phe397Leu mutation as the most prominent genomic determinants associated with azole and terbinafine (TRB) resistance, respectively. Structural modelling provided mechanistic support at the protein level for the functional impact of this mutation, revealing that the SQLE F397 substitution triggers a collapse of the hydrophobic binding pocket, thereby hindering TRB binding. Furthermore, a linear regression model was established to achieve molecular susceptibility prediction, showing a robust correlation between the CYP51B CNV and the MIC values of four azoles (P<0.05). Core-gene analysis against the reference genome identified a shared core genome. KEGG pathway analysis revealed the biological pathways where virulence genes are located, including the MAPK signalling pathway and the O-glycan biosynthesis pathway, which suggests potential pathogenic mechanisms. The study delineates the genomic landscape of T. indotineae isolates from China and demonstrates a stepwise elevation in azole MICs. The linear regression model reveals a significant positive correlation between CYP51B CNV and MIC values for four azoles, thereby advancing the CNV-resistance association from a qualitative observation to a quantitative prediction. These insights enhance the global understanding of the pathogen's genomic epidemiology and virulence, establishing a critical foundation for genome-guided surveillance and individualized antifungal therapy.

The Trichophyton mentagrophytes complex currently comprises three species (T. mentagrophytes, T. interdigitale, and T. indotineae) and exhibits substantial diversity in internal transcribed spacer (ITS) region sequences. Within this complex, Trichophyton indotineae and T. mentagrophytes ITS genotype VII have recently emerged as important public health concerns. The aim of the study was to describe the diversity of species and ITS genotypes among human clinical isolates belonging to the T. mentagrophytes complex recovered from glabrous skin and scalp samples in France. All isolates belonging to the T. mentagrophytes complex obtained from glabrous skin and scalp samples collected by three private clinical laboratories located in three French regions were sequenced for the ITS region. Clinical data were collected to compare patient characteristics according to ITS genotype. Among the 92 isolates, 62 (67.4%) corresponded to T. mentagrophytes sensu stricto, 21 (22.8%) to T. indotineae, and 9 (9.8%) to T. interdigitale. Among T. mentagrophytes sensu stricto isolates, five ITS genotypes were identified, in decreasing order of frequency: II*, III*, VII, III, and IV. Trichophyton mentagrophytes ITS genotype VII accounted for 16.3% of isolates within the T. mentagrophytes species complex and was isolated exclusively from adult men, unlike the other ITS genotypes. Twelve of the 21 T. indotineae isolates grew on a terbinafine screening medium and harbored the F397L or L393S substitution in the SQLE sequence. The emerging pathogens T. indotineae and T. mentagrophytes ITS genotype VII together account for 39.1% of T. mentagrophytes species-complex isolates identified in three private laboratories in France and infecting glabrous skin or scalp.

SUMMARYThe traditional landscape of dermatophyte infections has changed over the past decade. The emergence and global expansion of Trichophyton indotineae have highlighted the impact of irrational and uncontrolled antifungal and topical corticosteroid use, presented treatment challenges, and highlighted the deficiencies of currently available diagnostic methods. Trichophyton mentagrophytes genotype VII, which has until recently been associated with animal reservoirs, is now associated with human-to-human transmission and is frequently related to sexual transmission. Infections associated with emerging dermatophytes are notable for atypical presentations that may include widespread, inflamed lesions, terbinafine resistance, and frequent relapse. The classic presentation of tinea lesions is frequently obscured by the application of topical corticosteroids, leading to delays in clinical recognition, diagnosis, and appropriate treatment, perpetuating further misuse of topical medications. Deep or invasive dermatophytoses, including Majocchi's granuloma, may occur in immunocompromised patients. The introduction of matrix-assisted laser desorption/ionization-time of flight mass spectrometry and molecular detection of dermatophytes has improved the diagnostic landscape for dermatophytes. However, currently, most assays do not specifically detect T. indotineae or T. mentagrophytes genotype VII, hindering the diagnosis and surveillance. Sequencing of the internal transcribed spacer (ITS) region is required for definitive identification. Terbinafine and azole resistance is common in T. indotineae and increasingly being reported for other species. While nomenclatural changes have been introduced and debated over many decades, the last decade has seen the introduction of new genera, e.g., Nannizzia, Paraphyton, and Lophophyton. An overview of currently recognized dermatophyte species, complexes, and genera is presented here, describing phylogenetic, ecological, and biochemical relatedness. The ethical conundrum of the name Trichophyton indotineae is also discussed.

Introduction Tinea corporis, or ringworm, is a fungal infection caused by dermatophytes that affects the skin. It is a significant public health concern, particularly in tropical regions like India, due to issues like antifungal resistance and improper use of combination creams. Traditional diagnostic methods, such as potassium hydroxide (KOH) tests and fungal cultures, are reliable but time-consuming and require laboratory access. Dermoscopy, a non-invasive diagnostic tool, offers a faster alternative by revealing distinct patterns in skin infections, including tinea corporis, invisible to the naked eye. Objective This study aimed to analyse the clinical profile of tinea corporis and describe the utility of dermoscopy as an adjunctive diagnostic tool. Methods A prospective cross-sectional observational study at a tertiary care hospital in Karnataka, conducted from April to August 2024, included 200 clinically confirmed tinea corporis cases. Patients were evaluated using KOH tests and dermoscopy. Dermoscopic findings, recorded with a Derma India® M10A30 hybrid dermatoscope, were analyzed for specific patterns like scales and background color changes to aid diagnosis. Results The study indicated that 61% of the cases were men, with the highest prevalence observed in individuals aged 31-40 years. The key contributing risk factors were identified as poor hygiene and a previous history of dermatophytosis, both of which significantly increased susceptibility to infection. Dermoscopic examination revealed distinctive features, including peripheral scaling, reddish-brown backgrounds, and black dots, which were commonly present and proved essential for the precise and reliable diagnosis of tinea corporis. Conclusion Dermoscopy is a valuable, rapid, and non-invasive adjunctive diagnostic tool that complements clinical examination and potassium hydroxide microscopy. It facilitates the recognition of characteristic dermoscopic features, helping clinicians differentiate tinea corporis from other skin conditions, especially in resource-constrained settings.

Background Topical corticosteroids are widely used in dermatology because of their rapid anti-inflammatory effects. However, their easy availability and lack of awareness regarding their adverse effects have led to widespread misuse, resulting in a growing burden of steroid-induced cutaneous complications. Objectives This study aims to assess topical corticosteroid abuse, analyze the patterns and duration of use, identify the commonly used topical corticosteroid agents, and document the spectrum of associated cutaneous adverse effects. Methods A prospective observational study was conducted in the Department of Dermatology at Srinivasan Medical College & Hospital, Dhanalakshmi Srinivasan University, Trichy, Tamil Nadu, between November 2023 and December 2024. Adult patients with a history of topical corticosteroid use presenting with clinically evident corticosteroid-induced cutaneous adverse effects were consecutively enrolled after providing informed consent. Demographic data, indication for use, source of procurement, duration of application, and type of topical corticosteroid used were recorded. Patients underwent a detailed dermatological examination, and adverse effects were documented. Data were analyzed using descriptive statistics. Results A total of 120 patients were included, with a mean age of 33.88 ± 13.50 years. Females constituted the majority (60.8%, n=73). Non-prescription use of topical corticosteroids was observed in 60% (n=72) of patients. The most common indication for use was dermatophytosis (58.3%, n=70), followed by melasma (10%, n=12) and acne (5.8%, n=7). The duration of misuse ranged from less than one month to more than two years, with 31.7% of patients using topical corticosteroids for 1-3 months. Tinea incognito (33.3%, n=40) was the most frequent adverse effect, followed by acneiform eruptions (15%, n=18), acne flare (15.8%, n=19), and pigmentary changes. Conclusion Topical corticosteroid abuse is common and is largely driven by non-prescription use, particularly for fungal infections. The resulting cutaneous adverse effects cause significant morbidity. Strengthening regulatory control, promoting rational prescribing, and improving public awareness are essential to curb this preventable problem.