Dermatophytosis, commonly referred to as ringworm or tinea infection, represents a major public health concern and one of the most common reasons for dermatological consultations globally. ¹ These infections are caused by a group of closely related filamentous fungi known as dermatophytes, which possess a unique enzymatic capacity to invade and consume keratin, a protein abundant in the skin, hair, and nails. ² The clinical manifestation of dermatophytosis is diverse and is classified based on the anatomical site involved, leading to conditions such as Tinea corporis (body), Tinea cruris (groin), Tinea pedis (feet), Tinea capitis (scalp), Tinea unguium (nails), and Tinea faciei (face). ³ The ecological classification of dermatophytes divides them into three genera: Trichophyton, Microsporum, and Epidermophyton. ⁴ Furthermore, based on their natural habitat, they are categorized as anthropophilic (primarily infecting humans), zoophilic (primarily infecting animals), or geophilic (residing in soil). ⁵ This classification is crucial from an epidemiological standpoint, as anthropophilic species tend to cause chronic, low-grade inflammation, while zoophilic and geophilic species often provoke more acute and inflammatory responses. ⁶ For decades, Trichophyton rubrum has been recognized as the most prevalent etiological agent of dermatophytosis worldwide, responsible for a vast majority of chronic and recurrent infections. ⁷ However, recent reports from various parts of the world, particularly from the Indian subcontinent, indicate a significant epidemiological shift. There is a rising incidence of infections caused by the Trichophyton mentagrophytes complex, especially the more inflammatory and often terbinafine-resistant strains. ⁸,⁹ This shift is a cause for clinical concern as it is frequently associated with atypical presentations, treatment failures, and increased chronicity. ¹⁰ Several factors are hypothesized to contribute to this changing landscape, including the misuse of over-the-counter topical steroid-antifungal-antibacterial combinations, environmental changes, increased travel, and host factors such as immunosuppression. ¹¹,¹² Accurate and timely diagnosis is the cornerstone of managing dermatophytosis. While a clinical diagnosis is often attempted, laboratory confirmation is imperative for initiating species-directed therapy. Direct microscopic examination with Potassium Hydroxide (KOH) is a rapid and cost-effective method to visualize fungal hyphae, but it does not identify the species. ¹³ Fungal culture remains the gold standard for definitive identification of the dermatophyte species, which is vital for understanding local epidemiology, tracking resistance patterns, and guiding appropriate long-term management, especially in recurrent cases. ¹⁴,¹⁵ In this context, the present study was undertaken to determine the current prevalence, clinical patterns, and the spectrum of dermatophytes isolates among patients presenting with suspected superficial mycoses to our teaching hospital. The findings will provide contemporary local data that can help refine empirical treatment protocols and contribute to the broader understanding of the evolving mycological profile of dermatophytosis.

This was a hospital-based, prospective cross-sectional study conducted in the Department of Dermatology and Microbiology at a tertiary care teaching hospital over a period of 18 months, from January 2023 to June 2024. The study was approved by the Institutional Ethics Committee, and written informed consent was obtained from all participating patients or their guardians. Study Population and Sample Size: A total of 350 consecutive patients of all ages and both genders, who attended the Dermatology OPD with clinical features suggestive of dermatophytosis (such as erythematous, scaly, annular plaques with or without vesicles, alopecia, or onychodystrophy), were included in the study. Inclusion Criteria: 1. Patients of any age and either sex presenting with clinical lesions characteristic of dermatophytosis. 2. Patients who had not received any topical or systemic antifungal therapy for at least two weeks prior to sample collection. Exclusion Criteria: 1. Patients who had applied topical antifungal or corticosteroid-containing preparations within the last 2 weeks. 2. Patients who had taken systemic antifungal therapy within the last 4 weeks. 3. Patients with extensive skin conditions like psoriasis or eczema where dermatophytosis was a secondary or differential diagnosis, making clean sample collection difficult. 4. Patients who were unwilling to provide informed consent. Sample Collection and Processing: After a detailed clinical examination, the affected site was cleaned with 70% alcohol. Using a sterile blunt scalpel, skin scrapings were collected from the active, advancing border of the lesion. In cases of tinea capitis, hair stumps were epilated with sterile forceps. For suspected onychomycosis, nail clippings and subungual debris were collected. All samples were collected in sterile dry containers and transported to the microbiology laboratory for processing. Direct Microscopy: A portion of each sample was placed on a clean glass slide, and a few drops of 10% Potassium Hydroxide (KOH) were added. The preparation was gently heated and then examined under the microscope (10X and 40X objectives) for the presence of translucent, branching, septate hyphae and/or arthroconidia. A sample was considered KOH-positive if these fungal elements were visualized. Fungal Culture: The remaining sample was inoculated onto two sets of Sabouraud Dextrose Agar (SDA) slants supplemented with cycloheximide (0.5 g/L) and chloramphenicol (0.05 g/L) to inhibit saprophytic fungi and bacteria, respectively. The inoculated slants were incubated at 25-28°C and examined twice weekly for fungal growth for up to 4 weeks. The dermatophyte isolates were identified based on their colonial morphology (texture, surface, pigmentation on the obverse and reverse) and microscopic features observed in Lactophenol Cotton Blue (LPCB) mount, including macroconidia, microconidia, and other specialized structures. Data Analysis: The data regarding patient demographics, clinical presentation, and laboratory findings were entered into a Microsoft Excel spreadsheet. Descriptive statistics (frequencies, percentages) were used to analyze the data.

A total of 350 patients with clinically suspected dermatophytosis were investigated. Table 1: Sex-wise Distribution of Dermatophytosis Sex Number of Patients (n=210) Percentage Male 126 60.0% Female 84 40.0% Males were more commonly affected than females, with a male-to-female ratio of 1.5:1.* Table 2: Age-wise Distribution of Dermatophytosis Age Group (Years) Number of Patients (n=210) Percentage 0-10 18 8.6% 11-20 42 20.0% 21-40 95 45.2% 41-60 40 19.0% >60 15 7.1% The young and middle-aged adult population (21-40 years) constituted the largest affected group (45.2%), indicating this demographic is most susceptible, likely due to higher occupational and social exposure.* Table 3: Clinical Types of Dermatophytosis Clinical Type Number of Patients (n=210) Percentage Tinea corporis 80 38.1% Tinea cruris 45 21.4% Tinea faciei 20 9.5% Tinea capitis 18 8.6% Tinea unguium 15 7.1% Tinea pedis 12 5.7% Tinea manuum 10 4.8% Mixed* 10 4.8% *Mixed: Tinea corporis et cruris was the most common combination. Tinea corporis was the predominant clinical type, followed by tinea cruris. This pattern is consistent with the hot and humid climate of the region.* Table 4: Results of Direct Microscopy and Culture Laboratory Test Positive Results Percentage (from 210) KOH Positive 185 88.1% Culture Positive 117 55.7% Direct microscopy (KOH) demonstrated a higher positivity rate than culture, underscoring its high sensitivity as a rapid diagnostic tool. The lower culture positivity can be attributed to prior partial treatment, non-viable fungal elements, or fastidious organisms. Table 5: Spectrum of Dermatophyte Isolates Dermatophyte Species Number of Isolates (n=117) Percentage Trichophyton mentagrophytes complex 61 52.1% Trichophyton rubrum 42 35.9% Microsporum canis 7 6.0% Trichophyton tonsurans 4 3.4% Microsporum gypseum 2 1.7% Epidermophyton floccosum 1 0.9% The T. mentagrophytes complex emerged as the leading causative agent, surpassing the traditionally dominant T. rubrum. This finding highlights a significant shift in the local etiological spectrum. Table 6: Common Dermatophyte Species by Clinical Type Clinical Type Predominant Species (n) Tinea corporis T. mentagrophytes (35), T. rubrum (28) Tinea cruris T. rubrum (20), T. mentagrophytes (15) Tinea capitis T. mentagrophytes (8), M. canis (5) Tinea unguium T. rubrum (8), T. mentagrophytes (5) While T. mentagrophytes was overall dominant, T. rubrum was still more common in certain chronic infections like Tinea cruris and Tinea unguium. The presence of M. canis in tinea capitis indicates a probable zoophilic source

Our study provides a contemporary snapshot of the epidemiological and mycological profile of dermatophytosis in a tertiary care setting. The overall prevalence of laboratory-confirmed dermatophytosis was 60%, which is consistent with the high burden of the disease reported in other studies from tropical countries like India. ¹⁶,¹⁷ The predilection for males (60%) and the young adult age group (21-40 years, 45.2%) aligns with findings from similar studies. ¹⁸,¹⁹ This can be attributed to factors such as increased sweating, occupational hazards involving contact with soil or animals, and greater outdoor physical activity among males in this age bracket. Clinically, Tinea corporis (38.1%) was the most frequent presentation, followed by Tinea cruris (21.4%). The body and groin are common sites due to the favorable environment created by occlusion, sweating, and friction. The high prevalence of tinea corporis has been documented in several recent studies, reflecting its community-wide spread. ²⁰ The most significant finding of our study is the shifting etiological pattern. We observed that the Trichophyton mentagrophytes complex (52.1%) has overtaken Trichophyton rubrum (35.9%) as the predominant isolate. For many years, T. rubrum was the undisputed leader in causing chronic and recurrent dermatophytoses globally. ²¹ However, our results are in concordance with a growing body of evidence from South Asia reporting a surge in T. mentagrophytes infections. ⁸,²² A multi-center study in India by Verma et al. (2020) also reported a similar trend, with T. mentagrophytes being the most common isolate. ²³ This epidemiological shift is a matter of serious clinical concern. The T. mentagrophytes complex, particularly the newly identified T. indotineae genotype, is often associated with more inflammatory and extensive lesions, and more alarmingly, with in vitro and in vivo resistance to terbinafine, the first-line oral antifungal agent. ⁹,²⁴ The rampant misuse of topical corticosteroid combinations is considered a major driver for this shift. ¹²,²⁵ These steroid creams suppress inflammation and clinical signs, providing temporary symptomatic relief but facilitating deeper fungal invasion and altering the local microbiome, potentially giving a competitive advantage to T. mentagrophytes over T. rubrum. The higher sensitivity of KOH mount (88.1%) compared to culture (55.7%) is a well-established phenomenon. Culture, while essential for species identification, is less sensitive due to factors like non-viable hyphae in transported samples, prior antifungal use, or fastidious growth requirements of some species. ¹³,¹⁴ Therefore, a negative culture does not rule out dermatophytosis if the KOH mount is positive. The presence of zoophilic species like Microsporum canis (6.0%) and M. gypseum (1.7%) underscores the importance of considering animal contact in the patient's history. These species typically cause highly inflammatory lesions, as observed in our tinea capitis cases. The limitations of our study include its single-center design and the lack of molecular characterization of the T. mentagrophytes complex to confirm the T. indotineae strain and its antifungal susceptibility profile.

This study confirms the high prevalence of dermatophytosis in our patient population, with a distinct predilection for young adult males and a clinical presentation dominated by tinea corporis. The most critical finding is the emergence of the Trichophyton mentagrophytes complex as the predominant dermatophyte, indicating a significant epidemiological shift from the previously dominant Trichophyton rubrum. This change has profound implications for patient management, as it may be associated with atypical clinical presentations and reduced susceptibility to standard antifungal therapies. Our findings emphasize the indispensable role of mycological laboratory diagnostics, including culture, for species identification to guide appropriate therapy. There is an urgent need for continued surveillance, antifungal susceptibility testing, and public health education against the misuse of topical steroids to combat the growing challenge of recalcitrant dermatophytosis.

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