A 32-year-old male presents with pruritic, scaly patches on the groin and inner thighs for 3 weeks. KOH mount shows septate hyphae. Which is the most common causative organism of tinea cruris in India?
A. Epidermophyton floccosum
B. Candida albicans
C. Microsporum canis
D. Trichophyton rubrum
Explanation
Epidemiology of Tinea Cruris in India
Key Point
Trichophyton rubrum is the most common dermatophyte causing tinea cruris (jock itch) globally and in India, accounting for 60–70% of cases.
Causative Organisms — Frequency Comparison
Table
Organism
Frequency in Tinea Cruris
Geographic Notes
Trichophyton rubrum
60–70% (most common)
Worldwide, including India
Epidermophyton floccosum
15–20%
More common in tropical regions
Trichophyton mentagrophytes
10–15%
Zoophilic, less common in cruris
Microsporum canis
<5%
Zoophilic, rare in tinea cruris
Candida albicans
Not a dermatophyte
Causes candidiasis, not dermatophytosis
Clinical Features of Tinea Cruris
High-YieldNEET PG
Tinea cruris typically presents with:
Bilateral, symmetrical involvement of groin and inner thighs
Scaly, erythematous patches with raised borders
Intense pruritus, especially in warm, humid weather
Sparing of scrotum (distinguishes from candidiasis)
KOH mount: septate hyphae (branching pattern)
Clinical Pearl
The scrotum is typically spared in dermatophyte infection but involved in candidiasis — a key clinical differentiator.
Why Trichophyton rubrum Dominates
1.
Anthropophilic nature — spreads easily human-to-human via fomites and direct contact
2.
Thermotolerance — thrives in warm, moist skin folds
3.
Chronicity — establishes persistent infections
4.
Ubiquity — found worldwide; highest prevalence in tropical and subtropical climates like India
Mnemonic
T. rubrum = Tropical, Thrives in folds, Transmissible — the three T's of the most common dermatophyte.
Valia & Valia Textbook of Dermatology
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