A resurgence of tinea cruris caused by Epidermophyton floccosum: An outbreak among Thai naval cadets

Abstract

Background: A decreasing trend in tinea cruris caused by Epidermophyton floccosum, an anthropophilic dermatophyte, has been observed. Methods: This retrospective study involved Thai naval cadets aged 18 years or older with suspected groin lesions. Both clinical evaluations and laboratory investigations were conducted. Results: In total, 86 male participants with a median age of 19 years who presented with groin rash were enrolled in the study. Branching septate hyphae from KOH examination were found in 55 patients (64.0 %). Fungal identifications were Epidermophyton floccosum (42 cases; 76.4 %), Trichophyton mentagrophytes complex (3 cases; 5.5 %), and no growth (10 cases; 18.2 %). An E. floccosum outbreak was identified, with a prevalence of 76.4 %. Most lesions exhibited admixed erythema and hyperpigmentation. Approximately two-thirds displayed prominent, easily visible scaling. Scrotal involvement was absent in 95.2 % of lesions, with 87.2 % presenting bilaterally. A gradual symptom onset lasting up to 2 months was observed in 78.9 % of cases. Lesion morphologies included annular (73.8 %), patchy (14.3 %), and polycyclic (9.5 %). Severe itching disrupting daily activities was reported by only 7.1 % of participants. Approximately two-thirds used over-the-counter (OTC) topical medications without consulting a physician. Risk factors related to clothing included sharing clothes (59.5 %), wearing sweaty clothes (100 %), and reusing unwashed clothes (81.0 %). Conclusions: The E. floccosum tinea cruris outbreak among naval cadets was characterized by a gradual onset and mild symptoms. OTC medication use without physician consultation was prevalent.