Clonal outbreak of Trichophyton tonsurans causing tinea capitis among a wrestling team in Beijing, China

Abstract

Trichophyton tonsurans, an anthropophilic dermatophyte, mostly causes tinea capitis and tinea corporis and often associates with outbreaks among athletes involving in combat sports. Here, we report an outbreak of tinea capitis caused by T. tonsurans among five juvenile athletes aged ten to fourteen in a wrestling team in Beijing, China. Scrapings from the lesions of the five patients were performed by direct microscopic examination and fungal culture. The fungal pathogens were all identified as T. tonsurans by morphology and sequencing of the internal transcribed spacer (ITS) regions. Multilocus genotyping analysis was performed by sequencing of the five gene loci including the ITS and non-transcribed spacer (NTS) of the ribosomal RNA (rRNA) locus, alkalineprotease-1 (ALP1), metalloprotease-5 (MEP5), carboxypeptidases Y (CarbY). The sequences of these markers were identical among the five isolates, revealing a single genotype. Antifungal susceptibilities of terbinafine (TBF), itraconazole (ITC), fluconazole (FLC), ketoconazole (KTC), and amphotericin B (AMB) against T. tonsurans was determined by broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) M38-A3 document and the minimum inhibitory concentrations (MICs) were 0.015 µg/mL, 0.015 µg/mL, 8 µg/mL, 0.06 µg/mL, and 0.5 µg/mL, respectively. In conclusion, we report an outbreak of tinea capitis caused by T. tonsurans among wrestlers in Beijing, China. Multilocus genotyping analysis revealed that all isolates consisted of a single genotype, suggesting the outbreak may be caused by a single strain of T. tonsurans. The isolates were all susceptible to the common antifungal drugs treating tinea capitis.