P309 Clonal outbreak of Trichophyton tonsurans causing tinea capitis among wrestlers in Beijing, China

Abstract Poster session 2, September 22, 2022, 12:30 PM - 1:30 PM Objectives Trichophyton tonsurans, an anthropophilic dermatophyte, mostly causes tinea capitis and tinea corporis and is often associated with outbreaks among athletes involved in combat sports, such as wrestlers and judo athletes. Here, we report an outbreak of tinea capitis caused by Trichophyton tonsurans among five juvenile athletes aged ten to fourteen in a wrestling team in Beijing, China. Methods A total of 5 wrestlers aged 10-14 years presented with alopecia, erythema, scales, and pustule on the scalp (Fig. 1a). Scrapings from the lesions were performed by direct microscopic examination using 10% potassium hydroxide (KOH) with calcofluor white and fungal culture. The fungal pathogens were identified 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), which show intraspecies diversity and can be applied to epidemiological investigations and determining the route of infection transmission. Antifungal susceptibility of terbinafine (TBF), itraconazole (ITC), fluconazole (FLC), ketoconazole (KTC), and amphotericin B (AMB) against the causative fungal isolates was determined by broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) M38-A3 document. Results The five patients were diagnosed with tinea capitis because of the scalp lesions, spores, and hyphae observed by direct microscopic examination (Fig. 1b), and positive fungal culture. The causative isolates were all identified as T. tonsurans by macroscopic and microscopic characteristics (Fig. 2) and sequencing of ITS regions. The sequences of ITS, NTS, ALP1, MEP5, and CarbY were identical among the five isolates, revealing a single genotype. The abovementioned sequences have been deposited to Genbank. The minimum inhibitory concentrations (MICs) of TBF, ITC, FLC, KTC, and AMB against five T. tonsurans isolates were 0.015 μg/ml, 0.015 μg/ml, 8 μg/ml, 0.06 μg/ml, and 0.5 μg/ml, respectively. 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.