Isolation and Identification of Dermatophytes from Collegiate Runners

Abstract

Competitive runners experience various risk factors that render them more susceptible to superficial cutaneous fungal infections, including the use of occlusive footwear, shared locker rooms, submission of feet to constant maceration, trauma, sweating, and having depressed immune function. The goal of this work was to assess the prevalence of athlete’s foot fungi in cross country runners at St. John Fisher College. Toe webs of 16 collegiate runners were sampled and volunteers surveyed about their shoe habits, foot hygiene, and average miles run per week. Lack of tinea pedis-causing fungi in asymptomatic cross- country runners shifted the study to investigate the identities of fungi morphologically similar to athlete’s foot and look for correlations with volunteers’ running habits and hygiene. Thirty-five distinct fungal cultures were isolated and compared to a known Trichophyton rubrum strain both microscopically and macroscopically. Four samples were preliminarily identified as tinea pedis-causing fungi and sequenced to confirm molecular identification. Fungal DNA was isolated, purified, and PCR amplified using primers for the internal transcribed spacer region, D1/D2 region of the 28S subunit, and β-Tubulin gene. Three of the four isolates were identified as Fusarium equiseti, a soil-borne plant pathogen with rare human pathogenicity reported. The fourth isolate was Beauveria bassiana, a common soil-borne pathogen that can infect immunocompromised individuals. Correct dermatophytic identification and understanding of the interplay between species is important to provide correct treatment, prevent spread among athletes and within facilities, and determine how opportunistic pathogens might play a role in people with immune suppressed function, which includes runners.