Typing of Common Dermatophytes by Random Amplification of Polymorphic DNA

Seventy-six clinical isolates of dermatophytes and 8 preserved strains of Arthroderma were investigated by random amplification of polymorphic DNA (RAPD) assay to determine the DNA types of common dermatophytes and find any relationships of DNA-based typing with morphology, teleomorphs, geographic origins and sites of human infection. It was found that each species showed a distinct DNA pattern, which can be used as an identification marker. Forty-two isolates of Trichophyton mentagrophytes were classified into 3 main types and intratype polymorphism was revealed with some primers. No simple relationship was found between DNA type and morphology, but the DNA types of strains were closely related to their geographic origins. The RAPD groups of Arthroderma benhamiae, A. vanbreuseghemii, A. gypsea and A. otae were distinctly different, whereas the 42 clinical isolates of T. mentagrophytes shared similar patterns with A. vanbreuseghemii. Among 30 clinical isolates of T. rubrum, 22 showed almost identical RAPD type, while the other 8 strains differed slightly in band patterns. T. rubrum exhibited great differences from A. benhamiae and A. vanbreuseghemii. In conclusion, RAPD provides a stable and reliable means of typing common dermatophytes, and is a powerful tool for dermatophyte identification and epidemiological study.