Strain Differentiation of Trichophyton rubrum Isolated from 2 Sites of the Same Patients by Analysis of Ribosomal DNA Nontranscribed Spacer

Kim, Hyun Chull; Shin, Dong Hoon; Choi, Jong Soo; Kim, Ki Hong

Abstract

BACKGROUND: In Korea, Trichophyton (T.) rubrum is the most common dermatophyte and occupied more than 80% of all isolates. Although strains differentiation is essential for epidemiologic studies, differentiation of T. rubrum is difficult.
OBJECTIVE
The aim of this study was determined if 2 strains of T. rubrum, obtained from 2 different infection sites of the same patient, are the identical. METHOD: Amplification of tandemly repetitive subelements TRS-1 and TRS-2 of ribosomal DNA nontranscribed spacer (rDNA NTS) was performed on 20 strains of T. rubrum. They were isolated from skin lesions of tinea cruris and tinea pedis or tinea unguium in 10 patients.
RESULTS
Twenty strains were cultured on Sabouraud dextrose agar slant plate and all strains showed the portwine strain. The amplification of TRS-1 from 20 strains resulted in 15 strains (75%) with type 1 (434 bp), 2 strains (10%) with type 2 (634 bp), 2 strains (10%) with type 3 (834 bp) and 1 strain (5%) with type 6 (434 bp + 634 bp). Each strains from 4 of 10 (40%) patients had different types of TRS-1: one patients had type 2 (groin) and type 1 (sole), one patient had type 6 (groin) and type1 (sole), one patient had type 3 (groin) and type 2 (sole), and one patient had type 1 (groin) and type 3 (sole). The infected sites or disease duration did not have noticeable difference in type of TRS-1. The amplification of TRS-2 resulted in all 20 strains with type II (502 bp), since differentiation was not possible.
CONCLUSION
The patient with different type of strains present on infected sections of the body, indicated the possibility of different fungal transmission routes. Specific amplification of subrepeat elements in rDNA NTS was simple and reproducible method for typing of T. rubrum and was useful for epidemiologic studies.