For the development of diagnostic polymerase chain reaction (PCR) to fungal infection by dermatophytes Trichophyton and Microsporum, detection of the fungal DNA by PCR and analysis of the DNA pattern were undertaken in the present study. A total of 15 strains were tested and those consisted of 3 reference strains and 12 isolated such as: reference strains of T mentagrophytes (downy type, ATCC 9533), T rubrum (IFO 6204) and M gypseum (ATCC 9083), and each isolate of T mentagrophytes (powdery type), T mentagrophytes (granular type), T mentagrophytes (pruple-red type), T rubrum, T raubitschekii, T tonsurans, T equinum, T ajelloi, T verrucosum, M cookei, M nanum and M gypseum.
The DNA were purely isolated from all strains of Trichophyton spp. and Microsporum spp. by a simple method partly consisted of distruption of fungal cells by lyophilization and grinding and extraction of fungal DNA without phenol treatment which is a routine procedure in DNA isolation. For the detection of fungal DNAs, optimal condition of PCR was determined as preheating once at 94℃ for 5 min, 35 cycles of denaturation at 94℃ for 1 min, annealing at 38℃ for 1 min and polymerization at 72℃ for 2 min, and 1 cycle of final extension at 72℃ for 5 min.
In PCR using arbitrary primers AP-1 (5´ ACCCGACCTG3´) and AP-2 (5´ ACGGGCCAGT3´), DNAs in various numbers and sizes were detected from different species of Trichophyton and Microsporum, while DNAs in similar size were also detected in all strains of Trichophyton spp. and Microsporum spp. There were unique DNAs observed from certain dermatophytes by AP-1 such as 1,900 bases in T rubrum, 950 and 1,100 bases in T raubitschekii, 2,100 bases in T equinum, 400 bases in T verrucosum and 1,150 bases in M gypseum. The unique DNAs were also observed by AP-2 such as 1,200 bases in T ajelloi, 250 bases in T verrucosum, 1,150 bases in M cookei and 2,000 bases in M nanum.
The results indicated that PCR can detect a specific DNA from certain Trychophyton and Microsporum spp, which can be the information for further development of diagnostic PCR to dermatophytes.
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