Abstract:

Objective To evaluate the performance of nested PCR in the detection of different fungi in paraffin wax embedded tissues. Methods Forty-four tissue samples were resected from rats infected with Fonsecaea monophora, patients with chromoblastomycosis, sporotrichosis or penicilliposis marneffei followed by preparation of paraffin wax embedded tissue sections for pathological examination and DNA extraction. Nested PCR was performed by using specific primers targeting the ribosomal DNA of Fonsecaea, Sporothrix and Penicillium marneffei, respectively. The sensitivity and specificity of nested PCR were analyzed and compared with those of pathological examination. Results The nested PCR showed positive results in 8 of 20 samples from rats with chromoblastomycosis, 7 of 10 samples from patients with sporotrichosis and all of the 10 samples from patients with penicilliposis marneffei, but not in the control samples. In the detection of Fonsecaea, Sporothrix schenki and Penicillium marneffei, the sensitivity was 40%，70% and 100%, respectively, and the specificity was consistently 100%, for the nested PCR. Pathological examination revealed fungal elements in 95%, 70% and 80% of the corresponding samples, respectively. Conclusion Detection of fungal DNA in paraffin wax embedded tissue by nested PCR can be applied to the diagnosis of deep mycosis, especially to the diagnosis of penicilliposis marneffei.

Key words: Penicillium marneffei