Identification of Penicillium marneffei in Paraffin-Embedded Tissue Using Nested PCR

Penicillium marneffei is one of the unique thermally dimorphic fungi in Penicillium species that causes a disseminated, progressive and life threatening infection in immunocompromised patients. The diagnosis of Penicilliosis marneffei depends on culture that may delay the treatment due to the time-consuming process. In the present study, we evaluated the specificity and sensitivity of nested PCR to identify Penicillium marneffei from paraffin-embedded tissue. Two sets of oligonucleotide primers were derived from the sequence of 18S rRNA of Penicillium marneffei. The outer primers (RRF1 and RRH1) were specific to fungi. The inner primers (Pm1 and Pm2) were specific to Penicillium marneffei. The specific fragment of approximately 400 bp was amplified from all paraffin-embedded tissues from 14 patients with Penicilliosis marneffei and 10 bamboo rats. The detectable DNA concentration of single PCR and nested PCR were 14 pg/microl and 14 fg/microl, respectively. Further studies are required in order to use nested PCR for early diagnosis of the disease.