Phylogeny and PCR identification of the human pathogenic fungus Penicillium marneffei.

The phylogenetic position of the human pathogenic fungus Penicillium marneffei was assessed from the nucleotide sequences of the nuclear and mitochondrial ribosomal DNA regions. Phylogenetic analysis determined that P. marneffei is closely related to species of Penicillium subgenus Biverticillium and sexual Talaromyces species with asexual biverticillate Penicillium states. Knowledge of the phylogenetic position of P. marneffei facilitated the design of unique oligonucleotide primers, from the nuclear ribosomal DNA internal transcribed spacer region, for the specific amplification of P. marneffei DNA. These primers were successful at selectively amplifying DNA from six isolates of P. marneffei and excluding the other species tested, which included Penicillium subgenus Biverticillium and Talaromyces species and several well-known fungal pathogens, namely, Aspergillus fumigatus, Coccidioides immitis, Histoplasma capsulatum, and Pneumocystis carinii. The primers that we have developed for the specific amplification of P. marneffei have the potential to be incorporated in a PCR identification system which could be used for the identification of this pathogenic agent from clinical material.