With the present PCR system, 50 copies of rDNA are sufficient for identification of the target pathogen, so the sensitivity is high enough to find fungi in a small clinical specimen. For example, to obtain 50 copies of rDNA for A. fumigatus would require only one or two cells. Accordingly, quantification of real-time PCR data is important for appropriate evaluation of clinical samples containing both pathogenic and non-pathogenic fungi. In a few nail samples obtained from healthy volunteers, fewer than 1500 copies of fungal DNA were detected, suggesting that this represented commensal fungi living on the nails and skin or environmental contamination.