Development and Validation of a Quantitative PCR Assay for Diagnosis of Scedosporiosis

Abstract

ABSTRACT Scedosporium apiospermum and Scedosporium prolificans are fungal pathogens that can cause severe human infections, including disseminated mycosis in immunocompromised patients. Two real-time PCR (RT-PCR) assays for the diagnosis of these species were developed and validated for the classification of clinical strains and for the detection of DNA in clinical samples by use of a murine model of invasive infection. A total of 14 clinical strains and 141 samples, including blood, serum, and lung samples from infected CD1 mice, were analyzed. Each RT-PCR methodology used a species-specific molecular beacon probe targeting a highly conserved region of the fungal ribosomal DNA gene. Results showed 100% specificity and a detection limit of 10 fg of DNA for both assays. The sensitivities for the S. prolificans -specific PCR assay were 100% for cultured clinical strains, 95.5% for lung tissues, 85% for serum, and 83.3% for blood. For S. apiospermum , the sensitivities were 100% for clinical strains and 97.2%, 81.8%, and 54.5% for lung tissues, serum, and blood, respectively. Both techniques can be useful for clinical diagnosis, and further studies are warranted.