PCR-RFLP detection and species identification of fungal pathogens in patients with febrile neutropenia

Abstract

To assess the usefulness of polymerase chain reaction (PCR) assays in the diagnosis of fungal infections in immunocompromised patients. A rapid and sensitive PCR-based assay for the detection and identification of fungal pathogens was designed and applicability of this method was investigated in a group of children with cancer and febrile neutropenia (FN). The ITS2 sequences and adjacent regions of 40 fungal pathogens were analyzed and primers for detection of all analyzed fungal species were designed. Amplification product length polymorphism (APLP) and restriction fragment length polymorphism (RFLP) generated genus- or species-specific patterns. The sensitivity of the method was approximately three cells of Candida albicans per 1 mL of blood. The results were available within 8 h after sample collection. The method was tested on 53 blood samples and one lung biopsy sample from 24 children with cancer and febrile neutropenia (FN). The PCR assay detected fungal DNA in 25 clinical samples from ten patients. Blood cultures were positive in only five samples, while another two blood-culture negative patients had positive cultures from throat swabs. The remaining 14 patients were both culture- and PCR-negative. Culture-isolated strains matched completely those obtained by PCR-APLP-RFLP identification. The identity of fungal species was confirmed by direct sequencing of amplified products. Our results suggest that PCR-APLP-RFLP assays can be useful in the diagnosis of fungal infections in immunocompromised patients.