Rapid Speciation of the Five Most Medically Relevant Candida Species Using PCR Amplification and a Microtiter Plate-Based Detection System.

Background: Diagnosis of disseminated candidiasis can be difficult, as patient symptoms are often vague and blood cultures negative despite systemic involvement. Rapid detection of Candida would be advantageous, as delays in initiating antifungal therapy increase mortality. Conventional blood culturing methods require at least 3-7 days for detecting and speciating isolates, especially non-albicans species. In contrast, DNA amplification techniques make it possible to detect Candida DNA directly from clinical samples, thus eliminating the need to culture. Methods and Results: This study describes a polymerase chain reaction (PCR)-based assay, which permits amplification and speciation of the five most medically relevant Candida species, which cause over 95% of all Candida infections, namely, C. albicans, C. tropicalis, C. (Torulopsis) glabrata, C. parapsilosis, and C. krusei. Speciating these isolates has become more important recently with the introduction of fluconazole, and antifungal drug that has lower nephrotoxicity than fungizone but a narrower host range. Conclusions: By using this PCR-based assay in conjunction with a rapid microtiter plate-based detection system, samples can be analyzed for Candida DNA from five species in a single day. This represents a significant time saving as compared with the more lengthy but commonly used techniques of agarose gel electrophoresis and Southern blot hybridization for PCR product detection.