Simple and rapid detection of Candida albicans DNA in serum by PCR for diagnosis of invasive candidiasis

A rapid and sensitive PCR assay for the detection of Candida albicans DNA i n serum was established. DNA from human serum samples was purified using th e QIAamp blood kit, which proved to be a fast and simple method for isolati ng minute amounts of Candida DNA from clinical specimens for diagnosis of i nvasive candidiasis, Universal primer sequences used in the PCR assay are d erived from the internal transcribed spacer rRNA gene of fungi, whereas the biotinylated hybridization probe used in a DNA enzyme immunoassay (DEIA) b inds specifically to C. albicans DNA. The sensitivity of this PCR-DEIA meth od is very high; the detection limit for genomic Candida DNA is one C. albi cans genome per assay. Blood from uninfected and infected persons, ranging from healthy volunteers, patients with mucocutaneous infections, and patien ts at risk to develop a systemic Candida infection to patients with an esta blished systemic candidiasis, was analyzed for the presence of C, albicans to diagnose fungal infection. Candida DNA could not be detected in sera of 16 culture-negative controls and from 11 nonsystemic candidal infections by PCR or DEIA. Blood cultures from patients at risk were all negative for Ca ndida, whereas all blood cultures from systemic candidiasis patients were p ositive. However, Candida DNA could be detected by PCR and DEIA in the seru m from three out of nine patients who were at risk for a systemic infection and in the serum of all seven patients who had already developed an invasi ve Candida infection. PCR is more sensitive than blood culture, since some of the patients at risk for invasive yeast infection, whose blood cultures were all negative for Candida, tested positive in the PCR amplification. Th ese results indicate the potential value of PCR for detecting C, albicans i n serum samples and for identifying patients at risk for invasive candidias is.