Polymerase chain reaction-and RNA hybridization-based method for the investigation of deep-seated candidiasis

To determine the usefulness of a polymerase chain reaction (PCR) and RNA hybridization method for the diagnosis of invasive candidiasis and to compare its sensitivity with blood cultures.

Blood cultures and a blood sample for PCR were taken from patients with suspected invasive candidiasis. A 105 base pair conserved segment within the rDNA of Candida species was amplified. The amplicon was detected by hybridization and gel electrophoresis.

Intensive care units of two tertiary care hospitals.

One hundred and eighteen patients 16 years of age or older with four more risk factors for invasive candidiasis were enrolled. Present or recent past treatment with broad spectrum antibiotics, cancer chemotherapy, immunosuppressive drugs, granulocytopenia or granulocytosis, intravascular catheterization, tracheal intubation, recent abdominal surgery and parenteral nutrition were considered risk factors.

Forty-three patients had invasive candidiasis. PCR detected infections in 28 and 26 patients (sensitivity 65.1% and 60.4%) by hybridization and gel electrophoresis, respectively. The sensitivity of blood cultures was 58.1%. Of 25 patients with positive blood cultures, 17 were positive by PCR with the hybridization method. Eleven patients with invasive candidiasis had negative blood cultures but were positive by PCR.

PCR, especially with a hybridization detection method, is more sensitive than blood culture for invasive candidiasis and may facilitate the diagnosis of nonfungemic disease.