Detection of Candida spp. in blood cultures using nucleic acid sequence-based amplification (NASBA)

Candida spp. are the main causes of fungal infections in immunocompromised patients. It is known, that the routinely used automated blood culture systems may fail to detect yeasts. We therefore investigated, whether Nucleic Acid Sequence-Based Amplification (NASBA) can be used to improve the detection rate of Candida spp. in blood cultures. Culture-positive as well as negative blood cultures from patients with a proven candidaemia were analyzed, and the results of BacT/Alert monitoring were compared with the results of NASBA-based detection of yeast RNA. With the NASBA-assay, the number of positive blood cultures increased from 21% to 34%. The NASBA-assay may confirm the diagnosis and demonstrate the need for prolonged treatment. In addition it may shorten the time to detection. In summary, using NASBA for the detection of yeast RNA in blood cultures, we have shown for the first time that it is possible to improve the detection rate of yeasts in blood cultures by using amplification technology.