Rapid diagnosis of candidaemia by real-time PCR detection of Candida DNA in blood samples

1 Institute of Medical Microbiology and Hygiene, University Hospital of Ulm, Ulm, Germany 2 Dr Gaertner & Partner Laboratories, Ravensburg, Germany Correspondence Nele Wellinghausen nele.wellinghausen{at}labor-gaertner.de Received November 9, 2008 Accepted April 15, 2009 This study prospectively evaluated an 18S rRNA gene-targeted real-time PCR approach in comparison with standard blood culture (BC) diagnostics for rapid diagnosis of candidaemia in a large study population of 384 patients, including 902 whole blood samples from 468 infectious episodes (IEs) of 329 adults and 55 children with haematological malignancies and various forms of immunodeficiency, and intensive care unit patients. Seven out of eight BC-proven cases (87.5 %) of candidaemia and seven out of twelve BC-positive samples (58.3 %) were positive by the Candida -specific PCR. A positive PCR result was also obtained for 28/460 BC-negative samples from IEs, including 8 patients with culture-confirmed Candida infection at primary sterile body sites. Of the PCR-positive, culture-negative patients, more than 50 % received systemic antifungal therapy. In 432/460 BC-negative IEs, the Candida specific-PCR was negative, resulting in a negative predictive value of 99.8 %. In conclusion, the Candida specific-PCR approach facilitates rapid detection of Candida DNA in blood samples of patients at risk of candidaemia within a few hours. Although standard BC diagnostics appear to remain indispensable for the detection of all cases of candidaemia, this PCR assay allowed the detection of candidaemia at a mean of 3 days earlier than BC diagnostics. Thus, it enables earlier antifungal therapy for patients with suspected candidaemia and may prevent further complications. These authors contributed equally to this work.