Comparative evaluation of the QIAsymphony RGQ system with the easyMAG/R-gene combination for the quantitation of cytomegalovirus DNA load in whole blood

The detection of cytomegalovirus (CMV) DNA in blood is a key feature of the virological surveillance of immunocompromised patients. Methods The QIAsymphony RGQ system (QIAGEN S.A.S., France) combines the extraction/distribution steps on QIAsymphony SP/AS instruments with amplification on a Rotor-Gene Q RT-PCR machine. This system was compared to a strategy combining an extraction step on the NUCLISENS easyMAG platform (bioMérieux) with the CMV R-gene kit (Argene) on 100 whole blood specimens collected from immunocompromised patients of the University Hospital of Saint-Etienne, France. Results The overall agreement between the two strategies was 86% (kappa coefficient of 0.67); the 14 discrepant results corresponded to low DNA loads. The 62 samples found positive with both tests were correlated (Pearson r coefficient of 0.70, P < 0.01) despite an over quantitation of 0.25 log 10 copies/ml with the easyMAG/Argene strategy ( P < 0.001). Very close results were also obtained with a commercial panel of 10 samples with CMV loads ranging from 2.36 to 6.41 log 10 copies/ml. The inter-run and intra-run variability was consistently lower with the QIAGEN platform. Conclusions These results validate the performance of the QIAsymphony RGQ system for the routine quantitation of CMV DNA. This fully-automated platform reduces the hands-on time and improves standardization, traceability and quality control assessment.