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Extended evalution of the NucliSens easyMAG sytem (BioMérieux) for automated extraction of microbiological DNA/RNA

Abstract number: 1733_899

Beuselinck K., Verschueren E., Van Eldere J.

Objective: Nucleic acid (NA) extraction is the most critical and labour-intensive step in NA based diagnostics. Performance of NA based diagnostics is primarily dependent on NA extraction yield, purity and the amount of sample that can be extracted. Recently, BioMérieux introduced the Nuclisens easyMAG, an automated extraction system with magnetic micro-particle processing allowing extraction of up to 24 samples in 1 hour.

Methods: Performance of the easyMAG as a front-end extraction system for our `in-house' Taqman PCR assays (HSV-1, HSV-2, VZV, CMV, EBV, enterovirus, polyomavirus, Toxoplasma gondii, Chlamydophila pneumoniae, Mycoplasma pneumoniae, Legionella pneumophila and Pneumocystis jirovecii) was analysed and compared to manual Qiagen extraction for the following sample matrices: cerebrospinal fluid, amniotic fluid, phosphate buffer (swabs), plasma and bronchoalveolair lavage samples.

Results: Dilution series of the evaluated micro-organisms were spiked in the appropriate sample matrices and divided into two aliquots. One aliquot was manually extracted with QIAamp Viral RNA kit (enterovirus) or QIAamp DNA Mini kit (all other organisms) simultaneously with automated extraction of the other aliquot with the generic protocol on the easyMAG. Of 38 dilutions, 10 aliquots were made to test reproducibility of both extraction methods on 5 different days. Out of 424 duplicate extractions, 289 were positive and 113 negative for both extractions (94.8% concordance). 22 discrepant results all had one weak positive result close to the detection limit of the PCR with 4 manual extractions leading to a false positive result. The correlation coefficient between automated and manual extraction was 0.98; the mean difference in cycle treshold (Ct) was + 0.08 Ct for the easyMAG. The mean variability with 5 repeats for the 38 dilutions was 0.50 Ct (SD: 0.38 Ct) for easyMAG and 0.57 Ct (SD: 0.55 Ct) for manual extraction. No cross-contamination was observed with easyMAG when strongly positive polyomavirus samples (15.4 Ct) and polyomavirus negative samples were tested. Turn-around time on easyMAG for 24 samples was one hour and hands-on time was 15 minutes compared to 95 minutes for manual extraction. The reduced hands-on time partially compensates the higher easyMAG reagents list price.

Conclusion: Automated easyMAG extraction offers NA yield similar to manual Qiagen extraction with reduced cross-contamination risk and reduced hands-on time.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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