Company insight
ample pre-treatment is an essential step in molecular microbiology diagnostics, accounting for the conversion of clinical specimens into a form that is suitable for analysis. Many different types of approaches have been developed, typically consisting of multiple steps such as chemical or physical sample lysis, purification and separation of target analytes from other components, concentration of target analytes, and chemical or physical modifications to improve compatibility with various detection methods. Typically, more than half of the sample analysis time is consumed by the first sample preparation steps. In addition, complex pre-treatment may introduce much of the error in interlaboratory analyses and environmental as well as health hazards, due to the large volume of harmful reagents and waste processed during sample preparation. Sources of error arising from sample preparation may also be difficult to identify if a complex technique is used.
New sample preparation In early 2022, Abacus Diagnostica – part of Uniogen – introduced a new gel filtration- based sample preparation method for its updated GenomEra molecular microbiology assays. The method is based on size exclusion chromatography, where nucleic acids larger than 500 bp pass through the
Speed without compromise S
Abacus Diagnostica’s new gel filtration-based sample preparation method takes molecular testing to a new level. It guarantees high sensitivity and enables results in 50 minutes.
Analyte
SARS-CoV-2 Influenza A Influenza B RSV
Sample size (n) 751
751 751 751
PPA, % 98.4
98.3 100 94.4
NPA, % 100
100 100 100
The GenomEra SARS-CoV-2, Flu A/B + RSV 2.0 Assay Kit shows an excellent specificity and sensitivity in clinical respiratory specimens. PPA, positive percent agreement; NPA, negative percent agreement.
column, and impurities, such as debris and cellular compartments, inhibitors, small nucleotide fragments, and salts, are retained in the column and thus removed from the sample. This produces highly purified nucleic acid, which permits the use of an optimised PCR protocol with short assay run time and high sensitivity. The sample inactivation (lysis) is performed simply by collecting the primary specimen into transport medium consisting of high concentration of guanidine salts. The streamlined workflow is preceded by a simple pre-preparation of the GenomEra Extraction Column. This step can be done beforehand to further streamline the process; the pre-prepared columns can be stored at refrigerator for up to five days. To run a test, specimens in Copan eNAT transport medium are transferred into the pre-prepared Extraction Columns, followed by a one minute centrifugation at 1000 x g. Specimens collected in any other collection
media require 1:1 dilution with Copan eNAT prior to transfer into pre-prepared GenomEra Extraction Columns. In a final step, 35 μL of the spun flow-through is pipetted and placed in the GenomEra CDX instrument using a chip holder. Up to four samples can be analysed at the same time.
Rapid results With this new sample preparation method, the hands-on time is less than three minutes per specimen, and with four specimens processed at the same time, the total sample preparation time is less than five minutes. The method is used in the GenomEra SARS- CoV-2 2.0, GenomEra SARS-CoV-2, Flu A/B + RSV 2.0 and GenomEra HSV-1/2, VZV + EV Assay Kits and planned to be utilised also in the upcoming GenomEra assays. The recently conducted performance evaluation demonstrates the suitability and usability of the simplified sample preparation protocol even with a multiplex molecular assay. The GenomEra SARS-CoV-2, Flu A/B + RSV 2.0 Assay Kit is a 50-minute diagnostic (IVD) test for real-time reverse transcriptase polymerase chain reaction (rRT-PCR) detection and differentiation of the four target viruses as well as a specific human housekeeping gene mRNA (sample processing and amplification control) in respiratory swab specimens. The characteristics were evaluated with 751 clinical specimens from four institutions across Europe in early 2022. The overall agreement of the assay in comparison with the reference assays was 99.7% (95% CI: 99.5–99.9%). The specific sensitivities and specificities in the above table. ●
With GenomEra’s new sample preparation method, the hands-on time is less than three minutes. 26
www.uniogen.com Practical Patient Care /
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