Sample pooling on the Cepheid Xpert® Xpress SARS-CoV-2 assay

Authors:

• Graham, Maryza
• Williams, Eloise
• Isles, Nicole
• Buadromo, Eka
• Toatu, Tebuka
• Druce, Julian
• Catton, Mike
• Lin, Chantel
• Howden, Benjamin P.
• Williamson, Deborah A.

Details:

Diagnostic Microbiology and Infectious Disease, Volume 99, Issue 2, 2021-02-28

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The COVID-19 pandemic has placed unprecedented global demand on laboratory supplies required for testing. Sample pooling has been investigated by laboratories as a strategy to preserve testing capacity. We evaluate the performance of Cepheid Xpert® Xpress SARS-CoV-2 RT-PCR assay for testing samples in pools of 4 and 6. Clinical samples containing SARS-CoV-2, and confirmed negative clinical samples were used to create sample pools. Clinical samples had ‘neat’ Xpert® E gene cycle threshold values ranging between 20 and 28 and all were detected qualitatively when contained in pools of 4 or 6 samples. For these samples, pooling had a median change in cycle threshold value of 2.0 in pools of 4, and of 2.9 in pools of 6. With the use of Cepheid Xpert® Xpress SARS-CoV-2 RT-PCR assay, pooling of 4 or 6 samples may be an effective strategy to increase testing capacity.