Presenter Status
Fellow
Abstract Type
Research
Primary Mentor
Rangaraj Selvarangan BVSc, PhD, D(ABMM), FIDSA, FAAM
Start Date
13-5-2025 11:30 AM
End Date
13-5-2025 1:30 PM
Presentation Type
Poster Presentation
Description
Introduction
The COVID-19 pandemic, caused by SARS-CoV-2, highlighted severe gaps in broad testing and prompt diagnosis. Rapid real-time RT-PCR assay Xpert® Xpress CoV-2 Plus was developed to enhance SARSCoV-2 detection in respiratory specimens. Using ZeptoMetrix's inactivated organisms, this study seeks to assess its analytical performance and compare its accuracy with current standard of care diagnostic assay.
Methods
The accuracy of the Xpert® Xpress CoV-2 Plus test was evaluated using ZeptoMetrix NATtrol inactivated SARS-CoV-2 organisms diluted with pooled negative nasopharyngeal (NP) swabs. Ten positive and ten negative NP swabs were tested over five days at two sites, with >90% agreement required. Precision was assessed by testing high (<30 Ct) and low (>33 Ct) positive NP swabs in triplicate over three days by two operators at both locations, ensuring intra- and inter-assay consistency with >90% agreement. Reference intervals were established using three negative samples from healthy volunteers. A crossover study was conducted with twenty clinical samples (ten positive, ten negative) tested at both sites and compared to the EUA-approved Xpert Xpress CoV-2 Plus assay, with >95% agreement required for validation.
Results
The Xpert Xpress CoV-2 Plus assay demonstrated 100% accuracy (10/10), with SARS-CoV-2 detected in all tested samples (n=18, 100%), including both high and low controls. Intra- and inter-assay precision were consistent, with the high control showing a standard deviation (SD) ≤ 0.65 and a coefficient of variation (%CV) ≤ 2.2, while the low control showed an SD of 1.42 and a %CV ≤ 4.4. The assay also exhibited 100% agreement (10/10) with the standard of care (SOC) results in a crossover study. Additionally, three samples from healthy volunteers (preprocedural patients with negative SARS-CoV-2 SOC results) tested negative, confirming the assay’s specificity. Healthy samples were for reference interval and not specificity.
Conclusion
The assay's promise as a reliable diagnostic tool for SARS-CoV-2 detection is established by these results, which highlight its dependability under various viral loads. High sensitivity and specificity are demonstrated by the Xpert Xpress CoV-2 Plus test, which provides quick and precise SARS-CoV-2 identification in 45 minutes. Its self-contained, user-friendly cartridges drastically lower the chance of cross-contamination and require little training. Its point-of-care architecture makes it appropriate for a variety of healthcare settings, allowing for quick decision-making and efficient patient management, while integrated built-in controls guarantee consistent and dependable outcomes.
Included in
Analytical, Diagnostic and Therapeutic Techniques and Equipment Commons, Medical Education Commons, Pediatrics Commons
Analytical Verification of the FDA cleared Xpert® Xpress CoV-2 Plus test for SARS-CoV-2 Detection in Respiratory Specimens
Introduction
The COVID-19 pandemic, caused by SARS-CoV-2, highlighted severe gaps in broad testing and prompt diagnosis. Rapid real-time RT-PCR assay Xpert® Xpress CoV-2 Plus was developed to enhance SARSCoV-2 detection in respiratory specimens. Using ZeptoMetrix's inactivated organisms, this study seeks to assess its analytical performance and compare its accuracy with current standard of care diagnostic assay.
Methods
The accuracy of the Xpert® Xpress CoV-2 Plus test was evaluated using ZeptoMetrix NATtrol inactivated SARS-CoV-2 organisms diluted with pooled negative nasopharyngeal (NP) swabs. Ten positive and ten negative NP swabs were tested over five days at two sites, with >90% agreement required. Precision was assessed by testing high (<30 >Ct) and low (>33 Ct) positive NP swabs in triplicate over three days by two operators at both locations, ensuring intra- and inter-assay consistency with >90% agreement. Reference intervals were established using three negative samples from healthy volunteers. A crossover study was conducted with twenty clinical samples (ten positive, ten negative) tested at both sites and compared to the EUA-approved Xpert Xpress CoV-2 Plus assay, with >95% agreement required for validation.
Results
The Xpert Xpress CoV-2 Plus assay demonstrated 100% accuracy (10/10), with SARS-CoV-2 detected in all tested samples (n=18, 100%), including both high and low controls. Intra- and inter-assay precision were consistent, with the high control showing a standard deviation (SD) ≤ 0.65 and a coefficient of variation (%CV) ≤ 2.2, while the low control showed an SD of 1.42 and a %CV ≤ 4.4. The assay also exhibited 100% agreement (10/10) with the standard of care (SOC) results in a crossover study. Additionally, three samples from healthy volunteers (preprocedural patients with negative SARS-CoV-2 SOC results) tested negative, confirming the assay’s specificity. Healthy samples were for reference interval and not specificity.
Conclusion
The assay's promise as a reliable diagnostic tool for SARS-CoV-2 detection is established by these results, which highlight its dependability under various viral loads. High sensitivity and specificity are demonstrated by the Xpert Xpress CoV-2 Plus test, which provides quick and precise SARS-CoV-2 identification in 45 minutes. Its self-contained, user-friendly cartridges drastically lower the chance of cross-contamination and require little training. Its point-of-care architecture makes it appropriate for a variety of healthcare settings, allowing for quick decision-making and efficient patient management, while integrated built-in controls guarantee consistent and dependable outcomes.
