scholarly journals Analytical and Clinical Comparison of Three Nucleic Acid Amplification Tests for SARS-CoV-2 Detection

2020 ◽  
Vol 58 (9) ◽  
Author(s):  
Elizabeth Smith ◽  
Wei Zhen ◽  
Ryhana Manji ◽  
Deborah Schron ◽  
Scott Duong ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Severe Acute Respiratory Syndrome ◽  
Drug Administration ◽  
Clinical Performance ◽  
Absolute Quantification ◽  
Nucleic Acid Amplification ◽  
Clinical Correlation ◽  
Molecular Assays ◽  
Percent Agreement ◽  
Rna Transcript

ABSTRACT Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified in December 2019 and has quickly become a worldwide pandemic. In response, many diagnostic manufacturers have developed molecular assays for SARS-CoV-2 under the Food and Drug Administration (FDA) Emergency Use Authorization (EUA) pathway. This study compared three of these assays, the Hologic Panther Fusion SARS-CoV-2 assay (Fusion), the Hologic Aptima SARS-CoV-2 assay (Aptima), and the BioFire Defense COVID-19 test (BioFire), to determine analytical and clinical performance as well as workflow. All three assays showed similar limits of detection (LODs) using inactivated virus, with 100% detection, ranging from 500 to 1,000 genome equivalents/ml, whereas use of a quantified RNA transcript standard showed the same trend but had values ranging from 62.5 to 125 copies/ml, confirming variability in absolute quantification of reference standards. The clinical correlation found that the Fusion and BioFire assays had a positive percent agreement (PPA) of 98.7%, followed by the Aptima assay at 94.7%, compared to the consensus result. All three assays exhibited 100% negative percent agreement (NPA). Analysis of discordant results revealed that all four samples missed by the Aptima assay had cycle threshold (Ct) values of >37 by the Fusion assay. In conclusion, while all three assays showed similar relative LODs, we showed differences in absolute LODs depending on which standard was employed. In addition, the Fusion and BioFire assays showed better clinical performance, while the Aptima assay showed a modest decrease in overall PPA. These findings should be kept in mind when making platform testing decisions.

scholarly journals Analytical and Clinical Comparison of Three Nucleic Acid Amplification Tests for SARS-CoV-2 Detection

2020 ◽  
Author(s):  
Elizabeth Smith ◽  
Wei Zhen ◽  
Ryhana Manji ◽  
Deborah Schron ◽  
Scott Duong ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Severe Acute Respiratory Syndrome ◽  
Limit Of Detection ◽  
Clinical Performance ◽  
Absolute Quantification ◽  
Nucleic Acid Amplification ◽  
Clinical Correlation ◽  
Molecular Assays ◽  
Percent Agreement ◽  
Rna Transcript

AbstractSevere Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was first identified in December 2019 and has quickly become a worldwide pandemic. In response, many diagnostic manufacturers have developed molecular assays for SARS-CoV-2 under the Food and Drug Administration (FDA) Emergency Use Authorization (EUA) pathway. This study compared three of these assays: the Hologic Panther Fusion SARS-CoV-2 assay (Fusion), the Hologic Aptima SARS-CoV-2 assay (Aptima) and the BioFire Diagnostics COVID-19 test (BioFire), to determine analytical and clinical performance, as well as workflow. All three assays showed a similar limit of detection (LOD) using inactivated virus, with 100% detection ranging from 500-1,000 genome equivalents/ml, whereas use of a quantified RNA transcript standard showed the same trend, but had values ranging from 62.5 to 125 copies/ml, confirming variability in absolute quantification of reference standards. The clinical correlation found that the Fusion and BioFire assays had a positive percent agreement (PPA) of 98.7%, followed by the Aptima assay at 94.7% when compared to the consensus result. All three assays exhibited 100% negative percent agreement (NPA). Analysis of discordant results revealed that all four samples missed by the Aptima assay had Ct values >37 on the Fusion assay.In conclusion, while all three assays showed similar relative LODs, we showed differences in absolute LODs depending on which standard was employed. In addition, the Fusion and BioFire assays showed better clinical performance, while the Aptima assay showed a modest decrease in overall PPA. These findings should be kept in mind when making platform testing decisions.

scholarly journals 2356. Increased Clinical Specificity with Ultrasensitive Detection of Clostridioides difficile Toxins: Reduction of Overdiagnosis Compared with Nucleic Acid Amplification Tests

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S811-S812 ◽  
Author(s):  
Johanna Sandlund ◽  
Joel Estis ◽  
Phoebe Katzenbach ◽  
Niamh Nolan ◽  
Kirstie Hinson ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Disease Severity ◽  
Single Molecule ◽  
Clinical Performance ◽  
Neutralization Assay ◽  
Nucleic Acid Amplification ◽  
Clostridioides Difficile ◽  
Percent Agreement ◽  
Clostridioides Difficile Infection ◽  
Healthcare Associated

Abstract Background Clostridioides difficile infection (CDI) is one of the most common healthcare-associated infections, resulting in significant morbidity, mortality, and economic burden. Diagnosis of CDI relies on the assessment of clinical presentation and laboratory tests. We have evaluated the clinical performance of ultrasensitive Single Molecule Counting technology for detection of C. difficile toxins A and B. Methods Stool specimens from 298 patients with suspected CDI were tested with nucleic acid amplification test (NAAT; BD MAX™ Cdiff assay or Xpert® C. difficile assay) and Singulex Clarity® C. difficile toxins A/B assay. Specimens with discordant results were tested with cell cytotoxicity neutralization assay (CCNA), and results were correlated with disease severity and outcome. Results There were 64 NAAT-positive and 234 NAAT-negative samples. Of the 32 NAAT+/Clarity− and 4 NAAT-/Clarity+ samples, there were 26 CCNA− and 4 CCNA- samples, respectively. CDI relapse or overall death was more common in NAAT+/toxin+ patients than in NAAT+/toxin− and NAAT−/toxin− patients, and NAAT+/toxin+ patients were 3.7 times more likely to experience relapse or death (Figure 1). The clinical specificity of Clarity and NAAT was 97.4% and 89.0%, respectively, and overdiagnosis was over three times more common in NAAT+/toxin− than in NAAT+/toxin+ patients (Figure 2). Negative percent agreement between NAAT and Clarity was 98.3%, and positive percent agreement increased from 50.0% to effective 84.2% and 94.1% after CCNA testing and clinical assessment. Conclusion The Clarity assay was superior to NAATs in diagnosis of CDI, by reducing overdiagnosis and thereby increasing clinical specificity, and presence of toxins was associated with disease severity and outcome. Disclosures All authors: No reported disclosures.

scholarly journals Clinical Evaluation of Three Sample-to-Answer Platforms for Detection of SARS-CoV-2

2020 ◽  
Vol 58 (8) ◽  
Author(s):  
Wei Zhen ◽  
Elizabeth Smith ◽  
Ryhana Manji ◽  
Deborah Schron ◽  
Gregory J. Berry
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Drug Administration ◽  
Clinical Evaluation ◽  
Limit Of Detection ◽  
Clinical Performance ◽  
Molecular Diagnostic ◽  
Analytical Sensitivity ◽  
Reference Standard ◽  
Slight Improvement ◽  
Percent Agreement

ABSTRACT Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now spread across the globe. As part of the worldwide response, many molecular diagnostic platforms have been granted emergency use authorization (EUA) by the Food and Drug Administration (FDA) to identify SARS-CoV-2 positive patients. Our objective was to evaluate three sample-to-answer molecular diagnostic platforms (Cepheid Xpert Xpress SARS-CoV-2 [Xpert Xpress], Abbott ID NOW COVID-19 [ID NOW], and GenMark ePlex SARS-CoV-2 Test [ePlex]) to determine analytical sensitivity, clinical performance, and workflow for the detection of SARS-CoV-2 in nasopharyngeal swabs from 108 symptomatic patients. We found that Xpert Xpress had the lowest limit of detection (100% detection at 100 copies/ml), followed by ePlex (100% detection at 1,000 copies/ml), and ID NOW (20,000 copies/ml). Xpert Xpress also had highest positive percent agreement (PPA) compared to our reference standard (98.3%) followed by ePlex (91.4%) and ID NOW (87.7%). All three assays showed 100% negative percent agreement (NPA). In the workflow analysis, ID NOW produced the lowest time to result per specimen (∼17 min) compared to Xpert Xpress (∼46 min) and ePlex (∼1.5 h), but what ID NOW gained in rapid results, it lost in analytical and clinical performance. ePlex had the longest time to results and showed a slight improvement in PPA over ID NOW. Information about the clinical and analytical performance of these assays, as well as workflow, will be critical in making informed and timely decisions on testing platforms.

scholarly journals Performance evaluation of the BD SARS-CoV-2 reagents for the BD MAX™ system

2021 ◽  
Author(s):  
Karen Yanson ◽  
William Laviers ◽  
Lori Neely ◽  
Elizabeth Lockamy ◽  
Luis Carlos Castillo-Hernandez ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Clinical Study ◽  
Nucleic Acid ◽  
Clinical Performance ◽  
Nucleic Acid Amplification ◽  
Standard Approach ◽  
Limits Of Detection ◽  
Percent Agreement ◽  
Post Market ◽  
Roche Cobas

Background Nucleic acid amplification testing (NAAT) for SARS-CoV-2 is the standard approach for confirming COVID-19 cases. This study compared results between two Emergency Use Authorization (EUA) NAATs, with two additional EUA NAATs utilized for discrepant testing. Methods The limits of detection (LOD) for the BD SARS-CoV-2 Reagents for BD MAX™ System (“MAX SARS-CoV-2 assay”), the Biomerieux BioFire® Respiratory Panel 2.1 (“BioFire SARS-CoV-2 assay”), the Roche cobas SARS-CoV-2 assay (“cobas SARS-CoV-2 assay”), and the Hologic Aptima® SARS-CoV-2 assay Panther® (“Aptima SARS-CoV-2 assay”) NAAT systems were determined using a total of 84 contrived nasopharyngeal specimens with seven target levels for each comparator. The positive and negative percent agreement (PPA and NPA, respectively) of the MAX SARS-CoV-2 assay, compared to the Aptima SARS-CoV-2 assay, was evaluated in a post-market clinical study utilizing 708 nasopharyngeal specimens collected from suspected COVID-19 cases. Discordant testing was achieved using cobas and BioFire SARS-CoV-2 NAATs. Results In this study, the measured LOD for the MAX SARS-CoV-2 assay (251 copies/mL; [95%CI: 186, 427]) was comparable to the cobas SARS-CoV-2 assay (298 copies/mL; [95%CI: 225, 509]) and the BioFire SARS-CoV-2 assay (302 copies/mL; [95%CI: 219, 565]); the Aptima SARS-CoV-2 assay had a LOD of 612 copies/mL; [95%CI: 474, 918]. The MAX SARS-CoV-2 assay had a PPA of 100% (95%CI: [97.3%-100.0%]) and a NPA of 96.7% (95%CI: [94.9%-97.9%]) when compared to the Aptima SARS-CoV-2 assay. Conclusions The clinical performance of the MAX SARS-CoV-2 assay agreed with another sensitive EUA assay.

scholarly journals Increased Clinical Specificity with Ultrasensitive Detection of Clostridioides difficile Toxins: Reduction of Overdiagnosis Compared to Nucleic Acid Amplification Tests

2019 ◽  
Vol 57 (11) ◽  
Author(s):  
Johanna Sandlund ◽  
Joel Estis ◽  
Phoebe Katzenbach ◽  
Niamh Nolan ◽  
Kirstie Hinson ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Patient Outcomes ◽  
Single Molecule ◽  
Clinical Performance ◽  
Neutralization Assay ◽  
Nucleic Acid Amplification ◽  
Content Type ◽  
Clostridioides Difficile ◽  
Health Care Associated Infections ◽  
Stool Specimens

ABSTRACT Clostridioides difficile infection (CDI) is one of the most common health care-associated infections, resulting in significant morbidity, mortality, and economic burden. Diagnosis of CDI relies on the assessment of clinical presentation and laboratory tests. We evaluated the clinical performance of ultrasensitive single-molecule counting technology for detection of C. difficile toxins A and B. Stool specimens from 298 patients with suspected CDI were tested with the nucleic acid amplification test (NAAT; BD MAX Cdiff assay or Xpert C. difficile assay) and Singulex Clarity C. diff toxins A/B assay. Specimens with discordant results were tested with the cell cytotoxicity neutralization assay (CCNA), and the results were correlated with disease severity and outcome. There were 64 NAAT-positive and 234 NAAT-negative samples. Of the 32 NAAT+/Clarity− and 4 NAAT−/Clarity+ samples, there were 26 CCNA− and 4 CCNA− samples, respectively. CDI relapse was more common in NAAT+/toxin+ patients than in NAAT+/toxin− and NAAT−/toxin− patients. The clinical specificity of Clarity and NAAT was 97.4% and 89.0%, respectively, and overdiagnosis was more than three times more common in NAAT+/toxin− than in NAAT+/toxin+ patients. The Clarity assay was superior to NAATs for the diagnosis of CDI, by reducing overdiagnosis and thereby increasing clinical specificity, and the presence of toxins was associated with negative patient outcomes.

scholarly journals Commercial Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Molecular Assays: Superior Analytical Sensitivity of cobas SARS-CoV-2 Relative to NxTAG CoV Extended Panel and ID NOW COVID-19 Test

2020 ◽  
Vol 144 (11) ◽  
pp. 1303-1310 ◽  
Author(s):  
Run Jin ◽  
Matthew A. Pettengill ◽  
Nicole L. Hartnett ◽  
Herbert E. Auerbach ◽  
Stephen C. Peiper ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Nucleic Acid Amplification ◽  
Analytical Sensitivity ◽  
E Gene ◽  
Molecular Assays ◽  
Performance Variation ◽  
Wide Range ◽  
Reliable Detection ◽  
Testing Algorithms ◽  
Low Levels

Context.— We implemented multiple nucleic acid amplification test platforms because of the limited availability of test kits for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the early stages of the pandemic. Interpretation of results generated by different platforms and prioritization for testing algorithms required cross-comparison. Objective.— To compare the analytical sensitivity of 3 commercial SARS-CoV-2 molecular assays, selected samples were studied in parallel with Cobas SARS-CoV-2 test, NxTAG CoV Extended Panel, and ID NOW COVID-19 assays. Design.— A total of 8043 SARS-CoV-2 tests performed from March 22 to April 19, 2020, were included in this study. For all 1794 positive specimens detected by the cobas SARS-CoV-2 assay, the cycle threshold (Ct) values were manually tracked and plotted to demonstrate the distribution of sample viral levels. Additionally, 50 and 63 low-positive specimens (Ct values >32) as well as 50 and 61 consecutive positive specimens by the cobas assay were tested with NxTAG and ID NOW, respectively, to estimate their relative sensitivities. Results.— The Ct values of cobas SARS-CoV-2–positive samples were evenly distributed throughout ranges of 13.32 to 39.50 (mean, 25.06) and 13.60 to 42.49 (mean, 26.45) for ORF1 and E gene targets, respectively. NxTAG reliably detected only specimens with E gene Ct values lower than 33, and is estimated to detect 89.4% of positive specimens detected by cobas assay. ID NOW had performance variation independent of Ct value and is estimated to detect 83.5% of cobas positives. Conclusions.— Clinical specimens exhibit a wide range of viral burden, with a significant portion at low levels. Analytical sensitivity of testing platforms is critical for reliable detection of SARS-CoV-2 and uniform care to patients.

scholarly journals Comparison of the ID Now Influenza A & B 2, Cobas Influenza A/B, and Xpert Xpress Flu Point-of-Care Nucleic Acid Amplification Tests for Influenza A/B Virus Detection in Children

2020 ◽  
Vol 58 (3) ◽  
Author(s):  
Neena Kanwar ◽  
Jeffrey Michael ◽  
Kathryn Doran ◽  
Emily Montgomery ◽  
Rangaraj Selvarangan
Keyword(s):  
Nucleic Acid ◽  
Influenza A ◽  
Point Of Care ◽  
Virus Detection ◽  
Reference Method ◽  
Nucleic Acid Amplification ◽  
Molecular Assays ◽  
B Virus ◽  
Flu Virus ◽  
Xpert Assay

ABSTRACT Early diagnosis of influenza (Flu) is critical for patient management and infection control. The ID Now influenza A & B 2 (ID Now) assay (Abbott Laboratories), Cobas influenza A/B nucleic acid test (LIAT; Roche Molecular Systems, Inc.), and Xpert Xpress Flu (Xpert; Cepheid) are rapid, point-of-care molecular assays for Flu virus detection. The study aim was to compare the performances of these three commercially available Clinical Laboratory Improvement Amendments (CLIA)-waived Flu virus assays. We prospectively enrolled 201 children <18 years old from January to April 2018 and collected nasopharyngeal swab specimens in viral medium. Aliquots were frozen for testing on different diagnostic platforms, as per the manufacturers’ instructions. CDC Flu A/B PCR was used as a reference method to evaluate the performances of these three platforms. Among the 201 specimens tested, the CDC Flu A/B PCR assay detected Flu A/B virus in 107 samples (Flu A virus, 73 samples; Flu B virus, 36 samples; dual Flu A/B virus positive, 2 samples), while the ID Now virus detected 102 samples (Flu A virus, 69 samples; Flu B virus, 37 samples; dual Flu A/B virus positive, 4 samples; invalid rate, 1/201 [0.5%]), the LIAT detected 112 samples (Flu A virus, 74 samples; Flu B virus, 38 samples; invalid rate, 11/201 [5.5%]), and the Xpert assay detected 112 samples (Flu A virus, 76 samples; Flu B virus, 36 samples; invalid rate, 6/201 [3.0%]). The overall sensitivities for the ID Now assay, LIAT, and Xpert assay for Flu A virus detection (93.2%, 100%, and 100%, respectively) and Flu B virus detection (97.2%, 94.4%, and 91.7%, respectively) were comparable. The specificity for Flu A and B virus detection by all methods was >97%. These molecular assays had higher sensitivity than did a historical standard-of-care test from the BD Veritor antigen test (Flu A virus, 79.5%; Flu B virus, 66.7%).

scholarly journals Performance of the BinaxNOW COVID-19 Antigen Rapid Diagnostic Test for the Detection of SARS-CoV-2

2021 ◽  
Author(s):  
Fernando A Ocampo Gonzalez ◽  
Nicholas M Moore
Keyword(s):  
Nucleic Acid ◽  
Diagnostic Tests ◽  
Healthcare Workers ◽  
Turnaround Time ◽  
Rapid Diagnostic Tests ◽  
Nucleic Acid Amplification ◽  
Substantial Agreement ◽  
Cycle Number ◽  
Percent Agreement ◽  
Κ Statistic

Abstract Background: Diagnosis of COVID-19 disease primarily relies on nucleic acid amplification tests (NAAT) that amplify and detect viral RNA in specimens. These methods are expensive and time consuming. Antigen-based rapid diagnostic tests can substantially decrease turnaround time.Methods: We analyzed paired anterior nares swabs collected from symptomatic patients and asymptomatic healthcare workers being tested COVID-19. One swab was used for a direct RDT and the results were compared to NAAT.Results: 89 paired specimens were evaluated. The positive percent agreement (PPA) for the antigen RDT was 68.2%, and the negative percent agreement (NPA) was 98.5%. Despite a low PPA, the Κ statistic was 0.733 indicating substantial agreement with the NAAT result. The median cycle number in paired specimens with concordant results was significantly lower than in discordant specimens (21.3 versus 32.3; P=0.003).Conclusions: The RDT showed modest PPA and high NPA when compared to NAAT. The quick TAT and use of an inexpensive test more frequently could be useful in settings in which results from NAAT testing is delayed.

scholarly journals Performance Evaluation of the SAMBA II SARS-CoV-2 Test for Point-of-Care Detection of SARS-CoV-2

2020 ◽  
Vol 59 (1) ◽  
pp. e01262-20 ◽  
Author(s):  
Sonny M. Assennato ◽  
Allyson V. Ritchie ◽  
Cesar Nadala ◽  
Neha Goel ◽  
Cuijuan Tie ◽  
...  
Keyword(s):  
Public Health ◽  
Infection Control ◽  
Patient Management ◽  
Clinical Performance ◽  
Point Of Care ◽  
Turnaround Time ◽  
Control Measures ◽  
Nucleic Acid Amplification ◽  
Analytical Sensitivity ◽  
Percent Agreement

ABSTRACTNucleic acid amplification for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in respiratory samples is the standard method for diagnosis. The majority of this testing is centralized and therefore has turnaround times of several days. Point-of-care (POC) testing with rapid turnaround times would allow more effective triage in settings where patient management and infection control decisions need to be made rapidly. The inclusivity and specificity of the Simple AMplification-Based Assay (SAMBA) II SARS-CoV-2 test were determined by both in silico analyses of the primers and probes and wet testing. The SAMBA II SARS-CoV-2 test was evaluated for performance characteristics. Clinical performance was evaluated in residual combined throat/nose swabs and compared to that of the Public Health England real-time PCR assay targeting the RdRp gene. The SAMBA II SARS-CoV-2 test has an analytical sensitivity of 250 copies/ml for detecting two regions of the genome (open reading frame 1ab [ORF1ab] and nucleocapsid protein [N]). The clinical performance was evaluated in 172 residual combined nose/throat swabs provided by the Clinical Microbiology and Public Health Laboratory, Addenbrooke’s Hospital, Cambridge (CMPHL), which showed an estimated positive percent agreement of 98.9% (95% confidence interval [CI], 93.83 to 99.97) and negative percent agreement of 96.4% (95% CI, 89.92 to 99.26) compared to testing by the CMPHL. The data show that the SAMBA II SARS-CoV-2 test performs equivalently to the centralized testing methods, but with a shorter turnaround time of 86 to 101 min. Point-of-care tests such as SAMBA should enable rapid patient management and effective implementation of infection control measures.

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