ABSTRACT
BackgroundThe RT-qPCR assay for detecting SARS-CoV-2 virus is the favorable approach to test suspected COVID-19 cases. However, discordant results can occur when two or more assays are compared. Variability in analytical sensitivities between assays, among other factors, may account for these differences in reporting. MethodsThe limits of detection (LOD) for the BD SARS-CoV-2 Reagents for BD MAX System ("MAX SARS-CoV-2 assay"), the Biomerieux BioFire(R) 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(R) SARS-CoV-2 assay Panther(R) ("Aptima SARS-CoV-2 assay") RT-qPCR 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) for the MAX SARS-CoV-2 assay were compared to the Aptima SARS-CoV-2 assay in a post-market clinical study utilizing 708 paired nasopharyngeal specimens collected from suspected COVID-19 cases. Discordant results were further tested by the cobas and BioFire SARS-CoV-2 assays. ResultsThe measured LOD for the MAX SARS-CoV-2 assay (251 copies/mL) was comparable to the cobas SARS-CoV-2 assay (298 copies/mL) and the BioFire SARS-CoV-2 assay (302 copies/mL); the Aptima SARS-CoV-2 assay had a LOD of 612 copies/mL. 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. ConclusionsThe MAX SARS-CoV-2 assay exhibited a high analytical sensitivity and specificity for SARS-CoV-2 detection. The clinical performance of the MAX SARS-CoV-2 assay agreed with another sensitive EUA cleared assay.
ABSTRACT
Efficient and accurate assays for the differential diagnosis of COVID-19 and/or influenza (flu) could facilitate optimal treatment for both diseases. Diagnostic performance related to SARS-CoV-2 and Flu A/B detection was characterized for the BD SARS-CoV-2/Flu for BD MAX System ("MAX SARS-CoV-2/Flu") multiplex assay in comparison with BD BioGx SARS-CoV-2 Reagents for BD MAX System ("BioGx SARS-CoV-2") and the Cepheid Xpert(R) Xpress Flu/RSV ("Xpert Flu"). Two hundred and thirty-five nasopharyngeal specimens were obtained from external vendors. MAX SARS-CoV-2/Flu had positive percent agreement (PPA) and negative percent agreement (NPA) values for SARS-CoV-2 and Flu A/B that met FDA-EUA acceptance criteria of >95%.
ABSTRACT
BackgroundThe LumiraDx SARS-CoV-2 antigen test, which uses a high-sensitivity, microfluidic immunoassay to detect the nucleocapsid protein of SARS-CoV-2, was evaluated for diagnosing acute COVID-19 in adults and children across point-of-care settings. MethodsTwo paired anterior nasal swabs or two paired nasopharyngeal swabs were collected from each participant. Swabs were tested by the LumiraDx SARS-CoV-2 antigen test and compared with real-time PCR (rt-PCR; Roche cobas 6800 platform). Positive- and negative predictive values and likelihood ratios were calculated. Results stratified based on gender, age, duration of symptoms, and rt-PCR cycle threshold. ResultsOut of the 512 participants, aged 0-90 years, of this prospective validation study, 414 (81%) were symptomatic for COVID-19 and 123 (24%) swabs were positive for SARS-CoV-2 based on rt-PCR testing. Compared with rt-PCR, the 12-minute swab test had 97.6% sensitivity and 96.6% specificity within 12 days of symptom onset, representing the period of infectivity. All (100%) samples detected within 33 rt-PCR cycles were also identified using the antigen test. Results were consistent across age and gender. Despite being performed by minimally trained healthcare workers, the user error rate of the test system was 1%. ConclusionThe rapid high-sensitivity assay using nasopharyngeal or anterior nasal sampling may offer significant improvements for diagnosing acute SARS-CoV-2 infection in clinic- and community-based settings. SummaryA 12-minute nasal swab test detects 97.6% of COVID-19 infections, compared to gold standard real-time PCR testing, up to 12 days following symptom onset using a microfluidic immunoassay for SARS-CoV-2 nucleocapsid protein.
ABSTRACT
ObjectivesThe clinical performance of the BD Veritor System for Rapid Detection of SARS-CoV-2 antigen (Veritor), a chromatographic immunoassay that detects the SARS-CoV-2 nucleocapsid antigen as a point-of-care test, was evaluated on nasal specimens from individuals with COVID-19 symptoms. Methods and MaterialsTwo studies were completed to determine clinical performance. In the first study, nasal specimens and either nasopharyngeal or oropharyngeal specimens from 251 participants with COVID-19 symptoms ([≤]7 days from symptom onset [DSO]), [≥]18 years of age, were utilized to compare Veritor with the Lyra(R) SARS-CoV-2 PCR Assay (Lyra). In the second study, nasal specimens from 361 participants with COVID-19 symptoms ([≤]5 DSO), [≥]18 years of age, were utilized to compare performance of Veritor to that of the Sofia(R) 2 SARS Antigen FIA test (Sofia 2). Positive, negative, and overall percent agreement (PPA, NPA, and OPA, respectively) were the primary outcomes. ResultsIn study 1, PPA for Veritor, compared to Lyra, ranged from 81.8%-87.5% for 0-1 through 0-6 DSO ranges. In study 2, Veritor had a PPA, NPA, and OPA of 97.4%, 98.1%, and 98.1%, respectively, with Sofia 2. Discordant analysis showed one Lyra positive missed by Veritor and five Lyra positives missed by Sofia 2; one Veritor positive result was negative by Lyra. ConclusionsVeritor met FDA-EUA acceptance criteria for SARS-CoV-2 antigen testing ([≥]80% PPA point estimate) for the 0-5 and 0-6 DSO ranges. Veritor and Sofia 2 showed a high degree of agreement for SARS-CoV-2 detection. The Veritor test should facilitate rapid and reliable results for COVID-19 diagnosis utilizing easy-to-collect nasal swabs. SummaryThe BD Veritor SARS-CoV-2 antigen test met FDA-EUA acceptance criteria for SARS-CoV-2 antigen testing for subjects with COVID-19 symptoms (0-5 days post-onset). BD Veritor and Quidel Sofia 2 antigen tests had good agreement for SARS-CoV-2 detection; discordant analysis favored Veritor.
ABSTRACT
BACKGROUND: The application of image analysis technologies for the interpretation of microbiological cultures is evolving rapidly. The primary aim of this study was to establish whether the image analysis system named Automated Plate Assessment System (APAS; LBT Innovations Ltd., Australia) could be applied to screen urine cultures. A secondary aim was to evaluate differences between traditional plate reading (TPR) and the reading of cultures from images, or digital plate reading (DPR). METHODS: A total of 9,224 urine samples submitted for culture to three clinical laboratories, two in Australia and one in the USA, were included in the study. Cultures were prepared on sheep blood and MacConkey agar plates and read by panels of three microbiologists. The plates were then presented to APAS for image capture and analysis, and the images and results were stored for later review. RESULTS: Image analysis of cultures using APAS produced a diagnostic sensitivity and specificity of 99.0% and 84.5%, respectively. Colonies were detected by APAS on 99.0% of blood agar plates with growth and on 99.5% of MacConkey agar plates. DPR agreed with TPR for colony enumeration on 92.1% of the plates, with a sensitivity of 90.8% and specificity of 92.8% for case designation. However, several differences in the classification of colony morphologies using DPR were identified. CONCLUSIONS: APAS was shown to be a reliable screening system for urine cultures. The study also showed acceptable concordance between DPR and TPR for colony detection, enumeration, and case designation.
