Comparative evaluation of the Thermo fisher TaqPath™ COVID-19 combo kit with the Cepheid Xpert® Xpress SARS-CoV-2 assay for detecting SARS-CoV-2 in nasopharyngeal specimens.

PURPOSE: With over 50 SARS-CoV-2 gene amplification assays that have been EUA cleared with minimal experimental validation performed, it is likely that not all of these assays are comparable in their ability to detect SARS-CoV-2 in clinical specimens. Thermo Fisher Scientific is a relatively new company in the molecular diagnostics field and the purpose of this study was to compare the performance of the Thermo Fisher TaqPath™ Combo Kit with an established test, the Cepheid Xpert® Xpress SARS-CoV-2 assay, for its ability to detect SARS-CoV-2 in nasopharyngeal specimens. METHODS: A total of 300 randomly selected nasopharyngeal specimens were evaluated and tested by the TaqPath and GeneXpert assays. Discordant test specimens were arbitrated by performing an alternative PCR assay and Sanger sequencing. RESULTS: The TaqPath assay had a 96.7 and 99.6% positive and negative agreement respectively when compared to the Xpert Xpress test. However, after test arbitration, the three discordant specimens were arbitrated in favor of the TaqPath assay producing a positive and negative percent agreement of 100% for the TaqPath Combo Kit while the Xpress SARS-CoV-2 assay had a positive and negative percent agreement of 98.3 and 99.2% respectively. CONCLUSIONS: The TaqPath Combo Kit is a high complexity assay that compares favorably with the Xpert Xpress test and can be reliably used for the detection of SARS-CoV-2 in nasopharyngeal specimens.

Clinical Evaluation of the iCubate iC-GPC Assay for Detection of Gram-Positive Bacteria and Resistance Markers from Positive Blood Cultures.

The iC-GPC Assay (iCubate, Huntsville, AL) is a qualitative multiplex test for the detection of five of the most common Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Enterococcus faecalis, and Enterococcus faecium) responsible for bacterial bloodstream infections, performed directly from positive blood cultures. The assay also detects the presence of the mecA, vanA, and vanB resistance determinants. This study comparatively evaluated the performance of the iC-GPC Assay against the Verigene Gram-positive blood culture (BC-GP) assay (Luminex Corp., Austin, TX) for 1,134 patient blood culture specimens positive for Gram-positive cocci. The iC-GPC Assay had an overall percent agreement with the BC-GP assay of 95.5%. Discordant specimens were further analyzed by PCR and a bidirectional sequencing method. The results indicate that the iC-GPC Assay together with the iCubate system is an accurate and reliable tool for the detection of the five most common Gram-positive bacteria and their resistance markers responsible for bloodstream infections.