A prospective evaluation of the analytical performance of GENECUBE® HQ SARS-CoV-2 and GENECUBE® FLU A/B

BackgroundMolecular tests are the mainstay for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, their accessibility can be limited by the long examination time and inability to evaluate multiple samples at once. This study evaluated the analytical performance of the newly developed rapid molecular assays GENECUBE® HQ SARS-CoV-2 and the GENECUBE® FLU A/B.MethodThis prospective study was conducted between December 14, 2020, and January 9, 2021, at a polymerase chain reaction (PCR) center. Samples were collected from the nasopharynx with flocked swabs. Molecular tests were performed with the GENECUBE® system and reference reverse transcription (RT)-PCR, and the results of the two assays were compared.ResultAmong 1065 samples, 81 (7.6%) were positive for SARS-CoV-2 on the reference RT-PCR. Three showed discordance between GENECUBE® HQ SARS-CoV-2 and the reference RT-PCR; the total, positive and negative samples of concordance for the two assays were 99.7%, 100%, and 99.7%, respectively. All discordant cases were positive for GENECUBE® HQ SARS-CoV-2 and negative for the reference RT-PCR. SARS-CoV-2 was detected from all three samples by another molecular assay for SARS-CoV-2. For the GENECUBE® FLU A/B, the total, positive and negative samples of concordance for the two assays were 99.5%, 100%, and 99.1%.ConclusionThe GENECUBE® HQ SARS-CoV-2 and GENECUBE® FLU A/B demonstrated sufficient analytical performance to detect SARS-CoV-2 and influenza virus A/B.Key pointsWe prospectively evaluated the analytical performance of the newly developed rapid molecular assays GENECUBE® HQ SARS-CoV-2 and the GENECUBE® FLU A/B. The two assays showed >99% concordance rate compared with a reference PCR, which indicated their sufficient analytical performance to detect SARS-CoV-2 and influenza virus A/B.

Improved determination of Neisseria gonorrhoeae gyrase A genotype results in clinical specimens

Background The emergence of drug-resistant Neisseria gonorrhoeae has prompted the development of rapid molecular assays designed to determine antimicrobial susceptibility. One common assay uses high-resolution melt analysis to target codon 91 of the gyrase A gene (gyrA) to predict N. gonorrhoeae susceptibility to ciprofloxacin. Methods We extracted DNA from remnant clinical specimens that had previously tested positive for N. gonorrhoeae using the Aptima Combo 2 for CT/NG assay (Hologic, San Diego, CA, USA). We selected DNA extracts from specimens with indeterminate, WT and mutant gyrA genotype results from a previous study using high-resolution melt analysis to detect the gyrA codon 91 mutation. We re-tested those specimens using the recently CE-marked ResistancePlus GC (beta) assay (SpeeDx, Sydney, Australia). Results Of 86 specimens with indeterminate gyrA genotypes on high-resolution melt analysis, the ResistancePlus GC (beta) assay (SpeeDx) identified 30 (35%) WT, 22 (26%) mutant and 34 (40%) indeterminate gyrA genotypes. Conclusions The ResistancePlus GC (beta) assay showed improved N. gonorrhoeae gyrA genotype determination compared with a prior gyrA genotypic high-resolution melt assay.

Differentiation of infectious bronchitis virus vaccine strains Ma5 and 4/91 by TaqMan real-time PCR

The aim of this study was to develop rapid molecular assays for differentiating vaccine strains Ma5 and 4/91 of the infectious bronchitis virus (IBV). Specific primers and probes for S1 and N genes were designed based on the nucleotide sequences of both vaccine strains. Cross-reactivity was not observed. Assay sensitivity was 2.373 × 103 copies of the Ma5 strain, and 3.852 x 103 copies of the 4/91 strain. Samples belonging to a known genotype demonstrated that the designed assays supported rapid and sensitive detection of Ma5 and 4/91 vaccine strains of IBV.

Infectious Diseases (ID) Learning Unit: How Rapidly to Evaluate for Active Tuberculosis Disease in Low-Prevalence Settings

With declining tuberculosis (TB) incidence in low-prevalence settings, many clinicians are likely unaware that the approach to diagnosing active TB is evolving with newer technologies. Rapid molecular assays are commercially available, and more are likely to enter the market in the coming years. These tests, such as the Xpert MTB/RIF, which can detect TB and drug-resistance in 2 hours, are increasingly used in settings with higher TB prevalence; however, uptake has been slower in low-prevalence settings. Newer algorithms incorporating rapid TB diagnostics have the ability to alter current clinical and infection control practice patterns. In this learning unit, we review current and newly available tests for the detection of active TB disease and their usage in low-prevalence settings.