Rapid and Safe Detection of SARS-CoV-2 and Influenza Virus RNA using Onsite qPCR Diagnostic Testing from Clinical Specimens Collected in Molecular Transport Medium

Clinical performance of the Roche Cobas Liat SARS-CoV-2 & influenza A/B assay: A systematic review and meta-analysis

Respiratory tract infections caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza viruses are persistent and critical. The Cobas Liat SARS-CoV-2 & influenza A/B assay (Multiplex Liat), the FDA-authorized point-of-care reverse transcriptase polymerase chain reaction (RT-PCR) assay, has a turnaround time of 20 min and high accuracy. This study evaluates the pooled performance of this assay to provide practical information. This meta-analysis was registered in PROSPERO (registration number: CRD42023467579). A systematic literature search was conducted within PubMed, Ovid-EMBASE, and the Cochrane Library for articles evaluating the accuracy of the Multiplex Liat assay through September 2023. A random-effects model was used to calculate the pooled diagnostic values with real-time RT-PCR (rRT-PCR) as a reference test. A total of 4,705 samples from eight studies were included in the primary meta-analysis. The overall pooled sensitivity and specificity of Multiplex Liat were 100.0 % (95 % confidence interval [CI] = 96.7 %-100.0 %) and 99.7 % (95 % CI = 98.7 %-99.9 %), respectively. The presence of variants of concern or in-house rRT-PCR assays as reference standards did not significantly affect the pooled diagnostic performance of the Multiplex Liat. When 5,333 samples from nine studies were assessed for sensitivity, the pooled sensitivity was 100.0 % (95 % CI = 85.8 %-100.0 %) without a significant difference. This meta-analysis demonstrates the usefulness of Multiplex Liat for the detection of SARS-CoV-2 based on pooled diagnostic values. These practical findings may facilitate appropriate settings for the diagnosis and management of patients with respiratory tract infections.

Inactivation of highly transmissible livestock and avian viruses including influenza A and Newcastle disease virus for molecular diagnostics

There is a critical need for an inactivation method that completely inactivates pathogens at the time of sample collection while maintaining the nucleic acid quality required for diagnostic PCR testing. This inactivation method is required to alleviate concerns about transmission potential, minimize shipping complications and cost, and enable testing in lower containment laboratories, thereby enhancing disease diagnostics through improved turn-around time. This study evaluated a panel of 10 surrogate viruses that represent highly pathogenic animal diseases. These results showed that a commercial PrimeStore® molecular transport media (PSMTM) completely inactivated all viruses tested by >99.99%, as determined by infectivity and serial passage assays. However, the detection of viral nucleic acid by qRT-PCR was comparable in PSMTM and control-treated conditions. These results were consistent when viruses were evaluated in the presence of biological material such as sera and cloacal swabs to mimic diagnostic sample conditions for non-avian and avian viruses, respectively. The results of this study may be utilized by diagnostic testing laboratories for highly pathogenic agents affecting animal and human populations. These results may be used to revise guidance for select agent diagnostic testing and the shipment of infectious substances.

Simultaneous Detection of Infectious Diseases Using Aptamer-Conjugated Gold Nanoparticles in the Lateral Flow Immunoassay-Based Signal Amplification Platform

Various platforms for the accurate diagnosis of infectious diseases have been studied because of the emergence of coronavirus disease (COVID-19) in 2019. Recently, it has become difficult to distinguish viruses with similar symptoms due to the continuous mutation of viruses, and there is an increasing need for a diagnostic method to detect them simultaneously. Therefore, we developed a paper-based rapid antigen diagnostic test using DNA aptamers for the simultaneous detection of influenza A, influenza B, and COVID-19. Aptamers specific for each target viral antigen were selected and attached to AuNPs for application in a rapid antigen diagnosis kit using our company's heterogeneous sandwich-type aptamer screening method (H-SELEX). We confirmed that the three viruses could be detected on the same membrane without cross-reactivity based on the high stability, specificity, and binding affinity of the selected aptamers. Further, the limit of detection was 2.89 pg·mL-1 when applied to develop signal amplification technology; each virus antigen was detected successfully in diluted nasopharyngeal samples. We believe that the developed simultaneous diagnostic kit, based on such high accuracy, can distinguish various infectious diseases, thereby increasing the therapeutic effect and contributing to the clinical field.

Use of stool swabs in molecular transport media increases access to Xpert Ultra testing for TB in children

SETTING: Tertiary level hospital in Lusaka, Zambia.OBJECTIVE: To measure concordance between Xpert® MTB/RIF Ultra (Ultra) results of stool with and without transport media, and compare Ultra results from the two stool processing methods to Ultra and culture results using gastric aspirates (GA).DESIGN: This was a cross-sectional study collecting stool and GA from children 0-5 years presenting with signs and symptoms of TB. Stool was processed for Ultra testing by two methods: the Simple-One-Step (SOS) on an aliquot of stool and PrimeStore® MTM Molecular Transport Medium (PS-MTM) using a stool swab.RESULTS: A total of 114 children (median age: 17 months, IQR 7-30) provided both a stool and a GA sample. Stool Ultra results processed using the PS-MTM method showed high concordance with stool Ultra results processed by the SOS method, with only 1/114 discordant results. Concordance with GA Ultra was high as well, as 9/13 Mycobacterium tuberculosis (MTB) cases detected were identified by all three methods.CONCLUSION: Ultra results from stool swabs collected using PS-MTM were equivalent to results from stool using the SOS method and GA. Given that PS-MTM inactivates MTB and stabilises DNA without cold chain, using it for stool has the potential to increase access to a TB diagnosis for children in underserved areas.

Point of care molecular and antigen detection tests for COVID-19: current status and future prospects

INTRODUCTION

Detection of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has been critical to support and management of the COVID-19 pandemic. Point of care testing (POCT) for SARS-CoV-2 has been a widely used tool for detection of SARS-CoV-2.

AREAS COVERED

POCT nucleic acid amplification tests (NAATs) and rapid antigen tests (RATs) have been the most readily used POCT for SARS-CoV-2. Here, current knowledge on the utility of POCT NAATs and RATs for SARS-CoV-2 are reviewed and discussed alongside aspects of quality assurance factors that must be considered for successful and safe implementation of POCT.

EXPERT OPINION

Use cases for implementation of POCT must be evidence based, regardless of the test used. A quality assurance framework must be in place to ensure accuracy and safety of POCT.

FDA authorized molecular point-of-care SARS-CoV-2 tests: A critical review on principles, systems and clinical performances

Since the start of the COVID-19 pandemic, 10 manufacturers of molecular tests for SARS-CoV-2 have received Emergency Use Authorizations from the U.S. Food and Drug Administration for point-of-care or over the counter use. In this review, the working principle of these tests is described as well as the relevant characteristics (e.g. time-to-result and specimen type). The analytical (e.g. analytical sensitivity) and clinical performance (positive and negative percent agreement) and useability characteristics (e.g. cost, reusability and throughput) of these tests are compared and critically reviewed. Also details for relevant respiratory multiplex assays of these 10 manufacturers are discussed. Critical review of scientific literature on these authorized tests revealed that for many of these tests publications are almost or completely absent, with the exception of two systems. The Xpert Xpress has been thoroughly investigated and good performance has been reported, whereas ID NOW is also well-represented in literature, but has relatively low sensitivity.

SARS-CoV-2 screening in patients in need of urgent inpatient treatment in the Emergency Department (ED) by digitally integrated point-of-care PCR: A clinical cohort study

Patients in need of urgent inpatient treatment were recruited prospectively. A rapid point of care polymerase chain reaction test (POC-PCR; Liat®) for SARS-CoV2 was conducted in the Emergency Department (ED) and a second PCR-test from the same swab was ordered in the central laboratory (PCR). POC-PCR analyzers were digitally integrated in the laboratory information system.

Overall, 160 ED patients were included. A valid POC-PCR-test result was available in 96.3% (n = 154) of patients. N = 16 patients tested positive for Severe Acute Respiratory Syndrome-Corona Virus 2 (10.0%). The POC PCR test results were available within 102 minutes (median, interquartile range: 56–211), which was significantly earlier compared to the central laboratory PCR (811 minutes; interquartile range: 533–1289, P < 0.001). The diagnostic accuracy of the POC-PCR test was 100%. The implementation and digital laboratory information system integration was successfully done. Staff satisfaction with the POC process was high.

The POC-PCR testing in the ED is feasible and shows a very high diagnostic performance.

Trial registration: DRKS00019207