scholarly journals Implementation of an efficient SARS-CoV-2 specimen pooling strategy for high throughput diagnostic testing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lavanya Singh ◽  
Ugochukwu J. Anyaneji ◽  
Wilfred Ndifon ◽  
Neil Turok ◽  
Stacey A. Mattison ◽  
...  
Keyword(s):  
Diagnostic Testing ◽  
Professional Sports ◽  
Rapid Identification ◽  
Rt Pcr ◽  
Assay Sensitivity ◽  
Sports Team ◽  
Sample Pooling ◽  
Pooling Strategies ◽  
Frequent Testing ◽  
Liquid Handling Robot

AbstractThe rapid identification and isolation of infected individuals remains a key strategy for controlling the spread of SARS-CoV-2. Frequent testing of populations to detect infection early in asymptomatic or presymptomatic individuals can be a powerful tool for intercepting transmission, especially when the viral prevalence is low. However, RT-PCR testing—the gold standard of SARS-CoV-2 diagnosis—is expensive, making regular testing of every individual unfeasible. Sample pooling is one approach to lowering costs. By combining samples and testing them in groups the number of tests required is reduced, substantially lowering costs. Here we report on the implementation of pooling strategies using 3-d and 4-d hypercubes to test a professional sports team in South Africa. We have shown that infected samples can be reliably detected in groups of 27 and 81, with minimal loss of assay sensitivity for samples with individual Ct values of up to 32. We report on the automation of sample pooling, using a liquid-handling robot and an automated web interface to identify positive samples. We conclude that hypercube pooling allows for the reliable RT-PCR detection of SARS-CoV-2 infection, at significantly lower costs than lateral flow antigen (LFA) tests.

scholarly journals Implementation of an efficient SARS-CoV-2 specimen pooling strategy for high throughput diagnostic testing

2021 ◽  
Author(s):  
Lavanya Singh ◽  
Ugochukwu J. Anyaneji ◽  
Wilfred Ndifon ◽  
Neil Turok ◽  
Stacey A. Mattison ◽  
...  
Keyword(s):  
Diagnostic Testing ◽  
Professional Sports ◽  
Rapid Identification ◽  
Rt Pcr ◽  
Assay Sensitivity ◽  
Sports Team ◽  
Sample Pooling ◽  
Pooling Strategies ◽  
Frequent Testing ◽  
Liquid Handling Robot

Abstract The rapid identification and isolation of infected individuals remains a key strategy for controlling the spread of SARS-CoV-2. Frequent testing of populations to detect infection early in asymptomatic or presymptomatic individuals can be a powerful tool for intercepting transmission, especially when the viral prevalence is low. However, RT-PCR testing – the gold standard of SARS-CoV-2 diagnosis – is expensive, making regular testing of every individual unfeasible. Sample pooling is one approach to lowering costs. By combining samples and testing them in groups the number of tests required is reduced, substantially lowering costs. Here we report on the implementation of pooling strategies using 3-d and 4-d hypercubes to test a professional sports team in South Africa. We have shown that infected samples can be reliably detected in groups of 27 and 81, with minimal loss of assay sensitivity for samples with individual Ct values up to 32. We report on automation of sample pooling, using a liquid-handling robot and an automated web interface to identify positive samples. We conclude that hypercube pooling allows for the reliable RT-PCR detection of SARS-CoV-2 infection, at significantly lower cost than lateral flow antigen (LFA) tests.

scholarly journals SalivaSTAT: Direct-PCR and pooling of saliva samples collected in healthcare and community setting for SARS-CoV-2 mass surveillance

2020 ◽  
Author(s):  
Nikhil S Sahajpal ◽  
Ashis K Mondal ◽  
Sudha Ananth ◽  
Allan Njau ◽  
Pankaj Ahluwali ◽  
...  
Keyword(s):  
Clinical Sample ◽  
Diagnostic Testing ◽  
Rna Extraction ◽  
Community Setting ◽  
Absolute Quantification ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Direct Pcr ◽  
Sample Pooling ◽  
Saliva Collection

BackgroundThe limitations of widespread current COVID-19 diagnostic testing lie at both pre-analytical and analytical stages. Collection of nasopharyngeal swabs is invasive and is associated with exposure risk, high cost, and supply-chain constraints. Additionally, the RNA extraction in the analytical stage is the most significant rate-limiting step in the entire testing process. To alleviate these limitations, we developed a universal saliva processing protocol (SalivaSTAT) that would enable an extraction free RT-PCR test using any of the commercially available RT-PCR kits.MethodsWe optimized saliva collection devices, heat-shock treatment and homogenization. The effect of homogenization on saliva samples for extraction-free RT-PCR assay was determined by evaluating samples with and without homogenization and preforming viscosity measurements. Saliva samples (872) previously tested using the FDA-EUA method were reevaluated with the optimized SalivaSTAT protocol using two widely available commercial RT-PCR kits. Further, a five-sample pooling strategy was evaluated as per FDA guidelines using the SalivaSTAT protocol.ResultsThe saliva collection (done without any media) performed comparable to the FDA-EUA method. The SalivaSTAT protocol was optimized by incubating saliva samples at 95°C for 30-minutes and homogenization, followed by RT-PCR assay. The clinical sample evaluation of 630 saliva samples using the SalivaSTAT protocol with PerkinElmer (600-samples) and CDC (30-samples) RT-PCR assay achieved positive (PPA) and negative percent agreement (NPA) of 95.8% and 100%, respectively. The LoD was established as ∼20-60 copies/ml by absolute quantification. Further, a five-sample pooling evaluation using 250 saliva samples achieved a PPA and NPA of 92% and 100%, respectively.ConclusionWe have optimized an extraction-free direct RT-PCR assay for saliva samples that demonstrated comparable performance to FDA-EUA assay (Extraction and RT-PCR). The SalivaSTAT protocol is a rapid, sensitive, and cost-effective method that can be adopted globally, and has the potential to meet testing needs and may play a significant role in management of the current pandemic.

scholarly journals SalivaSTAT: Direct-PCR and Pooling of Saliva Samples Collected in Healthcare and Community Setting for SARS-CoV-2 Mass Surveillance

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 904
Author(s):  
Nikhil S. Sahajpal ◽  
Ashis K. Mondal ◽  
Sudha Ananth ◽  
Allan Njau ◽  
Pankaj Ahluwalia ◽  
...  
Keyword(s):  
Clinical Sample ◽  
Diagnostic Testing ◽  
Community Setting ◽  
Absolute Quantification ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Direct Pcr ◽  
Comparable Performance ◽  
Sample Pooling ◽  
Saliva Collection

Objectives: Limitations of widespread current COVID-19 diagnostic testing exist in both the pre-analytical and analytical stages. To alleviate these limitations, we developed a universal saliva processing protocol (SalivaSTAT) that would enable an extraction-free RT-PCR test using commercially available RT-PCR kits. Methods: We optimized saliva collection devices, heat-shock treatment, and homogenization. Saliva samples (879) previously tested using the FDA-EUA method were reevaluated with the optimized SalivaSTAT protocol using two widely available commercial RT-PCR kits. A five-sample pooling strategy was evaluated as per FDA guidelines. Results: Saliva collection (done without any media) showed performance comparable to that of the FDA-EUA method. The SalivaSTAT protocol was optimized by incubating saliva samples at 95 °C for 30-min and homogenization, followed by RT-PCR assay. The clinical sample evaluation of 630 saliva samples using the SalivaSTAT protocol with PerkinElmer (600-samples) and CDC (30-samples) RT-PCR assay achieved positive (PPA) and negative percent agreements (NPAs) of 95.0% and 100%, respectively. The LoD was established as ~60–180 copies/mL by absolute quantification. Furthermore, a five-sample-pooling evaluation using 250 saliva samples achieved a PPA and NPA of 92% and 100%, respectively. Conclusion: We have optimized an extraction-free RT-PCR assay for saliva samples that demonstrates comparable performance to FDA-EUA assay (Extraction and RT-PCR).

scholarly journals Agile design and development of a high throughput cobas® SARS-CoV-2 RT-PCR diagnostic test

2021 ◽  
Author(s):  
Chitra Manohar ◽  
Jingtao Sun ◽  
Peter Schlag ◽  
Chris Santini ◽  
Marcel Fontecha ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rapid Development ◽  
Diagnostic Testing ◽  
In Silico Analysis ◽  
Rt Pcr ◽  
Assay Sensitivity ◽  
Agile Design ◽  
Assay Design ◽  
Pcr Test ◽  
Dual Target

Diagnostic testing is essential for management of the COVID-19 pandemic. An agile assay design methodology, optimized for the cobas® 6800/8800 system, was used to develop a dual-target, qualitative SARS-CoV-2 RT-PCR test using commercially available reagents and existing sample processing and thermocycling profiles. The limit of detection was 0.004 to 0.007 TCID50/mL for USA-WA1/2020. Assay sensitivity was confirmed for SARS-CoV-2 variants Alpha, Beta, Gamma, Delta and Kappa. The coefficients of variation of the cycle threshold number (Ct) were between 1.1 and 2.2%. There was no difference in Ct using nasopharyngeal compared to oropharyngeal swabs in universal transport medium (UTM). A small increase in Ct was observed with specimens collected in cobas® PCR medium compared to UTM. In silico analysis indicated that the dual-target test is capable of detecting all >1,800,000 SARS-CoV-2 sequences in the GISAID database. Our agile assay design approach facilitated rapid development and deployment of this SARS-CoV-2 RT-PCR test.

scholarly journals Evaluation of sample pooling for screening of SARS CoV-2

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247767
Author(s):  
Andargachew Mulu ◽  
Dawit Hailu Alemayehu ◽  
Fekadu Alemu ◽  
Dessalegn Abeje Tefera ◽  
Sinknesh Wolde ◽  
...  
Keyword(s):  
Clinical Sample ◽  
Diagnostic Testing ◽  
Positive Sample ◽  
Clinical Samples ◽  
Global Public Health ◽  
Rt Pcr ◽  
Resource Saving ◽  
Public Health Importance ◽  
Ct Value ◽  
Sample Pooling

Background The coronavirus disease 2019 (COVID-19) pandemic has revealed the global public health importance of robust diagnostic testing. To overcome the challenge of nucleic acid (NA) extraction and testing kit availability, an efficient method is urgently needed. Objectives To establish an efficient, time and resource-saving and cost-effective methods, and to propose an ad hoc pooling approach for mass screening of SARS-CoV-2. Methods We evaluated pooling approach on both direct clinical and NA samples. The standard reverse transcriptase polymerase chain reaction (RT-PCR) test of the SARS CoV-2 was employed targeting the nucleocapsid (N) and open reading frame (ORF1ab) genomic region of the virus. The experimental pools were created using SARS CoV-2 positive clinical samples and extracted RNA spiked with up to 9 negative samples. For the direct clinical samples viral NA was extracted from each pool to a final extraction volume of 200μL, and subsequently both samples tested using the SARS CoV-2 RT-PCR assay. Results We found that a single positive sample can be amplified and detected in pools of up to 7 samples depending on the cycle threshold (Ct) value of the original sample, corresponding to high, and low SARS CoV-2 viral copies per reaction. However, to minimize false negativity of the assay with pooling strategies and with unknown false negativity rate of the assay under validation, we recommend pooling of 4/5 in 1 using the standard protocols of the assay, reagents and equipment. The predictive algorithm indicated a pooling ratio of 5 in 1 was expected to retain accuracy of the test irrespective of the Ct value samples spiked, and result in a 137% increase in testing efficiency. Conclusions The approaches showed its concept in easily customized and resource-saving manner and would allow expanding of current screening capacities and enable the expansion of detection in the community. We recommend clinical sample pooling of 4 or 5 in 1. However, we don’t advise pooling of clinical samples when disease prevalence is greater than 7%; particularly when sample size is large.

scholarly journals Efficient and Practical Sample Pooling for High-Throughput PCR Diagnosis of COVID-19

2020 ◽  
Author(s):  
Haran Shani-Narkiss ◽  
Omri David Gilday ◽  
Nadav Yayon ◽  
Itamar Daniel Landau
Keyword(s):  
High Throughput ◽  
Large Scale ◽  
Diagnostic Testing ◽  
Target Frequency ◽  
Public Health Agencies ◽  
Highly Efficient ◽  
Pcr Diagnosis ◽  
Sample Pooling ◽  
Pooling Strategies ◽  
Technical Advances

AbstractIn the global effort to combat the COVID-19 pandemic, governments and public health agencies are striving to rapidly increase the volume and rate of diagnostic testing. The most common form of testing today employs Polymerase Chain Reaction in order to identify the presence of viral RNA in individual patient samples one by one. This process has become one of the most significant bottlenecks to increased testing, especially due to reported shortages in the chemical reagents needed in the PCR reaction.Recent technical advances have enabled High-Throughput PCR, in which multiple samples are pooled into one tube. Such methods can be highly efficient, saving large amounts of time and reagents. However, their efficiency is highly dependent on the frequency of positive samples, which varies significantly across regions and even within regions as testing criterion and conditions change.Here, we present two possible optimized pooling strategies for diagnostic SARS-CoV-2 testing on large scales, both addressing dynamic conditions. In the first, we employ a simple information-theoretic heuristic to derive a highly efficient re-pooling protocol: an estimate of the target frequency determines the initial pool size, and any subsequent pools found positive are re-pooled at half-size and tested again. In the range of very rare target (<0.05), this approach can reduce the number of necessary tests dramatically, for example, achieving a reduction by a factor of 50 for a target frequency of 0.001. The second method is a simpler approach of optimized one-time pooling followed by individual tests on positive pools. We show that this approach is just as efficient for moderate target-product frequencies (0.05<0.2), for example, achieving a two-fold in the number of when the frequency of positive samples is 0.07.These strategies require little investment, and they offer a significant reduction in the amount of materials, equipment and time needed to test large numbers of samples. We show that both these pooling strategies are roughly comparable to the absolute upper-bound efficiency given by Shannon’s source coding theorem. We compare our strategies to the naïve way of testing and to alternative matrix-pooling methods. Most importantly, we offer straightforward, practical pooling instructions for laboratories that perform large scale PCR assays to diagnose SARS-CoV-2 viral particles. These two pooling strategies may offer ways to alleviate the bottleneck currently preventing massive expansion of SARS-CoV-2 testing around the world.

Molecular epidemiology of norovirus in Edinburgh healthcare facilities, Scotland 2007–2011

2012 ◽  
Vol 140 (12) ◽  
pp. 2273-2281 ◽  
Author(s):  
G. McALLISTER ◽  
A. HOLMES ◽  
L. GARCIA ◽  
F. CAMERON ◽  
K. CLOY ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Surveillance System ◽  
Diagnostic Testing ◽  
Temporal Distribution ◽  
Rapid Identification ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Predominant Genotype ◽  
Healthcare Facilities ◽  
Polymerase Chain

SUMMARYNorovirus (NoV) is a leading cause of outbreaks of gastroenteritis worldwide, and a major burden for healthcare facilities. This study investigated the NoV genotypes responsible for outbreaks in Edinburgh healthcare facilities between June 2008 and July 2011, and studied their temporal distribution to enable a better understanding of the epidemiology of the outbreaks. A total of 287 samples positive for NoV genogroup II (GII) RNA by reverse transcription–polymerase chain reaction (RT–PCR) during routine diagnostic testing were investigated. Nested RT–PCR (nRT–PCR) and sequencing was used to genotype the NoV strains. Overall, a total of 69 NoV strains belonging to six different genoclusters (GII.1, GII.2, GII.3, GII.4, GII.6, GII.13) were detected. The predominant genotype was GII.4 that included four variants, GII.4 2006a, GII.4 2006b, GII.4 2007 and GII.4 2010. Importantly, increases in NoV activity coincided with the emergence of new GII.4 strains, highlighting the need for an active surveillance system to allow the rapid identification of new strains.

scholarly journals Evaluation of SARS-CoV-2 antigen-based rapid diagnostic kits in Pakistan: formulation of COVID-19 national testing strategy

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Umar Saeed ◽  
Sara Rizwan Uppal ◽  
Zahra Zahid Piracha ◽  
Azhar Rasheed ◽  
Zubair Aftab ◽  
...  
Keyword(s):  
Gold Standard ◽  
Injection Drug Users ◽  
Drug Users ◽  
Diagnostic Testing ◽  
False Negative ◽  
Cross Sectional Study ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Negative Results

AbstractRapid diagnosis of SARS-CoV-2 during pandemic enables timely treatment and prevention of COVID-19. Evaluating the accuracy and reliability of rapid diagnostic testing kits is crucial for surveillance and diagnosis of SARS-CoV-2 infections in general population, injection drug users, multi-transfused populations, healthcare workers, prisoners, barbers and other high risk populations. The aim of this study was to evaluate performance and effectiveness of nasopharyngeal swab (NSP) and saliva based rapid antigen detection testing kits in comparison with USFDA approved triple target gold standard real-time polymerase chain reaction. A cross-sectional study was conducted on 33,000 COVID-19 suspected patients. From RT-PCR positive patients, nasopharyngeal swab (NSP) and saliva samples were obtained for evaluation of rapid COVID-19 testing kits (RDT). 100/33,000 (0.3%) of specimens were RT-PCR positive for SARS-CoV-2. Among RT-PCR positive, 62% were males, 34% were females, and 4% were children. The NSP-RDT (Lepu Medical China) analysis revealed 53% reactivity among males, 58% reactivity among females, and 25% reactivity among children. However saliva based RDT (Lepu Medical China) analysis showed 21% reactivity among males and 23% among females, and no reactivity in children. False negative results were significantly more pronounced in saliva based RDT as compared to NSP-RDT. The sensitivity of these NSP-RDT and saliva based RDT were 52% and 21% respectively. The RDTs evaluated in this study showed limited sensitivities in comparison to gold standard RT-PCR, indicating that there is a dire need in Pakistan for development of suitable testing to improve accurate COVID-19 diagnosis in line with national demands.

scholarly journals Athletes Drive Distinctive Trends of COVID-19 Infection in a College Campus Environment

2021 ◽  
Vol 18 (14) ◽  
pp. 7689
Author(s):  
Austin T. Hertel ◽  
Madison M. Heeter ◽  
Olivia M. Wirfel ◽  
Mara J. Bestram ◽  
Steven A. Mauro
Keyword(s):  
Risk Group ◽  
Temporal Trends ◽  
Rapid Identification ◽  
College Campus ◽  
Surveillance Program ◽  
Institutions Of Higher Education ◽  
Rt Pcr ◽  
Campus Environment ◽  
Incidence Risk ◽  
Academic Year

The COVID-19 pandemic forced most institutions of higher education to offer instruction and activities offsite, impacting millions of people. As universities consider resuming normal operations on campus, evidence-based guidance is needed to enhance safety protocols to reduce the spread of infectious disease in their campus environments. During the 2020/2021 academic year, Gannon University in Erie, PA, USA, was able to maintain most of its operations on campus. Part of Gannon’s disease mitigation strategy involved the development of a novel in-house, real-time RT-PCR-based surveillance program, which tested 23,227 samples to monitor the presence of COVID-19 on campus. Temporal trends of COVID-19 infection at Gannon were distinct from statewide data. A significant portion of this variance involved student athletes and associated staff, which identified as a higher incidence risk group compared with non-athletes. Rapid identification of athlete driven outbreaks allowed for swift action to limit the spread of COVID-19 among teammates and to the rest of the campus community. This allowed for successful completion of instruction and a modified season for all sports at Gannon. Our findings provide insights that could prove useful to the thousands of institutions seeking to resume a more traditional presence on campus.

scholarly journals Utility of forensic detection of rabies virus in decomposed exhumed dog carcasses

2015 ◽  
Vol 86 (1) ◽  
Author(s):  
Wanda Markotter ◽  
Jessica Coertse ◽  
Kevin Le Roux ◽  
Joey Peens ◽  
Jacqueline Weyer ◽  
...  
Keyword(s):  
Rabies Virus ◽  
Gold Standard ◽  
Diagnostic Method ◽  
Diagnostic Testing ◽  
Domestic Dogs ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Brain Material ◽  
Polymerase Chain ◽  
Genomic Material

This report describes four suspected rabies cases in domestic dogs that were involved inhuman exposures. In all these cases, the animals were buried for substantial times beforerabies testing was performed. Animal rabies is endemic in South Africa and domestic dogsare the main vector for transmission to humans. Diagnosis of rabies in humans is complicated,and diagnosis in the animal vector can provide circumstantial evidence to support clinicaldiagnosis of rabies in humans. The gold standard diagnostic method, fluorescent antibodytest (FAT), only delivers reliable results when performed on fresh brain material and thereforedecomposed samples are rarely submitted for diagnostic testing. Severely decomposed brainmaterial was tested for the presence of rabies virus genomic material using a quantitativereal-time reverse transcription polymerase chain reaction (q-real-time RT-PCR) assaywhen conventional molecular methods were unsuccessful. This may be a useful tool in theinvestigation of cases where the opportunity to sample the suspected animals post mortem wasforfeited and which would not be possible with conventional testing methodologies becauseof the decomposition of the material.

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