scholarly journals Recovery Efficiency, False Negative Rate, and Limit of Detection Performance of a Validated Macrofoam-Swab Sampling Method with Low Surface Concentrations of Two Bacillus anthracis Surrogates

2015 ◽  
Author(s):  
Gregory F. Piepel ◽  
Janine R. Hutchison ◽  
Brooke L Deatherage Kaiser ◽  
Brett G. Amidan ◽  
Michael A. Sydor ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Sampling Method ◽  
Limit Of Detection ◽  
False Negative ◽  
False Negative Rate ◽  
Detection Performance ◽  
Recovery Efficiency ◽  
Negative Rate

scholarly journals False-Negative Rate and Recovery Efficiency Performance of a Validated Sponge Wipe Sampling Method

2011 ◽  
Vol 78 (3) ◽  
pp. 846-854 ◽  
Author(s):  
Paula A. Krauter ◽  
Greg F. Piepel ◽  
Raymond Boucher ◽  
Matt Tezak ◽  
Brett G. Amidan ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Limit Of Detection ◽  
False Negative ◽  
False Negative Rate ◽  
Recovery Efficiency ◽  
Surface Material ◽  
Content Type ◽  
Negative Rate ◽  
Efficiency Performance

ABSTRACTRecovery of spores from environmental surfaces varies due to sampling and analysis methods, spore size and characteristics, surface materials, and environmental conditions. Tests were performed to evaluate a new, validated sponge wipe method usingBacillus atrophaeusspores. Testing evaluated the effects of spore concentration and surface material on recovery efficiency (RE), false-negative rate (FNR), limit of detection (LOD), and their uncertainties. Ceramic tile and stainless steel had the highest mean RE values (48.9 and 48.1%, respectively). Faux leather, vinyl tile, and painted wood had mean RE values of 30.3, 25.6, and 25.5, respectively, while plastic had the lowest mean RE (9.8%). Results show roughly linear dependences of RE and FNR on surface roughness, with smoother surfaces resulting in higher mean REs and lower FNRs. REs were not influenced by the low spore concentrations tested (3.10 × 10−3to 1.86 CFU/cm2). Stainless steel had the lowest mean FNR (0.123), and plastic had the highest mean FNR (0.479). The LOD90(≥1 CFU detected 90% of the time) varied with surface material, from 0.015 CFU/cm2on stainless steel up to 0.039 on plastic. It may be possible to improve sampling results by considering surface roughness in selecting sampling locations and interpreting spore recovery data. Further, FNR values (calculated as a function of concentration and surface material) can be used presampling to calculate the numbers of samples for statistical sampling plans with desired performance and postsampling to calculate the confidence in characterization and clearance decisions.

scholarly journals Microfluidic Nano-Scale qPCR Enables Ultra-Sensitive and Quantitative Detection of SARS-CoV-2

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1425
Author(s):  
Xin Xie ◽  
Tamara Gjorgjieva ◽  
Zaynoun Attieh ◽  
Mame Massar Dieng ◽  
Marc Arnoux ◽  
...  
Keyword(s):  
Viral Infections ◽  
Limit Of Detection ◽  
False Negative ◽  
False Negative Rate ◽  
Clinical Samples ◽  
Quantitative Detection ◽  
Rt Pcr ◽  
Viral Loads ◽  
Nano Scale ◽  
Negative Rate

A major challenge in controlling the COVID-19 pandemic is the high false-negative rate of the commonly used RT-PCR methods for SARS-CoV-2 detection in clinical samples. Accurate detection is particularly challenging in samples with low viral loads that are below the limit of detection (LoD) of standard one- or two-step RT-PCR methods. In this study, we implemented a three-step approach for SARS-CoV-2 detection and quantification that employs reverse transcription, targeted cDNA preamplification, and nano-scale qPCR based on a commercially available microfluidic chip. Using SARS-CoV-2 synthetic RNA and plasmid controls, we demonstrate that the addition of a preamplification step enhances the LoD of this microfluidic RT-qPCR by 1000-fold, enabling detection below 1 copy/µL. We applied this method to analyze 182 clinical NP swab samples previously diagnosed using a standard RT-qPCR protocol (91 positive, 91 negative) and demonstrate reproducible and quantitative detection of SARS-CoV-2 over five orders of magnitude (<1 to 106 viral copies/µL). Crucially, we detect SARS-CoV-2 with relatively low viral load estimates (<1 to 40 viral copies/µL) in 17 samples with negative clinical diagnosis, indicating a potential false-negative rate of 18.7% by clinical diagnostic procedures. In summary, this three-step nano-scale RT-qPCR method can robustly detect SARS-CoV-2 in samples with relatively low viral loads (<1 viral copy/µL) and has the potential to reduce the false-negative rate of standard RT-PCR-based diagnostic tests for SARS-CoV-2 and other viral infections.

scholarly journals SARS-CoV2 Testing: The Limit of Detection Matters

2020 ◽  
Author(s):  
Ramy Arnaout ◽  
Rose A. Lee ◽  
Ghee Rye Lee ◽  
Cody Callahan ◽  
Christina F. Yen ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Diagnostic Testing ◽  
False Negative ◽  
False Negative Rate ◽  
Fold Increase ◽  
Test Results ◽  
Rt Pcr ◽  
False Negatives ◽  
Healthcare Network ◽  
Negative Rate

AbstractResolving the COVID-19 pandemic requires diagnostic testing to determine which individuals are infected and which are not. The current gold standard is to perform RT-PCR on nasopharyngeal samples. Best-in-class assays demonstrate a limit of detection (LoD) of ~100 copies of viral RNA per milliliter of transport media. However, LoDs of currently approved assays vary over 10,000-fold. Assays with higher LoDs will miss more infected patients, resulting in more false negatives. However, the false-negative rate for a given LoD remains unknown. Here we address this question using over 27,500 test results for patients from across our healthcare network tested using the Abbott RealTime SARS-CoV-2 EUA. These results suggest that each 10-fold increase in LoD is expected to increase the false negative rate by 13%, missing an additional one in eight infected patients. The highest LoDs on the market will miss a majority of infected patients, with false negative rates as high as 70%. These results suggest that choice of assay has meaningful clinical and epidemiological consequences. The limit of detection matters.

scholarly journals False negative rate and other performance measures of a sponge-wipe surface sampling method for low contaminant concentrations.

2011 ◽  
Author(s):  
Wayne Einfeld ◽  
Paula A. Krauter ◽  
Raymond M. Boucher ◽  
Mathew Tezak ◽  
Brett G. Amidan ◽  
...  
Keyword(s):  
Performance Measures ◽  
Sampling Method ◽  
False Negative ◽  
False Negative Rate ◽  
Surface Sampling ◽  
Negative Rate
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