scholarly journals Experimental Design for a Macrofoam Swab Study Relating the Recovery Efficiency and False Negative Rate to Low Concentrations of Two Bacillus anthracis Surrogates on Four Surface Materials

2014 ◽  
Author(s):  
Gregory F. Piepel ◽  
Janine R. Hutchison
Keyword(s):  
Experimental Design ◽  
Bacillus Anthracis ◽  
False Negative ◽  
False Negative Rate ◽  
Recovery Efficiency ◽  
Negative Rate ◽  
Low Concentrations ◽  
Surface Materials

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.

Effects of Previous Surgery on the Detection of Sentinel Nodes in Women With Vulvar Cancer

2011 ◽  
Vol 21 (9) ◽  
pp. 1679-1683 ◽  
Author(s):  
Tessa A. Ennik ◽  
David G. Allen ◽  
Ruud L.M. Bekkers ◽  
Simon E. Hyde ◽  
Peter T. Grant
Keyword(s):  
Vulvar Cancer ◽  
False Negative ◽  
False Negative Rate ◽  
Blue Dye ◽  
Previous Surgery ◽  
Detection Rates ◽  
Reliable Technique ◽  
Appearance Time ◽  
Negative Rate ◽  
Significant Difference

BackgroundThere is a growing interest to apply the sentinel node (SN) procedure in the treatment of vulvar cancer. Previous vulvar surgery might disrupt lymphatic patterns and thereby decrease SN detection rates, lengthen scintigraphic appearance time (SAT), and increase SN false-negative rate. The aims of this study were to evaluate the SN detection rates at the Mercy Hospital for Women in Melbourne and to investigate whether previous vulvar surgery affects SN detection rates, SAT, and SN false-negative rate.MethodsData on all patients with vulvar cancer who underwent an SN procedure (blue dye, technetium, or combined technique) from November 2000 to July 2010 were retrospectively collected.ResultsSixty-five SN procedures were performed. Overall detection rate was 94% per person and 80% per groin. Detection rates in the group of patients who underwent previous excision of the primary tumor were not lower compared with the group without previous surgery or with just an incisional biopsy. There was no statistical significant difference in SAT between the previous excision group and the other patients. None of the patients with a false-negative SN had undergone previous excision.ConclusionsResults indicate that previous excision of a primary vulvar malignancy does not decrease SN detection rates or increase SN false-negative rate. Therefore, the SN procedure appears to be a reliable technique in patients who have previously undergone vulvar surgery. Previous excision did not significantly lengthen SAT, but the sample size in this subgroup analysis was small.

scholarly journals Temporal dynamics of viral load and false negative rate influence the levels of testing necessary to combat COVID-19 spread

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Katherine F. Jarvis ◽  
Joshua B. Kelley
Keyword(s):  
Viral Load ◽  
Temporal Dynamics ◽  
Reproduction Number ◽  
False Negative ◽  
False Negative Rate ◽  
Agent Based Model ◽  
Agent Based ◽  
Viral Spread ◽  
Negative Rate

AbstractColleges and other organizations are considering testing plans to return to operation as the COVID-19 pandemic continues. Pre-symptomatic spread and high false negative rates for testing may make it difficult to stop viral spread. Here, we develop a stochastic agent-based model of COVID-19 in a university sized population, considering the dynamics of both viral load and false negative rate of tests on the ability of testing to combat viral spread. Reported dynamics of SARS-CoV-2 can lead to an apparent false negative rate from ~ 17 to ~ 48%. Nonuniform distributions of viral load and false negative rate lead to higher requirements for frequency and fraction of population tested in order to bring the apparent Reproduction number (Rt) below 1. Thus, it is important to consider non-uniform dynamics of viral spread and false negative rate in order to model effective testing plans.

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