Assessing an alpha-defensin lateral flow device for diagnosing septic arthritis: reporting on a false-negative case and a false-positive case

2019 ◽  
Vol 4 (1) ◽  
pp. 156-160
Author(s):  
Atsushi Narita ◽  
Akemi Suzuki ◽  
Taku Nakajima ◽  
Yuya Takakubo ◽  
Juji Ito ◽  
...  
Keyword(s):  
Septic Arthritis ◽  
False Positive ◽  
False Negative ◽  
Lateral Flow ◽  
Positive Case ◽  
False Positive Case ◽  
Lateral Flow Device ◽  
False Negative Case ◽  
Negative Case ◽  
Flow Device

scholarly journals More than the eye can see – shedding new light on SARS-CoV-2 Lateral Flow Device-based immunoassays

2021 ◽  
Author(s):  
Garrit Koller ◽  
Alexander P Morrell ◽  
Rui Pedro Galão ◽  
Suzanne Pickering ◽  
Eithne MacMahon ◽  
...  
Keyword(s):  
Public Health ◽  
False Negative ◽  
Significant Risk ◽  
High Specificity ◽  
Lateral Flow ◽  
Health Concern ◽  
X Ray ◽  
Lateral Flow Device ◽  
Fluorescence Measurements ◽  
Flow Device

AbstractContaining the global SARS-CoV-2 pandemic has been an unprecedented challenge due to high rates of both horizontal transmissivity and asymptomatic carriage. Lateral Flow Device (LFD) immunoassays were introduced in late 2020 to rapidly detect SARS-CoV-2 infection in asymptomatic or pre-symptomatic individuals in the population. Although LFD technologies have been used for over 60 years, their widespread use as a public health tool during a pandemic is unprecedented. By the end of 2020, data from studies into the efficacy of the LFDs emerged and showed these point-of-care devices to have very high specificity (ability to identify true negatives), but inadequate sensitivity with high false-negative rates. In particular, the low sensitivity (<50%) shown in several studies is a critical public health concern, given that asymptomatic or pre-symptomatic carriers may wrongly be assumed to be non-infectious, and posing a significant risk of further spread in the community. Here we show that the direct visual readout of SARS-CoV-2 LFDs is an inadequate approach to discriminate a potentially infective viral concentration in a bio-sample. Using high sensitivity synchrotron X-ray fluorescence imaging we were able to quantify significant immobilized antigen-antibody-label conjugates within the LFDs visually scored as negative. Correlating quantitative X-ray fluorescence measurements and qRT-PCR determined numbers of viral copies we identified that negatively scored samples could contain up to 100 PFU (equivalent here to ∼10,000 RNA copies/test). This is of significant concern should these tests be used to control community spread. The study demonstrates where the shortcomings arise in many of the current direct-readout SARS-CoV-2 LFDs, namely being a deficiency in the readout as opposed to the potential level of detection of the test which is orders of magnitude higher. Our findings are of importance both to public health monitoring during the COVID-19 pandemic and to the rapid refinement of these tools for immediate and future applications.

scholarly journals Soft drinks can be misused to give false false positive SARS-CoV-2 lateral flow device results

2021 ◽  
Author(s):  
Louise Oni ◽  
Daniel Hawcutt ◽  
Iain Buchan ◽  
Malcom G Semple
Keyword(s):  
False Positive ◽  
Large Scale ◽  
Ph Value ◽  
Low Cost ◽  
Sugar Content ◽  
Soft Drinks ◽  
Lateral Flow ◽  
Artificial Sweeteners ◽  
Lateral Flow Device ◽  
Flow Device

Background The COVID-19 pandemic created the need for very large scale, rapid testing to prevent and contain transmission of the SARS-CoV-2 virus. Lateral flow device (LFD) immunoassays meet this need by indicating the presence of SARS-CoV-2 antigen from nose/throat swab washings in 30 minutes without laboratory processing, and can be manufactured quickly at low cost. Since March 2021, UK schools have asked pupils without symptoms to test twice weekly. Pupils have posted on social media about using soft drinks to create positive results. The aim of this study was to systematically test a variety soft drinks to determine whether they can cause false false positive LFD results. Methods This study used 14 soft drinks and 4 artificial sweeteners to determine the outcome of misusing them as analyte for the Innova SARS-CoV-2 antigen rapid qualitative LFD. The pH value, sugar content and ingredients of each sample are described. The LFD results were double read and a subset was repeated using the same devices and fake analytes but differently sourced. Findings One sample (1/14; 7%), spring water, produced a negative result. Ten drinks (10/14; 71%) produced a positive or weakly positive result. Three samples (3/14; 21%) produced void results, mostly the fruit concentrate drinks. There was no apparent correlation between the pH value (pH 5.0 in 13/14, 93%; pH 6.5 in 1/14; 7%) or the sugar content (range 0-10.7 grams per 100mls) of the drinks and their LFD result. The 4 artificial sweeteners all produced negative results. A subset of the results was fully replicated with differently sourced materials. Interpretation Several soft drinks can be misused to give false positive SARS-CoV-2 LFD results. Daily LFD testing should be performed first thing in the morning, prior to the consumption of any food or drinks, and supervised where feasible. Funding This work was self-funded by author LO and the LFD were gifted for use in this study.

Evaluation of rapid test kits for quantification of HT-2 and T-2 toxins in naturally contaminated oats

2013 ◽  
Vol 6 (1) ◽  
pp. 31-41 ◽  
Author(s):  
H.U. Aamot ◽  
I.S. Hofgaard ◽  
G. Brodal ◽  
O. Elen ◽  
B. Holen ◽  
...  
Keyword(s):  
Concentration Ratio ◽  
Rapid Test ◽  
Reference Method ◽  
Lateral Flow ◽  
Cross Reaction ◽  
Cross Reactions ◽  
Lateral Flow Device ◽  
Simultaneous Testing ◽  
Flow Device ◽  
Mycotoxin Analysis

The aim of this study was to evaluate the performance and usefulness of three rapid test kits for analysis of HT-2 and T-2 toxins (HT-2 and T-2), two of the most potent trichothecenes commonly found in European oats. Concentrations of these two toxins combined (HT-2+T-2) were analysed in naturally contaminated oat samples (n=68) using the following test kits: Ridascreen® FAST T-2 Toxin (‘Fast ELISA’), DRAFT Ridascreen® HT-2/T-2 (‘Standard ELISA’, not commercially available), and the lateral flow device ROSA® HT-2-T-2 (‘Rosa LFD’). Mycotoxin analysis by LC-MS/MS was used as a reference method. Rosa LFD offered the best reliability, achieving detection that was stable across toxin levels, whereas detection by both ELISA kits differed significantly among toxin levels (P<0.01). The kits were also evaluated regarding agreement with the reference method (measured as Cohen's kappa) at a HT-2+T-2 concentration of 1000 μg/kg in naturally contaminated oats. Agreement was greatest for Rosa LFD (89.2%), intermediate for Standard ELISA (66.8%), and lowest for Fast ELISA (62.2%). Rosa LFD showed cross-reaction of 100% with both T-2 and HT-2. For the ELISA kits, cross-reactions were 100% with T-2 but below 100% with HT-2. Therefore, to estimate the sum of HT-2 and T-2 in an oat sample, it was necessary to re-calculate the data from both ELISA kits according to the known cross-reaction of each kit with HT-2 and the concentration ratio of HT-2 to T-2 in Norwegian oats. Rosa LFD had the highest correlation with LC-MS/MS (R2=0.94), and the corresponding R2 values for Fast and Standard ELISA were 0.61 and 0.83, respectively. Rosa LFD was well suited for on-site detection. Standard ELISA allows simultaneous testing of several samples that are useful for centralised laboratories.

scholarly journals P077 Reliability of the Clinical Characterization of Isolated REM Sleep Behavior Disorder

2021 ◽  
Vol 2 (Supplement_1) ◽  
pp. A46-A46
Author(s):  
D Levendowski ◽  
J Lee-Iannotti ◽  
D Shprecher ◽  
C Guevarra ◽  
P Timm ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Rem Sleep ◽  
False Positive ◽  
False Negative ◽  
Rem Sleep Behavior Disorder ◽  
Behavior Disorder ◽  
Sleep Behavior ◽  
Negative Case ◽  
Rem Sleep Without Atonia

Abstract Purpose Compare agreements between polysomnography-based (PSG) diagnosis of isolated REM-sleep-behavior-disorder (iRBD) and Non-REM-Hypertonia (NRH), a novel biomarker independently associated with synucleinopathy-related neurodegenerative diseases. Methods Sixteen patients with histories of dream-enactment-behavior (DEB)(women=38%; age:64.6±13.0) underwent PSG with simultaneously-recorded Sleep Profiler (SP). Two boarded sleep neurologists independently characterized iRBD. Physician1 combined abnormal qualitative REM-sleep-without-atonia (RSWA) by submental electromyography, with video-confirmation of probably DEB. Physician2 relied solely on qualitative RSWA. SP was auto-staged, technically reviewed, and reprocessed for automated abnormal NRH detection. Kappa scores measured physician and NRH agreements. Results In the 14 records with REM sleep, iRBD was characterized in: Physician1=64%, Physician2=79%, NRH=71% of the records. Across the three methods, unanimous iRBD agreement occurred in 57% of the records (positive=7, negative=1). The between-physician agreement in iRBD classifications was fair (kappa=0.32). The agreement between NRH and Physician1 was moderate (kappa=0.52) versus slight with Physician2 (kappa=0.05). NRH comparisons to consensus physician agreement yielded one false-positive and one false-negative iRBD finding. Physician2 classified: a) iRBD in two cases that were negative by Physician1 and NRH, and b) one negative case that Physician1 and NRH characterized as iRBD. Physician1 identified one negative case that was classified iRBD by Physician2 and NRH. Additionally, NRH was abnormal in one of the two records with no REM sleep. Discussion NRH may assist in iRBD risk assessment, given it agreed with at least one physician in 86% of the cases and the between-physician iRBD agreement was only fair. NRH also characterized iRBD-risk in patients with insufficient REM sleep for RSWA assessment.

scholarly journals Engineering a simple lateral flow device for animal blood coagulation monitoring

2018 ◽  
Vol 12 (1) ◽  
pp. 014110 ◽  
Author(s):  
Hua Li ◽  
Daewoo Han ◽  
Giovanni M. Pauletti ◽  
Andrew J. Steckl
Keyword(s):  
Blood Coagulation ◽  
Lateral Flow ◽  
Animal Blood ◽  
Lateral Flow Device ◽  
Coagulation Monitoring ◽  
Flow Device

scholarly journals A point-of-care neutrophil elastase activity assay identifies bronchiectasis severity, airway infection and risk of exacerbation

2019 ◽  
Vol 53 (6) ◽  
pp. 1900303 ◽  
Author(s):  
Amelia Shoemark ◽  
Erin Cant ◽  
Luis Carreto ◽  
Alexandria Smith ◽  
Martina Oriano ◽  
...  
Keyword(s):  
Neutrophil Elastase ◽  
Point Of Care ◽  
Severity Index ◽  
Forced Expiratory Volume ◽  
Lateral Flow ◽  
Elastase Activity ◽  
Lateral Flow Device ◽  
Airway Infection ◽  
Independent Validation ◽  
Flow Device

IntroductionNeutrophil elastase activity in sputum can identify patients at high risk of airway infection and exacerbations in bronchiectasis. Application of this biomarker in clinical practice is limited, because no point-of-care test is available. We tested whether a novel semi-quantitative lateral flow device (neutrophil elastase airway test stick – NEATstik®) can stratify bronchiectasis patients according to severity, airway infection and exacerbation risk.MethodsSputum samples from 124 patients with stable bronchiectasis enrolled in the UK and Spain were tested using the NEATstik®, which scores neutrophil elastase concentration from 0 (<8 µg·mL−1 elastase activity) to 10 (maximum detectable neutrophil elastase activity). High neutrophil elastase activity was regarded as a NEATstik® grade >6. Severity of disease, airway infection from sputum culture and exacerbations over the 12 months were recorded. An independent validation was conducted in 50 patients from Milan, Italy.Measurements and main resultsPatients had a median age of 69 years and forced expiratory volume in 1 s (FEV1) 69%. High neutrophil elastase activity was associated with worse bronchiectasis severity using the bronchiectasis severity index (p=0.0007) and FEV1 (p=0.02). A high NEATstik® grade was associated with a significant increase in exacerbation frequency, incident rate ratio 2.75 (95% CI 1.63–4.64, p<0.001). The median time to next exacerbation for patients with a NEATstik® grade >6 was 103 days compared to 278 days. The hazard ratio was 2.59 (95% CI 1.71–3.94, p<0.001). Results were confirmed in the independent validation cohort.ConclusionsA novel lateral flow device provides assessment of neutrophil elastase activity from sputum in minutes and identifies patients at increasing risk of airway infection and future exacerbations.

Sign in / Sign up

Export Citation Format

Share Document