Variables affecting laboratory diagnosis of acute rickettsial infection

2018 ◽  
Vol 39 (4) ◽  
pp. 220
Author(s):  
Cecilia Kato
Keyword(s):  
Molecular Detection ◽  
False Negative ◽  
Laboratory Diagnosis ◽  
Acute Stage ◽  
Detection Methods ◽  
Rickettsial Infection ◽  
Negative Results ◽  
Enhanced Sensitivity ◽  
False Negative Results ◽  
Antibody Titres

The reference standard for the confirmation of a recent rickettsial infection is by the observation of a four-fold or greater rise in antibody titres when testing paired acute and convalescent (two to four weeks after illness resolution) sera by serological assays (Figure 1). At the acute stage of illness, diagnosis is performed by molecular detection methods most effectively on DNA extracted from tissue biopsies (eschars, skin rash, and organs) or eschar swabs. Less invasive and more convenient samples such as blood and serum may also be used for detection; however, the low number of circulating bacteria raises the possibility of false negative results. Optimal sampling practices and enhanced sensitivity must therefore be considered in order to provide a more accurate laboratory diagnosis.

scholarly journals Emerging approaches for detection of methylation sites in RNA

Open Biology ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 180121 ◽  
Author(s):  
Anna Ovcharenko ◽  
Andrea Rentmeister
Keyword(s):  
High Throughput Sequencing ◽  
De Novo ◽  
Direct Detection ◽  
False Negative ◽  
Detection Methods ◽  
Rna Modifications ◽  
Negative Results ◽  
Third Generation Sequencing ◽  
False Negative Results ◽  
Generation Sequencing

RNA methylations play a significant regulatory role in diverse biological processes. Although the transcriptome-wide discovery of unknown RNA methylation sites is essential to elucidate their function, the development of a bigger variety of detection approaches is desirable for multiple reasons. Many established detection methods for RNA modifications heavily rely on the specificity of the respective antibodies. Thus, the development of antibody-independent transcriptome-wide methods is beneficial. Even the antibody-independent high-throughput sequencing-based methods are liable to produce false-positive or false-negative results. The development of an independent method for each modification could help validate the detected modification sites. Apart from the transcriptome-wide methods for methylation detection de novo , methods for monitoring the presence of a single methylation at a determined site are also needed. In contrast to the transcriptome-wide detection methods, the techniques used for monitoring purposes need to be cheap, fast and easy to perform. This review considers modern approaches for site-specific detection of methylated nucleotides in RNA. We also discuss the potential of third-generation sequencing methods for direct detection of RNA methylations.

scholarly journals Freezing Induces Biased Results in the Molecular Detection of Flavobacterium columnare

2006 ◽  
Vol 72 (2) ◽  
pp. 1702-1704 ◽  
Author(s):  
Lotta-Riina Suomalainen ◽  
Hilkka Reunanen ◽  
Ritva Ijäs ◽  
E. Tellervo Valtonen ◽  
Marja Tiirola
Keyword(s):  
Electron Microscopy ◽  
Molecular Detection ◽  
False Negative ◽  
Infected Fish ◽  
Flavobacterium Columnare ◽  
Fish Pathogen ◽  
Freezing And Thawing ◽  
Negative Results ◽  
Specific Pcr ◽  
False Negative Results

ABSTRACT Specific PCR detection and electron microscopy of Flavobacterium columnare revealed the risk of false-negative results in molecular detection of this fish pathogen. Freezing and thawing destroyed the cells so that DNA was for the most part undetectable by PCR. The detection of bacteria was also weakened after prolonged enrichment cultivation of samples from infected fish.

scholarly journals The value of repeat patient testing for SARS-CoV-2: real-world experience during the first wave

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
Alex Zhu ◽  
Margaret Creagh ◽  
Chao Qi ◽  
Shannon Galvin ◽  
Maureen Bolon ◽  
...  
Keyword(s):  
False Negative ◽  
Laboratory Diagnosis ◽  
Nucleic Acid Amplification ◽  
Repeat Testing ◽  
The Third ◽  
Reverse Transcription Pcr ◽  
Negative Results ◽  
False Negative Results ◽  
Number Of Patients ◽  
Control And Prevention

Introduction. Reports of false-negative quantitative reverse transcription PCR (RT-qPCR) results from patients with high clinical suspension for coronavirus disease 2019 (COVID-19), suggested that a negative result produced by a nucleic acid amplification assays (NAAs) did not always exclude the possibility of COVID-19 infection. Repeat testing has been used by clinicians as a strategy in an to attempt to improve laboratory diagnosis of COVID-19 and overcome false-negative results in particular. Aim. To investigate whether repeat testing is helpful for overcoming false-negative results. Methods. We retrospectively reviewed our experience with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing, focusing on the yield of repeat patient testing for improving SARS-CoV-2 detection by NAA. Results. We found that the yield from using repeat testing to identify false-negative patients was low. When the first test produced a negative result, only 6 % of patients tested positive by the second test. The yield decreased to 1.7 and then 0 % after the third and fourth tests, respectively. When comparing the results produced by three assays, the Centers for Disease Control and Prevention (CDC) SARS CoV-2 RT-qPCR panel, Xpert Xpress CoV-2 and ID NOW COVID-19, the ID NOW assay was associated with the highest number of patients who tested negative initially but positive on repeat testing. The CDC SARS CoV-2 RT-qPCR panel produced the highest number of indeterminate results. Repeat testing resolved more than 90 % of indeterminate/invalid results. Conclusions. The yield from using repeat testing to identify false-negative patients was low. Repeat testing was best used for resolving indeterminate/invalid results.

scholarly journals An appraisal of various pathogen detection methods in eggs and poultry

2020 ◽  
Vol 1 (2) ◽  
pp. 93-97
Author(s):  
A. A. P. Milton ◽  
G. Bhuvana Priya ◽  
K. M. Momin ◽  
M. Angappan ◽  
Samir Das ◽  
...  
Keyword(s):  
Pathogen Detection ◽  
False Negative ◽  
Foodborne Pathogen ◽  
Detection Methods ◽  
Immunological Methods ◽  
Culturable Bacteria ◽  
Product Recalls ◽  
Poultry Products ◽  
Negative Results ◽  
False Negative Results

Abstract: To ensure safety in egg and poultry products, timely detection of pathogenic microbes is of paramount importance. This review offers an appraisal of different routinely used and novel emerging pathogen detection methods in egg, poultry and their products. Timely detection of pathogens is decisive to curtail outbreak risks, reduce hospitalisation, and provide product assurance. It will also reduce the cost of holding food products in cold storage and reduces product recalls. Some crucial issues need to be taken care of in choosing or developing a foodborne pathogen detection method. They are requirement of costly or sophisticated equipment, portability, trained personnel, viable but non-culturable bacteria (may give false-negative results), dead microbes (may give false-positive results), stressed or sub-lethally damaged bacteria and slow-growing microbes (require enrichment). In this review, the focus has been given on culture-based methods, nucleic acid-based methods, immunological methods and biosensor based methods. Keywords: Egg; poultry; detection methods; product assurance; safety.

scholarly journals COVID-19 Clinical and Laboratory Diagnosis Overview

2020 ◽  
Author(s):  
Rania Zayed ◽  
Dalia Omran ◽  
Abeer Zayed
Keyword(s):  
False Negative ◽  
Laboratory Diagnosis ◽  
Laboratory Diagnostics ◽  
Rt Pcr ◽  
Serologic Test ◽  
Negative Results ◽  
Global Pandemic ◽  
Pcr Diagnosis ◽  
False Negative Results ◽  
Important Approach

COVID-19 was identified in Wuhan, China in in December 2019, and rapidly spread worldwide, being declared global pandemic one month later on 30 January 2020. Since its emergence, COVID-19 has raised global concerns associated with drastic measures that were never adopted in any previous outbreak, to contain the situation as early as possible. The 2019 novel corona virus (2019-nCoV) or SARS-CoV-2 is the causative agent of COVID-19. 2019-nCoV genetic sequence was rapidly identified within few days since the first reported cases and RT-PCR kits became available for COVID-19 diagnosis. However, RT-PCR diagnosis carries a risk of false-negative results, therefore additional serologic test are needed. The most important approach in the battle against COVID-19 is rapid diagnosis of suspicious cases, timely therapeutic intervention and isolation to avoid community spread. In this review, we summarize the clinical scenario that raises suspicion of COVID-19 and available laboratory diagnostics.

scholarly journals Influence of canine brain decomposition on laboratory diagnosis of rabies

1999 ◽  
Vol 32 (1) ◽  
pp. 19-22 ◽  
Author(s):  
Avelino Albas ◽  
Clara Izabel de Lucca Ferrari ◽  
Luzia Helena Queiroz da Silva ◽  
Fernanda Bernardi ◽  
Fumio Honma Ito
Keyword(s):  
Rabies Virus ◽  
Room Temperature ◽  
False Negative ◽  
Laboratory Diagnosis ◽  
Accurate Diagnosis ◽  
Intracerebral Inoculation ◽  
Negative Results ◽  
Canine Brain ◽  
False Negative Results

Canine brains infected with rabies virus were submitted to decomposition by being left at room temperature of 25 to 29oC for up to 168h. At 24h intervals, brain fragments were analyzed by immunofluorescence (IF) and by the mouse intracerebral inoculation (MI) test to confirm the diagnosis of rabies and to measure the putrefaction effect on the accuracy of the diagnosis. Forty eight h after the beginning of the experiment, the MI test showed signs of impairment with four negative results, while after 72h, 100% of the results were negative to the MI test and only one result was negative to the IF test, indicating that the threshold period for accurate diagnosis is 24 to 48h before putrefaction. The authors recommend the shipment of suspected cases of rabies to the laboratory for confirmation, but the use of putrid materials for diagnosis is meaningless because of false-negative results.

scholarly journals Molecular detection of SARS-CoV-2 using a reagent-free approach

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243266
Author(s):  
Ronan Calvez ◽  
Andrew Taylor ◽  
Leonides Calvo-Bado ◽  
Donald Fraser ◽  
Colin G. Fink
Keyword(s):  
Internal Control ◽  
Molecular Detection ◽  
False Negative ◽  
Rna Extraction ◽  
Processing Method ◽  
Heat Processing ◽  
Negative Results ◽  
Treatment Conditions ◽  
False Negative Results ◽  
Different Temperatures

Shortage of reagents and consumables required for the extraction and molecular detection of SARS-CoV-2 RNA in respiratory samples has led many laboratories to investigate alternative approaches for sample preparation. Many groups recently presented results using heat processing method of respiratory samples prior to RT-qPCR as an economical method enabling an extremely fast streamlining of the processes at virtually no cost. Here, we present our results using this method and highlight some major pitfalls that diagnostics laboratories should be aware of before proceeding with this methodology. We first investigated various treatments using different temperatures, incubation times and sample volumes to optimise the heat treatment conditions. Although the initial data confirmed results published elsewhere, further investigations revealed unexpected inhibitory properties of some commonly used universal transport media (UTMs) on some commercially available RT-qPCR mixes, leading to a risk of reporting false-negative results. This emphasises the critical importance of a thorough validation process to determine the most suitable reagents to use depending on the sample types to be tested. In conclusion, a heat processing method is effective with very consistent Ct values and a sensitivity of 96.2% when compared to a conventional RNA extraction method. It is also critical to include an internal control to check each sample for potential inhibition.

scholarly journals Epidemiology, diagnosis, treatment, and future perspectives concerning SARS-COV-2: a review article

2020 ◽  
Vol 66 (3) ◽  
pp. 370-374 ◽  
Author(s):  
Arthur Ricardo Vilar Scavuzzi de Carvalho ◽  
Murilo Lobo Cezarotti Filho ◽  
Pedro Cavalcanti Pires de Azevedo ◽  
Robson Natario Silveira Filho ◽  
Fabiano Timbó Barbosa ◽  
...  
Keyword(s):  
Clinical Course ◽  
False Negative ◽  
Laboratory Diagnosis ◽  
Healthy Population ◽  
Future Perspectives ◽  
Gold Standard Method ◽  
Negative Results ◽  
Medical Observation ◽  
False Negative Results ◽  
And Control

SUMMARY The present study aimed to review the epidemiology, clinical manifestation, laboratory diagnosis, treatment, and future perspectives related to COVID-19 infections. The following electronic databases were used searched: MEDLINE, SCIELO, and LILACS. It became clear that COVID-19 infections occur through exposure to the virus, and both the immunosuppressed and healthy population appear susceptible. The clinical course of COVID-19 is still not clear, although the SARS-CoV-2 infection seems to develop with mild, influenza-like symptoms in the vast majority of subjects, i.e., 10%–15% of COVID-19 patients. Since rRT-PCR tests serve as the gold standard method to confirm a SARS-CoV-2 infection, false-negative results could hinder the prevention and control of the epidemic, particularly considering the test plays a key role in the decision for continued isolated medical observation or discharge. Our findings also indicate that a radical increase in the identification and isolation of currently undocumented infections would be needed to fully control SARS-CoV2.

scholarly journals COVID-19: Test, Test and Test

2020 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Fatima A Saleh ◽  
Aleen Sleem
Keyword(s):  
Diagnostic Testing ◽  
False Negative ◽  
Detection Methods ◽  
Nucleic Acid Detection ◽  
Rt Pcr ◽  
Negative Results ◽  
Immunological Tests ◽  
False Negative Results ◽  
Different Types ◽  
Polymerase Chain

A new virus was identified in late December 2019 when China reported the first cases of pneumonia in Wuhan, and a global COVID-19 pandemic followed. The world was not late to respond, with a number of sweeping measures ranging from social distancing protocols, stringent hygienic practices, and nation-wide lockdowns, as well as COVID-19 testing campaigns in an attempt to prevent the transmission of the disease and contain the pandemic. Currently, different types of diagnostic testing have been adopted globally, such as nucleic acid detection tests, immunological tests and imaging approaches; however, real-time reverse transcriptase–polymerase chain reaction (RT-PCR) remains the “gold standard” for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pre-analytical factors, such as specimen selection and collection, are crucial for RT-PCR, and any suboptimal collection may contribute to false-negative results. Herein, we address some of the specimen types that have been used in molecular detection methods for COVID-19. However, the pandemic is still evolving, and information might change as more studies are conducted.

scholarly journals Improved Sensitivity of Allergen Detection by Immunoaffinity LC-MS/MS Using Ovalbumin as a Case Study

Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2932
Author(s):  
Martin Röder ◽  
Claudia Wiacek ◽  
Frauke Lankamp ◽  
Jonathan Kreyer ◽  
Wolfgang Weber ◽  
...  
Keyword(s):  
Food Processing ◽  
False Negative ◽  
Detection Methods ◽  
Food Allergies ◽  
Negative Results ◽  
False Negative Results ◽  
Allergen Detection ◽  
Current Mass ◽  
Egg Powder

Food allergies are caused by severe hypersensitivity to specific food allergens such as the egg protein ovalbumin. It is therefore important to test food products for the presence of allergens to protect allergic people from accidental ingestion. For egg detection, ELISA is the only reasonable commercially available test format, although the recognition of target allergens can be affected by food processing, which may lead to false negative results. Current mass spectrometry-based detection methods may overcome this issue, but these approaches are often less sensitive. Here we combined the advantages of antibody-based and MS-based methods by developing an immunoaffinity LC-MS/MS technique to detect the common egg allergen Gal d 2. We investigated the principal functionality of this method with incurred cookie material containing whole egg powder. We found that the new method matched easily the sensitivity of egg specific ELISA tests. Further western blot experiments indicated that this strategy may be unaffected by food processing, providing an important alternative strategy for the detection and quantification of allergens in food.

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