scholarly journals Diagnosing SARS-CoV-2 with Antigen Testing, Transcription-Mediated Amplification and Real-Time PCR

2021 ◽  
Vol 10 (11) ◽  
pp. 2404
Author(s):  
Sascha Dierks ◽  
Oliver Bader ◽  
Julian Schwanbeck ◽  
Uwe Groß ◽  
Michael Weig ◽  
...  
Keyword(s):  
Real Time ◽  
Sensitivity And Specificity ◽  
Real Time Pcr ◽  
Gold Standard ◽  
Latent Class ◽  
Antigen Assay ◽  
Low Prevalence ◽  
Antigen Testing ◽  
Positive Results ◽  
Higher Sensitivity

This study was performed as a head-to-head comparison of the performance characteristics of (1) two SARS-CoV-2-specific rapid antigen assays with real-time PCR as gold standard as well as (2) a fully automated high-throughput transcription-mediated amplification (TMA) assay and real-time PCR in a latent class analysis-based test comparison without a gold standard with several hundred samples in a low prevalence “real world” setting. Recorded sensitivity and specificity of the NADAL and the LumiraDx antigen assays and the Hologic Aptima SARS-CoV-2 TMA assay were 0.1429 (0.0194, 0.5835), 0.7644 (0.7016, 0.8174), and 0.7157 (0, 1) as well as 0.4545 (0.2022, 0.7326), 0.9954 (0.9817, 0.9988), and 0.9997 (not estimable), respectively. Agreement kappa between the positive results of the two antigen-based assays was 0.060 (0.002, 0.167) and 0.659 (0.492, 0.825) for TMA and real-time PCR. Samples with low viral load as indicated by cycle threshold (Ct) values > 30 were generally missed by both antigen assays, while 1:10 pooling suggested higher sensitivity of TMA compared to real-time PCR. In conclusion, both sensitivity and specificity speak in favor of the use of the LumiraDx rather than the NADAL antigen assay, while TMA results are comparably as accurate as PCR, when applied in a low prevalence setting.

Latent class analysis for the diagnosis of Clostridioides difficile infection

2020 ◽  
Author(s):  
Cody P Doolan ◽  
Thomas Louie ◽  
Christopher Lata ◽  
Oscar E Larios ◽  
William Stokes ◽  
...  
Keyword(s):  
Latent Class Analysis ◽  
Real Time ◽  
Clinical Diagnosis ◽  
Real Time Pcr ◽  
Gold Standard ◽  
Latent Class ◽  
Fecal Calprotectin ◽  
Clostridioides Difficile ◽  
Toxigenic Culture ◽  
Clostridioides Difficile Infection

Abstract Background Clostridioides difficile infection (CDI) is an opportunistic disease that lacks a gold standard test. Nucleic acid amplification tests (NAATs) such as real-time PCR demonstrate excellent an limit of detection (LOD) whereas antigenic methods are able to detect free toxin. Latent class analysis (LCA) provides an unbiased statistical approach to resolving true disease. Methods A cross-sectional study was conducted with suspected CDI patients (n=96). Four commercial real-time PCR tests, toxin antigen detection by enzyme immunoassay (EIA), toxigenic culture, and fecal calprotectin were performed. CDI clinical diagnosis was determined by consensus majority of three experts. LCA was performed using laboratory and clinical variables independent of any gold standard. Results Six LCA models were generated to determine CDI probability using four variables including toxin EIA, toxigenic culture, clinical diagnosis, and fecal calprotectin levels. Three defined zones as a function of real-time PCR cycle threshold (Ct) were identified using LCA: CDI likely (>90% probability), equivocal (<90% and >10%), CDI unlikely (<10%). A single model comprising toxigenic culture, clinical diagnosis, and toxin EIA showed the best fitness. The following Ct cut-offs for four commercial test platforms were obtained using this model to delineate three CDI probability zones: [GeneXpert ® : 24.00, 33.61], [Simplexa ® 28.97, 36.85], [Elite MGB ® 30.18, 37.43], and [BD Max ™ 27.60, 34.26]. Conclusion The clinical implication of applying LCA to CDI is to report Ct values assigned to probability zones based on the commercial real-time PCR platform. A broad range of equivocation suggests clinical judgement is essential to the confirmation of CDI.

scholarly journals Challenges in laboratory diagnosis of Malaria in a low resource country among cases of acute febrile illness at tertiary care hospital in eastern Nepal: Comparative study on Conventional Vs Molecular approach

2020 ◽  
Author(s):  
Pragyan Dahal ◽  
Basudha Khanal ◽  
Keshav Rai ◽  
Vivek Kattel ◽  
Satish Yadav ◽  
...  
Keyword(s):  
Real Time ◽  
Sensitivity And Specificity ◽  
Malaria Elimination ◽  
Real Time Pcr ◽  
Gold Standard ◽  
Febrile Illness ◽  
Acute Febrile Illness ◽  
Low Resource ◽  
Elimination Programme ◽  
Low Resource Country

Abstract Background For ongoing malaria elimination programme, available methods like microscopy and rapid diagnostic test (RDT) are not able to detect all the cases of malaria in acute febrile illness. These methods are entirely dependent on the course of infection, parasite load and skilled technical resources thus the study was carried out to compare performance of microscopy and RDT which are commonly used in a low resource country along with reference to real-time PCR. Methods Altogether 52 blood samples collected from patients with acute febrile illness were tested by microscopy, RDT and real-time PCR. The results were compared in terms of sensitivity and specificity. Results The test results were as follows: 5.8% positivity by Microscopy, 13.5% positivity by RDT and 27% by real time PCR. Taking into consideration of PCR as a gold standard method microscopy showed 21.4% sensitivity and 100% specificity. Likewise, RDT results revealed 28.6% sensitivity and 92.1% specificity. Conclusion Despite of various diagnostic tools available, microscopy stills remains the gold standard for the diagnosis and RDT is the user friendly to execute the test under the tree, but our preliminary results emphasized the need to implement the test with the higher sensitivity and specificity in context of malaria elimination programme which could be another important opportunity to understand the parasite circulation in case of low endemic region. However, these results should be further verified with the large study cohort in order to document the submicroscopic infection.

scholarly journals Comparative Assessment of Sensitivity and Specificity of Rose Bengal Test and Modified In-house ELISA by using IS711 TaqMan Real Time PCR Assay as a Gold Standard for the Diagnosis of Bovine Brucellosis

2018 ◽  
Vol 11 (2) ◽  
pp. 951-957
Author(s):  
Amira M. Zakaria
Keyword(s):  
Positive Predictive Value ◽  
Real Time ◽  
Sensitivity And Specificity ◽  
Rose Bengal ◽  
Real Time Pcr ◽  
Predictive Value ◽  
Gold Standard ◽  
Bovine Brucellosis ◽  
Rt Pcr ◽  
Rose Bengal Test

Serological approaches such as Rose Bengal Test (RBT) and enzyme linked immunosorbent assay (ELISA) are common tests, however they are generally not sensitive or specific enough for diagnosis of Brucella because of cross-reactivity with different bacterial antigens. The work objected to evaluate the sensitivity and specificity of rose Bengal and modified in-house ELISA using IS711 real time PCR as a gold test to detect Brucella in calves sera. Two hundred and thirty (n=230) blood samples were collected from (2-3) years asymptomatic male calves in two Egyptian abattoirs. Rose Bengal test (RBT) and modified in-house ELISA were applied to determine the seroprevalence of brucellosis in abattoirs animals while quantitative Taqman real-time PCRs (RT-PCR) were implemented for the identification of Brucella genus. The overall prevalence of brucellosis was (53.9 %), (75.2 %) and (79.1 %) as determined by ELISA,RBT and RT- PCR assays respectively. Regarding statistical analysis of the reported data and considering real time PCR the gold standard, the RBT recorded a sensitivity of (79.12%) and a specificity of (39.58 %) with an accuracy of (70.87%). While (83.24%) was reported as positive predictive value and (33.33 %) as a negative predictive value. The sensitivity and specificity of ELISA were (55.49%) and (52.08 %) respectively while the accuracy was (54.78%). Positive predictive value and negative predictive value for ELISA were determined as (81.45%) and (23.58 %) respectively. RBT can be routinely used for diagnosis of Brucella as cost effective , more sensitive and accurate test than ELISA However, real time PCR is highly recommend as gold test for identification and differentiation of bovine brucellosis.

scholarly journals Comparison of two commercial and one in-house real-time PCR assays for the diagnosis of bacterial gastroenteritis

2020 ◽  
Vol 10 (4) ◽  
pp. 210-216
Author(s):  
Konstantin Tanida ◽  
Andreas Hahn ◽  
Hagen Frickmann
Keyword(s):  
Latent Class Analysis ◽  
Real Time ◽  
Real Time Pcr ◽  
Gold Standard ◽  
Latent Class ◽  
Class Analysis ◽  
Cohen's Kappa ◽  
Bacterial Gastroenteritis ◽  
Pcr Assays ◽  
Inter Assay Variation

AbstractIntroductionThe aim of the study was a comparative evaluation of in-house real-time PCR and commercial real-time PCR (Fast Track Diagnostics (FTD), ampliCube/Mikrogen) targeting enteropathogenic bacteria from stool in preparation of Regulation (EU) 2017/746 on in vitro diagnostic medical devices.MethodsBoth 241 stool samples from patients and 100 samples from German laboratory control schemes (“Ringversuche”) were used to comparatively assess in-house real-time PCR, the FTD bacterial gastroenteritis kit, and the ampliCube gastrointestinal bacterial panels 1&2 either with the in-house PCRs as gold standard and as a test comparison without gold standard applying latent class analysis. Sensitivity, specificity, intra- and inter-assay variation and Cohen’s kappa were assessed.ResultsIn comparison with the gold standard, sensitivity was 75–100% for strongly positive samples, 20–100% for weakly positive samples, and specificity ranged from 96 to 100%. Latent class analysis suggested that sensitivity ranges from 81.2 to 100% and specificity from 58.5 to 100%. Cohen’s kappa varied between moderate and nearly perfect agreement, intra- and inter-assay variation was 1–3 to 1–4 Ct values.ConclusionAcceptable agreement and performance characteristics suggested replaceability of the in-house PCR assays by the commercial approaches.

Isolation and identification of Marek’s disease virus (MDV) from feather follicle epithelium and internal organs of diseased chickens in Dakahlia Governorate, Egypt

2019 ◽  
Vol 20 (2) ◽  
pp. 6-11
Author(s):  
Aly El-Kenawy ◽  
Mohamed El-Tholoth ◽  
Emad A
Keyword(s):  
Real Time ◽  
Disease Virus ◽  
Real Time Pcr ◽  
Marek's Disease Virus ◽  
Marek's Disease ◽  
Marek’S Disease Virus ◽  
Marek’S Disease ◽  
Field Samples ◽  
Feather Follicle ◽  
Positive Results

In the present study, a total of 16 samples including feather follicle epithelium, ovary, spleen and kidney (4 samples for each organ) were collected from diseased chicken flocks suspected to be infected with Marek’s disease virus (MDV) at Dakahlia Governorate, Egypt during the period from October 2016 to October 2017. Each sample was pooled randomly from three to five birds (90 to 360 days old). The isolation of the suspected virus from the collected samples was carried out via chorioallantoic membranes (CAMs) of 12 days old embryonated chicken eggs (ECEs). Three egg passages were carried out for each sample. Hyperimmune serum was prepared against standard MDV. MDV in both field and egg passaged samples (after 3rd passage) was identified by agar gel precipitation test (AGPT) and indirect fluorescence antibody test (IFAT). Molecular identification of virus was carried out by conventional polymerase chain reaction (PCR) and real- time PCR in four selected samples. The results revealed that 14 samples (87.5%) including 4 (100%) samples from feather follicle epithelium, ovary and kidney and 2 (50%) samples from spleen, showed positive results in virus isolation after 3rd passage. The positive results percentage by AGPT for field samples were 50% (8 out of 16 samples), while after the 3rd passage in ECEs were 37.5% (6 out of 16 samples) and the positive results percentage by IFAT for field samples were 62.5% (10 out of 16 samples), while after the 3rd passage in ECEs were 81.25 % (13 out of 16 samples). Viral nucleic acid was detected in all selected samples by conventional and real- time PCR. The results indicate that feather follicle epithelium is the best organ for MDV detection. IFAT is superior over AGPT in virus detection. Conventional and real - time PCR could be efficiently used for molecular detection of the virus.

scholarly journals Comparative Assessment of In-House Real-Time PCRs Targeting Enteric Disease-Associated Microsporidia in Human Stool Samples

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 656
Author(s):  
Konstantin Tanida ◽  
Andreas Hahn ◽  
Kirsten Alexandra Eberhardt ◽  
Egbert Tannich ◽  
Olfert Landt ◽  
...  
Keyword(s):  
Real Time ◽  
Indigenous People ◽  
Real Time Pcr ◽  
Latent Class ◽  
Enterocytozoon Bieneusi ◽  
Enteric Disease ◽  
Immunosuppressed Patients ◽  
Study Population ◽  
Stool Samples ◽  
Pcr Assays

Microsporidiosis is an infection predominantly occurring in immunosuppressed patients and infrequently also in travelers. This study was performed to comparatively evaluate the diagnostic accuracy of real-time PCR assays targeting microsporidia with etiological relevance in the stool of human patients in a latent class analysis-based test comparison without a reference standard with perfect accuracy. Thereby, two one-tube real-time PCR assays and two two-tube real-time PCR assays targeting Enterocytozoon bieneusi and Encephalocytozoon spp. were included in the assessment with reference stool material (20), stool samples from Ghanaian HIV-positive patients (903), and from travelers, migrants and Colombian indigenous people (416). Sensitivity of the assays ranged from 60.4% to 97.4% and specificity from 99.1% to 100% with substantial agreement according to Cohen’s kappa of 79.6%. Microsporidia DNA was detected in the reference material and the stool of the HIV patients but not in the stool of the travelers, migrants, and the Colombian indigenous people. Accuracy-adjusted prevalence was 5.8% (n = 78) for the study population as a whole. In conclusion, reliable detection of enteric disease-associated microsporidia in stool samples by real-time PCR could be demonstrated, but sensitivity between the compared microsporidia-specific real-time PCR assays varied.

scholarly journals Evaluation of the New BD Max GC Real-Time PCR Assay, Analytically and Clinically as a Supplementary Test for the BD ProbeTec GC Qx Amplified DNA Assay, for Molecular Detection of Neisseria gonorrhoeae

2015 ◽  
Vol 53 (12) ◽  
pp. 3935-3937 ◽  
Author(s):  
Daniel Golparian ◽  
Stina Boräng ◽  
Martin Sundqvist ◽  
Magnus Unemo
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Real Time ◽  
Sensitivity And Specificity ◽  
Real Time Pcr ◽  
Molecular Detection ◽  
Analytical Sensitivity ◽  
Pcr Assay ◽  
Content Type ◽  
Dna Assay ◽  
Supplementary Test

The new BD Max GC real-time PCR assay showed high clinical and analytical sensitivity and specificity. It can be an effective and accurate supplementary test for the BD ProbeTec GC Qx amplified DNA assay, which had suboptimal specificity, and might also be used for initial detection ofNeisseria gonorrhoeae.

scholarly journals Comparison of the sensitivity and specificity of real-time PCR and in situ hybridization in HPV16 and 18 detection in archival cervical cancer specimens

2012 ◽  
Vol 50 (2) ◽  
pp. 239-247 ◽  
Author(s):  
Beata Biesaga ◽  
Sława Szostek ◽  
Małgorzata Klimek ◽  
Jerzy Jakubowicz ◽  
Joanna Wysocka
Keyword(s):  
Cervical Cancer ◽  
Real Time ◽  
Sensitivity And Specificity ◽  
Real Time Pcr
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