scholarly journals Gold-standard diagnostics are tarnished by lytic bacteriophage

2020 ◽  
Author(s):  
E.J. Nelson ◽  
J.A. Grembi ◽  
D.L. Chao ◽  
J.R. Andrews ◽  
L. Alexandrova ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
Gold Standard ◽  
Diagnostic Performance ◽  
Diarrheal Disease ◽  
Current Approach ◽  
Lytic Bacteriophage ◽  
Antibiotic Exposure ◽  
First Line ◽  
Negative Effect

ABSTRACTBackgroundA fundamental clinical and scientific concern is how lytic bacteriophage, as well as antibiotics, impact diagnostic positivity.MethodsCholera was chosen as a model disease to investigate this important question. Patients with diarrheal disease were enrolled at two remote hospitals in Bangladesh. Diagnostic performance was assessed as a function of lytic bacteriophage detection, as well as exposure to the first-line antibiotic azithromycin detected by mass spectrometry.ResultsAmong diarrheal samples positive by nanoliter quantitative PCR for Vibrio cholerae (n=78/849), the odds that a rapid diagnostic test (RDT) or qPCR was positive was reduced by 89% (OR 0.108; 95%CI 0.002-0.872) and 87% (OR 0.130; 95%CI 0.022-0.649) when lytic bacteriophage were detected, respectively. The odds that a rapid diagnostic test (RDT) or qPCR was positive was reduced by more than 99% (OR 0.00; 95% CI: 0.00-0.28) and 89% (OR 0.11; 95% CI: 0.03-0.44) when azithromycin was detected, respectively.ConclusionsEstimations of cholera burden may improve by accommodating for the negative effect of antimicrobial exposure on diagnostic positivity. Furthermore, the findings herein challenge our current approach to interpreting and developing bacterial diagnostics given variable rates of lytic bacteriophage and antibiotic exposure.

scholarly journals Development and evaluation of a new IgM/IgG rapid diagnostic test for SARS-CoV-2

2020 ◽  
Author(s):  
P.J. Ducrest
Keyword(s):  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
Gold Standard ◽  
Diagnostic Performance ◽  
Point Of Care ◽  
Negative Control ◽  
Simple Point ◽  
Rt Pcr ◽  
High Diagnostic Accuracy ◽  
Plasma Displays

AbstractThere is an urgent need in rapid diagnostic test (RDT) to detect antibodies against SARS-CoV-2. We have developed a rapid and simple point-of-care lateral flow immunoassay (LFIA) detecting IgM and IgG against SARS-CoV-2 in 10 minutes. The aim of this study is to evaluate the diagnostic performance of this RDT. RT-PCR positive plasma samples (n=35) for SARS-CoV-2 and 97 negative control samples were studied. Diagnostic performance of IgG/IgM RDT was assessed using both gold standard RT-PCR and Electro-chemiluminescence immunoassay (ECLIA) Elecsys® Anti-SARS-CoV-2 total Ig. Overall, RDT sensitivity was 100% (95% confidence interval [95%CI]: 88-100%) and specificity 93% (95% CI: 85-97%). This IgG/IgM RDT done in plasma displays a high diagnostic accuracy for SARS-CoV-2 IgG/IgM in high COVID-19 prevalence settings. Its use could be considered in the absence of routine diagnostic serology facilities for samples collected between 10 and 180 days after symptoms onset.

scholarly journals Performance evaluation of the Simtomax® CoronaCheck rapid diagnostic test

2020 ◽  
Author(s):  
P. J. Ducrest ◽  
A. Freymond ◽  
J.-M. Segura
Keyword(s):  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
Diagnostic Performance ◽  
High Sensitivity ◽  
High Specificity ◽  
Negative Control ◽  
List Type ◽  
Plasma Samples ◽  
Rt Pcr ◽  
Two Samples

AbstractThe aim of this study was to evaluate the diagnostic performance of Simtomax® CoronaCheck, a serology rapid diagnostic test (RDT) for the detection of IgG and IgM against SARS-CoV-2. 48 plasma samples positive for SARS-CoV-2 based on RT-PCR and 98 negative control samples were studied. Diagnostic performance of the IgG/IgM RDT was assessed against RT-PCR and the electro-chemiluminescence immunoassay (ECLIA) Elecsys® Anti-SARS-CoV-2 total Ig. Overall, the RDT sensitivity was 92% (95% confidence interval [95%CI]: 79-97), specificity 97% (95% CI: 91-99%), PPV 94% (95% CI: 81-98) and the NPV 96% (95% CI: 89-99). When considering only samples collected ≥ 15 days post-symptoms (DPS), the sensitivity increased to 98% (95%CI: 86-100) and the specificity was 97% (95% CI: 91-99%). Two samples with 180 DPS were still positive for IgG. Globally, this IgG/IgM RDT displayed a high diagnostic accuracy for SARS-CoV-2 IgG/IgM detection in plasma samples in high COVID-19 prevalence settings. It could be effectively used, in absence of facilities for routine diagnostic serology, for samples with a DPS between 15 and 180 days.Highlights–The rapid diagnostic test Simtomax CoronaCheck displays a high sensitivity of 98% and a high specificity of 97% for SARS-CoV-2 IgG/IgM detection in plasma samples after 15 days post-symptoms.–The rapid diagnostic test Simtomax CoronaCheck can detect SARS-CoV-2 antibodies in plasma up to 180 days after symptom onset.–The rapid diagnostic test Simtomax CoronaCheck could be effectively used as an alternative to serological analysis using laboratory facilities.

scholarly journals Gold Standard Cholera Diagnostics Are Tarnished by Lytic Bacteriophage and Antibiotics

2020 ◽  
Vol 58 (9) ◽  
Author(s):  
E. J. Nelson ◽  
J. A. Grembi ◽  
D. L. Chao ◽  
J. R. Andrews ◽  
L. Alexandrova ◽  
...  
Keyword(s):  
Pathogen Detection ◽  
Diarrheal Disease ◽  
Etiologic Agent ◽  
Lytic Bacteriophage ◽  
Negative Effects ◽  
First Line ◽  
Field Methods ◽  
Content Type ◽  
Stool Samples ◽  
Large Enrollment

ABSTRACT A fundamental, clinical, and scientific concern is how lytic bacteriophage, as well as antibiotics, impact diagnostic positivity. Cholera was chosen as a model disease to investigate this important question, because cholera outbreaks enable large enrollment, field methods are well established, and the predatory relationship between lytic bacteriophage and the etiologic agent Vibrio cholerae share commonalities across bacterial taxa. Patients with diarrheal disease were enrolled at two remote hospitals in Bangladesh. Diagnostic performance was assessed as a function of lytic bacteriophage detection and exposure to the first-line antibiotic azithromycin, detected in stool samples by mass spectrometry. Among diarrheal samples positive by nanoliter quantitative PCR (qPCR) for V. cholerae (n = 78/849), the odds that a rapid diagnostic test (RDT) or qPCR was positive was reduced by 89% (odds ratio [OR], 0.108; 95% confidence interval [CI], 0.002 to 0.872) and 87% (OR, 0.130; 95% CI, 0.022 to 0.649), respectively, when lytic bacteriophage were detected. The odds that an RDT or qPCR was positive was reduced by more than 99% (OR, 0.00; 95% CI, 0.00 to 0.28) and 89% (OR, 0.11; 95% CI, 0.03 to 0.44), respectively, when azithromycin was detected. Analysis of additional samples from South Sudan found similar phage effects on RDTs; antibiotics were not assayed. Cholera burden estimates may improve by accommodating for the negative effects of lytic bacteriophage and antibiotic exposure on diagnostic positivity. One accommodation is using bacteriophage detection as a proxy for pathogen detection. These findings have relevance for other diagnostic settings where bacterial pathogens are vulnerable to lytic bacteriophage predation.

scholarly journals Comparative Study of Malaria Diagnosis: Rapid Diagnostic Test (RDTs) Against Microscopy among Pregnant Women Attending Antenatal Clinic in Specialist Hospital, Sokoto

2021 ◽  
pp. 9-16
Author(s):  
K. Mohammed ◽  
M. U. Iduh ◽  
S. M. Saheed ◽  
O. F. Ashcroft ◽  
M. K. Garba ◽  
...  
Keyword(s):  
Comparative Study ◽  
Pregnant Women ◽  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
Study Design ◽  
Gold Standard ◽  
Malaria Parasite ◽  
Malaria Diagnosis ◽  
Sub Saharan Africa ◽  
Cross Sectional

Background: Malaria is an infectious disease caused by a protozoan parasite of the genus Plasmodium. It was estimated that 219 million cases of malaria occur in 87 countries, with an estimated death of 435,000 in 2017 among pregnant women. Other species include P. ovale, P. vivax, and P. malariae is a blood parasite of human and is one of the major public health burdens in developing countries, particularly in Sub-Saharan Africa. It is estimated that about 3.5 billion people globally and 450 million people are thought to be ill as a result of such infections, the majority being children. Aims: This study was aimed at comparing RDTs against microscopy in the detection of malaria parasite among pregnant women. Samples were collected and analyzed following cross-sectional comparative study design. It was conducted between Septembers to November 2019. Study Design: This was a cross-sectional, comparative study Place and Duration of Study: This study was conducted among patients attending Specialist Hospital Sokoto, Sokoto State, between March and November, 2019. Methodology: A total of 106 participants were enrolled for the study. Standard parasitological examination was carried out on blood samples using microscopy followed by Rapid Diagnostic test (RDTs). Results: Finding revealed, in this study, CareStart kit had sensitivity of 77.7%, specificity of 100s%. It is expected that any RDT used for malaria diagnosis should have a high sensitivity of 95% and specificity 97% (WHO, 2003); this is in contrast with the RDTs results in this study. The false negative (FN) Carestart and SD-Bioline kits in this study were 10% and 21%, respectively using microscopy as the gold standard due to lack of sensitivity of RDTs at low parsitaemia compared to microscopy. The false positive rate in this study for the Carestart and SD-Bioline kits are 0% and 0% respectively. Out of 106 patients screened, 35% and 24% tested positive for Plasmodiumfalciparum using Carestart and SD-Bioline RDTs respectively, while 45% were positive to malaria by microscopic examination. There was high prevalence of malaria parasite among age group 18-23 which is 42.2%. Conclusion: It can be concluded that using microscopy is more time consuming compared to RDTs due to the fact that the time taken to read the results for RDTs is within five minutes and that of microscopy is higher compared to RDTs. Over all prevalence of malaria by microscopy was 42.5% while the prevalence of malaria by Carestart and SD-bioline was 33% and 22.6% respectively. Conventional microscopy remains the gold standard compared to RDTs according to this study with the level of its sensitivity and specificity which is higher than RDTs.

scholarly journals Prevalence of Immunoglobulin G (IgG) Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and Evaluation of a Rapid MEDsan IgG Test in Children Seeking Medical Care

2020 ◽  
Author(s):  
Klara M Posfay-Barbe ◽  
Diego O Andrey ◽  
Julien Virzi ◽  
Patrick Cohen ◽  
Fiona Pigny ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Medical Care ◽  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
Infection Rate ◽  
Immunoglobulin G ◽  
Gold Standard ◽  
Igg Antibodies ◽  
Rt Pcr ◽  
Seropositivity Rate

Abstract In 208 children seeking medical care, the seropositivity rate of anti–SARS-CoV-2 IgG antibodies was 8.7%, suggesting an infection rate similar to that observed in adults but >100-fold the incidence of RT-PCR–confirmed pediatric cases. Compared with the gold-standard combined ELISA + immunofluorescence, the MEDsan IgG rapid diagnostic test performed accurately.

scholarly journals Evaluation of a SARS‐CoV‐2 antigen‐detecting rapid diagnostic test as a self‐test: diagnostic performance and usability

2021 ◽  
Author(s):  
Nino Guy Cassuto ◽  
Anne Gravier ◽  
Mathilda Colin ◽  
Aurelie Theillay ◽  
Daniela Pires‐Roteira ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
Diagnostic Performance ◽  
Self Test

scholarly journals Diagnostic performance of HRP2-only malaria rapid diagnostic test in Ghanaian pregnant women with asymptomatic peripheral blood infection: the case of First Response® test kit

2020 ◽  
Vol 1 (2) ◽  
pp. 86-92
Author(s):  
Joseph Osarfo ◽  
Harry Tagbor ◽  
Michael Alifragis ◽  
Pascal Magnuess
Keyword(s):  
Pregnant Women ◽  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
Peripheral Blood ◽  
Diagnostic Performance ◽  
False Negative ◽  
Malaria Rapid Diagnostic Test ◽  
First Response ◽  
Test Kit ◽  
In Pregnancy

Background: The use of malaria rapid diagnostic test(RDT) enables targeted treatment that mitigates against the development of parasite drug resistance. With detection thresholds at ≥200 parasites/μL, their diagnostic performance in pregnant women may be challenging as asymptomatic infections with low parasite densities are common. Few data exist on the performance of histidine-rich protein-2 (HRP2) RDTs in Ghanaian pregnant women considering commonly occurring low parasite densities. Objective: The study sought to contribute more knowledge on test performance on First Response® test kit to guide the continuous evaluation of HRP2 RDTs in pregnancy. Methods: As part of an antimalarial drug trial in pregnancy, First Response® RDT results were compared to microscopy of peripheral blood slides in 1664 women. The diagnostic performance indicators were computed as proportions with 95% confidence intervals. The risk of having a positive RDT result was computed for age, gravidity and parasite density using binomial regression methods. Results: Parasitaemia prevalence by microscopy was 5.71%(n =95/1664) while that by RDT was 21.57%(n = 359/1664). Sensitivity was 82.11% (n=78/95), specificity was 82.09% (n=1288/1569), positive predictive value was 21.73% (n=78/359), and the likelihood ratio for a positive test was 4.58. False-negative RDT results were recorded for low parasite densities as well as densities ≥ 200/ μL while false-positive results were recorded in 281of 1664 tests. Primigravidae and younger aged women were more likely to have positive RDT results compared to multigravidae and women aged ≥ 30 yr. Conclusion: The moderate sensitivity, specificity and other diagnostic parameters reported suggest the First Response® malaria RDT is useful for detecting peripheral parasitaemia in pregnant women but the use of HRP2-only RDTs is limited by the existence of parasites with HRP2 gene deletion. The use of RDTs based on combined antigens continues to be recommended. Further research is needed on RDT performance in pregnant women with declining malaria transmission.

scholarly journals Laboratory and Field Evaluation of the Crystal VC-O1 Cholera Rapid Diagnostic Test

2021 ◽  
Author(s):  
Amanda K. Debes ◽  
Kelsey N. Murt ◽  
Ethyl Waswa ◽  
Gerald Githinji ◽  
Mama Umuro ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
High Performance ◽  
Performance Metrics ◽  
Diarrheal Disease ◽  
Low Cost ◽  
Field Evaluation ◽  
Outbreak Detection ◽  
Case Definitions ◽  
Dipstick Test

Cholera is a severe acute, highly transmissible diarrheal disease which affects many low- and middle-income countries. Outbreaks of cholera are confirmed using microbiological culture, and additional cases during the outbreak are generally identified based on clinical case definitions, rather than laboratory confirmation. Many low-resource areas where cholera occurs lack the capacity to perform culture in an expeditious manner. A simple, reliable, and low-cost rapid diagnostic test (RDT) would improve identification of cases allowing rapid response to outbreaks. Several commercial RDTs are available for cholera testing with two lines to detect either serotypes O1 and O139; however, issues with sensitivity and specificity have not been optimal with these bivalent tests. Here, we report an evaluation of a new commercially available cholera dipstick test which detects only serotype O1. In both laboratory and field studies in Kenya, we demonstrate high sensitivity (97.5%), specificity (100%), and positive predictive value (100%) of this new RDT targeting only serogroup O1. This is the first field evaluation for the new Crystal VC-O1 RDT; however, with these high-performance metrics, this RDT could significantly improve cholera outbreak detection and improve surveillance for better understanding of cholera disease burden.

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