Rapid Detection Test Research Articles

Rapid detection of carbapenem resistance among gram-negative organisms directly from positive blood culture bottles

BackgroundCarbapenemase producing gram-negative bacteria (GNB) has become a huge problem in majority of tertiary care centers worldwide. They are associated with very high morbidity and mortality rates, especially when they cause invasive infections. Therefore, rapid detection of these organisms is very important for prompt and adequate antibiotic therapy as well as infection control. The aim of this study was rapid detection of carbapenemase genes and thereby likely carbapenem resistance, 24–48 hours in advance, directly from the positive-flagged blood culture bottles using CHROMagar and Xpert® Carba-R. MethodsAspirate from positively flagged blood culture bottles was subjected to differential centrifuge. All gram-negative bacilli on gram stain from the deposit were processed in Xpert® Carba-R and inoculated on CHROMagar. The presence of genes and growth on CHROMagar was compared with carbapenem resistance on VITEK-2 Compact. ResultsA total of 119 GNB isolates were processed. One or more of the carbapenemase genes were detected in 80 isolates. On comparison with VITEK-2 result, 92 samples showed concordance for carbapenem resistance 48 hours in advance. There was discordance in 21 isolates with 12 major errors and 09 minor errors. The sensitivity of direct Xpert® Carba-R test for rapid detection of carbapenem resistance, 48 hours in advance, was 81.42%. The sensitivity of direct CHROMagar test for accurate detection of carbapenem resistance, 24 hours in advance, was 92.06%. ConclusionThe ability to detect carbapenem resistance with very high accuracy, 48 hours in advance, helps in appropriate antibiotic therapy and implementation of effective infection control practices.

Evaluación de la prueba diagnóstica de detección rápida de antígeno de covid-19 (Panbio Covid rapid test) en atención primaria

ObjectiveCOVID-19 infection requires early diagnosis, with PCR being the gold standard test. The protocols advocate the use of rapid antigenic tests that require evaluation in actual clinical practice. The objective was to evaluate the diagnostic test for rapid antigen detection, Panbio Covid rapid test, compared with PCR, in patients with symptoms of 5 or less days of evolution and with a high-suspicion of infection by COVID-19 in a health center. Materials and methods103 patients over 14 years of age who attended an urban health center located in the Usera District of Madrid, with high-suspicion of COVID-19 infection, in the first 5 days of evolution from the onset of symptoms during the month of November 2020. Interventions: diagnostic tests for COVID-19 are performed: antigen and PCR. ResultsThe prevalence of the disease was 24.3% according to the PCR test and 17.5% according to the rapid antigenic test. The sensitivity was 72% (95% CI: 54.3–89.6%). The specificity was 100%. The positive and negative predictive values were 100% and 91.8% respectively. In the bivariate analysis, there was no relationship between symptoms and the presence of disease, except for myalgias (p=0.030). The multivariate analysis found a relationship between cough, dyspnea, fever, myalgia, anosmia/ageusia, and ocular symptoms and the presence of disease. ConclusionsThe sensitivity and specificity for the Panbio rapid antigen test are similar to other studies performed in primary care. In high-prevalence of disease and with highly suspected symptoms, positive test results can be considered definitive, but negative results will require confirmation. Myalgia, fever, dyspnea, anosmia/ageusia, and ocular symptoms may be more related to the presence of COVID-19.

Optimization of the rapid carbapenem inactivation method for use with AmpC hyperproducers.

Detection of carbapenemase-producing Enterobacterales (CPEs) is sometimes difficult with AmpC-hyperproducing Enterobacterales (AHEs), as they may falsely be classified as CPEs. Here, we present a rapid Carbapenem Inactivation Method (rCIM) optimized for AmpC producers (rCIM-A) that allows rapid and easy discrimination between AHEs and CPEs. Enterobacterales (n = 249), including natural AmpC producers, AHEs, CPEs and non-carbapenemase-producing carbapenem-resistant control strains were evaluated, using Carba NP, rCIM and rCIM-A. The rCIM-A differs from the rCIM by the addition of cloxacillin (400 μg/mL) to the initial antibiotic incubation step. The rCIM-A yielded a sensitivity and specificity of 84.26% (95% CI: 76.00%-90.55%) and 99.29% (95% CI: 96.11%-99.98%), respectively, while those of the rCIM were 86.11% (95% CI: 78.13%-92.01%) and 80.85% (95% CI: 73.38%-86.99%), respectively; those of Carba NP were lower at 84.04% (95% CI: 75.05%-90.78%) and 91.37% (95% CI: 85.41%-95.46%), respectively, due to indeterminate results. The rCIM-A was capable of discriminating between AHEs and true CPEs, but still failed to identify OXA-23-producing Proteus mirabilis isolates and remained only partially reliable for identifying IMI-like producers and a few MBL (2 NDM-1, 1 LMB-1, 1 TMB-1 and 1 IMP-13) producers. One chromosomally encoded AmpC variant, MIR-10, gave repeatedly positive results using all three tests and was thus considered a false positive. Specificity for AHEs greatly improved with the rCIM-A without altering the test performance for the other resistance mechanisms. It may replace the rCIM as a cheap, easy, rapid and accurate CPE detection test.

Laboratory Evaluation of Hepatitis C Virus Infection in Patients Undergoing Hemodialysis from North East India

Subjects undergoing hemodialysis have enhanced vulnerability to hepatitis C virus (HCV) infection due to invasive procedures and poor infection control practices. Early detection and treatment are essential to prevent cross-infection and mortality/morbidity. However, common use anti-HCV antibody tests lack the necessary accuracy, and alternative tests (e.g. core antigen detection kits) which are available need to be examined as a viable alternative. A total of 270 continuous serum samples were collected from patients undergoing dialysis within 15 months of study period. Sequentially, multiple tests were performed - immunochromatography-based rapid test, third-generation ELISA i.e. (anti-HCV antibody detection), fourth-generation ELISA (HCV antigen-antibody combined detection assay), and HCV RNA quantitative real time polymerase chain reaction (qPCR) assay. Diagnostic parameters of serological kits were compared in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and so on. Statistical Package for the Social Sciences was used. HCV-combined core antigen-antibody assays performed better than other serological assays in reference to the gold standard HCV RNA. This fourth-generation assay yielded a Kappa value of 0.947 compared with the value of 0.747 and 0.619 for anti-HCV ELISAand rapid detection test. Other parameters such as sensitivity, specificity, PPV, NPV, and so on were also better for fourth-generation ELISA compared with third-generation ELISA and other serological assays. HCV RNA was negative in 7.3% of anti-HCV-positive patients and was detected in 11.4% of anti-HCV ELISA-negative patients. In about 1.6% of HCV RNA-positive cases, fourth-generation ELISA was negative and had low HCV viral load (650 IU/ml and below). Fourth generation ELISA detected additional 7.4% HCV positive cases (compared to third generation kits) and upon cost effective analyis, additional cost to be bear for the better detection (by fourth generation kit) was found to be only INR 27 per 1% increased case detection. In resource scant setup, screening and follow-up of patients undergoing hemodialysis can be performed by fourth-generation HCV ELISA (antigen-antibody combined assay) instead of the current practice of anti-HCV antibody ELISA. Better yield in detection rate will compensate for slight addition to costs.

Electrochemical Immuno-Biosensors on Nanostructured Electrodes for Rapid Sensitive Detection of Disease Biomarkers

Development of rapid tests for quantitative detection of analytes in complex matrices, plays an important role in medical diagnostics, prognostics and therapeutics. Current methods for molecular diagnostics are time-consuming and multiple-step reliant on well-trained technicians and fully-equipped laboratories to provide quantitative detection of biomarkers. In this case, the challenges to overcome the sensitivity and selectivity of working directly in biological fluids in a timely manner have always been the main step for the development of such rapid tests.Electrochemical sensors, analogous to glucometer, are known to be rapid with the ability to provide direct electronic signal without any interference from the biological phenomena. When functionalized with specific biological substances, they intend to provide the required specificity in addition to signal selectivity in biological fluids. Inspired by nature, we design biorecognition probes that are combined with newest advancement in the engineering for the development of electrochemical immune-biosensors. These molecular recognition probes are designed using the ability of antibodies to bind antigens, and DNA construct to hybridize to the complementary construct, to create specificity for direct detection in complex media. On the other hand, we rely on the innovative approaches in nanomaterials, surface sciences, and self-assembly techniques to improve the conductivity and sensitivity of electrode surface. This includes the incorporation of high-curvature nanostructured microelectrodes that helps with the efficiency of molecular interactions at the surface and the transfer of electrons for the ease of signal transduction.In this regard, we fabricate small-scale nanostructured electrodes and engineer the surface for the immobilization of the biomolecular monolayer at the interface to provide the desired specificity for biomarkers in real biological samples, e.g. whole blood. We adapted our nano-bio-sensors for translational applications such as (1) at-line monitoring of signaling proteins in hematopoietic stem cell expansion, (2) rapid diagnosis of pathogenic infections through quantitative detection of antibodies directly in patient samples, and (3) rapid diagnosis of inner ear disorders based on the detection of blood biomarkers. We showed that our electrochemical immune-biosensors are capable of detecting at therapeutic concentrations with tunable ranges while performing in a 10 µL sample within less than 30 minutes.

Real-world assessment of Fluorecare SARS-CoV-2 Spike Protein Test Kit.

Since commercial SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antigen rapid detection tests (Ag-RDTs) display broad diagnostic efficiency, this study aimed to evaluate the clinical performance of Fluorecare SARS-CoV-2 Spike Protein Test Kit in a real-life scenario. The study population consisted of a series of patients undergoing SARS-Cov-2 diagnostic testing at Pederzoli Hospital of Peschiera del Garda (Verona, Italy). A nasopharyngeal swab was collected upon hospital admission and assayed with molecular (Altona Diagnostics RealStar® SARSCoV-2 RT-PCR Kit) and antigen (Fluorecare SARS-CoV-2 Spike Protein Test Kit) tests. The study population consisted of 354 patients (mean age, 47±20 years; 195 women, 55.1%), 223 (65.8%) positive at molecular testing. A significant correlation was found between Fluorecare SARS-CoV-2 Spike Protein Test Kit and Altona (both S and E genes: r=-0.75; p<0.001). The cumulative area under the curve in all nasopharyngeal samples was 0.68. At≥1.0S/CO manufacturer's cut-off, the sensitivity, specificity, negative and positive predictive values were 27.5, 99.2, 41.5 and 98.5%, respectively. Considerable improvement of sensitivity was observed as Ct values decreased, becoming 66.7% in samples with mean Ct values <30, 90.5% in those with mean Ct values <25, up to 100% in those with mean Ct values <20. The modest sensitivity and negative predictive value of Fluorecare SARS-CoV-2 Spike Protein Test Kit makes unadvisable to use this assay as surrogate of molecular testing for definitively diagnosing SARS-CoV-2 infection, though its suitable sensitivity at high viral load could make it a reliable screening test for patients with higher infective potential.

The burden of active infection and anti-SARS-CoV-2 IgG antibodies in the general population: Results from a statewide sentinel-based population survey in Karnataka, India

ObjectiveTo estimate the burden of active infection and anti-SARS-CoV-2 IgG antibodies in Karnataka, India, and to assess variation across geographical regions and risk groups. MethodsA cross-sectional survey of 16,416 people covering three risk groups was conducted between 3–16 September 2020 using the state of Karnataka’s infrastructure of 290 healthcare facilities across all 30 districts. Participants were further classified into risk subgroups and sampled using stratified sampling. All participants were subjected to simultaneous detection of SARS-CoV-2 IgG using a commercial ELISA kit, SARS-CoV-2 antigen using a rapid antigen detection test (RAT) and reverse transcription-polymerase chain reaction (RT-PCR) for RNA detection. Maximum-likelihood estimation was used for joint estimation of the adjusted IgG, active and total prevalence (either IgG or active or both), while multinomial regression identified predictors. ResultsThe overall adjusted total prevalence of COVID-19 in Karnataka was 27.7% (95% CI 26.1–29.3), IgG 16.8% (15.5–18.1) and active infection fraction 12.6% (11.5–13.8). The case-to-infection ratio was 1:40 and the infection fatality rate was 0.05%. Influenza-like symptoms or contact with a COVID-19-positive patient were good predictors of active infection. RAT kits had higher sensitivity (68%) in symptomatic people compared with 47% in asymptomatic people. ConclusionThis sentinel-based population survey was the first comprehensive survey in India to provide accurate estimates of the COVID-19 burden. The findings provide a reasonable approximation of the population immunity threshold levels. Using existing surveillance platforms coupled with a syndromic approach and sampling framework enabled this model to be replicable.

A rapid test for the environmental detection of pigeon antigen

IntroductionAvoidance of inhaled bird antigens is essential to prevent hypersensitivity pneumonitis disease progression. The aim of the present study was to develop a sandwich enzyme link immunoassay (ELISA) and an immunochromatographic test (ICT) and compare their ability to detect pigeon antigens in environmental samples. MethodsAn amplified sandwich ELISA using pigeon serum as a calibration standard and a ICT using gold-labeled anti-pigeon serum antibodies for the rapid detection of pigeon antigens in environmental samples were developed. Twenty-two different airborne samples were collected and analysed using both methods. Strip density values obtained with ICT were calculated and compared with the concentrations determined by the ELISA method for pigeon antigens. Strips results were also visually analysed by five independent evaluators. ResultsThe ELISA method to quantify pigeon antigen had a broader range (58.4 and 10,112.2 ng/ml), compared to the ICT assay (420 to 3360 ng/ml). A kappa index of 0.736 (p < 0.0001) was obtained between the observers evaluating the ICT strips. The results of the ELISA and the relative density of the ICT showed a highly significant correlation (rs:0.935; p < 0.0001). Bland-Altman plot also confirmed excellent agreement between the two methods (mean difference: −1.626; p < 0.0001). ConclusionsSince there was a good correlation between both assays, we can conclude that the rapid and simple ICT assay is a good and valid alternative, which does not require expensive equipment, for the validated ELISA technique.

Cas12a and Lateral Flow Strip-Based Test for Rapid and Ultrasensitive Detection of Spinal Muscular Atrophy.

Spinal muscular atrophy (SMA) is characterized by severe lethality and irreversible progression. Early diagnosis of SMA is of more practical significance with the emergence of effective therapy. However, existing techniques to identify SMA patients rely on cumbersome instruments, hindering their accessibility and application. An SMA-Cas12a-strip assay was developed with the integration of Cas12a-based nucleic acid detection, isothermal amplification, and lateral flow strip. The analytical performance of the assay was assessed with clinical samples. To explore its extensible utility, various specimens were tested. Validated with 168 clinical samples, the sensitivity and specificity of the SMA-Cas12a-strip assay were both 100%. The minimum detectable concentration of genomic DNA containing the target gene achieved 526 aM. The assay was compatible with specimens from several sources, and the turnaround time could be within 1.5 h. We developed a simple, cost-effective, and highly sensitive and specific assay to detect SMA patients. With little and field-portable equipment, the assay holds great promise in the detection of SMA patients, particularly in low-resource regions.

Peste des Petits Ruminants Virus Infection at the Wildlife-Livestock Interface in the Greater Serengeti Ecosystem, 2015-2019.

Peste des petits ruminants (PPR) is a viral disease of goats and sheep that occurs in Africa, the Middle East and Asia with a severe impact on livelihoods and livestock trade. Many wild artiodactyls are susceptible to PPR virus (PPRV) infection, and some outbreaks have threatened endangered wild populations. The role of wild species in PPRV epidemiology is unclear, which is a knowledge gap for the Global Strategy for the Control and Eradication of PPR. These studies aimed to investigate PPRV infection in wild artiodactyls in the Greater Serengeti and Amboseli ecosystems of Kenya and Tanzania. Out of 132 animals purposively sampled in 2015–2016, 19.7% were PPRV seropositive by ID Screen PPR competition enzyme-linked immunosorbent assay (cELISA; IDvet, France) from the following species: African buffalo, wildebeest, topi, kongoni, Grant’s gazelle, impala, Thomson’s gazelle, warthog and gerenuk, while waterbuck and lesser kudu were seronegative. In 2018–2019, a cross-sectional survey of randomly selected African buffalo and Grant’s gazelle herds was conducted. The weighted estimate of PPRV seroprevalence was 12.0% out of 191 African buffalo and 1.1% out of 139 Grant’s gazelles. All ocular and nasal swabs and faeces were negative by PPRV real-time reverse transcription-polymerase chain reaction (RT-qPCR). Investigations of a PPR-like disease in sheep and goats confirmed PPRV circulation in the area by rapid detection test and/or RT-qPCR. These results demonstrated serological evidence of PPRV infection in wild artiodactyl species at the wildlife–livestock interface in this ecosystem where PPRV is endemic in domestic small ruminants. Exposure to PPRV could be via spillover from infected small ruminants or from transmission between wild animals, while the relatively low seroprevalence suggests that sustained transmission is unlikely. Further studies of other major wild artiodactyls in this ecosystem are required, such as impala, Thomson’s gazelle and wildebeest.

Engineered NS1 for Sensitive, Specific Zika Virus Diagnosis from Patient Serology.

Dengue virus (DENV) and Zika virus (ZIKV) belong to the Flaviviridae family of viruses spread by Aedes aegypti mosquitoes in tropical and subtropical areas. Accurate diagnostic tests to differentiate the 2 infections are necessary for patient management and disease control. Using characterized ZIKV and DENV patient plasma in a blind manner, we validated an ELISA and a rapid immunochromatographic test for ZIKV detection. We engineered the ZIKV nonstructural protein 1 (NS1) for sensitive serologic detection with low cross reactivity against dengue and developed monoclonal antibodies specific for the ZIKV NS1 antigen. As expected, the serologic assays performed better with convalescent than acute plasma samples; the sensitivity ranged from 71% to 88%, depending on the performance of individual tests (IgM/IgG/NS1). Although serologic tests were generally less sensitive with acute samples, our ZIKV NS1 antibodies were able to complement the serologic tests to achieve greater sensitivity for detecting early infections.

COVID-19, deployment of antigenic tests in EHPAD

During the second epidemic wave of COVID-19 in the fall of 2020, residents of accommodation facilities for dependent elderly people were not totally confined. They were able to continue to receive visits from their families under a strict health protocol. But these facilities are very fragile, and many have been affected. The marketing of rapid detection tests for severe acute respiratory syndrome coronavirus 2 using an antigenic method has made it possible to carry out massive screening campaigns for staff in these facilities since the beginning of November.

Utility of Antigen-Based Rapid Diagnostic Test for Detection of SARS-CoV-2 Virus in Routine Hospital Settings.

ObjectiveThis study aims to evaluate the performance of an antigen-based rapid diagnostic test (RDT) for the detection of the SARS-CoV-2 virus. MethodsA cross-sectional study was conducted on 677 patients. Two nasopharyngeal swabs and 1 oropharyngeal swab were collected from patients. The RDT was performed onsite by a commercially available immune-chromatographic assay on the nasopharyngeal swab. The nasopharyngeal and oropharyngeal swabs were examined for SARS-CoV-2 RNA by real-time reverse-transcription quantitative polymerase chain reaction (RT-qPCR) assay. ResultsThe overall sensitivity of the SARS-CoV-2 RDT was 34.5% and the specificity was 99.8%. The positive predictive value and negative predictive value of the test were 96.6% and 91.5%, respectively. The detection rate of RDT in RT-qPCR positive results was high (45%) for cycle threshold values <25. ConclusionThe utility of RDT is in diagnosing symptomatic patients and may not be particularly suited as a screening tool for patients with low viral load. The low sensitivity of RDT does not qualify its use as a single test in patients who test negative; RT-qPCR continues to be the gold standard test.

IFCC interim guidelines on rapid point-of-care antigen testing for SARS-CoV-2 detection in asymptomatic and symptomatic individuals.

With an almost unremittent progression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections all around the world, there is a compelling need to introduce rapid, reliable, and high-throughput testing to allow appropriate clinical management and/or timely isolation of infected individuals. Although nucleic acid amplification testing (NAAT) remains the gold standard for detecting and theoretically quantifying SARS-CoV-2 mRNA in various specimen types, antigen assays may be considered a suitable alternative, under specific circumstances. Rapid antigen tests are meant to detect viral antigen proteins in biological specimens (e.g. nasal, nasopharyngeal, saliva), to indicate current SARS-CoV-2 infection. The available assay methodology includes rapid chromatographic immunoassays, used at the point-of-care, which carries some advantages and drawbacks compared to more conventional, instrumentation-based, laboratory immunoassays. Therefore, this document by the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) Taskforce on COVID-19 aims to summarize available data on the performance of currently available SARS-CoV-2 antigen rapid detection tests (Ag-RDTs), providing interim guidance on clinical indications and target populations, assay selection, and evaluation, test interpretation and limitations, as well as on pre-analytical considerations. This document is hence mainly aimed to assist laboratory and regulated health professionals in selecting, validating, and implementing regulatory approved Ag-RDTs.

Evaluation of 32 rapid tests for detection of antibodies against SARS-CoV-2

AimsTo evaluate the analytical performance of 32 rapid tests for detection of antibodies against coronavirus SARS-CoV-2. Materials and methodsWe used at total of 262 serum samples (197 pre-pandemic and 65 convalescent COVID-19), and three criteria to evaluate the rapid tests under standardized and optimal conditions: (i) Immunoglobulin G (IgG) specificity “good” if lower limit of the 95% confidence interval was ≥ 97.0%, “acceptable” if point estimate was ≥ 97.0%, otherwise “not acceptable”. (ii) IgG sensitivity “good” if point estimate was ≥ 90.0%, “acceptable” if ≥ 85.0%, otherwise “not acceptable”. (iii) User-friendliness “not acceptable” if complicated to perform or difficult to read result, otherwise “good”. We also included partial evaluations of three automated immunoassay systems. ResultsSensitivity and specificity varied considerably; IgG specificity between 90.9% (85.9–94.2) and 100% (97.7–100.0), and IgG sensitivity between 53.8% (41.9–65.4) and 98.5% (91.0–100.0). Combining our evaluation criteria, none of the 28 rapid tests that detected IgG had an overall performance considered “good”, seven tests were considered “acceptable”, while 21 tests were considered “not acceptable”. Four tests detected only total antibodies and were not given an overall evaluation. IgG sensitivity and/or specificity of the automated immunoassays did not exceed that of many rapid tests. ConclusionWhen prevalence is low, the most important analytical property is a test’s IgG specificity, which must be high to minimize false positive results. Out of 32 rapid tests, none had a performance classified as “good”, but seven were classified as “acceptable”.

Acute Hepatopancreases Necrosis Diseases (AHPND) as Challenging Threat in Shrimp

White feces syndrome (WFS) is an emerging problem for penaeid shrimp farming industries in South East Asia countries. Outbreaks began in cultivated shrimp Penaeus (Penaeus) monodon, and Penaeus (Litopenaeus) vannamei and spread progressively worldwide, although the disease's cause was unknown. In 2011 a case definition for AHPND (as acute hepatopancreatic necrosis diseases) and white fecal syndrome (WFS) were reported. The presence of white feces floating on water and clinical symptoms include pale empty gut region, reduced growth, movable shell, and black discoloration. The pacific white shrimp, Litopenaeus vannamei, with the major shrimp cultivable species globally, is currently in danger by a severe disease- WFS, which causes serious losses worldwide. It has been confirmed that the causative agent of WFS/AHPND is a bacterium that is a pathogen - probably Vibrio parahaemolyticus. This bacterium currently reported has acquired plasmids that encode lethal binary toxins PirA/PirB causing rapid death of infected shrimp. Additionally, this plasmid acquired some virulence factor which is directly related to pathogenicity. Further rapid diagnostic tests for early detection of WFS/AHPND pathogens will promote the production of hatchery and pond maintenance and contribute to the long-term explication of the disease's various aspects.

Evaluation of the diagnostic accuracy of a hemoglobin S and C screening test: Sickle Scan

New tools for the rapid diagnosis of hemoglobinosis could encourage the extension of their screening in Africa. Our goal was to assess the analytical performances of a rapid hemoglobin S and C detection test, the Sickle Scan. This was a cross-sectional study carried out in March 2019 at the Yopougon Teaching Hospital. The subjects followed for hemoglobinosis as well as the subjects seeking out an electrophoresis of their hemoglobin were included. We carried out the hemogram, the electrophoresis of hemoglobin at alkaline pH (reference method) coupled with the metabisulfite sickling test (Emmel test) and the rapid detection test to be evaluated. This immunochromatographic test is capable of detecting hemoglobins A, S, and C, and to infer the hemoglobin phenotype from there. The study recruited 191 individuals. The test detected hemoglobins S and C with a sensitivity of 99.4% and 97.7% respectively; a specificity of 93.3% and 99.3%. The positive likelihood ratio for hemoglobins S and C was 15 and 144 respectively. The negative likelihood ratio was 0.01 for hemoglobin S, and 0.02 for hemoglobin C. The intrinsic characteristics obtained make this test an interesting screening tool for hemoglobinosis S and C. &#x0D; Keywords: Diagnostic test, hemoglobinosis, Abidjan, sensitivity, specificity.

Avoiding Over-indication for Surgical Debridement Using a Rapid Antigen Detection Test of Group A Streptococcus.

Avoiding Over-indication for Surgical Debridement Using a Rapid Antigen Detection Test of Group A Streptococcus.

Accuracy of Serological And Stool Antigen Tests (non-invasive) for Detection of H. Pylori

Background &nbsp;Helicobacter pylori is a major bacterial causative pathogen of various gasto-doudenal diseases, including chronic gastritis, peptic ulcer disease (PUD), gastric cancer, and mucosa-associated lymphoid tissue lymphoma. The prevalence of H. pylori is about 50% worldwide and could reach more than 70% in developing countries. The aim of the present study was to&nbsp; evaluate the diagnostic accuracy of both serological and stool antigen tests comparing &nbsp;with rapid urease test for detection of H. pylori. Methods A 114 patients with gastroduodenal disorders&nbsp;aged 20- 60 years were&nbsp;&nbsp; recruited in this study. Endoscopic biopsy was obtained from each patient at endoscopic unite in the Al Sader Hospital, Basrah/Iraq. All biopsies were used for rapid urease test. Three ml. of venous blood were collected from each patient and used for serological test.&nbsp; Stool samples were collected and used for detection of H.pylori Ag. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and area of these under receiver operating characteristic (ROC) curve for detection H.pylori Ag/antibody tests were determined using rapid urease test as gold standard method. Result The results showed that the sensitivity of H. pylori Ag and serological test&nbsp;&nbsp; were (92.6%, 69%), specificity (69.9%, 63.6%), positive predictive value (98.6 %, 82%)&nbsp; negative predictive value (84%, 45.6%) accuracy (93.8%, 67%) and area under ROS (0.9-0.996, 0.664-0.776) respectively. Conclusion: Stool antigen test is more reliable test for detection H. pylori in comparison to rapid urease test.

A haemagglutination test for rapid detection of antibodies to SARS-CoV-2

Serological detection of antibodies to SARS-CoV-2 is essential for establishing rates of seroconversion in populations, and for seeking evidence for a level of antibody that may be protective against COVID-19 disease. Several high-performance commercial tests have been described, but these require centralised laboratory facilities that are comparatively expensive, and therefore not available universally. Red cell agglutination tests do not require special equipment, are read by eye, have short development times, low cost and can be applied at the Point of Care. Here we describe a quantitative Haemagglutination test (HAT) for the detection of antibodies to the receptor binding domain of the SARS-CoV-2 spike protein. The HAT has a sensitivity of 90% and specificity of 99% for detection of antibodies after a PCR diagnosed infection. We will supply aliquots of the test reagent sufficient for ten thousand test wells free of charge to qualified research groups anywhere in the world.