Rapid Antigen Detection Methods Research Articles

Ensuring diagnostic testing accuracy for patient care and public health- COVID-19 testing scale-up from an EQA provider's perspective.

In response to the coronavirus pandemic (COVID-19) and scale up of diagnostic testing, the Canadian Microbiology Proficiency Testing program created a new proficiency testing (PT) program for the molecular and antigen detection of SARS-CoV-2. The program was geared to point of care testing (POCT) sites located in each of the eight provincial Health Authorities across British Columbia, Canada, with the intention to monitor testing quality. The PT program consisted of 6 shipments in a year, each containing a set of 4 samples either positive for SARS-CoV-2 virus or negative. The program began with initial 23 sites enrolling in March 2021, expanding to >100 participants by December 2021. After the first two surveys, it was observed that testing performance (accuracy) was consistently acceptable for sites using nucleic acid technology (NAT), however performance by sites using rapid antigen detection (RAD) methods was poor, especially when testing the weakly positive samples. A root cause investigation of poor testing performance revealed gaps in the execution of testing methods and also in results interpretation. These quality issues were most commonly associated with new testers who lacked experience with diagnostic testing. Tester training and mentoring was reinforced as was retraining of personnel; sample processing instructions were modified, and a training video was also created for testing sites. As a result of these interventions, sites improved their testing accuracy and the performance of POCT sites using RAD methods came to more closely match the performance of sites utilizing NAT. Overall, the PT program was highly successfully and improved quality of testing in the province. This work demonstrates the critical value of an external quality assessment (EQA) partner towards improving patient and public health and safety, especially when testing is conducted outside of an accredited medical laboratory setting.

Comparative Study of Outcomes of COVID-19 Infection in Vaccinated and Unvaccinated Patients- A Retrospective Analysis

Introduction: Vaccine development was the highest priority during the Coronavirus disease 2019 (COVID-19) pandemic. An ideal vaccine should decrease the risk of infection and reduce the incidence and severity of the disease. Risk of disease or infection following COVID-19 vaccination needs to be evaluated for its efficacy and effectiveness. Aim: To compare the severity of the disease, oxygen requirement, and mortality between vaccinated and unvaccinated COVID-19 patients. Materials and Methods: This retrospective study was done on the data of the patients who were admitted to Nizams Institute of Medical Sciences. All the admitted patients with COVID-19 disease, diagnosed by either Reverse Transcriptase Polymerase Chain Reaction (RTPCR) or rapid antigen detection method from April 2021 to October 2021, were included. Parameters recorded were: age, gender, co-morbidities, clinical staging as per institute protocol, vaccination status, oxygen requirement, the requirement of non invasive or invasive ventilation, inflammatory markers like C-Reactive Protein (CRP), ferritin, D dimer, Computed Tomography (CT) severity index, and outcomes. Results: The mean age of patients was 49.7±14.8 yrs in the unvaccinated group, and 52.75±16.2 yrs in the vaccinated group. Out of 175 patients, 102 (58.28 %) were unvaccinated. There were 25 (14.28%) deaths, of which 20 (80%) were unvaccinated and 5 (20%) were vaccinated. Oxygen requirement was more among the unvaccinated 73/96 (76.04%). High flow oxygen / mechanical ventilation requirement was higher in unvaccinated compared to vaccinated, 38 (76%) vs 12 (24%) respectively (p-value <0.005). The mortality rate was higher in unvaccinated patients with co-morbidity, with an odds ratio of 3.32 (1.2-9.3), p-value=0.02. Serum ferritin levels were significantly higher in the unvaccinated group, 858.15±935.5 vs 473.4±663.2 ng/mL, p-value 0.007. CT severity index in the unvaccinated group was 13.82±5.4, and for the vaccinated group, it was 11.58±5.49. Conclusion: Severe disease, oxygen requirement, and mortality were low in vaccinated patients. Vaccination has also resulted in a statistically significant decrease in mortality in patients with co-morbidities. Serum ferritin levels were also found to be lower in vaccinated patients.

Dual ligand-induced photoelectrochemical sensing by integrating Pt/MoS2 heterostructure and Au polyhedra for sensitive detection of SARS-CoV-2

The continuous evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with discovery of multiple mutants, has caused widespread panic and concern worldwide. The rapid antigen detection method via a single ligand recognition, although currently implemented in many countries, remains challenging for mutated antigens. Herein, we present a novel strategy using a dual recognition by two types of targeted ligands, based on photoelectrochemical (PEC) sensing for detection of SARS-CoV-2 spike protein. To demonstrate this strategy, the specific antibodies are modified onto the photoactive material with a supported nanostructure, created by loading the Pt nanoparticles onto MoS2 nanosheets (Pt/MoS2) to boost photon-to-electricity conversion efficiency. By subsequent binding of the targeted aptamers to the Au polyhedra, which act as a signal amplifier to suppress PEC photocurrent by competing with the Pt/MoS2 for the absorption of excitation light energy, the dual recognition is successfully achieved. The constructed biosensor not only shows satisfactory stability, high sensitivity, and selectivity, but is effective for test of the pseudovirus of SARS-CoV-2. The work provides useful advance for the development of PEC biosensors for sensitive detection of SARS-CoV-2.

Peptide Binder with High-Affinity for the SARS-CoV-2 Spike Receptor-Binding Domain.

Rapid antigen detection tests are urgently needed for the early diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The discovery of a binder with high affinity and selectivity for the biomarkers presented by SARS-CoV-2 is crucial to the development of the rapid antigen detection method. We utilized the surface biopanning to identify a peptide binder R1 from a phage-displayed peptide library consisting of 109 independent phage recombinants. The R1 peptide exhibited high-affinity for specific binding with the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein with a dissociation constant KD of (7.5 ± 1.9) × 10–10 M, which maintained high binding affinity with the RBD derived from Gamma, Lambda, Delta, and Omicron variants. The composition and sequence dependence of binding characteristics in R1–RBD interactions was revealed by the binding affinity fluctuations between RBD and the scrambled sequences or single-site mutants of R1. The R1-functionalized gold nanoparticles possessed concentration-dependent response to RBD and selectivity over bovine serum albumin and human serum albumin. The peptide binder R1 shows the potential to be used for constructing a rapid detection method for the early-stage diagnostics for SARS-CoV-2.

Can a ‘3-tier Screening’ Strategy be Adopted during COVID-19 Pandemic for Safer Air Travel and to Help Curb its Spread Across Borders?

Since the appearance of SARS-CoV-2 in 2019, it spread quickly crossing geographical borders and thus affected almost the entire world. It was alarming to note its quick spread, which obviously was due to the increased frequency and ease of air travel in this era. Currently, many airlines (and countries too) have a prerequisite to have a negative COVID-19 RT-PCR test within 72 hrs. prior to boarding the flight. Although all the necessary precautions are strictly enforced during air travel, there is still a possibility that a person with a negative COVID-19 test (RT-PCR) around 72hrs prior to boarding the flight would have an infection and that the person would pass it on to fellow passengers on board and thus can further spread SARS-CoV-2 infection into the community if robust action is not initiated. There is also a subconscious apprehension among the passengers that co-passengers may have an infection on board. This is especially worrisome seeing the appearance of new variants recently. Here I present the logistics for a ‘3-tier screening’ protocol (1st test by RT-PCR within 72hrs of the flight schedule, 2nd test by rapid antigen detection method 1-5hrs prior to flight schedule, 3rd test post-arrival or to follow the destination country post-arrival protocol), which would at least provide an extra filter to separate the recently identified positive cases and thus prevent the spread of this threatening disease across the borders.

Comparative evaluation of different antigen detection methods for the detection of peste des petits ruminants virus

Peste des petits ruminants (PPR) is a fatal disease of small ruminants which has spread rapidly to previously PPR-free countries in recent decades, causing enormous economic losses in the affected regions. Here, two newly emerged PPR virus (PPRV) isolates from India and from the Middle East were tested in an animal trial to analyse their pathogenesis, and to evaluate serological and molecular detection methods. Animals infected with the two different PPRV isolates showed marked differences in clinical manifestation and scoring. The PPRV isolate from India was less virulent than the virus from the Middle East. Commercially available rapid detection methods for PPRV antigen (two Lateral Flow Devices (LFDs) and one antigen ELISA) were evaluated in comparison with a nucleic acid detection method. For this purpose, ocular and nasal swabs were used. Due to the easy non-invasive sampling, faecal samples were also analysed. For all rapid antigen detection methods, a high specificity of 100% was observed independent of the sample matrix and dilution buffers used. Both antigen ELISA and LFD tests showed highest sensitivities for nasal swabs. Here, the detection rate of the antigen ELISA, the LFD-PESTE-TEST and the LFD-ID Rapid-Test was 78%, 75% and 78%, respectively. Ocular swabs were less suitable for antigen detection of PPRV. These results reflect the increased viral load in nasal swabs of PPRV infected goats compared to ocular swabs. The faecal samples were the least suitable for antigen detection. In conclusion, nasal swab samples are the first choice for the antigen and genome detection of PPRV. Nevertheless, based on the excellent diagnostic specificity of the rapid tests, positive results generated with other sample matrices are solid. In contrast, negative test results can be caused on the reduced analytical sensitivity of the rapid antigen tests and must be treated with caution.

The clinical benefit of instituting a prospective clinical community-acquired respiratory virus surveillance program in allogeneic hematopoietic stem cell transplantation

BackgroundThere is a lack of studies comparing clinical outcomes among retrospective versus prospective cohorts of allogeneic stem cell transplant (allo-HCT) recipients with community acquired respiratory virus (CARV) infections. MethodsWe compare outcomes in two consecutive cohorts of allo-HCT recipients with CARV infections. The retrospective cohort included 63 allo-HCT recipients with 108 CARV infections from January 2013 to April 2016 who were screened and managed following standard clinical practice based on influenza and respiratory syncytial virus rapid antigen detection methods. The prospective cohort was comprised of 144 consecutive recipients with 297 CARV episodes included in a prospective interventional clinical surveillance program (ProClinCarvSur-P) based on syndromic multiplex PCR as first-line test from May 2016 to December 2018 at a single transplant center. ResultsCARV infections in the retrospective cohort showed more severe clinical features at the time of diagnosis compared to the prospective cohort (fever 83% vs. 57%, hospital admission 69% vs. 28% and lower respiratory tract 58% vs. 31%, respectively, p ≤ 0.002 for all comparisons). Antiviral therapy was more commonly prescribed in the prospective cohort (69 vs. 43 treated CARV episodes), particularly at the upper respiratory tract disease stage (34 vs. 12 treated CARV episodes). Three-month all-cause mortality was significantly higher in the retrospective cohort (n = 23, 37% vs. n = 10, 7%, p < 0.0001). Multivariate logistic regression analysis showed that recipients included in ProClinCarvSur-P had lower mortality rate [odds ratio 0.31, 95% confidence interval 0.12–0.7, p = 0.01]. ConclusionThis study report on outcome differences when reporting retrospective vs. prospective CARV infections after allo-HCT. Recipients included in a ProClinCarvSur-P had lower mortality.

Does Your “Backup” Method Have Your Back? Controversies Surrounding Backup of Rapid Antigen Detection Methods for Group A Streptococcus

AbstractAccurate diagnosis of streptococcal pharyngitis followed by appropriate antibiotic therapy is important for the prevention and control of group A streptococcus (GAS) infection and its sequelae. Rapid antigen detection methods (RADTs) for detection of GAS antigen are commonly used to speed the diagnosis of streptococcal pharyngitis; however, reports of false-negative antigen tests are common. In this review, we describe the conflicting strategies that surround GAS testing and reflexive backup testing for samples found to be negative for Streptococcus pyogenes antigen. We invite you to examine your GAS backup or reflexive testing strategy and ask yourself, “Does my laboratory's GAS backup method have my back?” More importantly, “Is reflexive testing designed to provide optimized diagnostic care for my patient population?”

A COMPARATIVE STUDY OF BLOOD SMEAR, QBC AND ANTIGEN DETECTION FOR DIAGNOSIS OF MALARIA

Background and Objectives: Rapid diagnosis is prerequisite for effective treatment and reducing mortality and morbidity of malaria. Microscopy has been the Gold standard for malaria diagnosis for decades. We made an attempt to compare blood smear, Quantitative Buffy Coat (QBC) and rapid antigen detection methods for the rapid diagnosis of malaria. Methods and Materials: A retrospective study was conducted for 6 months in G.G. Hospital, Jamnagar. A total number of 90 hospitalized clinically suspected malarial cases were collected and confirmed by conventional blood smear, QBC and antigen based Rapid Diagnostic Test (RDT). Blood smears were prepared and stained with Leishman stain. QBC and Rapid Diagnostic tests were done using commercially available kits. Patients were followed-up for signs of clinical recovery. Results: Malaria was diagnosed in 50, 54 and 59 patients by Leishman staining technique, QBC method and Rapid antigen detection test respectively. Sensitivity, specificity, positive and negative predictive values of Antigen detection test were 94%, 70% 79% and 90%, respectively while, those of QBC were 84%, 77%, 82% and 79%, respectively. The sensitivity of rapid diagnostic test is high with grade 3 and 4 parasitemia. Conclusion: In our study, rapid diagnostic tests were found more accurate than PBS and QBC. Microscopy is cost effective but microscopy and QBC requires technical expertise to interpret the results. In places where facilities are not available, rapid, simple and easy to interpret antigen detection test can be used, especially in endemic areas.

&#x0D; Rapid Detection of Respiratory Syncytial Virus (RSV) in Children with Acute Lower Respiratory Tract Infections: A Pilot Evaluation of an Immuno-Chromatographic Rapid Antigen Detection Method

&#x0D; Rapid Detection of Respiratory Syncytial Virus (RSV) in Children with Acute Lower Respiratory Tract Infections: A Pilot Evaluation of an Immuno-Chromatographic Rapid Antigen Detection Method

Diagnóstico etiológico de las infecciones respiratorias agudas de origen vírico en un hospital pediátrico de Gran Canaria

ObjetivoLas infecciones respiratorias agudas (IRA) de origen vírico son una causa frecuente de consulta y hospitalización pediátrica. El objetivo de este estudio fue conocer la etiología de dichas infecciones en la isla de Gran Canaria.MétodosDurante 3 años (de mayo de 2002 a mayo de 2005) se recogieron 1957 lavados nasofaríngeos de 1.729 niños atendidos en Urgencias con síntomas compatibles con IRA. En todas las muestras se realizó una técnica rápida de detección de antígeno de virus respiratorio sincitial (VRS) y, en las que se obtuvo resultado negativo, inmunofluorescencia (IF) y cultivo celular (CC).ResultadosLa mediana de edad fue de 2 meses (intervalo: 0,03-119). Se identificó el agente causal del cuadro respiratorio en 1.032 niños (59,7%). El VRS se detectó en 769 niños (74,5%). Los demás virus identificados, por orden de frecuencia, fueron: virus parainfluenza, rinovirus, adenovirus, virus de la gripe, enterovirus y coronavirus. Se encontraron diferencias estadísticamente significativas al comparar la edad y el tipo de virus detectado: los adenovirus fueron responsables de cuadros en niños de mayor edad (mediana: 6 meses; intervalo: 1-74). Hubo 6 casos de infección mixta. La sensibilidad de la IF en relación con el CC fue del 55,8%, y la especificidad del 99,2%.ConclusionesLos virus respiratorios son responsables de un alto número de casos de IRA, principalmente el VRS. Su identificación es determinante en el tratamiento clínico de los pacientes y en el empleo adecuado de antibacterianos y antivirales.

Laboratory diagnosis of respiratory virus infections in 24 hours by utilizing shell vial cultures.

Immunofluorescence staining of centrifugation-enhanced shell vial (SV) cultures for respiratory viruses (RV) after 24 h of incubation, rather than the more commonly prescribed times of 48 h and 5 days, allowed for the detection of 77% of the RV-positive specimens that would ordinarily not have been detected as positive until 48 h. Staining SVs at 24 h also permitted earlier detection of viruses that were missed by rapid antigen detection methods.

Evaluation of abbott TestPack RSV for the diagnosis of respiratory syncytial virus infections

Abbott TestPack RSV, a 20-minute enzyme immunoassay, is available for the rapid diagnosis of respiratory syncytial virus (RSV) infections. We have compared TestPack with a “gold standard” method of virus isolation in traditional tube cultures and shell vials to determine the sensitivity and specificity of this rapid method. Respiratory specimens were collected prospectively from 402 children and assayed by the rapid antigen detection method and isolation in culture. Virus was isolated by inculation of specimen in a total of eight tubes and 2–3 shell vials. Isolation of RSV was confirmed by characteristic cytopathic effect and immunofluorescence using monoclonal antibodies to RSV. Of the 402 specimens tested, there were only 18 discrepant results (seven TestPack-positive, culture-negative, and 11 TestPack-negative, culture-positive specimens). The sensitivity of TestPack RSV versus culture was 93.6% (162 of 173) and the specificity was 97.0% (222 of 229). Using a very rigorous culture system, we have obtained high values for the sensitivity and specificity of TestPack RSV. This assay is an excellent method for the rapid diagnosis of RSV infections in young children.

Diagnosing Streptococcal Pharyngitis

<h3>To the Editor.</h3> —The article entitled "Insensitivity of Rapid Antigen Detection Methods and Single Blood Agar Plate Culture for Diagnosing Streptococcal Pharyngitis" by Wegner and colleagues,¹while attempting to assist clinicians in management of group A streptococcal infections, unfortunately reaches unjustified conclusions without taking a number of important factors into consideration. First and most important, it is very difficult to believe that experienced microbiologists can find group A streptococci on only 58% of the plates after 24 hours and on only approximately 70% of the plates after 2 days. Even if there is an accepted discordance rate (one positive and one negative) of about 10% when using two swabs as shown in reference 8 of the article, this still indicates that those who read the single plates missed about 20%. This is unacceptably high for a laboratory. The authors could have attempted to explain this unexpected finding by performing

Insensitivity of rapid antigen detection methods and single blood agar plate culture for diagnosing streptococcal pharyngitis: Wegner DL, Witte DL, Schrantz RD JAMA 266:695–697 Feb 1992

Insensitivity of rapid antigen detection methods and single blood agar plate culture for diagnosing streptococcal pharyngitis: Wegner DL, Witte DL, Schrantz RD JAMA 266:695–697 Feb 1992

Insensitivity of rapid antigen detection methods and single blood agar plate culture for diagnosing streptococcal pharyngitis

Insensitivity of rapid antigen detection methods and single blood agar plate culture for diagnosing streptococcal pharyngitis

Diagnosis of Neisseria gonorrhoeae and Chlamydia trachomatis infections using antigen detection methods

Rapid antigen detection methods have great potential value in managing sexually transmitted gonococcal and chlamydial infections. Ideally, such tests should be rapid, technically simple, inexpensive, accurate, and applicable to all sites of infection commonly sampled (cervix, urethra, pharynx). For gonorrhea, the Gram stain fulfills these criteria in men with symptomatic urethritis, but lacks sensitivity when used at other sites or in asymptomatic patients. Antigen detection for gonorrhea would thus be of greatest value in 1) the diagnosis of gonococcal cervical infections in women with mucopurulent cervicitis or pelvic inflammatory disease, 2) the diagnosis of gonococcal proctitis in homosexual men, and 3) in situations requiring lengthy specimen transport. Because culture confirmation of Chlamydia trachomatis infections is not widely available, antigen detection tests could be of great value in management of these infections. Major uses include 1) confirming infection in women with cervicitis, endometritis, and pelvic inflammatory disease; 2) screening for asymptomatic infections in high risk groups of women; and 3) confirmation of Chlamydia trachomatis infections in infants and in adult males. The currently available methods for diagnosis of gonococcal and chlamydial infection by antigen detection are reviewed herein. Continued experience with antigen detection tests in well defined populations having high and low risk of gonococcal and chlamydial infection is needed to more fully determine how best to utilize these assays.