Integration of Group A Streptococcus Rapid Tests with the Open Fluidic CandyCollect Device.

The CandyCollect device is a lollipop-inspired open fluidic oral sampling device designed to provide a comfortable user sampling experience. We demonstrate that the CandyCollect device can be coupled with a rapid antigen detection test (RADT) kit designed for Group A Streptococcus (GAS). Through in vitro experiments with pooled saliva spiked with Streptococcus pyogenes we tested various reagents and elution volumes to optimize the RADT readout from CandyCollect device samples. The resulting optimized protocol uses the kit-provided reagents and lateral flow assay (LFA) while replacing the kit's pharyngeal swab with the CandyCollect device, reducing the elution solution volume, and substituting the tube used for elution to accommodate the CandyCollect device. Positive test results were detected by eye with bacterial concentrations as low as the manufacturer's "minimal detection limit" - 1.5×105 CFU/mL. LFA strips were also scanned and quantified with image analysis software to determine the signal-to-baseline ratio (SBR) and categorize positive test results without human bias. We tested our optimized protocol for integrating CandyCollect and RADT using CandyCollect clinical samples from pediatric patients (n=6) who were previously diagnosed with GAS pharyngitis via pharyngeal swabs tested with RADT as part of their clinical care. The LFA results of these CandyCollect devices and interspersed negative controls were determined by independent observers, with positive results obtained in four of the six participants on at least one LFA replicate. Taken together, our results show that CandyCollect devices from children with GAS pharyngitis can be tested using LFA rapid tests.

Prevalence of Positive Rapid Antigen Detection Test for Group A Streptococcus Among Patients With Respiratory Symptoms in Eastern Province, Kingdom of Saudi Arabia.

Background During the COVID-19 pandemic, there was a dramatic upsurge in the prevalence of respiratory symptoms, which may have altered the usual pattern of bacterial infections and relevant decision-making. Objectives This study aimed to investigate the prevalence of rapid antigen detection test (RADT) positivity for group A Streptococcus (GAS) in patients with respiratory symptoms and signs during the COVID-19 pandemic. In addition, we evaluated the association between a positive test and the modified Centor criteria in a population of children and adults with upper respiratory tract infections (URTIs). Methods A prospective study was conducted in primary health care centres (PHCCs) and the paediatric emergency department (ED) of the Maternity and Children Hospital in Dammam City, Kingdom of Saudi Arabia (KSA). Trained physicians collected data from patients aged three years and older or their guardian(s) regarding URTI symptoms. The modified Centor score was calculated, and RADT was performed for all patients. Results Data were collected from 469 patients. The prevalence of positive RADT was 19 (4.1%), and the setting was associated with RADT positivity, as 14% of ED visitors tested positive compared with 0.6% of PHCC visitors. The RADT results had an area under the curve of 0.856 (95% confidence interval (CI)=0.774-0.939), with Centor scores of 2 and 3 having a sensitivity of 89.5%/78.9% and specificity of 70.6%/80.8%, respectively. Individuals with a score of 5 had the highest rate of positive RADT (33.3%, P<0.001); a score less than 0 excluded the possibility of GAS infection. Conclusion The Centor score can improve effective antibiotic prescribing; however, Centor scores ≥2 should be supplemented with an additional confirmatory test. The high specificity of RADT makes it a useful tool in preventing the prescription of unneeded antibiotics.

Evaluation of the usefulness of COVID-19 antigen tests in primary health care on the example of Kashubian Medical Centre in Sierakowice.

Introduction: The SARS-CoV-2 pandemic is described as a global health crisis. The most typical symptoms of infection prompt most patients to visit a primary care clinic (PCC). From December 2020, COVID-19 can be diagnosed in European Union countries on the basis of a positive antigen test result. These tests are widely used at the primary care level. Material and methods: The analysis covered the period from 01.09.2021 to 28.02.2022. Statistical analysis was performed on the results of a study of 1,849 patients who underwent antigen testing in primary care clinics at the Kashubian Medical Centre (KCM) in Sierakowice and data published by the Ministry of Health on the results of tests performed from the whole country, Pomeranian Voivodeship and Kartuzy County. Results: Statistical analysis showed that the results of studies conducted in KCM in Sierakowice (antigen-only tests) were consistent with the results of studies conducted in Kartuzy County, Pomeranian Voivodeship and nationwide (molecular PCR - Polymerase Chain Reaction and antigen tests). Conclusions: Rapid antigen tests are a useful diagnostic tool in the fight against the SARS-CoV-2 pandemic because of their easy availability and simplicity of performance, and their widespread dissemination, especially in primary care settings, could contribute to multibillion-dollar savings in the health care system.

Enhancing the sensitivity of rapid antigen detection test (RADT) of different SARS-CoV-2 variants and lineages using fluorescence-labeled antibodies and a fluorescent meter.

RT-qPCR is considered the gold standard for diagnosis of COVID-19; however, it is laborious, time-consuming, and expensive. RADTs have evolved recently as relatively inexpensive methods to address these shortcomings, but their performance for detecting different SARS-COV-2 variants remains limited. RADT test performance could be enhanced using different antibody labeling and signal detection techniques. Here, we aimed to evaluate the performance of two antigen RADTs for detecting different SARS-CoV-2 variants: (i) the conventional colorimetric RADT (Ab-conjugated with gold beads); and (ii) the new Finecare™ RADT (Ab-coated fluorescent beads). Finecare™ is a meter used for the detection of a fluorescent signal. 187 frozen nasopharyngeal swabs collected in Universal transport (UTM) that are RT-qPCR positive for different SARS-CoV-2 variants were selected, including Alpha (n = 60), Delta (n = 59), and Omicron variants (n = 108). Sixty flu and 60 RSV-positive samples were included as negative controls (total sample number = 347). The conventional RADT showed sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 62.4% (95%CI: 54-70), 100% (95%CI: 97-100), 100% (95%CI: 100-100), and 58% (95%CI: 49-67), respectively. These measurements were enhanced using the Finecare™ RADT: sensitivity, specificity, PPV, and NPV were 92.6% (95%CI: 89.08-92.3), 96% (95%CI: 96-99.61), 98% (95%CI: 89-92.3), and 85% (95%CI: 96-99.6) respectively. The sensitivity of both RADTs could be greatly underestimated because nasopharyngeal swab samples collected UTM and stored at -80 °C were used. Despite that, our results indicate that the Finecare™ RADT is appropriate for clinical laboratory and community-based surveillance due to its high sensitivity and specificity.

Diagnosis of group A streptococcal pharyngitis in the paediatric emergency department using a fluorescence-based RADT: predicted impact on antibiotic prescription.

Introduction. Using rapid antigen diagnostic tests (RADTs) in clinical practice has shown excellent specificity but often has diminished sensitivity.Gap Statement. Local data for evaluating the diagnostic performance of a new fluorescence-based RADT and its influence on the antibiotic prescription rate are not available.Aim. To evaluate the accuracy of fluorescent immunoassay (FIA)-RADTs for diagnosing group A streptococcal (GAS) pharyngitis among children and its estimated effect as a point of care test (POCT) on the antibiotic prescription rate at the paediatric emergency department.Methodology. A prospective study was conducted, comprising children 3 to 14 years old presenting with pharyngitis. Throat swab culture and FIA-RADTs were performed on all samples. Conventional PCR was performed on the discordant samples.Results. A total of 246 children were included in this study. The sensitivity, specificity, and positive and negative predictive values of the FIA-RADT, based on culture results and PCR detection combined, were 95.6, 96.8, 94.6 and 97.4 %, respectively. Antibiotics have been prescribed to 162 (65.9 %) children; however, if FIA-RADTs had been added in the clinical practice as a POCT, only 92 (37.4 %) children would have received antibiotics in total. Additionally, implementation of FIA-RADTs would significantly reduce the antibiotic prescription rate from 48.8 and 60.6 % to 9.5 and 31.9 % among patients with clinical scores of 2 and 3, respectively.Conclusion. The new FIA-RADT is simple, prompt and reliable. It is helpful in clinical settings and may be used to reduce antibiotic overprescription, especially for children who have a low risk for GAS pharyngitis, according to the clinical score.

Development of a risk assessment profile tool to determine appropriate use of SARS-CoV-2 rapid antigen detection tests for different activities and events in Ireland, since October 2021.

We describe the development of a risk assessment profile tool that incorporates data from multiple domains to help determine activities and events where rapid antigen detection tests (Ag-RDT) could be used to screen asymptomatic individuals to identify infectious cases as an additional mitigation measure to reduce transmission of SARS-CoV-2. The tool aims to stratify, in real time, the overall risk of SARS-CoV-2 transmission associated with common activities and events, and this can be matched to an appropriate Ag-RDT testing protocol.

Evaluation of three rapid lateral flow antigen detection tests for the diagnosis of SARS-CoV-2 infection.

INTRODUCTION: The COVID-19 pandemic has led to high demand of diagnostic tools. Rapid antigen detection tests have been developed and many have received regulatory acceptance such as CE IVD or FDA markings. Their performance needs to be carefully assessed. MATERIALS AND METHODS: 158 positive and 40 negative retrospective samples collected in saline and analyzed by a laboratory-developed RT-PCR test were used to evaluate Sofia (Quidel), Standard Q (SD Biosensor), and Panbio™ (Abbott) rapid antigen detection tests (RADTs). A subset of the specimens was subjected to virus culture. RESULTS: The specificity of all RADTs was 100 % and the sensitivity and percent agreement was 80 % and 85 % for Sofia, 81 % and 85 % for Standard Q, and 83 % and 86 % for Panbio™, respectively. All three RADTs evaluated in this study reached a more than 90 % sensitivity for samples with a high viral load as estimated from the low Ct (Cycle threshold) values in the reference RT-PCR. Virus culture was successful in 80 % of specimens with a Ct value <25. CONCLUSIONS: As expected, the RADTs were less sensitive than RT-PCR. However, they benefit from the speed and ease of testing, and lower price as compared to RT-PCR. Repeated testing in appropriate settings may improve the overall performance.

Survey of diagnostic testing for respiratory syncytial virus (RSV) in adults: Infectious disease physician practices and implications for burden estimates.

Respiratory syncytial virus (RSV) often causes respiratory illness in adults. Over 40 RSV vaccine and monoclonal antibody products are currently in preclinical development or clinical trials. Because RSV diagnostic practices may impact disease burden estimates, we investigated infectious disease physicians' RSV diagnostic practices among their adult patients.

Clinical Impact of a Rapid Streptococcal Antigen Test on Antibiotic Use in Adult Patients.

INTRODUCTION: Adult pharyngitis is rarely attributable to group A streptococci. Utilization of a rapid streptococcal antigen test (RADT) may improve appropriate prescribing for bacterial pharyngitis. METHODS: Clinic 1 performed RADTs with subsequent Group A DNA probe test (GADNA) from November 2014-March 2015 and November 2015-March 2016 while Clinic 2 was the control clinic, then implemented the RADT with a GADNA from November 2015-March 2016. All GADNA results were obtained for each clinic from October 2013-March 2016. RESULTS: At Clinic 1, 22.2% versus 8.5% of patients received inappropriately prescribed antibiotics for a GADNA or RADT result, respectively (p=0.048). For Clinic 2, 51.1% compared to 21.4% of patients were inappropriately prescribed antibiotic for a GADNA or RADT result, respectively (p=0.038). Overall, the total GADNA without RADT testing or RADTs with subsequent GADNA testing, 41.6% versus 11% of patients were inappropriately prescribed antibiotics, respectively (p=<0.0001). CONCLUSION: Utilizing the RADT prevented unnecessary prescribing of antibiotics in adults.

Rapid antigen detection test for respiratory syncytial virus diagnosis as a diagnostic tool / Teste rápido de detecção de antígenos para o diagnóstico do Vírus Sincicial Respiratório como ferramenta de diagnóstico

Abstract Objective: The aim of this study was to evaluate the QuickVue® RSV Test Kit (QUIDEL Corp, CA, USA) as a screening tool for respiratory syncytial virus in children with acute respiratory disease in comparison with the indirect immunofluorescence assay as gold standard. In Brazil, rapid antigen detection tests for respiratory syncytial virus are not routinely utilized as a diagnostic tool, except for the diagnosis of dengue and influenza. Methods: The authors retrospectively analyzed 486 nasopharyngeal aspirate samples from children under age 5 with acute respiratory infection, between December 2013 and August 2014, the samples were analyzed by indirect immunofluorescence assay and QuickVue® RSV Test kit. Samples with discordant results were analyzed by real time PCR and nucleotide sequencing. Results: From 313 positive samples by immunofluorescence assays, 282 (90%) were also positive by the rapid antigen detection test, two were positive only by rapid antigen detection test, 33 were positive only by immunofluorescence assays, and 171 were positive by both methods. The 35 samples with discordant results were analyzed by real time PCR; the two samples positive only by rapid antigen detection test and the five positive only by immunofluorescence assays were also positive by real time PCR. There was no relation between the negativity by QuickVue® RSV Test and viral load or specific strain. The QuickVue® RSV Test showed sensitivity of 90%, specificity of 98.8%, predictive positive value of 99.3%, and negative predictive value of 94.6%, with accuracy of 93.2% and agreement κ index of 0.85 in comparison to immunofluorescence assay. Conclusions: This study demonstrated that the QuickVue® RSV Test Kit can be effective in early detection of Respiratory syncytial virus in nasopharyngeal aspirate and is reliable for use as a diagnostic tool in pediatrics.

Resumo Objetivo: Avaliar o teste QuickVue® RSV Test Kit (QUIDEL Corp, CA, EUA) para o diagnóstico rápido do vírus sincicial respiratório em crianças com doença respiratória aguda, comparandoo com a imunofluorescência indireta como padrão ouro. Visto que, no Brasil, testes rápidos para detecção de antígenos para vírus sincicial respiratório não são rotineiramente utilizados como ferramenta de diagnóstico, exceto para Dengue e Influenza. Métodos: Um total de 486 amostras de aspirado de nasofaringe de crianças menores de 5 anos com doença respiratória aguda, coletadas entre dezembro de 2013 e agosto de 2014, foram analisadas por imunofluorescência e pelo teste QuickVue®. Amostras com resultados discordantes entre os métodos foram submetidas a PCR em tempo real e sequenciamento. Resultados: Das 313 amostras positivas por IFI, 282 foram positivas no teste rápido (90%), 2 amostras foram positivas apenas no teste rápido (0.6%), 33 apenas na imunofluorescência (10.5%) e 171 foram negativas em ambos os métodos. As 35 amostras com resultados discordantes foram testadas por PCR em tempo real, sendo que duas que foram positivas apenas no teste rápido e 5 apenas na imunofluorescência confirmaram-se positivas. Não houve relação entre a ausência de positividade no teste QuickVue® com a carga ou com a cepa viral. O teste QuickVue® mostrou sensibilidade de 90.1%, especificidade 98.9%, valor preditivo positivo 99.3%, valor preditivo negativo de 94.6%, acurácia de 93.2% e índice de concordância de 0.85 em comparação à imunofluorescência. Conclusões: Nosso estudo demonstrou que o teste QuickVue® RSV pode ser efetivo na detecção precoce do vírus sincicial respiratório em amostras de aspirado de nasofaringe e é confiável como uma ferramenta de diagnósticos em pediatria.

Rapid antigen detection test for respiratory syncytial virus diagnosis as a diagnostic tool.

OBJECTIVE: The aim of this study was to evaluate the QuickVue® RSV Test Kit (QUIDEL Corp, CA, USA) as a screening tool for respiratory syncytial virus in children with acute respiratory disease in comparison with the indirect immunofluorescence assay as gold standard. In Brazil, rapid antigen detection tests for respiratory syncytial virus are not routinely utilized as a diagnostic tool, except for the diagnosis of dengue and influenza. METHODS: The authors retrospectively analyzed 486 nasopharyngeal aspirate samples from children under age 5 with acute respiratory infection, between December 2013 and August 2014, the samples were analyzed by indirect immunofluorescence assay and QuickVue® RSV Test kit. Samples with discordant results were analyzed by real time PCR and nucleotide sequencing. RESULTS: From 313 positive samples by immunofluorescence assays, 282 (90%) were also positive by the rapid antigen detection test, two were positive only by rapid antigen detection test, 33 were positive only by immunofluorescence assays, and 171 were positive by both methods. The 35 samples with discordant results were analyzed by real time PCR; the two samples positive only by rapid antigen detection test and the five positive only by immunofluorescence assays were also positive by real time PCR. There was no relation between the negativity by QuickVue® RSV Test and viral load or specific strain. The QuickVue® RSV Test showed sensitivity of 90%, specificity of 98.8%, predictive positive value of 99.3%, and negative predictive value of 94.6%, with accuracy of 93.2% and agreement κ index of 0.85 in comparison to immunofluorescence assay. CONCLUSIONS: This study demonstrated that the QuickVue® RSV Test Kit can be effective in early detection of Respiratory syncytial virus in nasopharyngeal aspirate and is reliable for use as a diagnostic tool in pediatrics.

Multicenter clinical evaluation of the novel Alere™ i Influenza A&B isothermal nucleic acid amplification test.

BACKGROUND: Rapid detection of influenza infection is important for patient management and timely anti-viral therapy. Rapid antigen detection tests for influenza have inferior sensitivity when compared to nucleic acid-based amplification tests. An isothermal nucleic acid amplification test that offers the potential for rapid molecular testing at the clinical point-of-care with simple equipment can improve influenza detection rates. OBJECTIVES: To evaluate the performance of Alere™ i Influenza A&B isothermal nucleic acid amplification test to detect influenza A and B in comparison to viral cell culture as reference method. STUDY DESIGN: A prospective, multicenter, clinical study to evaluate the clinical performance of the Alere™ i Influenza A&B assay in a point-of-care setting using prospectively enrolled specimens from both children and adults was conducted in seven sites. RESULTS: In comparison with viral cell culture, the overall sensitivity and specificity of the Alere™ i Influenza A&B assay was 97.8% and 85.6% for the detection of influenza A, and 91.8% and 96.3% for the detection of influenza B, respectively. Following resolution of discrepant results by real-time RT-PCR the sensitivity and specificity of the Alere™ i Influenza A&B assay improved to 99.3% and 98.1% for influenza A, and 97.6% and 100% for influenza B, respectively. CONCLUSIONS: The Alere™ i Influenza A&B isothermal nucleic acid amplification test is an ideal point-of-care test for influenza detection in children and adults due to its high sensitivity and specificity and ability to generate results within 15 min from specimen receipt.

Host and viral factors affecting clinical performance of a rapid diagnostic test for respiratory syncytial virus in hospitalized children.

Respiratory syncytial virus rapid antigen detection tests (RADT) are used widely. RADT exhibited high specificity (97%) and moderate sensitivity (80%) compared with reverse-transcriptase polymerase chain reaction in 720 hospitalized children <3 years old. Older age, prolonged symptoms, and respiratory syncytial virus genotype-B infection were significantly associated with false-negative results of RADT.

Management of acute streptococcal pharyngitis: still the subject of controversy.

Although most cases of acute pharyngitis are viral in origin, antibiotics are overused in its treatment. Streptococcus pyogenes (group A streptococcus, GAS), the principal bacterial pathogen of acute sore throat, is responsible for merely 5-30% of cases. Moreover, GAS pharyngitis is currently the only commonly occurring form of acute pharyngitis for which antibiotic therapy is definitely indicated. Therefore the differentiation between GAS pharyngitis and that of viral etiology is crucial. Accordingly, scientific societies as well as respected advisory bodies in Europe and North America, issued guidelines for the management of acute pharyngitis with the aim of minimizing unnecessary antibiotic prescriptions in its treatment. The aim of this review work is to confront the state of the art in acute GAS pharyngitis diagnosis and treatment with different approaches to its management represented by current European and North American guidelines. Although based on scientific evidence, international guidelines differ substantially in opinions whether GAS pharyngitis diagnosis should be based on microbiological testing, clinical algorithm or a combination of both. On the other hand, some European guidelines consider GAS pharyngitis to be a mild, self-limiting disease that does not require a specific diagnosis or antimicrobial treatment except in high-risk patients. There is an agreement among guidelines that if antibiotic therapy is indicated, phenoxymethyl penicillin should be the drug of choice to treat GAS pharyngitis.

Prevalence of Group A b-Hemolytic Streptococcus Among Children with Tonsillopharyngitis in Kyrgyzstan: The Difficulty of Diagnostics and Therapy.

OBJECTIVE: Rheumatic fever (RF) is well known disease as a result of frequent complication of the group A b-hemolytic streptococcal (GABHS) tonsillopharyngitis, have noticeably grown for the last 15 years among young generation in the Kyrgyz Republic. It is important to hold a study about the prevalence of RF and GABHS and their susceptibility to antibiotics in the Kyrgyz Republic. MATERIALS AND METHODS: We have studied 200 children with chronic tonsillopharyngitis at the National Center of Pediatrics and Child Surgery in Bishkek (the Kyrgyz Republic) from August till September 2008. 188 (48 out of them are with RF) out of total 200 children are Kyrgyz and 12 are Russian (2 out of them are with RF). 111 out of total are female (34 out of them are with RF) and 89 are male (17 out of them are with RF). The average age of the subjects is 10.9±6.0 (from 3 to 17 years old). The presence of GABHS was assessed using two ways: by the rapid antigen detection test (RADT) for outcrop of streptococcus antigen in smear from mucosal surface of tonsils, and by bacterial culture analysis (BA). RADT was used to determine its specificity and sensitivity in order to recommend practitioners its further wide use. Furthermore, the discovered culture of GABHS have been investigated on susceptibility to antibiotics by disc-diffusion method. RESEARCH RESULTS: GABHS antigen was positive in 72 (36.0 %) subjects from RADT and in 80 (40.0%) subjects from BA out of 200 total subjects. In the patients with RF (n=51), GABHS was positive in 18 (35.2%) subjects by RADT and in 24 (47.0%) subjects by BA. In the subjects without RF (n=149), GABHS was positive in 54 (36.2%) subjects by RADT and in 56 (37.5%) by BA. Among 80 GABHS positive results sensitive to antibiotics were: to penicillin only 10 (12.5%), to ampicillin-29 (36.2%), to amoxicillin-36 (45.0%), to ceftriaxon - 31 (38.7%), to roxithromycin - 21 (26.2%), to erythromycin- 19 (23.7%). It is noted that 21 (26.2%) GABHS positive results were absolutely resistant for all these tested antibiotics. RADT showed that its specificity is 85% as well as its sensitivity is equal to 67.5%. CONCLUSION: In this study the sensitivity of RADT was low; therefore, the negative results of RADT don't exclude presence of GABHS. High prevalence of GABHS antigen demonstrates not only in patients with RF, but also among healthy children (without RF) of the Kyrgyz Republic. The high prevalence of GABHS at children with RF (47.0%), probably, presents a low sensitivity to antibiotics and irregular secondary prophylaxis. Significant presence of GABHS among healthy children (37.5%) requires improvement of primary prevention to prevent further spread of RF and Rheumatic Heart Disease (RHD) in the country.