Viral Load-based Evaluation of the Sensitivity of Antigen-based Rapid Detection Assay for SARS-CoV-2

Background: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has become a global public health problem. The real-time reverse transcription-polymerase chain reaction (RT-PCR) is the gold standard test for the detection of SARS-CoV-2. However, the assay requires hours to get the final results. Therefore, antigen-based rapid assays are being used extensively to reduce the time. We have evaluated the performance of the antigen-based rapid test for the detection of SARS-CoV-2 virus in comparison with RT-PCR. Materials and methods: Nasopharyngeal and throat swabs were collected from 366 suspected patients of COVID-19 visiting our institute and subjected to qualitative RT-PCR and antigen-based rapid assays to detect the presence of SARS-CoV-2 virus. The sensitivity and specificity of the antigen-based assay were calculated in comparison with RT-PCR. Results: Compared with RT-PCR, sensitivity and specificity of the antigen-based rapid assay were observed to be 70.5% and 98.6%, respectively, in comparison with RT-PCR. However, the sensitivity of antigen-based rapid assay varied significantly with decreasing viral load. The sensitivity of the rapid antigen assay was equivalent to RT-PCR (23/23, 100%) at a higher viral load (Ct value 15�). In contrast, the antigen assay could only detect 3/21 (14.28%) samples with Ct value >30. Conclusion: The antigen-based assay could assist in the rapid screening of a large population. However, the rapid antigen assay might not detect early stages of infection represented by low viral load. Therefore, the antigen-based assay could not replace RT-PCR testing. The study reiterates that all antigen-based negative tests should be confirmed by RT-PCR.

Ophthalmology practice in COVID-19 pandemic: Performance of rapid antigen test versus real time-reverse transcription polymerase chain reaction in a tertiary eye care institute in South India

Purpose: To assess the rapid antigen test (RAT) against the gold standard reverse transcription?polymerase chain reaction (RT?PCR) to screen COVID?19 infection in asymptomatic patients undergoing ophthalmic procedures. Methods: This was a retrospective hospital?based study. Point?of?care (PoC) RAT was performed using nasopharyngeal swab, while RT?PCR for SARS?CoV?2 viral RNA was performed using both nasopharyngeal and throat swabs. Results: A total of 629 patients were tested for SARS?CoV?2 by using both RAT and RT?PCR. Only one patient had tested positive for SARS?CoV?2 with both RAT and RT?PCR, while two patients had tested positive with RT?PCR after an initial negative RAT. The positivity rate for RAT was 0.15% (1/629), and that for RT?PCR was 0.47%. Percent agreement or proportion of agreement observed between the two tests was 99.68%, while Cohen’s kappa coefficient value was 0.49. The sensitivity of RAT in comparison to RT?PCR was 33.33%, specificity was 100%, positive predictive value was 100%, and negative predictive value was 99.68%. Conclusion: The sensitivity and Cohen’s kappa coefficient in our study were low but that can be attributed to the overall low positivity rates with both RAT and RT?PCR. However, percent agreement observed between the two tests was very high. Therefore, we recommend initial screening of all the patients for COVID?19 symptoms followed by RAT before performing any ophthalmic surgical procedure to ensure the safety of the health care professionals as well as the patients.

The importance of disease prevalence in clinical decision making: a real practice study on COVID-19 antigen test in Curacao

ABSTRACT The performance of a test can be suboptimal, but in appropriate setting such a test is still useful for clinical decision making. We investigated the role of Antigen Rapid Diagnostic Test (Ag-RDT) for clinical decision making in an Emergency Department (ED) in Curacao during peak of COVID-19 pandemic. Ag-RDT was performed in the naso- and oropharynxswabs from patients with respiratory insufficiency presented to the ED. Ag-RDT was performed in 153 patients, of which 64 (41.8%) showed positive results. Comparing Ag-RDT results with molecular tests, its sensitivity was 68.8% (95% CI 57.4 to 78.7), and specificity of 94.6% (95% CI 84.9 to 98.9). The positive and negative predictive value were 95.1% (95% CI 86.5 to 98.3) and 66.3 (95% CI 58.6 to 73.3), respectively. All patients with Ag-RDT positive test were admitted to the cohorted COVD-19 department of the hospital. By using Ag-RDT, 35.9% of rapid PCR tests (that are more costly and laborious to perform) could be avoided at cost of 5.8% patients with false positive result. In conclusion, in real practice, disease prevalence is as important as test's performance for clinical decision making. The conclusion may also be applicable for other diagnostic tests than COVID-19 diagnostic.

Clinical Manifestations of Group A Streptococcal Pharyngitis and Comparison of Usefulness of Two Rapid Streptococcal Antigen Tests

BACKGROUND: Throat culture is the golden standard for diagnosis of group A streptococcal (GAS) pharyngitis. However, because it is a time-consuming procedure, antibiotics are often empirically administrated. Rapid antigen tests (RATs) can detect bacterial infections within 15 minutes, thus helping to reduce unnecessary administration of antibiotics. METHODS: In total, 108 patients, between 3 and 17 yr of age, who visited our hospital from August 2011 to July 2012, were tested for suspected acute pharyngitis with two RATs––SD Bioline Strep A (SD, Korea) and BinaxNOW Strep A (Binax, Inc., USA)––as well as throat culture. We compared the sensitivity, specificity, and consistency of the two RATs and assessed the clinical manifestations of GAS pharyngitis. RESULTS: Of the 108 patients, 15 were confirmed to have GAS pharyngitis by throat culture. The SD test showed a sensitivity of 93.3% and a specificity of 97.8%; the positive and negative predictive values were 87.5% and 98.9%, respectively. The Binax test showed a sensitivity of 86.7% and a specificity of 100%; the positive and negative predictive values were 100% and 97.9%, respectively. The Kappa values for conformity degree were high, 0.887 and 0.918 in the SD and the Binax tests, respectively (P=0.00). Clinical manifestation assessment of GAS pharyngitis indicated that scarlatiniform rash and strawberry tongue were significantly associated signs (P<0.05). CONCLUSIONS: GAS pharyngitis diagnosis based on clinical manifestations alone has practical limitations. The two RATs are useful as substitutes for throat culture and their frequent use in clinical settings is advisable.

Performance of colloidal gold immunochromatography assay in rapid detection of respiratory syncytial virus antigen / 中国感染与化疗杂志

Objective To investigate the sensitivity and specificity of colloidal gold immunochromatography assay in rapid detection of respiratory syncytial virus (RSV)antigen.Methods A total of 197 nasal-pharyngeal swabs (NPs)or nasal-pharyngeal aspirates (NPAs ) obtained from patients were tested by RSV assay kits, i. e., colloidal gold immunochromatography assay.The results determined by reverse-transcription polymerase chain reaction (RT-PCR)were taken as reference.Compared to the results of RT-PCR,the sensitivity of the kit was different when testing different types of specimens or specimensobtained from patients of different ages.Results A total of 95 (48.2%)samples were positive for RSV tested by RT-PCR.The sensitivity and specificity of colloidal gold immunochromatography assay were 34.7% and 100%, respectively compared with RT-PCR results.The positive rate of the assay was higher in testing NPAs than NPs (36.2% vs 8.6%,P < 0.01 ), which was the same in the sensitivity (22.1% vs 12.6%). The positive rate of colloidal gold year old,RT-PCR method should be used for RSV detection in clinical practice to avoid missed diagnosis.

Sensitivities of seasonal and pandemic rapid antigen tests differentiated by the level of immunofluorescence for the detection of pandemic influenza A/H1N1 2009 virus

No abstract available.

Comparison of Rapid Antigen Test and Real-Time Reverse Transcription PCR for the Detection of Influenza B Virus / 임상검사와정도관리

BACKGROUND: Rapid antigen test and real-time reverse transcription PCR (rRT-PCR) are widely used for the detection of influenza A virus. In this study, we evaluated and compared the effectiveness of a rapid antigen test, currently used for detecting influenza B virus, with the effectiveness of using rRT-PCR for the same purpose. METHODS: Samples obtained from 92 patients during an outbreak of influenza B were assessed using the rapid antigen test (SD BIOLINE Influenza Ag; SD, Korea) and rRT-PCR (Anyplex FluA/B Real-time Detection; Seegene, Korea). RESULTS: The sensitivity and specificity of the rapid antigen test were 69% and 100%, respectively, in detecting influenza B when compared to rRT-PCR. Twenty-nine patients (31.5%) were positive for both rapid antigen test and rRT-PCR, while 50 (54.3%) were negative for both rapid antigen test and rRT-PCR. The overall concordance rate between rapid antigen test and rRT-PCR was 85.9%. Thirteen patients (14.1%) were positive only for rRT-PCR. CONCLUSIONS: The rapid antigen test showed high specificity and good correlation with rRT-PCR and is likely to be as useful in the detection of influenza B viruses.

Usefulness of Influenza Rapid Antigen Test in Influenza A (H1N1) / 소아알레르기및호흡기학회지

PURPOSE: The aim of this study was to examine the sensitivity and specificity of the influenza rapid antigen test, in comparison with reverse transcription polymerase chain reaction (RT-PCR), according to the time of the test from symptom onset and the clinical manifestations in the patients tested for suspected infection of the influenza A (H1N1) at a second hospital. METHODS: A total of 529 pediatric patients, aged between 6 and 12 years old, who visited the emergency department from October 1, 2009 to December 31, 2009, received the influenza rapid antigen test and RT-PCR. We examined the sensitivity and specificity of the influenza rapid antigen test in comparison with RT-PCR according to the time of the test from symptom onset (72 hours) and clinical manifestations (fever, cough, rhinorrhea.nasal obstruction, sore throat, gastrointestinal symptoms, and general symptoms) in a retrospective study based on hospital charts. RESULTS: The sensitivity of the influenza rapid antigen test at elapsed times of less than 24 hours, 24 to 48 hours, and 48 to 72 hours after the onset of the symptoms was 53.9%, 61.4%, and 62.1% respectively. When the elapse time was greater than 72 hours, the sensitivity was 31.6%; thus, the sensitivity of the influenza rapid antigen test tended to decrease with elapsed time. The sensitivity of the test was 79% in patients presenting with gastrointestinal symptoms, which was the highest, but there was no statistical difference according to the clinical manifestations of the patients. CONCLUSION: Our study suggests that more accurate results might be gained when the influenza rapid antigen test is performed within 72 hours after symptom onset.

The Sensitivity according to the Time Gap between Fever Onset and the Performance of Rapid Antigen Test for 2009 H1N1 Influenza / 소아알레르기및호흡기학회지

PURPOSE: Rapid antigen test (RAT) is used to screen influenza rapidly. The clinical sensitivity of RAT was poor for 2009 H1N1 influenza. The aim of this study was to identify the correlation of time gap (TG) between fever onset and the sensitivity of RAT for 2009 H1N1 influenza. METHODS: Data were collected retrospectively during the pandemic H1N1 2009 influenza season between October 2009 and February 2010. The RAT was done by using SD Bioline influenza antigen (Standard Diagnostics Inc.) in nasopharyngeal swab. The 2009 H1N1 influenza was confirmed by real-time reverse transcriptase polymerase chain reaction (rRT-PCR). Specimens were categorized according to the TG between fever onset and performance of RAT. They were classified into 120 hours (TG6). RESULTS: The overall sensitivity of RAT was 69.9%. The TG dependent sensitivity of RAT at TG1, TG2, TG3, TG4, TG5, and TG6 was 64.3%, 73.3%, 61.1%, 88.9%, 83.3%, and 61.1% respectively. The sensitivity of RAT was the highest when the TG was 72 to 96 hours. But this result was not statistically significant. CONCLUSION: Correlation of TG between fever onset and the sensitivity of RAT for 2009 H1N1 influenza was not statistically significant. But our study suggested that 72 to 96 hours after fever onset is the most sensitive time of RAT. Timely optimal performance of the RAT could have a significant impact on improving results. Further evaluation for better sensitivity would be needed.

BinaxNOW® - An immunochromatographic test for the diagnosis of human influenza viruses: Comparison with viral culture and polymerase chain reaction.

Purpose: A rapid test for influenza viruses (Binax NOW® ) was evaluated. Materials and Methods: In season-1, 35 respiratory samples were tested retrospectively; in season-2, 45 samples were tested prospectively [gold-standard: viral culture in season-1, culture+ reverse transcriptase-polymerase chain reaction (RT-PCR) in season-2]. Results: Sensitivity for Binax for influenza A was 59.3 and 0% in season-1 and -2, respectively. Sensitivity was low for influenza B (33.3% in season-1, 26.1% in season-2). Samples having low viral load were more likely to have a negative Binax test. Specificity of Binax was high (100 and 94.7% with influenza A and B, respectively). Conclusion: Sensitivity information provided in the kit insert does not always reflect post licensure performance in clinical settings.

Clinical Characteristics and Comparison of the Various Methods Used for the Diagnosis of the New Influenza A Pandemic in Korea

BACKGROUND: Laboratory diagnosis of new influenza A (H1N1) is crucial for managing patients and establishing control and prevention measures. We compared the diagnostic accuracies of the real time RT-PCR (rRT-PCR) test recommended for the confirmation of the new flu and the viral culture method used conventionally for viral disease with that of the rapid antigen test (RAT). METHODS: We performed RAT, R-mix culture, and real-time PCR by using 861 respiratory samples collected from December 2009 to January 2010 and evaluated the abilities of these methods to detect new influenza A. The relationship among the positive rates of RAT, grades of culture, and the cycle threshold (Ct) values of rRT-PCR was also evaluated. RESULTS: Of the 861 patients, 308 (35.8%) were diagnosed with new influenza A. The sensitivities, specificities, positive predictive values, and negative predictive values of the tests were respectively as follows: 59.7%, 99.5%, 98.4%, and 81.6% for RAT; 93.2%, 100%, 100%, and 96.3% for R-mix culture; and 95.8%, 100%, 100%, and 97.7% for rRT-PCR. Samples with weak positive grade in culture and those with Ct values of 30-37 in rRT-PCR showed positivities as low as 25.3% and 2.3% in RAT, respectively. The hospitalization rate and death rate of the confirmed patients were 3.2% and 0.3%, respectively, and gastrointestinal symptoms were observed in 7.2% of the patients. CONCLUSIONS: R-mix culture and rRT-PCR tests showed excellent reliability in the diagnosis of new influenza A and could be very useful, especially for samples with low viral load.

Clinical characteristics of 2009 pandemic influenza A (H1N1) infection in children and the performance of rapid antigen test / 소아과

PURPOSE: In autumn 2009, the swine-origin influenza A (H1N1) virus spread throughout South Korea. The aims of this study were to determine the clinical characteristics of children infected by the 2009 H1N1 influenza A virus, and to compare the rapid antigen and real-time polymerase chain reaction (PCR) tests. METHODS: We conducted a retrospective review of patients > or =18 years of age who presented to Soonchunhyang University Hospital in Seoul with respiratory symptoms, including fever, between September 2009 and January 2010. A real-time PCR test was used to definitively diagnose 2009 H1N1 influenza A infection. Medical records of confirmed cases were reviewed for sex, age, and the time of infection. The decision to perform rapid antigen testing was not influenced by clinical conditions, but by individual factors such as economic conditions. Its sensitivity and specificity were evaluated compared to real-time PCR test results. RESULTS: In total, 934 patients tested positive for H1N1 by real-time PCR. The highest number of patients (48.9%) was diagnosed in November. Most patients (48.2%) were aged between 6 and 10 years. Compared with the H1N1 real-time PCR test results, the rapid antigen test showed 22% sensitivity and 83% specificity. Seventy-eight patients were hospitalized for H1N1 influenza A virus infection, and fever was the most common symptom (97.4%). CONCLUSION: For diagnosis of 2009 H1N1 influenza A virus infection, the rapid antigen test was inferior to the real-time PCR test in both sensitivity and specificity. This outcome suggests that the rapid antigen test is inappropriate for screening.

Evaluation of Rapid Antigen Test for the Detection of Norovirus Infection: Comparison with ELISA and Real Time Quantitative Reverse Transcription PCR Assays

BACKGROUND: Norovirus is a leading cause of epidemic and sporadic acute gastroenteritis worldwide. Because of the rapid transmission of the virus, early detection is important to prevent outbreak of norovirus infection. To evaluate the performance of a newly introduced rapid antigen test for detecting human norovirus in stool specimens, we compared it with the established ELISA test and real time quantitative reverse transcription PCR (qRT-PCR). METHODS: One hundred and eighty-four stool samples were analyzed by rapid antigen test (Denka-Seiken, Japan), ELISA (R-Biopharm, Germany), and qRT-PCR (R-Biopharm, Germany). Overall percent agreement, percent positive agreement (PPA), and percent negative agreement (NPA) of the rapid antigen test in comparison with ELISA and qRT-PCR were obtained. RESULTS: Positive rates of rapid antigen test, ELISA, and qRT-PCR were 44.0% (81/184), 51.6% (95/184), and 42.9% (79/184), respectively. Seventy samples (38.0%) showed all positive, and 86 samples (46.7%) showed all negative results by three methods. Overall percent agreement of three methods was 84.8% (156/184). Overall percent agreement, PPA, and NPA of the rapid antigen test in comparison with qRT-PCR were 89.1%, 88.6%, and 89.5%, respectively, and those of the rapid antigen test in comparison with ELISA were 90.2%, 83.2%, and 97.8%, respectively. Total procedure of the rapid antigen test was finished within 20 min. CONCLUSIONS: Rapid antigen test was easier and quicker to perform, and showed high agreement rates with ELISA and qRT-PCR. This test may be useful for rapid screening of norovirus infection.

Comparison of Rapid Antigen Test and Real-Time Reverse Transcriptase PCR for Diagnosing Novel Swine Influenza A (H1N1) / 대한임상미생물학회지

BACKGROUND: Novel swine influenza (H1N1) was first identified in Mexico in April 2009. Because of its high infectivity and worldwide distribution, a rapid and efficient screening test is necessary. Here we evaluated the usefulness of a rapid antigen test currently in use, compared to real-time RT-PCR (rRT-PCR) as a screening test for detection of novel swine influenza (H1N1). METHODS: A total of 1,228 patients who visited Hallym University Kangdong Sacred Heart Hospital with influenza-like illness between 14 August 2009 and 30 September 2009, and were tested by both rapid antigen and rRT-PCR tests, were enrolled in this study. RESULTS: Sensitivity, specificity, predictive value of a positive test, and predictive value of a negative test for the rapid antigen test were 30.5%, 99.2%, 86.4% and 90.1%, respectively. Fifty-one (4.2%) patients were positive for both rapid antigen test and rRT-PCR, and 1,053 (85.7%) were negative for both rapid antigen test and rRT-PCR. A total of 124 (10.1%) patients showed a discrepancy between the two tests. Among them, 116 (9.4%) were only positive for rRT-PCR and 8 (0.7%) were only positive for the rapid antigen test. The latter 8 patients all showed negative H1/M2 results in rRT-PCR. There were significant differences in detection rates of the rapid antigen test between different H1 Ct (threshold cycle) interval groups and for different age groups (P<0.05). CONCLUSION: Although the rapid antigen test is easy to perform and provides fast results, its limits as a screening test for detection of novel swine influenza (H1N1) due to its low sensitivity compared to rRT-PCR need to be considered in practical situations.

Evaluation of the Efficacies of Rapid Antigen Test, Multiplex PCR, and Real-time PCR for the Detection of a Novel Influenza A (H1N1) Virus / 대한진단검사의학회지

BACKGROUND: In April 2009, a novel influenza A (H1N1) virus was detected in the US, and at the time of conducting this study, H1N1 infection had reached pandemic proportions. In Korea, rapid antigen tests and PCR assays have been developed to detect the H1N1 virus. We evaluated the efficacies of rapid antigen test, multiplex PCR, and real-time PCR for detecting the H1N1 virus. METHODS: From August to September 2009, we tested 734 samples obtained from nasopharyngeal swab or nasal swab using rapid antigen test (SD Influenza Antigen, Standard Diagnostics, Inc., Korea) and multiplex PCR (Seeplex FluA ACE Subtyping, Seegene, Korea). We also tested 224 samples using the AdvanSure real-time PCR (LG Life Sciences, Korea) to compare the results obtained using real-time PCR with those obtained using multiplex PCR. Furthermore, 99 samples were tested using the AdvanSure real-time PCR and the AccuPower real-time PCR (Bioneer, Korea). RESULTS: In comparison with the results of multiplex PCR, the sensitivity and specificity of the rapid antigen test were 48.0% and 99.8%, respectively. The concordance rate for multiplex PCR and the AdvanSure real-time PCR was 99.6% (kappa=0.991, P=0.000), and that for the AdvanSure real-time PCR and the AccuPower real-time PCR was 97.0% (kappa=0.936, P=0.000). CONCLUSIONS: The rapid antigen test is significantly less sensitive than PCR assay; therefore, it is not useful for H1N1 detection; however multiplex PCR, the AdvanSure real-time PCR, and the Accu-Power real-time PCR can be useful for H1N1 detection.

Detection Rate of Rapid Antigen Test for Pandemic Influenza A (H1N1 2009)

There are few datas on the diagnostic accuracy of rapid antigen test for pandemic influenza A (H1N1). We evaluated the performance of rapid antigen test for the diagnosis of pandemic influenza A (H1N1). During the period from 21 August 2009 to 20 September 2009, 451 patients with influenza-like symptom underwent the rapid antigen test (SD Influenza Antigen, Standard Diagnostics, Yongin, Korea) and real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) at the same time. Rapid antigen test results were positive for 65 of 90 patients with the positive results for pandemic influenza A (H1N1) on rRT-PCR assay. The sensitivity of the rapid antigen test was 72.2% (95% CI, 61.8-81.1) and the specificity was 100% (95% CI, 99.0-100). The positive predictive value was 100% (95% CI, 94.5-100) and negative predictive value was 93.5% (95% CI, 90.6-95.8).

Characteristics of Diagnosed Novel Influenza A (H1N1) Cases in the Community Sentinel Hospital and Usefulness of Clinical Diagnosis / 가정의학회지

BACKGROUND: The purpose of this paper is to investigate for the epidemiologic and clinical characteristics of patients with diagnosed novel influenza A (H1N1) and to evaluate the usefulness of clinical diagnosis. METHODS: Out of 696 patients who visited the community sentinel hospital for novel influenza from 27 Aug 2009 to 10 Sep 2009, 557 patients had performed the conventional RT-PCR test. Of these patients, 540 patients were enrolled to our study excluding 17 patients who had performed the test for their own request without clinical suspicion. RESULTS: The 79 patients (14.6%) were finally diagnosed as novel influenza by conventional RT-PCR, with median age 19. Main clinical symptoms were febrile sense, cough, rhinorrhea, and sore throat. The odd ratios of the symptoms with fever, febrile sense and myalgia, acute febrile respiratory disease, influenza-likely illness, the age with 10 to 19, and students were statistically significantly higher in finally diagnosed patients group. The sensitivity, specificity, and positive and negative predictive values of rapid antigen test for influenza were 29.4%, 99.3%, 90.9%, and 85.7%, respectively. In the acute febrile respiratory disease and influenza-likely illness, the sensitivity, specificity, and positive and negative predictive value were 77.2%, 38.3%, 17.7%, and 90.7%, and 69.6%, 46.6%, 18.3%, and 89.9%, respectively. CONCLUSION: In the community sentinel hospital, the patients with novel influenza A (H1N1) present the clinical manifestations similar to the common seasonal influenza. Primary health care providers might have a lot of difficulties in differentiation and treatment necessitating consideration of a variety of diagnostic methods.

The Evaluation of SD Bioline Strep A Rapid Antigen Test in Acute Pharyngitis in Pediatric Clinics / 대한진단검사의학회지

BACKGROUND: Acute pharyngitis is a very common respiratory tract infection. Rapid antigen tests (RATs) that detect group A streptococci (GAS) have an advantage over conventional throat culture in determining the cause of acute pharyngitis quickly. The efficiency of RAT should be good enough to be used in the laboratory or in the clinics. METHODS: From October 2008 through February 2009, throat swabs were taken from 293 children with acute pharyngitis and conveyed to the Gyeongsang National University Hospital in a transport medium. Two swabs from each patient were inoculated onto a blood agar plate, then returned to the transport medium and stored at -20 degrees C for several months. After the samples were thawed at room temperature, the SD Bioline Strep A RAT (SD, Korea) was performed. RESULTS: The sensitivity, specificity, positive predictive value, and negative predictive value of SD Bioline Strep A compared with throat culture were 95.9% (95% confidence interval [CI]: 93.6-98.2%), 91.8% (95% CI: 88.5-95.1%), 95.9% (95% CI: 93.6-98.2%), and 91.8% (95% CI: 88.5-95.1%), respectively. CONCLUSIONS: The SD Bioline Strep A RAT kit can be useful as an alternative to throat cultures in the clinics for rapid diagnosis of GAS pharyngitis and for an early decision on the use of antibiotics.

Clinical usefulness of rapid antigen test to detect respiratory syncytial virus infection / 소아과

PURPOSE: Respiratory syncytial virus (RSV) is the most frequent cause of lower respiratory infections in infants and young children. Early detection allows quarantining of infected inpatients to prevent nosocomial transmission and to choose a treatment. To achieve rapid reporting, to facilitate prompt antiviral therapy, and to avoid unnecessary use of antibiotics, an easy, rapid diagnostic method for RSV is needed. We evaluated a lateral flow immunochromatography (RSV Respi-Strip test) and EIA (Enzyme immuno assay) compared to RT-PCR. METHODS: From April 2007 to March 2008, 112 consecutive respiratory specimens (nasopharyngeal aspirates, throat swabs, tracheal aspirates, sputum) from patients who were suffering from the clinical signs and symptoms of respiratory tract infection were enrolled in Busan. A total of 112 patients were tested with RSV Respi-Strip (Corio-BioConcept, Belgium), EIA, and RT-PCR at the same time. RESULTS: Of the 112 specimens tested, the number of children who showed positive results at RT-PCR and Respi-Strip were 45 and 42, respectively. The Respi-Strip rapid antigen test had a sensitivity of 88% and a specificity of 94%. The positive and negative predictive values were 90% and 92%, respectively. The agreement was 83%. CONCLUSION: In our study, the rapid antigen test had as much sensitivity as any method for detection of RSV. The test has many advantages such as easy performance, simple interpretation, and rapid results. If the rapid antigen test is widely applied in the clinical setting, the may be useful for diagnostic and epidemiological studies of RSV infection.

Evaluation of SD Bioline Strep A for Rapid Antigen Testing in Elementary Schoolchildren / 대한임상미생물학회지

BACKGROUND: Rapid antigen tests (RAT) of group A streptococci (GAS) are easy to perform and can save two days of bacterial culture time. Performance of SD Bioline Strep A was analyzed in comparison with throat culture. METHODS: Three consecutive throat swabs were taken from 308 healthy elementary schoolchildren. The first two swabs were tested for SD Bioline Strep A and Quidel Quick Vue Dipstick Strep A rapid antigen tests, and the third one was inoculated onto blood agar plate to grow GAS. RESULTS: Sensitivity, specificity, positive predictive value and negative predictive value of SD Bioline Strep A were 79.3%, 88.9%, 72.2%, and 92.2% respectively. Those of Quidel Quick Vue Strep A were 58.5%, 93.8%, 77.4%, and 86.2% respectively. CONCLUSION: SD Bioline Strep A showed a significantly higher sensitivity and a slightly lower specificity compared to Quidel Quick Vue Strep A. SD Bioline Strep A RAT should be useful for the rapid diagnosis of bacterial pharyngitis and the optimum use of antibiotics.