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.

Viral etiology among the elderly presenting acute respiratory infection during the influenza season / Etiologia viral de infecção respiratória aguda entre idosos, durante a temporada de gripe

INTRODUCTION: Acute respiratory tract infections are the most common illness in all individuals. Rhinoviruses have been reported as the etiology of more than 50 percent of respiratory tract infections worldwide. The study prospectively evaluated 47 elderly individuals from a group of 384 randomly assigned for acute respiratory viral infections (cold or flu) and assessed the occurrence of human rhinovirus (HRV), influenza A and B, respiratory syncytial virus and metapneumovirus (hMPV) in Botucatu, State of São Paulo, Brazil. METHODS: Forty-nine nasal swabs collected from 47 elderly individuals following inclusion visits from 2002 to 2003 were tested by GenScan RT-PCR. HRV-positive samples were sequenced for phylogenetic analysis. RESULTS: No sample was positive for influenza A/B or RSV. HRV was detected in 28.6 percent (14/47) and hMPV in 2 percent (1/47). Of 14 positive samples, 9 isolates were successfully sequenced, showing the follow group distribution: 6 group A, 1 group B and 2 group C HRVs. CONCLUSIONS: The high incidence of HRV during the months of the influenza season requires further study regarding HRV infection impact on respiratory complications among this population. Infection caused by HRV is very frequent and may contribute to increasing the already high demand for healthcare during the influenza season.

INTRODUÇÃO: Infecções agudas do trato respiratório estão entre as doenças mais comuns em todas as pessoas. Os rinovírus têm sido descritos como agente etiológico de mais de 50 por cento das infecções do trato respiratório ao redor do mundo. O objetivo deste trabalho foi avaliar a ocorrência de rinovírus humano (HRV), influenza vírus A e B, vírus respiratório sincicial humano e metapneumovírus (hMPV) em uma população de idosos que apresentava sintomas de gripe ou resfriado, e que residiam na Cidade de Botucatu, Estado de São Paulo, Brasil. MÉTODOS: Foram coletados swabs nasais de 47 idosos após visitas de inclusão, entre os anos de 2002 e 2003 e que foram testadas através de GeneScan RT-PCR. RESULTADOS: HRV foi detectado em 28.6 por cento (14/47) e hMPV em 2 por cento (1/47). De 14 amostras positivas para HRV, 9 foram sequenciadas, mostrando a seguinte distribuição de grupos: grupo A: 6 amostras, grupo B: 1 amostra e grupo C: 2 amostras. CONCLUSÕES: A alta incidência de HRV durante os meses de ocorrência de gripe necessita de estudos posteriores para avaliar o impacto desse vírus entre os idosos. A alta frequência de HRV pode contribuir para o aumento da demanda por serviços de saúde durante a estação de influenza.