ABSTRACT
Introduction: The specific diagnosis of influenza A infection makes it possible to control its spread, decreases the unnecessary use of antibiotics, clinical procedures and laboratory test, and allows early recognition of outbreaks. Different technologies are currently available in Chile for this purpose. Objective: The study presented here compares the sensitivity for influenza A virus detection of immunocromatography (RIDT), direct fluorescent antibodies-DFA and DFA with cytocentrifugation against the gold standard, RT-PCR. Material and Methods: In 175 nasal swab samples influenza A RIDT and RT-PCR were performed. Another 1689 nasal swab samples were tested by DFA and RT-PCR for influenza A. Finally, 29 nasal swab samples confirmed as Influenza A positive by RT-PCR were tested by DFA with cytocentrifugation. Results: The RIDT, DFA and DFA + cytocentrifugation sensitivity was 47,3%, 57,2% and 72,4%, respectively. Discussion and Conclusion: Their lower cost and faster turnaround time when compared to PCR make RIDT and DFA the tests of choice in diagnostic laboratories in Chile. However, their low sensitivity and NPV, especially during low season, makes more sensitive diagnostic tools necessary to confirm the results. In our study cytocentrifugation increased DFA sensitivity from 57% to 72%.
Introducción: El diagnóstico específico de influenza permite controlar la diseminación de la enfermedad, disminuir el uso de antimicrobianos, procedimientos clínicos y exámenes, e identificar rápidamente brotes. Diferentes tecnologías están actualmente disponibles en Chile para este propósito. Objetivo: Comparar la sensibilidad diagnóstica para la infección por el virus influenza A de las técnicas inmunocromatografía, inmunofluorescencia directa-IFD e IFD con citocentrifugado contra el estándar de oro, RPC-TR. Materiales y Método: En 175 muestras de hisopado nasofaríngeo se realizó inmunocromatografía y RPC-TR para influenza A. Otras 1.689 muestras de hisopado nasofaríngeo fueron procesadas mediante IFD y RPC-TR para influenza A. Finalmente, en 29 muestras de hisopado nasofaríngeo, confirmadas positivas para influenza A mediante RPC-TR, se realizó IFD con citocentrifugado. Resultados: La sensibilidad de la inmunocromatografía, IFD e IFD + citocentrifugado fue de 47,3%, 57,2% y 72,4%, respectivamente. Discusión y Conclusión: El menor costo y tiempo de respuesta de las técnicas rápidas (inmunocomatografía e IFD) en relación a la RPC-TR hacen que se mantengan como exámenes de rutina en los laboratorios diagnósticos del país. Sin embargo, su baja sensibilidad y VPN, especialmente durante períodos de baja prevalencia, obligaría a confirmar los resultados negativos con técnicas más sensibles. En nuestra comparación la citocentrifugación mejoró la sensibilidad de la IFD de 57% a 72%.
Subject(s)
Humans , Influenza, Human/diagnosis , Reverse Transcriptase Polymerase Chain Reaction , Fluorescent Antibody Technique, Direct/methods , Chromatography, Affinity , Sensitivity and SpecificityABSTRACT
The bronchoalveolar lavage (BAL) is a sensitive method to diagnose diseases of the distal portion of the lower respiratory tract and has been broadly used by numerous researchers. Cytocentrifugation is the choice cytological preparation technique, but demands specific and costly equipment. Therefore, the present paper intends to verify the applicability of the linear smear technique to evaluate BAL samples. For this, BAL samples of 30 equines were used and the cytological preparations were done by cytocentrifugation and linear smear techniques. All glass microscope slides were fixed and stained with Giemsa for the differential cell count. Regarding the effect of the preparation technique on differential counts, no significant difference in any cell type was found. The linear smear is a reliable alternative and can be recommended as a substitution to cytocentrifugation.
O lavado broncoalveolar (LBA) é um método sensível para diagnosticar doenças do trato respiratório posterior e vem sendo utilizado por diversos pesquisadores. A citocentrifugação, técnica de escolha para processar amostras citológicas de LBA, exige equipamentos específicos e caros. Por isso, este trabalho verificou a aplicabilidade da técnica de esfregaço linear para avaliação citológica do LBA. Foram utilizadas amostras de LBA de 30 equinos adultos. As preparações citológicas foram realizadas tanto por citocentrifugação quanto por esfregaço linear. Todas as lâminas foram fixadas e coradas com Giemsa para realização da contagem celular diferencial. Não foram encontradas alterações morfológicas significativas e nem diferenças estatísticas entre nenhum dos tipos celulares processados pelos dois métodos, o que permite afirmar que o método de esfregaço linear é uma alternativa segura para avaliação morfológica celular do LBA de equinos, podendo ser utilizado no lugar da citocentrifugação quando esta não estiver disponível.
Subject(s)
Animals , Respiratory Tract Diseases/pathology , Respiratory System/anatomy & histology , Cell Biology/trends , Horses , Bronchoalveolar LavageABSTRACT
BACKGROUND: Currently, many laboratories have selected several different methods for the detection of M. tuberculosis in the sputum. To select efficient method for clinical laboratories among the various methods, we compared the results of several methods. METHODS: Total 72 sputums were examined by the six combinations of stain methods. The samples were constructed as follows on the result of direct smear ZN stain; negatives (26), traces (3), 1+(9), 2+(12), 3+(12) and 4+(10). The true positives were determined after close evaluation of the clinical, radiological and other laboratory findings. RESULTS: The sensitivities and specificities of each methods were as follows; direct smear ZN stain were 83.6% and 100%, direct smear Auramine stain were 90.9% and 100%, centrifugation ZN stain were 94.6% and 100%, centrifugation Auramine stain were 98.2% and 94.1%, cytocentrifugation ZN stain were 96.4% and 100%, cytocentrifugation Auramine stain were 100% and 64.7%, nested PCR were 80% and 94.1% and culture were 67.3% and 100% respectively. CONCLUSIONS: Concentration method by centrifugation is suitable for routine laboratory if enough centrifugal force were engaged. Auramine stain is more suitable staining method than ZN stain in direct smear but not in concentrated smear because it has the potency of false positivity. The PCR assay is thought to be not only a fast, sensitive method but also a specific method for the direct detection of M. tuberculosis in the sputum. The culture method using Ogawa media is specific but not sensitive.