A Brief Discussion on the in Vitro Diagnostic Reagent Inspection Practice of Self-examination Management Regulations for Medical Device Registration / 中国医疗器械杂志

On October 21, 2021, the National Medical Products Administration issued and implemented the Self-examination Management Regulations for Medical Device Registration. The regulations clarify the specific requirements of the registration applicants in the process of self-examination, and put forward detailed requirements from the aspects of self-examination ability, self-examination report, declaration materials and responsibility requirements, so as to ensure the orderly development of the self-examination of medical device registration. Based on the actual verification work of in vitro diagnostic reagent, this study briefly discussed the understanding of the relevant contents of the regulations, aiming to provide some reference for enterprises and related supervision departments that have the requirement of registered self-examination.

Analysis of Class II Common Problems in the Registration of / 中国医疗器械杂志

From the perspective of technical review, this paper made statistics on the supplement contents of

Transferencia de intervalos de referencia en Valencia-Venezuela / Transference of reference intervals in Valencia-Venezuela / Transferência de intervalos de referência em Valência-Venezuela

El objetivo de la presente investigación consistió en revisar si los valores de referencia producidos por la industria de diagnóstico in vitro eran transferibles a una determinada población. Para este estudio fueron analizadas muestras de suero de una población de 23 individuos. El análisis de las muestras estudiadas fue realizado mediante el método de colorimetría usando equipos Rx Daytona. Los analitos determinados para el estudio fueron glucemia, colesterol, triglicéridos por método enzimático y creatinina por método cinético, empleando el kit de reactivos de la misma casa comercial del instrumento. Para la evaluación y análisis estadístico de los datos fue empleado el logaritmo de decisión propuesto por Ventimiglia y Fink en 2002. Como resultado se obtuvieron porcentajes de transferibilidad de 100% para la totalidad de los analitos. De acuerdo con los resultados obtenidos, se dieron por verificados y se aceptó la transferibilidad de los intervalos de referencia comerciales para la población en estudio.

The aim of this investigation was to review if the reference values produced by the in vitro diagnostic industry were transferable to a specific population; for the study, serum samples from a population of 23 individuals were analyzed.The analysis of the samples was carried out using the colorimetric method with Rx Daytona equipment. The analytes determined for the study were glycemia, cholesterol, triglycerides by enzymatic method and creatinine by kinetic method, using the reagent kit from the same commercial brand of said equipment. The statistical analysis was done applying the decision logarithm proposed by Ventimiglia F and Fink N (2002). As a result, percentages of 100% of transferability were found on all the analytes. According to the results obtained, the transferability of the commercial reference intervals for the population under study was accepted.

O objetivo da presente investigação foi revisar se os valores de referência produzidos pela indústria de diagnóstico in vitro eram transferíveis para uma população específica. Para esse estudo amostras de soro foram analisadas de uma população de 23 indivíduos. A análise das amostras estudadas foi realizada utilizando o método de colorimetria, utilizando equipamentos Rx Daytona. Os analitos determinados para o estudo foram glicemia, colesterol, triglicerídeos pelo método enzimático e creatinina pelo método cinético, utilizando o kit de reagentes da mesma casa comercial do instrumento. Para a avaliação e análise estatística dos dados foi utilizado o logaritmo de decisão proposto por Ventimiglia F e Fink N 2002. Como resultados, percentuais de transferibilidade de 100% foram obtidos para todos os analitos. De acordo com os resultados obtidos, foram tidos como verificados e se aceita a transferibilidade dos intervalos de referência comerciais para a população em estudo.

Clinical Evaluation of Rapid Diagnostic Test Kit Using the Polysaccharide as a Genus-Specific Diagnostic Antigen for Leptospirosis in Korea, Bulgaria, and Argentina

Leptospirosis, a zoonotic disease that is caused by many serovars which are more than 200 in the world, is an emerging worldwide disease. Accurate and rapid diagnostic tests for leptospirosis are a critical step to diagnose the disease. There are some commercial kits available for diagnosis of leptospirosis, but the obscurity of a species- or genus-specific antigen of pathogenic Leptospira interrogans causes the reduced sensitivity and specificity. In this study, the polysaccharide derived from lipopolysaccharide (LPS) of nonpathogenic Leptospira biflexa serovar patoc was prepared, and the antigenicity was confirmed by immunoblot and enzyme linked immunosorbent assay (ELISA). The performance of the rapid diagnostic test (RDT) kit using the polysaccharide as a diagnostic antigen was evaluated in Korea, Bulgaria and Argentina. The sensitivity was 93.9%, 100%, and 81.0% and the specificity was 97.9%, 100%, and 95.4% in Korea (which is a rare region occurring with 2 serovars mostly), Bulgaria (epidemic region with 3 serovars chiefly) and Argentina (endemic region with 19 serovars mainly) respectively. These results indicate that this RDT is applicable for global diagnosis of leptospirosis. This rapid and effective diagnosis will be helpful for diagnosis and manage of leptospirosis to use and the polysaccharide of Leptospira may be called as genus specific antigen for diagnosis.

Clinical Evaluation of Rapid Diagnostic Test Kit Using the Polysaccharide as a Genus-Specific Diagnostic Antigen for Leptospirosis in Korea, Bulgaria, and Argentina

Leptospirosis, a zoonotic disease that is caused by many serovars which are more than 200 in the world, is an emerging worldwide disease. Accurate and rapid diagnostic tests for leptospirosis are a critical step to diagnose the disease. There are some commercial kits available for diagnosis of leptospirosis, but the obscurity of a species- or genus-specific antigen of pathogenic Leptospira interrogans causes the reduced sensitivity and specificity. In this study, the polysaccharide derived from lipopolysaccharide (LPS) of nonpathogenic Leptospira biflexa serovar patoc was prepared, and the antigenicity was confirmed by immunoblot and enzyme linked immunosorbent assay (ELISA). The performance of the rapid diagnostic test (RDT) kit using the polysaccharide as a diagnostic antigen was evaluated in Korea, Bulgaria and Argentina. The sensitivity was 93.9%, 100%, and 81.0% and the specificity was 97.9%, 100%, and 95.4% in Korea (which is a rare region occurring with 2 serovars mostly), Bulgaria (epidemic region with 3 serovars chiefly) and Argentina (endemic region with 19 serovars mainly) respectively. These results indicate that this RDT is applicable for global diagnosis of leptospirosis. This rapid and effective diagnosis will be helpful for diagnosis and manage of leptospirosis to use and the polysaccharide of Leptospira may be called as genus specific antigen for diagnosis.

Performance of LIFECODES HLA-DQB1 Typing Kit Using Luminex Platform in Koreans

Intermediate-resolution HLA-DQ typing has gained importance in organ transplantation recently. We evaluated the performance of the LIFECODES HLA-DQB1 typing kit (Immucor, USA) using sequence-specific oligonucleotide (SSO) probe and Luminex platform (Luminex Corp., USA) on 100 samples tested by sequence-based typing (SBT) using the AlleleSEQR HLA-DQB1 kit (Abbott Molecular, USA) in Korean individuals. No sample showed ambiguity in the assignment of 4-digit HLA-DQB1 allele with the LIFECODES HLA-DQB1 SSO typing kit, and the results were fully concordant with those of high-resolution typing of AlleleSEQR HLA-DQB1 SBT up to 4-digit level. Three samples required adjustment of false reactions (3/100, 3.0%): two samples with DQB1*03:03/*06:01 showed false-positive result in probe 253, and 1 sample with DQB1*04:02/*05:02 showed false-negative result in probe 217. We tested an additional sample with DQB1*03:03/*06:01, which showed same false-positivity in probe 253 and 2 samples with DQB1*04:02/*05:02, which showed no false reaction. The false reactions did not result in ambiguity or change in the HLA allele assignment. We could assign HLA-DQB1 alleles to 4 digit-level without ambiguity, with 100% concordance with the SBT results. Thus, LIFECODES HLA-DQB1 SSO typing kit showed good performance for intermediate-resolution HLA-DQB1 typing in clinical laboratory for organ transplantation in Koreans.

Three Cases of Candidiasis Misidentified as Candida famata by the Vitek 2 System

No abstract available.

Female hyperandrogenemia and normal serum levels of testosterone and sex hormone binding globulin

It is well known that the reference values usually employed for endocrine biochemical measurements are those suggested by the suppliers of commercial kits despite their advice that each laboratory should set its own reference values. Our objectives were to (i) determine reference ranges for serum testosterone (T) and sex hormone binding globulin (SHBG) appropriate to our laboratory and population, and (ii) to analyze their influence on evaluating hyperandrogenemia. SHBG and T were measured, and free and bioavailable testosterone calculated, in (a) 30 selected non-hyperandrogenic women, (b) 87 non-selected healthy female blood donors, (c) 53 women with hyperandrogenism, and (d) 38 women with hyperandrogenic disorders but without biochemical hyperandrogenemia according to normal ranges suggested by the kit manufacturer. Mean serum SHBG concentrations were significantly different among all four groups. SHBG levels were significantly higher in selected normal women (group a). Using our results for this selected control group as new reference values, 12 out of 38 (31.6%) women with hyperandrogenic disorders without apparent hyperandrogenemia (group d) were recategorized as hyperandrogenemic. Similarly, 4 out of 63 (6.4%) non-selected, normal weight, women (group b), were recategorized as hyperandrogenic. Therefore, the diagnosis of hyperandrogenemia would improve accuracy by using customized reference SHBG values instead of those suggested by the suppliers.

Con frecuencia los valores de referencia utilizados para las evaluaciones bioquímicas endocrinológicas son los sugeridos por los kits utilizados, a pesar de las recomendaciones de que cada laboratorio debiera obtener sus propios valores de normalidad. Nuestros objetivos fueron (i) analizar los rangos de referencia para testosterona (T) y globulina ligadora de esteroides sexuales (SHBG) apropiados para nuestro laboratorio y población, y (ii) analizar su influencia en la evaluación de la hiperandrogenemia. Se midió T y SHBG y se calculó testosterona libre y biodisponible en un grupo (a) control de 30 mujeres no hiperandrogénicas, (b) 87 mujeres no seleccionadas donantes de sangre, (c) 53 mujeres con hiperandrogenismo, y (d) 38 mujeres con desórdenes hiperandrogénicos pero sin hiperandrogenemia de acuerdo a los rangos de normalidad sugeridos por el kit. La concentración media de SHBG fue significativamente diferente entre los cuatro grupos. Los niveles de SHBG fueron significativamente más altos en las mujeres controles seleccionadas (grupo a). Tomando en consideración los resultados obtenidos en este grupo y estableciendo los rangos de referencia adecuados, 12 de 38 mujeres (31.6%) hiperandrogénicas sin hiperandrogenemia (grupo d) fueron recategorizadas como con exceso androgénico bioquímico. De igual manera, al analizar mujeres normopesas no seleccionadas, en edad reproductiva (grupo b), 4 de 63 (6.4%) pudieron ser definidas como hiperandrogénicas. Utilizando valores adecuados de referencia para SHBG, se mejora la precisión del diagnóstico de exceso androgénico.

Evaluation of four molecular methods for the diagnosis of tuberculosis in pulmonary and blood samples from immunocompromised patients

The present study analysed the concordance among four different molecular diagnostic methods for tuberculosis (TB) in pulmonary and blood samples from immunocompromised patients. A total of 165 blood and 194 sputum samples were collected from 181 human immunodeficiency virus (HIV)-infected patients with upper respiratory complaints, regardless of suspicious for TB. The samples were submitted for smear microscopy, culture and molecular tests: a laboratory-developed conventional polymerase chain reaction (PCR) and real-time quantitative PCR (qPCR) and the Gen-Probe and Detect-TB Ampligenix kits. The samples were handled blindly by all the technicians involved, from sample processing to results analysis. For sputum, the sensitivity and specificity were 100% and 96.7% for qPCR, 81.8% and 94.5% for Gen-Probe and 100% and 66.3% for Detect-TB, respectively. qPCR presented the best concordance with sputum culture [kappa (k) = 0.864)], followed by Gen-Probe (k = 0.682). For blood samples, qPCR showed 100% sensitivity and 92.3% specificity, with a substantial correlation with sputum culture (k = 0.754) and with the qPCR results obtained from sputum of the corresponding patient (k = 0.630). Conventional PCR demonstrated the worst results for sputa and blood, with a sensitivity of 100% vs. 88.9% and a specificity of 46.3% vs. 32%, respectively. Commercial or laboratory-developed molecular assays can overcome the difficulties in the diagnosis of TB in paucibacillary patients using conventional methods available in most laboratories.

Análise de um radioimunoensaio iodado para determinação de 11-deoxicortisol / Analysis of an iodide radioimmunoassay for 11-deoxicortisol measurement

Objetivo : Nosso objetivo foi comparar duas técnicas de dosagem do 11-desoxicortisol: a técnica de radioimunoensaio iodado, a qual foi validada neste trabalho, e a cromatografia líquida de alta performance seguida por espectrometria de massa em tandem (LC-MS/MS), sendo a última considerada o padrão-ouro para dosagem dos hormônios esteroides. Materiais e métodos : Para a comparação entre os resultados de 11-desoxicortisol, foram selecionadas 88 amostras. Resultados : A sensibilidade analítica do radioimunoensaio foi de 0,30 ng/mL, com linearidade e perfil de precisão inadequado (34% das amostras com CV ≥ 20%). Das 88 amostras selecionadas, apenas 54 apresentaram resultados mensuráveis em ambos os métodos. A comparação desses resultados, por meio da regressão de Deming, resultou em um coeficiente de correlação de 0,610, inclinação de 3,751, intercepção de 0,145, evidenciando a pobre correlação entre os resultados e a superestimação dos resultados pelo RIA. Conclusão : Concluímos que o método de dosagem de 11-desoxicortisol por radioimunoensaio iodado apresentou resultados inadequados nos diversos parâmetros avaliados, inviabilizando sua utilização como método de dosagem do 11-desoxicortisol. Arq Bras Endocrinol Metab. 2014;58(3):232-6 .

Objective : Our aim was to correlate 11-deoxycortisol levels obtained by two currently available techniques for 11-deoxycortisol measurement: radioimmunoassay, and high performance liquid chromatography followed by tandem mass spectrometry (MS/MS). The latter is the gold standard method for steroid hormone measurement. Materials and methods : We selected 88 samples and the results of these two methods were compared by Deming regression. Results : The analytical sensitivity of the RIA was 0.30 ng/mL, with inadequate linearity and inadequate precision profile (34% of the samples had a CV ≥ 20%). From the selected samples, 54 had measurable levels of 11-deoxycortisol in both methods and were used in the comparison. The comparison of RIA with LC-MS/MS showed an overestimation of the results by RIA. The correlation coefficient was 0.610; linear regression slope was 3.751; and the intercept was 0.145, indicating a poor correlation between the two methods. Conclusion : We concluded that 11-deoxycortisol measured by radioimmunoassay, despite a good analytical sensitivity, showed very low specificity, precluding its use as a reliable method for 11-deoxycortisol measurement. Arq Bras Endocrinol Metab. 2014;58(3):232-6 .

Performance evaluation of the HepB Typer-Entecavir kit for detection of entecavir resistance mutations in chronic hepatitis B

BACKGROUND/AIMS: Molecular diagnostic methods have enabled the rapid diagnosis of drug-resistant mutations in hepatitis B virus (HBV) and have reduced both unnecessary therapeutic interventions and medical costs. In this study we evaluated the analytical and clinical performances of the HepB Typer-Entecavir kit (GeneMatrix, Korea) in detecting entecavir-resistance-associated mutations. METHODS: The HepB Typer-Entecavir kit was evaluated for its limit of detection, interference, cross-reactivity, and precision using HBV reference standards made by diluting high-titer viral stocks in HBV-negative human serum. The performance of the HepB Typer-Entecavir kit for detecting mutations related to entecavir resistance was compared with direct sequencing for 396 clinical samples from 108 patients. RESULTS: Using the reference standards, the detection limit of the HepB Typer-Entecavir kit was found to be as low as 500 copies/mL. No cross-reactivity was observed, and elevated levels of various interfering substances did not adversely affect its analytical performance. The precision test conducted by repetitive analysis of 2,400 replicates with reference standards at various concentrations showed 99.9% agreement (2398/2400). The overall concordance rate between the HepB Typer-Entecavir kit and direct sequencing assays in 396 clinical samples was 99.5%. CONCLUSIONS: The HepB Typer-Entecavir kit showed high reliability and precision, and comparable sensitivity and specificity for detecting mutant virus populations in reference and clinical samples in comparison with direct sequencing. Therefore, this assay would be clinically useful in the diagnosis of entecavir-resistance-associated mutations in chronic hepatitis B.

Valores de referência para níveis séricos do fator de crescimento semelhante à insulina tipo I (IGF-I) numa população adulta do Estado do Rio de Janeiro, Brasil / Reference ranges for serum levels of insulin-like growth Factor I (IGF-I) in an adult population of Rio de Janeiro State, Brazil

O nível sérico do Fator de crescimento semelhante à insulina tipo I (IGF-I) é fundamental para auxiliar no dignóstico e controle terapêutico dos transtornos relacionados à secreção do Hormônio de Crescimento (GH), bem como no diagnóstico e seguimento de outras doenças. Estabelecer valores de referência para as dosagens séricas de IGF-I por um ensaio imunoquimioluminométrico (ICMA), utilizando o sistema automatizado Immulite 2000/Diagnostic Products Corporation (DPC), e por um ensaio imunoradiométrico (IRMA), utilizando o kit comercial ACTIVE IGF-I/Diagnostic System Laboratories (DSL)-5600, numa população brasileira adulta da cidade do Rio de Janeiro. Este estudo, aprovado pelo Comitê de Ética do Instituto Estadual de Hematologia Arthur de Siqueira Cavalcanti, Rio de Janeiro, Brasil, incluiu amostras de 484 indivíduos saudáveis (251 homens e 233 mulheres) com idades entre 18 e 70 anos. As amostras foram estudadas por ICMA- Immulite 2000/DPC and IRMA- ACTIVE IGF-I/DSL-5600. Para análise dos dados foram utilizados modelos específicos para idade e sexo, após transformação dos dados de IGF-I. Foi observada uma lenta diminuição dos níveis de IGF-I com a idade usando ambos os ensaios. Os níveis de IGF-I foram signicativamente (p=0,0181) mais elevados em mulheres do que em homens, quando as amostras foram analisadas usando ICMA. Não houve diferença significativa dos níveis de IGF-I entre homens e mulheres quando as amostras foram analisadas usando IRMA. Este estudo estabeleceu valores de referência de IGF-I específicos para idade e sexo, determinados com o sistema automatizado ICMA-Immulite 2000/DPC, e valores de referência de IGF-I específicos para idade, determinados com o kit comercial IRMA- ACTIVE IGF-I/DSL-5600, em uma população adulta brasileira, da cidade do Rio de Janeiro

Serum level of insulin-like growth factor I (IGF-I) is fundamental in order to aid in the diagnosis and follow-up of growth hormone (GH)-related disorders, as well as in the diagnosis and follow-up of other diseases. The aim of this investigation was to determine reference values for IGF-I using an automated immunochemiluminometric assay (ICMA) system Immulite 2000/Diagnostic Products Corporation (DPC); and an immunoradiometric assay (IRMA), using the commercial kit ACTIVE IGF-I/Diagnostic System Laboratories (DSL)-5600, in an adult Brazilian population of Rio de Janeiro city. The study, approved by the Ethical Committee of the Instituto Estadual de Hematologia Arthur de Siqueira Cavalcanti, Rio de Janeiro, Brazil, included samples of blood taken from 484 healthy subjects (251men, 233 women) aged from 18 up to 70. The samples were analyzed by ICMA- Immulite 2000/DPC and IRMA- ACTIVE IGF-I/DSL-5600. For statistical analysis, age and sex-specific models were fitted after transformation of IGF-I values. In adulthood, a slow age-dependent decrease was found, using both assays. IGF-I in women were significantly (p=0,0181) higher than in men when samples were analayzed using ICMA.There was no significant difference between men and women IGF-I values when samples were analayzed using IRMA. The present study established age- and sex specific IGF-I reference values, determined with the automated system: ICMA-Immulite 2000/DPC and age-specific IGF-I reference values determined with the IRMA- ACTIVE IGF-I/DSL-5600, in an adult Brazilian population of Rio de Janeiro city

Efficiency of two commercial kits in serodiagnosis of leptospiral uveitis.

Purpose: Uveitis is an important complication of systemic leptospirosis that can occur months to years after systemic infection. The gold standard technique Microscopic Agglutination Test (MAT) is less sensitive and more complicated. All the commercial kits currently available are for early detection of acute systemic leptospiral infection. The purpose of this study is to evaluate the efficiency of two commercial kits in serodiagnosis of leptospiral uveitis, which is a late manifestation. Materials and Methods: Serum samples from leptospiral uveitis patients 20 MAT positive, 20 MAT negative, 15 non-leptospiral uveitis patients, 20 systemic leptospiral infected patients and 21 controls were selected. These samples were tested for the presence of leptospiral IgM antibodies by (i) MAT using a panel of 20 serovars, (ii) LEPTO IgM MICROLISA (J.Mitra & Co.Pvt. Ltd, India) and (iii) Leptocheck (Zephyr Biomedicals, India). The statistical analysis was carried out using stata 11.0. Results: Total of 96 samples were tested with two commercial kits, Lepto IgM MICROLISA and Leptocheck. The sensitivity and specificity of Lepto IgM MICROLISA was 60% and 55% and Leptocheck was 80% and 59% respectively in comparison to MAT. In comparison to clinical diagnosis the sensitivity of IgM Microlisa was 55%, Leptocheck 70% and specificity of IgM MICROLISA was 58.33% and leptocheck was 69.44%. Conclusion: Commercial kits though sensitive and specific for systemic leptospirosis, have limited diagnostic capacity for leptospiral uveitis. Therefore it is essential to develop an inhouse serodiagnostic method specific for leptospiral uveitis patients using local leptospiral isolates.

Evaluation of two indigenous rapid and two ELISA assays for the diagnosis of HIV infection India.

Purpose: Human immunodeficiency virus (HIV) diagnostic tests are being used extensively in India. However, the evaluation data on these assays are very limited. The present study evaluates indigenous HIV test kits manufactured in India. Materials and Methods: A total of 200 characterised specimens were assayed with Comb AIDS - RS Advantage HIV 1+2 Immunodot Test, Enzaids HIV 1+2 ELISA test, Enzaids Duet HIV Antigen+antibody ELISA test and Signal HIV Flow Through HIV 1+2 test kits. Performance characteristics of these assays were calculated. Results: Sensitivity, specificity, positive predictive value, negative predictive value and efficiency of all the assays were 100% except for Signal HIV Flow Through HIV 1+2 test kit. The specificity, positive predictive value and efficiency of the Signal HIV Flow Through HIV 1+2 test kit were 98.9%, 98.9% and 99.4%, respectively. The Enzaids Duet HIV kit was found to be extremely sensitive in detecting p24 Ag with the sensitivity of 1.5 pg/mL. Conclusions: To conclude, selection of better diagnostic assay is very much important to resolve discrepancies in HIV diagnosis. All these assays under evaluation in this report have got excellent performance characteristics and much suitable to use in serial testing algorithms in use for resources limited settings.

Análise comparativa de quatro kits de FAN HEp-2 para a detecção de autoanticorpos séricos / Comparative analysis of four ANA HEp-2 kits for the detection of serum autoantibodies

INTRODUÇÃO: O objetivo deste estudo foi avaliar a concordância entre os kits de fator antinúcleo (FAN) HEp-2 em relação aos padrões de fluorescência observados. Objetivou-se, ainda, avaliar o desempenho dos kits em relação à intensidade de fluorescência apresentada pelo uso dos conjugados fluorescentes, o número de mitoses por campo presentes no poço de reação e a titulação necessária para se obter o limiar de reatividade mínima (1+) dos soros controle reagentes presentes nos kits. MATERIAIS E MÉTODOS: Setenta e quatro amostras com resultados conhecidos foram testadas em quatro kits comerciais para a pesquisa de FAN HEp-2. O processamento estatístico foi feito pelo programa STATA® 9.2 e a concordância entre os resultados foi aferida pelo teste Kappa. RESULTADOS: O índice de concordância entre os kits, obtido pelo teste Kappa, foi superior a 0,94. Houve grande variabilidade quanto ao número de mitoses por campo presentes por poço de reação e quanto à intensidade de fluorescência dos conjugados, além de ter havido significativa diferença em dois kits em relação à diluição necessária para obtenção do limiar de reatividade mínima (1+). CONCLUSÃO: A taxa de concordância geral obtida pelo teste Kappa foi elevada, atingindo índice superior a 0,94. As maiores diferenças foram devido à presença de amostras com padrão variando entre nuclear pontilhado fino (PF), nuclear pontilhado fino denso (PFD) e nuclear homogêneo (HOMO). É necessária maior padronização dos kits quanto ao soro controle para a obtenção do limiar de reatividade mínima e em relação à intensidade de fluorescência dos conjugados.

INTRODUCTION: The objective of this study was to assess the concordance among antinuclear antibody (ANA) HEp-2 kits as to the observed fluorescent patterns. The objective was also to evaluate their performance concerning the following items: fluorescence intensity due to the use of fluorescent conjugates, the number of mitosis per field on the reaction wells, and the required dilution to obtain minimum reactivity (1+) of the reagent control-serum present in the kits. MATERIAL AND METHODS: Seventy-four samples previously known results were tested using four commercial kits ANA HEp-2 kits. The statistical evaluation was carried out with STATA® 9.2 software and the concordance among the results was assessed with Kappa test. RESULTS: The concordance coefficient among the kits obtained with Kappa test was higher than 0.94. There was a great variability as to the number of mitosis per field on the reaction wells and the intensity of fluorescence conjugates. Concerning the required dilution to obtain a minimum reactivity (1+), there was a significant difference in two kits. CONCLUSION: The general concordance level obtained with Kappa test was higher than 0.94. The greatest differences were observed in samples with nuclear fine speckled (FS), nuclear dense fine speckled (DFS) and nuclear homogeneous (HOMO) patterns. As far as serum for minimum reactivity level and intensity of fluorescent conjugates are concerned, a better standardization is yet to be pursued.

Evaluation of the Xpert Clostridium difficile Assay for the Diagnosis of Clostridium difficile Infection

Infection with Clostridium difficile is a growing concern because of the increasing prevalence and spread of nosocomial infections. Emergence of the hypervirulent 027/NAP1/BI strain is also notable. Existing diagnostic methods have low sensitivity or are time-consuming. Therefore, establishing a rapid and accurate microbiological diagnostic assay is needed. We evaluated the Xpert C. difficile assay (Xpert CD assay; Cepheid, USA) to detect toxigenic C. difficile. This assay is a real-time multiplex PCR assay that can be used to detect toxigenic C. difficile strains and differentiate the C. difficile presumptive 027/NAP1/BI strain. A total of 253 loose stool specimens were collected and toxigenic cultures, VIDAS C. difficile A & B assays (VIDAS CDAB assay; bioMerieux, France), and the Xpert CD assay were performed. In comparison to toxigenic cultures, the sensitivity, specificity, and positive and negative predictive values were 100%, 94.6%, 83.1%, and 100%, respectively, for the Xpert CD assay and 40.8%, 98.0%, 100%, and 88.9%, respectively, for VIDAS CDAB assay. Because of the low prevalence of the PCR ribotype 027 in Korea, the evaluation of the usefulness of the Xpert CD assay for screening for the 027 strain was limited. The Xpert CD assay provides great sensitivity in diagnosing toxigenic C. difficile infection. In addition, this method has excellent usability because it is simple and fast.

Comparison of Diagnostic Performance of Three Real-Time PCR Kits for Detecting Mycobacterium Species

PURPOSE: PCR is widely used for rapidly and accurately detecting Mycobacterium Species. The purpose of this study was to assess the diagnostic performance of three real-time PCR kits and evaluate the concordance with two older PCR methods. MATERIALS AND METHODS: Using 128 samples, the five PCR methods were assessed, including an in-house PCR protocol, the COBAS Amplicor MTB, the COBAS TaqMan MTB, the AdvanSure TB/NTM real-time PCR, and the Real-Q M. tuberculosis kit. The discrepant results were further examined by DNA sequencing and using the AdvanSure Mycobacteria Genotyping Chip for complete analysis. RESULTS: For Mycobacterium tuberculosis (MTB) detection, all five kits showed 100% matching results (positive; N = 11 and negative; N = 80). In non-tuberculous mycobacterium (NTM) discrimination, the AdvanSure yielded two true-positive outcomes from M. intracellulare and one false positive outcome, while the Real-Q resulted in one true-positive outcome and one false negative outcome for each case and another false negative result using the provided DNA samples. CONCLUSION: Real-time PCR, yielded results that were comparable to those of the older PCR methods for detecting MTB. However, there were disagreements among the applied kits in regard to the sample test results for detecting NTM. Therefore, we recommend that additional confirmatory measures such as DNA sequencing should be implemented in such cases, and further research with using a larger numbers of samples is warranted to improve the detection of NTM.

Validação laboratorial de um método automatizado de dosagem da atividade de adenosina desaminase em líquido pleural e em líquido cefalorraquidiano / Laboratorial validation of an automated assay for the determination of adenosine deaminase activity in pleural fluid and cerebrospinal fluid

OBJETIVO: A incidência global de tuberculose reforça a necessidade de melhores ensaios para o diagnóstico desta doença, principalmente da tuberculose extrapulmonar. O objetivo do trabalho foi validar o desempenho de um método automatizado para a determinação da atividade de adenosina desaminase (ADA) no líquido pleural (LP) e no líquido cefalorraquidiano (LCR), comparando-o com um método convencional (Giusti modificado). MÉTODOS: Selecionaram-se 134 amostras da rotina laboratorial: 94 de LP e 40 de LCR. Foram realizadas as determinações da atividade de ADA através dos dois métodos. Calculou-se a precisão inter- e intra-ensaios, análise de regressão linear, testes de concordância simples e médias das diferenças. RESULTADOS: Os coeficientes de correlação para as amostras de LP e LCR foram, respectivamente, 0,96 e 0,95. A precisão interensaio foi determinada pela média de 21 amostras replicadas em ensaios diferentes para 3 níveis de atividade: baixa, média e alta. Os coeficientes de variação em porcentagem ( por centoCV) foram, respectivamente, 5,9, 8,1 e 5,8 para amostras de LP; e 21,9, 18,6 e 13,8 para amostras de LCR, respectivamente. A precisão intra-ensaio em por centoCV foi, respectivamente, 1,3 e 11,7 por cento para amostras de LP e LCR. A concordância entre os dois métodos em amostras de LP e LCR foi, respectivamente, 96,8 por cento e 100 por cento, considerando-se como valores de referência para o diagnóstico de TB 40 U/L (convencional) e 30 U/L (automatizado) em amostras de LP, e 9 U/L em amostras de LCR para os dois métodos. CONCLUSÕES: Os resultados validaram o método automatizado de determinação da atividade de ADA para o uso em amostras de LP e LCR como alternativa ao método convencional.

OBJECTIVE: The incidence of tuberculosis worldwide has emphasized the need for better assays designed to diagnose the disease, principally the extrapulmonary form. The objective of the present study was to validate the performance of an automated method for the determination of adenosine deaminase (ADA) activity in pleural fluid (PF) and cerebrospinal fluid (CSF), comparing it with a conventional method (the modified Giusti method). METHODS: In total, 134 samples were selected from among those tested in our laboratory: 94 PF samples and 40 CSF samples. The ADA activity was determined using the two methods. Inter- and intra-assay precision was determined, linear regression analysis was performed, simple concordance tests were conducted, and the means of the differences were calculated. RESULTS: The correlation coefficients for PF and CSF samples were, respectively, 0.96 and 0.95. Inter-assay precision was determined using 21 replicates at 3 different activity levels: low, medium and high. The percentage coefficient of variation ( percentCV) was, respectively, 5.9, 8.1 and 5.8 for PF samples, compared with 21.9, 18.6 and 13.8 for CSF samples. Intra-assay precision in percentCV was 1.3 and 11.7, respectively, for PF and CSF samples. The concordance between the methods in PF and CRF samples was, respectively, 96.8 percent and 100 percent, considering the reference values for the diagnosis of TB to be 40 U/L (conventional) and 30 U/L (automated) in PF samples, versus 9 U/L (for both methods) in CSF samples. CONCLUSIONS: The results validate the use of the automated method of determining ADA activity in PF and CSF samples as an alternative to the conventional method.

Evaluation of five screening tests licensed in Argentina for detection of hepatitis C virus antibodies

This study was conducted to compare among the most recent generation of five screening tests licensed in Argentina, in order to evaluate which of the tests has the best sensitivity for detection of antibodies against hepatitis C virus (HCV). The tests analyzed were: Detect-HCV™ (3.0) Biochem ImmunoSystems, Canada; Hepatitis C EIA Wiener Lab., Argentina; Equipar HCV Ab, Italy; Murex HCV 4.0, UK and Serodia-HCV particles agglutination test, Japan. The results obtained showed high discrepancy between the different kits used and show that some of the tests assessed have a low sensitivity for anti-HCV detection in both chronic infections and early seroconversion, and indicate that among the commercially available kits in Argentina, Murex HCV 4.0 (UK) and Serodia-HCV particles agglutination test (Japan) have the best sensitivity for HCV screening. Although the sensitivity of the assays is the first parameter to be considered for blood screening, more studies should be carried out to assess the specificity of such assays.