Evaluación de un nuevo inmunoensayo para detectar anticuerpos contra el virus de la hepatitis C / Evaluation of new immunoassay for detection of antibodies against hepatitis C virus

Se evaluó el desempeño de un nuevo inmunoensayo de tercera generación para la detección de anticuerpos contra el virus de la Hepatitis C, HCV ELISA 3ª generación (Wiener-lab. Rosario. Argentina). Este equipo presenta reactivos coloreados para permitir el monitoreo de adición de muestras y control de procesos. Se evaluó la sensibilidad, especificidad y precisión de HCV ELISA 3ª generación mediante 5 paneles de seroconversión, 8 paneles de desempeño, 1 panel de sensibilidad para diferentes genotipos de HCV, 23 muestras de pacientes infectados con diferentes genotipos de HCV, 546 muestras de pacientes infectados, 556 muestras que contenían interferentes potenciales y 3.024 muestras de individuos no infectados. La sensibilidad en paneles de desempeño y en pacientes infectados fue 99,72%, y en muestras de pacientes infectados con diferentes genotipos fue 100%. La especificidad obtenida en muestras de donantes de sangre y Centros de Salud fue 99,50%. Finalmente, en los estudios de precisión se observó un coeficiente de variación intraensayo menor al 10%, e interensayo menor al 15% para muestras reactivas débiles. HCV ELISA 3ª generación, desarrollado por Wiener-lab, presenta un desempeño adecuado para el diagnóstico de la infección por HCV en el laboratorio serológico y en el tamizaje de donantes de sangre.

The performance of a new third-generation Anti-HCV, HCV ELISA third-generation (Wiener-lab. Rosario. Argentina), was evaluated. This kit presents sample addition monitoring and process control. Sensibility, specificity and precision of HCV ELISA 3ª generation were evaluated by means of 5 seroconversion panels, 8 performance panels, 1 worldwide HCV performance panel (which includes different HCV genotypes), on 546 samples of patients infected with HCV, 556 samples containing potentially interfering substances, and 3024 samples of persons not infected with HCV. Sensibility was 99.72% on performance panels and samples of HCV infected patients, and 100% on samples of patients infected with different genotypes. The specificity obtained from samples from blood donors and health centers was 99.50%. Finally, in precision studies the intra-assay coefficient of variation found was smaller than 10% and the inter-assay CV was smaller than 15% for weak reactive samples. In summary, HCV ELISA 3ª generation developed by Wiener-lab presents an adequate performance for the diagnosis of hepatitis C virus infection in clinical laboratory and blood donations screening.

The Clinical significance of STAT-PAT-PAK ULTRA FAST(R) and ICT Tuberculosis for Serologic Diagnosis of Tuberculosis / 결핵

BACKGROUND: In recent years, tuberculosis has re-emerged as a major health problem in both industrialized and developing countries. Recent advances in identifying and purifying antigens secreted in active tuberculosis infection have lead to the development of serological assays based on a number of immunodominant antigens. To date, the most sensitive and specific of these antigens has been the 38-kDa antigen. METHOD: Two rapid membrane-based serologic assays using antigen(38-kDa) from mycobacterium tuberculosis for the diagnosis of tuberculosis were evaluated in 22 patients with smear-positive pulmonary tuberculosis, 14 patients with inactive pulmonary tuberculosis, and 9 patients with non-tuberculous lung disease. RESULT: The evaluation of validity(sensitivity, specificity, positive predictive value, negative predictive value, false positivity and false negativity) of STAT-PAK ULTRA FAST(R) were 77.3%, 28.6%, 63.0%, 44.4%, 71.4%, and 22.7% for differential diagnosis of active pulmonary tuberculosis and inactive pulmonary tuberculosis, respectively. The evaluation of validity of STAT-PAK ULTRA FAST(R) were 77.3%, 33.3%, 73.9%, 37.5%, 66.7%, and 22.7% for differential diagnosis of active pulmonary tuberculosis and non-tuberculosis. The evaluation of validity of ICT Tuberculosis were 54.5%, 57%, 66.7%, 44.4%, 42.9%, and 45.5% for differential diagnosis of active pulmonary tuberculosis and inactive pulmonary tuberculosis. The evaluation of validity of ICT Tuberculosis were 54.5%, 100%, 100%, 47.4%, 0%, and 45.4% for differential diagnosis of active pulmonary tuberculosis and non-tuberculosis. CONCLUSION: We concluded no effectiveness of STAT-PAK ULTRA FAST(R) and ICT tuberculosis on serologic diagnosis of pulmonary tuberculosis. In the future, further large-scale study should be needed for serologic diagnosis of pulmonary tuberculosis.

The Re-evaluation of the Serologic ELISA tests for the Diagnosis of Helicobacter pylori Infection / 대한임상병리학회지

BACKGROUND: Helicobacter pylori (H. pylori), a Gram negative spiral bacilli, is known to be the cause of chronic gastritis and peptic ulcer disease and is strongly associated with gastric cancer. Therefore, the rapid detection of H. pylori infection is necessary for prevention and treatment. Of the diagnostic tests currently used, the serologic tests, which makes use of the immune response, do not need a biopsy specimen. This method is relatively accurate, rapid, simple and inexpensive. We re-evaluated the clinical usefulness of the isotypes of H. pylori (IgG, IgA, IgM) antibodies for the detection of H. pylori infection. MATERIALS AND METHODS: Serum samples were obtained from 1,851 patients confirmed to have gastric or duodenal disease by gastric endoscopy from June, 1993 to December, 1994 at Hanyang University Hospital. The phenol-red urease test was done during endoscopy and the H-E stain on the gastric biopsies. Serologic tests (GAP Test IgG, IgA, IgM kits) were performed with patient sera. RESULTS: The sensitivities of the GAP EIA were 80% for IgG, 27% for IgA, and 85% for IgM. The specificities were 33%, 79%, and 14%, respectively. The detection rates of H. pylori were highest for the phenol-red urease test (88%), followed by IgM by ELISA (86%), IgG (72%), H-E stain (43%), and IgA (21%). The serum levels of IgG and IgA antibodies were higher in those with H. pylori infection than in those without, but there was no difference in IgM levels. And, no difference of serologic antibody levels according to disease state. Where follow-up was possible, the majority of IgG levels decreased, but IgA or IgM levels are not changed. CONCLUSION: A positive serologic test is incapable of discriminating between actual infection and normal bacterial colonization, or between recent and past infections. Therefore a serologic test seems unsatisfactory for confirming a diagnosis of H. pylori infection, but because the serial IgG levels of treated patients decreased significantly, we believe that this test may be used as an indirect means of assessing the response to therapy.

Application of serologic diagnosis of tsutsugamushi disease (scrub typhus) in Korea where the disease was recently recognized to be endemic

In Korea, tsutsugamushi disease is a recently recognized infection. It has become clear that it is more prevalent than leptospirosis or hemorrhagic fever with renal syndrome. Accurate diagnosis of the disease is necessary for the selection of effective antimicrobial agents which can prevent fatalities and shorten the course. For the diagnosis, various serologic tests are used. Sensitivity and specificity of a test depend on various factors. In this report, microbiological aspects of the infection were briefly described and the Weil-Felix, indirect immunofluorescence and indirect immunoperoxidase tests were compared for their applicability in routine use and usefulness in the diagnosis. Their interpretations were also briefly discussed.