Comparison of the Commercial QuantiFERON-CMV and Overlapping Peptide-based ELISPOT Assays for Predicting CMV Infection in Kidney Transplant Recipients

Cytomegalovirus (CMV) is one of the most important opportunistic infections in transplant recipients. Tests for CMV-specific T cell responses have been proposed to change the current risk stratification strategy using CMV assays. We evaluated the usefulness of pre-transplant CMV-specific T cell assays in kidney transplant (KT) candidates for predicting the development of CMV infection after transplantation comparing the results of the overlapping peptides (OLPs)-based enzyme-linked immunospot (ELISPOT) assay and the commercial QuantiFERON-CMV assay. We prospectively enrolled all cases of KT over a 5-month period, except donor CMV-seropositive and recipient seronegative transplants that are at highest risk of CMV infection. All the patients underwent QuantiFERON-CMV, CMV OLPs-based pp65, and immediate-early 1 (IE-1)-specific ELISPOT assays before transplantation. The primary outcome was the incidence of CMV infection at 6 months after transplant. The total of 47 KT recipients consisted of 45 living-donor KTs and 2 deceased-donor KTs. There was no association between positive QuantiFERON-CMV results and CMV infection. However, 10 of 34 patients with phosphoprotein 65 (pp65)- or IE-1-specific ELISPOT results higher than cut-off value developed CMV infections compared with none of 13 patients with results lower than cut-off value developed CMV. The OLPs-based ELISPOT assays are more useful than the QuantiFERON-CMV assay for predicting CMV infection. Patients with higher CMV-specific T cell immunity at baseline appear to be more likely to develop CMV infections after KT, suggesting that the abrupt decline in CMV-specific T cell responses after immunosuppression, or high CMV-specific T cell responses due to frequent CMV activation before KT, may promote CMV infection.

The value of quantitative TB-DNA test,interferon gamma release test,tuberculosis antibody detection in the pulmonary tuberculosis smear positive patients / 国际检验医学杂志

Objective To investigate the value of quantitative TB‐DNA test ,interferon gamma release test and the detection of tuberculosis antibodies for the diagnosis of active pulmonary tuberculosis .Methods 51 patients were diagnosed as tuberculosis from 2013 July to 2014 June in the hospital ,whose sputum smear microscopy for acid fast bacilli were positive .Then TB‐DNA quantitative test ,interferon gamma release test (T‐SPOT .TB)and tuberculosis antibody detection were performed for those pa‐tients .All the result were retrospectively analysed .Results The positive rate of T‐SPOT .TB was 90 .1% ,the positive rate of quan‐titative TB‐DNA test was 74 .5% and the positive rate of tuberculosis antibody detection was 37 .3% .Conclusion Because the re‐sult of T‐SPOT .TB is not affected by the process of specimen collection ,it is the most sensitive test of the three tests at present , and has higher value in the auxiliary diagnosis of active pulmonary tuberculosis than the other two .

La utilidad de la reacción tuberculina / The usefulness of the tuberculin skin test

Tuberculin skin test (TST) is a test based on purified protein derivative of Mycobacterium tuberculosis (or PPD). TST has been considered a standard for identifying tuberculous infected people by the World Health Organization (WHO) since 1955. However, other immunological tests that measure the interferon gamma production(Interferon gamma release assays or IGRAs) in the individual`s cells with latent tuberculosis (TB) infection (LTBI) have been used as surrogate TST, despite having certain restrictions. WHO has made several recommendations for preventive treatment in cases of LTBI aiming to supplant the universal shortage of PPD since 2014. Some rules for identifying LTBI individuals without the TST still reiterate the importance of this test in many countries.

La reacción tuberculina (RT) es una prueba cutánea que emplea el derivado proteico purificado de Mycobacterium tuberculosis o PPD. Desde 1955 ha sido considerada estándar para identificar personas infectadas por el bacilo de la tuberculosis por la Organización Mundial de la Salud (OMS). Sin embargo, otras pruebas inmunológicas que miden la producción de interferon gama (IGRAs) por las células del individuo con infección latente de TB (ILTB) se han empleado como sucedáneas de la RT, a pesar de presentar ciertas restricciones. La OMS ha hecho diversas recomendaciones para la conducta preventiva en casos de ILTB que de alguna forma buscan suplantar la falta universal de PPD desde 2014. Algunas perspectivas de identificar personas con ILTB sin contar con el PPD reiteran todavía la importancia de la RT en muchos países.

Pesquisa de infección tuberculosa latente en personal de la salud en cuatro instituciones de salud en Santiago de Chile / Latent tuberculosis infection screening in healthcare workers in four large hospitals in Santiago, Chile

Background: It is currently unknown which is the prevalence of latent tuberculosis infection in healthcare workers in Chile, but this group has been described as at higher risk of developing active tuberculosis than general population. Objectives: To determine the prevalence of latent tuberculosis infection in a sample of healthcare workers from at risk areas. Methodology: A cross-sectional, descriptive study, conducted in health care workers from clinical laboratories or respiratory care areas in four hospitals in Santiago. Latent tuberculosis infection detection was determined by Quantiferon® TB Gold In Tube testing (QFT). Results: QFT resulted positive in 20 of 76 (26.3%) of the individuals tested. Test positivity reached 62.5% among the personnel that reported history of past TB contact in the community, 50% among the personnel who belonged to the national tuberculosis control program and 38% among those doing induced sputum, acid fast smear or mycobacterial cultures. The proportion of individuals with positive QFT was significantly lower in those personnel who had no such risk factors (15.7%, p = 0.03). The proportion of latent tuberculosis infection also increased in direct relation to the age of the subject. Conclusion: Latent tuberculosis infection as detected by QFT testing was highly prevalent in healthcare workers included in the present study. Further exploring the limitations and possible scenarios for this new diagnostic tool is needed, with emphasis on health personnel at higher-risk and younger individuals.

Introducción: Se desconoce en la actualidad cuál es la real prevalencia de infección tuberculosa latente en el personal de salud en Chile; sin embargo, este grupo ha sido descrito como con mayor riesgo de desarrollar tuberculosis activa que la población general. Objetivo: Determinar la prevalencia de infección tuberculosa latente en funcionarios de la salud en diferentes áreas laborales de riesgo. Metodología: Estudio de corte transversal, descriptivo, realizado en funcionarios pertenecientes a laboratorios clínicos o áreas de atención broncopulmonar de cuatro hospitales de la Región Metropolitana en quienes se hizo test de Quantiferon TB Gold®In tube(QFT). Resultados: Se evidenció infección tuberculosa latente en 20 de las 76 (26,3%) personas estudiadas. En aquellos funcionarios que referían antecedente de contacto en el pasado en la comunidad con enfermos de tuberculosis, la positividad del test llegó a 62,5%; en aquellos que pertenecían al Programa Nacional de Control de la Tuberculosis, a 50% y en los que realizaban toma de esputo inducido, baciloscopias o cultivo de micobacterias, a 38%. La proporción de individuos con QFT positivo fue significativamente menor en aquellos funcionarios que no tenían estos antecedentes (15,7%, p = 0,03). Se encontró además una mayor proporción de infección tuberculosa latente a mayor edad del individuo estudiado. Conclusión: La infección tuberculosa latente medida por QFT resultó altamente prevalente en el personal de la salud incluido en el presente estudio. Es necesario seguir profundizando en los posibles escenarios de implementación y limitaciones del uso de esta nueva herramienta diagnóstica, haciendo énfasis en el personal de la salud de mayor riesgo y menor edad.

Diagnosis and treatment of latent tuberculosis infection

Tuberculosis (TB) is still an important cause of morbidity and mortality worldwide. Nearly one-third of the world's population is latently infected with Mycobacterium tuberculosis, and 10% of them will develop active TB during their lifetime. The tuberculin skin test or interferon-gamma release assay (IGRA) is the method for diagnosis of latent TB infection. Although commercially available IGRAs have limitations in serial testing, and testing children and immunosuppressive patients, IGRAs have superior sensitivity and specificity compared with conventional tuberculin skin testing, especially in Bacillus Calmette-Guerin vaccinated populations. For the treatment of latent TB infection, 9 months isoniazid is the standard treatment in Republic of Korea. However, shorter treatment regimens, including 4 months of rifampin, 3 months of isoniazid/rifampin, and once weekly isoniazid/rifapentine are currently alternatives. Identification and treatment of latent TB infection has lowered the TB incidence in developed countries. Therefore, for TB control, diagnosis and treatment of latent TB infection is important. However, there is lack of research on latent TB infection in South Korea. To revise the guideline, a large prospective trial on the treatment of latent TB infection is needed.