Performance Evaluation of a New Automated Chemiluminescent Immunoanalyzer-Based Interferon-Gamma Releasing Assay AdvanSure I3 in Comparison With the QuantiFERON-TB Gold In-Tube Assay

BACKGROUND: The interferon-gamma (IFN-γ) releasing assay (IGRA) is widely used for latent tuberculosis infection (LTBI) diagnosis. We evaluated the analytical performance of a new automated chemiluminescent immunoanalyzer-based IGRA (CLIA-IGRA), AdvanSure I3 (LG Life Sciences, Seoul, Korea) and compared it with that of the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay. METHODS: Repeatability and reproducibility were evaluated at four levels. Detection capability, including limit of blank (LoB), limit of detection (LoD), and limit of quantification (LoQ), was evaluated using IFN-γ standard material (National Institute for Biological Standards and Control code: 87/586). Agreement between the results of two assays was evaluated using 341 blood samples from healthcare workers and patients at a tertiary care hospital. To determine the cut-off value of CLIA-IGRA for diagnosing LTBI, the ROC curve was analyzed. RESULTS: Repeatability and reproducibility were 4.86–7.00% and 6.36–7.88% CV, respectively. LoB, LoD, and LoQ were 0.022, 0.077, and 0.249 IU/mL, respectively. IFN-γ values between CLIA-IGRA and QFT-GIT showed a strong correlation within the analytical measurable range of both assays, especially when the value was low. Qualitative comparison of the two assays yielded a 99.1% overall agreement (kappa coefficient=0.98). A cut-off value of 0.35 IU/mL was appropriate for diagnosing LTBI. CONCLUSIONS: CLIA-IGRA is a reliable assay for LTBI diagnosis, with performance similar to that of QFT-GIT.

Performance and correlation of QuantiFERON-TB Gold, T-SPOT.TB and tuberculin skin test in young children with tuberculosis exposure or tuberculosis disease

To evaluate the performance of interferon gamma release assays and tuberculin skin test in Bacillus Calmette-Guerin vaccinated young children. Methods: A cross-sectional study was conducted in healthy children younger than 5 years who were recently diagnosed with tuberculosis or had recent exposure to active tuberculosis. QuantiFERON-TB Gold, T-SPOT.TB and tuberculin skin test were performed in each patient. Results: Of the 60 children, median age 3.3 years, 17 had tuberculosis and 43 had recent tuberculosis exposure. Overall, 15 (25.0%) children had tuberculin skin test reaction =10 mm; 8 (13.3%) were positive by QuantiFERON-TB Gold In-Tube test, and 12 (20.0%) by T-SPOT.TB. Nineteen (31.7%) children had at least one positive test. There was a moderate agreement between interferon gamma release assays and tuberculin skin test. Conclusions: The positive rates of interferon gamma release assays and tuberculin skin test were low in young children who were infected with tuberculosis, supporting the management strategy of not testing children younger than 5 years. (IGRA) do not react to BCG and most NTM[2], are preferred to TST in older children and adults[3], but may be less reactive in young children with immature T-cell function. Due to the limited knowledge of IGRA in BCG-vaccinated young children, we evaluated the performance and correlation of IGRA tests and TST in young children in a high TB burden setting who received BCG vaccination at birth and recently diagnosed with LTBI, or with active TB.

Different Quantitative Interferon-γ Response in Active Tuberculosis of Various Primary Infection Sites

Performance and correlation of QuantiFERON-TB Gold, T-SPOT.TB and tuberculin skin test in young children with tuberculosis exposure or tuberculosis disease

To evaluate the performance of interferon gamma release assays and tuberculin skin test in Bacillus Calmette-Guerin vaccinated young children. Methods: A cross-sectional study was conducted in healthy children younger than 5 years who were recently diagnosed with tuberculosis or had recent exposure to active tuberculosis. QuantiFERON-TB Gold, T-SPOT.TB and tuberculin skin test were performed in each patient. Results: Of the 60 children, median age 3.3 years, 17 had tuberculosis and 43 had recent tuberculosis exposure. Overall, 15 (25.0%) children had tuberculin skin test reaction =10 mm; 8 (13.3%) were positive by QuantiFERON-TB Gold In-Tube test, and 12 (20.0%) by T-SPOT.TB. Nineteen (31.7%) children had at least one positive test. There was a moderate agreement between interferon gamma release assays and tuberculin skin test. Conclusions: The positive rates of interferon gamma release assays and tuberculin skin test were low in young children who were infected with tuberculosis, supporting the management strategy of not testing children younger than 5 years. (IGRA) do not react to BCG and most NTM[2], are preferred to TST in older children and adults[3], but may be less reactive in young children with immature T-cell function. Due to the limited knowledge of IGRA in BCG-vaccinated young children, we evaluated the performance and correlation of IGRA tests and TST in young children in a high TB burden setting who received BCG vaccination at birth and recently diagnosed with LTBI, or with active TB.

Utility of QuantiFERON®-TB gold In-Tube test compared with tuberculin skin test in diagnosing tuberculosis in Indian children with malnutrition

This prospective cohort study was conducted to compare the accuracy of QuantiFERON®-TB (QFT) Gold In-Tube test and tuberculin skin test (TST) in diagnosing tuberculosis (TB) in predominantly bacille Calmette–Guerin-vaccinated children with a high incidence of malnutrition. The sensitivity of the QFT versus the TST was 69.6% versus 52.9% for WHO-defined TB, with specificity of 86% versus 78.3%, respectively. The concordance of the TST and QFT was 79% overall (? = 0.430), 62.5% in those with WHO-defined TB and 85.7% in those without TB. Majority of the QFT+/TST ? discordance was seen in children with TB, whereas majority of the TST+/QFT ? discordance was seen in those without TB. The TST was more likely to be negative in children with moderate-to-severe malnutrition (P = 0.003) compared to the QFT, which was more likely to be positive in younger children. The significantly better performance of the QFT in malnourished children and those at younger ages supports its use for TB diagnosis in these subpopulations.

The Performance of the Agility System for Interferon Gamma Release Assay Using QuantiFERON TB Gold In-Tube Assay / 임상검사와정도관리

BACKGROUND: As stated in ‘The Action Strategy for Tuberculosis-Free Korea,’ last March, high-throughput, large-scale analytical instruments for interferon gamma release assays (IGRA) are demanded by many clinical laboratories using the QuantiFERON-TB Gold In-Tube assay (Cellestis/Qiagen, Australia). Agility (Dynex Technologies, USA) is an automated high-throughput enzyme linked immunosorbent assay analyser. The present study aimed to evaluate its accuracy and speed. METHODS: Pooled plasma was prepared using samples obtained after IGRA testing. Analyses of precision, linearity, cut-off evaluation, and comparison with conventional methods were performed for multiple Agility instruments according to the Clinical and Laboratory Standards Institute EP5-A3, EP6-A, EP9-A3 and EP12-A2 guidelines. The turnaround time and throughput were also analysed. RESULTS: The coefficient of variation range was 2.48%–4.0%, 7.01%–11.17%, and 9.69%–14.84% for the repeatability, between-run precision, and between-day precision analyses, respectively. The linearity ranged from 0 to 10.541. Comparison analysis presented a high concordance of Agility with the conventional instrument, DS2 (Dynex Technologies), and manual method for IGRA. The cut-off value of 0.35 IU/mL was well compatible with the C50. It was identified that the C50±20% contained the C5–C95 interval. The average turnaround time was 3.84 hours, from the submission of pre-treated samples to the reporting of results. The throughput was determined to be 290 tests during a routine working time of 8 hours. CONCLUSIONS: Agility showed high precision, linearity, concordance, and had a 2.5 times faster throughput than with the conventional and manual method. It could be useful for large-scale IGRA testing in latent tuberculosis infection screening project. Samples within C50±20% are suspected to show relatively low reporducible results of high inversion between postivie and negative.

A Feasibility Study for Diagnosis of Latent Tuberculosis Infection Using an IGRA Point-of-Care Platform in South Korea

PURPOSE: This study aimed to evaluate ichroma™ IGRA-TB, a novel point-of-care platform for assaying IFN-γ release, and to compare it with QuantiFERON-TB Gold In-Tube (QFT-GIT) for identifying Mycobacterium tuberculosis (M. tb) infection. MATERIALS AND METHODS: We recruited 60 healthy subjects, and blood samples were obtained in QFT-GIT blood collection tubes. The blood collection tubes were incubated at 37℃, and culture supernatant was harvested after 18–24 hours. IFN-γ responses were assessed by the ichroma™ IGRA-TB cartridge and the QFT-GIT IFN-γ enzyme-linked immunosorbent assay. Three active TB patients were recruited as a positive control for M. tb infection. RESULTS: The area under the receiver operating characteristic curve of the ichroma™ IGRA-TB test for differentiating between infected and non-infected individuals was 0.9706 (p < 0.001). Inconsistent positivity between the two tests was found in three participants who showed weak positive IFN-γ responses ( < 1.0 IU/mL) with QFT-GIT. However, the two tests had excellent agreement (95.2%, κ=0.91, p < 0.001), and a very strong positive correlation was observed between the IFN-γ values of both tests (r=0.91, p < 0.001). CONCLUSION: The diagnostic accuracy demonstrated in this study indicates that the ichroma™ IGRA-TB test could be used as a rapid diagnostic method for detecting latent TB infection. It may be particularly beneficial in resource-limited places that require cost-effective laboratory diagnostics.

Multiple Skin Colored Nodules on both Legs in Patient with Positive QuantiFERON®-TB Gold Test

Nodular tuberculid (NT) was originally described by Jordaan et al. in 2000 in 4 patients from South Africa. It appeared as nodules on the legs; the pathologic changes were situated in the deep dermis and adjacent subcutaneous fat. A 34-year-old woman visited our hospital with subcutaneous skin-colored or slightly erythematous round to oval nodules. Skin biopsies revealed granulomatous inflammation at the dermo-subcutaneous junction with vasculitis. Chest X-ray, tuberculosus (TB)-polymerase chain reaction and TB culture of the skin specimen were normal. A QuantiFERON®-TB Gold test (QUIAGEN, Germany) was positive, which suggested a diagnosis of latent TB infection. The patient was treated with anti-TB medication and her condition has not recurred. Herein, we report a case of a patient with latent TB diagnosed by a positive QuantiFERON®-TB Gold test whose skin lesions had the clinical and histopathologic features of NT.

Multiple Skin Colored Nodules on both Legs in Patient with Positive QuantiFERON®-TB Gold Test

Nodular tuberculid (NT) was originally described by Jordaan et al. in 2000 in 4 patients from South Africa. It appeared as nodules on the legs; the pathologic changes were situated in the deep dermis and adjacent subcutaneous fat. A 34-year-old woman visited our hospital with subcutaneous skin-colored or slightly erythematous round to oval nodules. Skin biopsies revealed granulomatous inflammation at the dermo-subcutaneous junction with vasculitis. Chest X-ray, tuberculosus (TB)-polymerase chain reaction and TB culture of the skin specimen were normal. A QuantiFERON®-TB Gold test (QUIAGEN, Germany) was positive, which suggested a diagnosis of latent TB infection. The patient was treated with anti-TB medication and her condition has not recurred. Herein, we report a case of a patient with latent TB diagnosed by a positive QuantiFERON®-TB Gold test whose skin lesions had the clinical and histopathologic features of NT.

СҮРЬЕЭГИЙН ДАЛД ХАЛДВАРЫН ТАРХАЛТЫГ ТОДОРХОЙЛЖ, ТҮҮНД НӨЛӨӨЛӨХ ЗАРИМ ХҮЧИН ЗҮЙЛИЙН ЭРСДЛИЙГ ҮНЭЛСЭН НЬ / Шинэ санаа Шинэ нээлт

@#BACKGROUND. 2.3 billion Individuals have latent TB infection(LTBI), up to 10 million new cases of TB arise and killing nearly 2 million individuals around this globe, annually [1,2]. In Mongolia, tuberculinskin test is used to detection of mycobacterial infection, which has many disadvantages. Interferon gamma release assay (IGRA, QFT-G), a method advised by WHO, is the most reliable detection of latent infection. If we can detect LTBI in childhood, it is possible to prevent from active TB decreasing prevalence in the future. That is why it is important to screen the LTBI among children. GOAL: To estimate the prevalence of LTBI among 6-13 age children and to define the LTBI risk factors. Methods: We enrolled 9126 children for our study, indicating a possible estimation for LTBI prevalence among 6-13 age children in Ulaanbaatar city. Under ethical permission, our study was performed, as well as the consent of parents and children. We determined the LTBI by using QFT-G. We took a questionnaire about a socio-economic status, a history of TB contact and also conducted anthropometric measurements in all participants. The study design was a descriptive, cross-sectional and a case-control which based on QFT-G results. SPSS version 20.0.0 was used for statistical analyses. RESULTS: Regardingthe QFT-G test, 8214(90%) number of children were negative, 908 (10%) were positive, 4 (<0.1%) samples were indeterminable. There were statistically significant differences between control and case group in some questionnaire of socio-economic status. No significant difference was seen between two groups in all anthropometric measurements. In multinomial logistic regression, a tuberculosis contact, a household type, and passive smoking were identified as independent LTBI risk factors (p<0.01). CONCLUSIONS: The LTBI prevalence is high (10%) in school-age children living in Ulaanbaatar. It has increased at 6-13 age (p<0.05). Several important risk factors for LTBI in school age children elicited. Most powerful risk factors were tuberculosis contact (p<0.001), type of residence (p<0.05) and passive smoking (p<0.001).

Comparison of the tuberculin skin test and the QuantiFERON-TB Gold test in detecting latent tuberculosis in health care workers in Iran / 한국역학회지

OBJECTIVES: The tuberculin skin test (TST) and the QuantiFERON-TB Gold test (QFT) are used to identify latent tuberculosis infections (LTBIs). The aim of this study was to determine the agreement between these two tests among health care workers in Iran. METHODS: This cross-sectional study included 177 tuberculosis (TB) laboratory staff and 67 non-TB staff. TST indurations of 10 mm or more were considered positive. The Student's t-test and the chi-square test were used to compare the mean score and proportion of variables between the TB laboratory staff and the non-TB laboratory staff. Kappa statistics were used to evaluate the agreement between these tests, and logistic regression was used to assess the risk factors associated with positive results for each test. RESULTS: The prevalence of LTBIs according to both the QFT and the TST was 17% (95% confidence interval [CI], 12% to 21%) and 16% (95% CI, 11% to 21%), respectively. The agreement between the QFT and the TST was 77.46%, with a kappa of 0.19 (95% CI, 0.04 to 0.34). CONCLUSIONS: Although the prevalence of LTBI based on the QFT and the TST was not significantly different, the kappa statistic was low between these two tests for the detection of LTBIs.

Comparison of interferon gamma release assay & tuberculin skin tests for diagnosis of latent tuberculosis in patients on maintenance haemodialysis.

Background & objectives: Tuberculosis (TB) is a common infection in patients on haemodialysis. There is a definite role of treatment of latent TB (LTB) in these patients. However, diagnosis of LTB in these patients by tuberculin skin test (TST) is unreliable. There is suggestion that interferon gamma release assay (IGRA) will be more reliable test for diagnosis of LTB in this setting. Thus, we evaluated value of IGRA and TST for the diagnosis of LTB in patients on dialysis in an Indian setting. Methods: Patients with end stage kidney disease on dialysis were included. Patients with active TB were excluded. Each patient was subjected to TST (induration of ≥10 mm was taken as positive) and QuantiFERON TB Gold In-Tube test (QFT-GIT) for diagnosis of LTB. Results: A total of 185 patients were included; 129 (69.7%) were males and mean age was 36.7 ± 12.3 yr. Past history of TB was present in 18 (9.7%) patients. One hundred and thirty four (72.4%) patients had scar of BCG vaccination. QFT-GIT test was positive in 66 (36%), TST in 32 (17%) and both in 13 (7%) patients. Of the 66 patients positive with QFT-GIT, only 13 (19.6%) were positive for TST. Of the 32 patients positive with TST, only 13 (40.6%) were positive with QFT-GIT; 100 (54%) patients were negative for both the tests. Overall, 85 (45.9%) patients were positive for either of the two tests. Poor agreement was shown between the two methods. On logistic regression analysis, odds of QFT-GIT to be positive in patients with BCG vaccination was 1.23 and with history of TB 0.99, both being insignificant. odds of tuberculin skin test to be positive in patients with BCG vaccination was 1.04 and with history of TB 0.99, both again being insignificant. Interpretation & conclusions: Our findings showed that more number of patients (36%) on haemodialysis were positive for QuantiFERON Gold In-Tube test as compared to TST (17%). There was poor agreement between the two tests. no significant effect of BCG vaccination and history of TB in past was observed on both tests.

Custo-efetividade da prova tuberculínica versus QuantiFERON-TB Gold-In-Tube no diagnóstico e tratamento da infecção latente tuberculosa em profissionais de saúde da Atenção Básica no Brasil / Cost-effectiveness of tuberculin skin test versus QuantiFERON-TB Gold-In-Tube in the diagnosis and treatment of latent tuberculosis infection in the primary health care workers in Brazil

Os profissionais da área da saúde formam um dos grupos mais vulneráveis à infecção pelo Mycobacterium tuberculosis (Mtb). Segundo estimativas da Organização Mundial de Saúde (OMS), 8,8 milhões de pessoas estavam infectadas pelo Mtb e ocorreram 1,4 milhão de óbitos por tuberculose (TB) em 2010. A identificação de pessoas com Infecção Latente Tuberculosa (ILTB) é considerada pela OMS como uma prioridade no controle da doença, especialmente em países em desenvolvimento em que a incidência da doença ativa tem apresentado redução. O objetivo do presente trabalho foi avaliar, no Brasil, o custo-efetividade dos testes Prova Tuberculínica (PT) e Quantiferon TB Gold-In-Tube (QTF-GIT) no diagnóstico e tratamento da ILTB em profissionais de saúde atuantes na atenção básica, sob a perspectiva do Sistema Único de Saúde (SUS), comparando cinco estratégias que incluem o QTF-GIT, distintos pontos de corte para a PT e uso sequencial dos dois testes; e analisar o impacto do tabagismo sobre o risco de ILTB entre os profissionais de saúde, destacando-se a categoria da Enfermagem. Foi realizada uma avaliação econômica completa do tipo custo-efetividade, conduzida considerando uma coorte hipotética de 10.000 profissionais de saúde atuantes na atenção básica, com horizonte temporal restrito a um ano. Um modelo analítico de decisão, caracterizado por uma árvore de probabilidades de eventos, foi desenvolvido utilizando o software TreeAge ProTM 2013 para simular os resultados clínicos e impactos econômicos em saúde da nova tecnologia diagnóstica (QTF-GIT) versus a PT tradicional. Esse modelo simulou cinco estratégias diagnósticas para detecção e tratamento da ILTB: (a) PT, usando ponto de corte de 5mm; (b) PT, usando ponto de corte de 10 mm; (c) teste QTF-GIT; (d) PT, com ponto de corte de 5mm, seguida de teste QTF-GIT quando PT positiva; (e) PT, com ponto de corte de 10mm, seguida de teste QTF-GIT quando PT positiva. Foi realizada análise de sensibilidade determinística univariada. Na determinação dos fatores associados à ILTB, foi elaborado um modelo de regressão logística múltipla com seleção hierarquizada, utilizando o software Stata. A estratégia mais custo-efetiva foi a PT no ponto de corte ≥10mm, considerando como medida de desfecho tanto o número de indivíduos corretamente classificados pelos testes assim como o número de casos de TB evitados. A utilização isolada do QTF-GIT revelou-se a estratégia de menor eficiência, com RCEI= R$ 343,24 por profissional corretamente classificado pelo teste. Encontrou-se risco à ILTB significantemente maior para sexo masculino [OR=1,89; IC 95%:1,11-3,20], idade ≥ 41 anos [OR=1,56; IC 95%: 1.09-2,22], contato próximo com familiar com TB [OR=1,55; IC 95%: 1.02-2,36], status do tabagismo fumante [OR=1,75; IC 95%: 1.03-2,98] e categoria profissional da Enfermagem [OR=1,44; IC 95%: 1.02-2,03]. Concluiu-se que a PT no ponto de corte de 10mm é a estratégia diagnóstica mais custo-efetiva para ILTB entre os profissionais de saúde na atenção básica e que a ILTB está associada ao hábito do tabagismo e à categoria profissional de Enfermagem

Health professionals form one of the groups most vulnerable to infection by Mycobacterium tuberculosis (Mtb). According to estimates by the World Health Organization (WHO), 8.8 million people were infected with Mtb and were 1.4 million deaths from TB in 2010. The identification of persons with Latent Tuberculosis Infection (LTBI) is considered by WHO as a priority in the control of disease, especially in developing countries where the incidence of active disease has shown reduction. The aim of this study was to evaluate, in Brazil, the cost-effectiveness of tests Tuberculin Skin Test (TST) and Quantiferon TB Gold-In-Tube (QFT-GIT) in the diagnosis and treatment of LTBI in health professionals working in primary care from the perspective of SUS, comparing five strategies that include the QFT -GIT, different cutoff points for TST and sequential use of two tests; and analyze the impact of smoking on the risk of LTBI among health professionals, highlighting the category of Nursing. A full economic assessment of the type cost-effectiveness was performed, conducted considering a hypothetical cohort of 10,000 health professionals working in primary care, with limited time horizont of one year. A decision analytical model, characterized by a tree of probabilities of events, was developed using the TreeAge ProTM software 2013 (TreeAge Software Inc, Williamstown, MA, USA) to simulate the clinical and economic impacts on health of new diagnostic technology (QFT -GIT) versus the traditional TST. This model simulated five diagnostic strategies for detection and treatment of LTBI (a) TST, using a cut-off of 5 mm; (B) TST, using 10 mm cut-off currently recommended by the TNP; (C) QFT-GIT test; (D) TST, with a cut-off of 5 mm, followed by QFT-GIT test when positive TST; (E) TST, with a cut-off point of 10 mm, followed by QFT-GIT test when positive TST. Univariate deterministic sensitivity analysis was performed to assess the robustness of the results. In determining the factors associated with LTBI, a multiple logistic regression model with hierarchical selection was made, using the Stata software. TST strategy at the cut-off ≥ 10mm was the most cost-effective strategy, while the QFT-GIT alone was the most effective strategy, but showed higher cost. It was found to significantly greater risk for LTBI male [OR = 1.89; 95% CI: 1.11 to 3.20], age ≥ 41 years [OR = 1.56; 95% CI: 1.09-2,22], close contact with a family with TB [OR = 1.55; 95% CI: 1.02-2,36], the smoker smoking status [OR = 1.75; 95% CI: 1.03-2,98] and professional nursing category [OR = 1.44; 95% CI: 1.02-2,03]. It was concluded that TST in 10mm cut-off is the diagnostic strategy more cost-effective for LTBI among health professionals in primary care and that LTBI is associated with the smoke and professional category nurse

Evaluation of QuantiFERON-TB Gold in- Tube and Immunological Tests for TB Diagnosis in Iraqi Patients.

Aims: Tuberculosis is an infectious disease caused by the bacillus Mycobacterium tuberculosis and other related species. It typically affects the lungs (pulmonary TB) but can affect other sites (extra-pulmonary TB). A profusion of articles have been published on the accuracy and uses of interferon-gamma releasing assays for detection of this disease. Experimental Design: A prospective study. Place and Duration of Study: This study was done in Kirkuk city between November 2012 to February 2013. Methodology: The present study included 50 individuals (40 suspected tuberculosis patients and 10 healthy controls). The patient were examined for the presence of TB by using QuantiFERON-TB Gold In-Tube(QFT-GIT) assay, polymerase chain reaction (PCR) and compared them with certain new and routine tests like AFB smear, OnSite TB rapid test, erythrocyte sedimentation rate and chest X-ray. Result: The present study showed a relation between QFT-GIT and OnSite TB rapid test, and they were positive in 25(86%) at the same time; QFT-GIT positive and OnSite TB rapid test were negative in 4(14%) of patients; QFT-GIT negative and OnSite TB rapid test positive were seen in 5(45%); while QFT-GIT and OnSite TB rapid test were negative in 6(55%) of patients. In the control group only one QFT-GIT positive but it was OnSite TB test negative. 9(100%) of individuals for both tests were negative, 29 were males and 21 were females. Conclusion: The study highlighted the sensitivity of IGRAs for diagnosis of active TB in combination with the rapid IgM/lgG tests for TB.The QFT assay appeared to be a more specific indicator of latent TB infection than TST. The association with blood groups and vaccination is also significant.

Lurking in the dark: Latent Tuberculosis infection.

A subset of the tuberculous population has latent tuberculosis infection (LTBI). It is a condition wherein the affected individual is infected with Mycobacterium tuberculosis, but does not have any signs or symptoms of tuberculosis nor is he infectious to others. Risk of progression to active tuberculous infection is influenced by co-morbidities like HIV, diabetes, malignancy requiring chemotherapy, infants and children in close contact with susceptible individuals, and healthcare workers. Early diagnosis of LTBI is paramount. In addition to tuberculin test, Interferon gamma release assay (IGRA) is the new diagnostic modality that can be used for this purpose. Quantiferon-TB Gold In-Tube (QFTGIT) and T-SPOT TB are the two currently available IGRAs, of which the latter is slightly more preferred. More recently, TB PCR (Polymerase Chain Reaction) has aided accurate and early diagnosis of all forms of TB. While treating LTBI, it is observed that Isoniazid (INH) has stood the test of time and still prevails as the treatment of choice for active infection and for LTBI. Of course, adverse effects of INH and need for regular laboratory monitoring persist. Recently, moxifloxacin has been used as a substitute for INH. Newer drugs like rifapentine, nitromidazopyran, metronidazole and nitrofurans have all been tried with variable success and several clinical limitations, depending on comorbid conditions. India’s burden of extensive prevalence of TB is compounded by paucity of data on the same. The World Health Organization has estimated a mortality of 36 million by 2020 due to TB. This projection should encourage aggressive research into this entity.

A Case Report of Primary Duodenal Tuberculosis Mimicking a Malignant Tumor

Tuberculosis remains a serious infectious disease with primary features of pulmonary manifestation in Korea. However, duodenal tuberculosis is rare in gastrointestinal cases of extrapulmonary tuberculosis. Here, we report a case of primary duodenal tuberculosis mistaken as a malignant tumor and diagnosed with QuantiFERON-TB GOLD (Cellestis Ltd.) in an immunocompetent male patient.

Poor agreement between QuantiFERON-TB Gold test and tuberculin skin test results for the diagnosis of latent tuberculosis infection in rheumatoid arthritis patients and healthy controls

BACKGROUND/AIMS: We investigated the agreement between the QuantiFERON-TB Gold (QFT-Gold) test and the tuberculin skin test (TST) in the diagnosis of latent tuberculosis infection in patients with rheumatoid arthritis (RA), compared with healthy controls, in Korea. METHODS: We recruited 64 patients with RA and 79 healthy controls at two university hospitals in South Korea. The participants underwent both the QFT-Gold test and the TST simultaneously between August 2006 and February 2009. All patients were diagnosed using the classification criteria for RA revised in 1987 by the American College of Rheumatology. Bacillus Calmette-Guerin vaccination status and current medications were evaluated, and disease activities were assessed using the Disease Activity Score in 28 joints. Eleven patients with RA produced indeterminate QFT-Gold test results and were thus excluded from the kappa analysis. RESULTS: Based on an induration of 10 mm in diameter as the TST cutoff value, the QFT-Gold test and TST demonstrated 75.0% agreement (kappa = 0.23) in patients with RA and 75.9% agreement (kappa = 0.19) in healthy controls. Among the 56 patients with RA who had negative TST results, 11 patients (17.2%) also yielded indeterminate QFT-Gold results. CONCLUSIONS: Our study showed poor agreement between the results of the QFT-Gold test and the TST in both RA patients and healthy controls. Based on these findings, we emphasize the importance of making clinical decisions in the diagnosis of latent tuberculosis in Koreans with or without RA.

Evaluation of a new tuberculosis-related interferon gamma release assay for tuberculosis infection diagnosis in Huzhou, eastern China.

Objective: To compare the performance of a new tuberculosis-related interferon gamma release assay (TB-IGRA) with that of QuantiFERON-TB Gold In-Tube (QFT-GIT) for TB infection diagnosis in China. Materials and Methods: A total of 458 active TB patients and 378 healthy individuals were enrolled. Among the 458 active TB patients, 395 had pulmonary TB and 63 had extra-pulmonary TB. The blood samples were collected from the active TB patients and health controls; then TB-IGRA and QFT-GIT were used to detect interferon gamma (IFN-) levels. Results: The sensitivity, specifi city, positive predictive value, and negative predictive value in TB infection diagnosis for active TB by the TB-IGRA were 83.4%, 94.2%, 94.5%, and 82.4%, respectively. For QFT-GIT, the sensitivity, specifi city, positive predictive value, and negative predictive value in TB infection diagnosis for active TB were 81.4%, 97.1%, 97.1%, and 81.2%, respectively. Conclusions: TB-IGRA had a high sensitivity and specifi city for TB infection; it could be comparable with the QFT-GIT assay. It might be a powerful assisting tool for TB infection diagnosis in the Chinese clinical setting.

Comparison of Results between Tuberculin Skin Test and QuantiFERON(R)-TB In-Tube Assay for Diagnosis of Latent Tuberculosis Infection in Children and Adolescents / 소아감염

PURPOSE: Recently, two tests are commercially available for the identification of latent tuberculosis infection (LTBI): tuberculin skin test (TST) and interferon-gamma release assay (IGRA). Due to its false positiveness, TST tends to be preferred by IGRA until now. In our study, we simultaneously performed both TST and QuantiFERON(R)-TB Gold In-Tube (QFT-GIT) and compared their results. METHODS: TST and QFT-GIT were done for the diagnosis of LTBI among children who visited pediatric out-patient clinic at St. Vincent's Hospital, The Catholic University of Korea from February of 2007 to May of 2008. The study group was stratified into two groups in terms of whether there was intrafamilial contact or not. RESULTS: Out of total 35 children, 29 were tuberculosis (TB)-exposed cases and the remainders were diagnosed as clinical pulmonary TB. Among these 29 children, TST was positive 38.9% (7/18) for the intrafamilial and 45.5% (5/11) for the non-intrafamilial, and at the same time, the result for QFT-GIT was positive 5.6% (1/18) and 9.1% (1/11), respectively which implies that TST was more sensitive than QFT-GIT. Among 29 TB-exposed cases, 26 initially went through TST and QFT-GIT together on their first visit to out-patient clinic, and 15 continued the follow-up tests. Out of total 41 cases collected, the agreement (known as kappa value) was 0.063 which was relatively low. Including 6 cases with pulmonary TB who were all positive for TST and only 5 being positive for QFT-GIT, the final kappa value was 0.334. CONCLUSION: In our study, the agreement for TST and QFT-GIT was low, and the majorities were almost the cases of positive TST. In current situation with lacking a gold standard test and limited data on children to adolescents, this result is quite alarming that the recent trend tends to replace TST by QFT-GIT when diagnosing LTBI.

Clinical Usefulness of Combined Anti-tuberculosis Antibody Test and Interferon-gamma Release Assay for the Diagnosis of Tuberculosis

BACKGROUND: For the diagnosis of tuberculosis (TB), a variety of tests based on the patients' immune response has been introduced. We evaluated the clinical usefulness of combined anti-tuberculosis antibody (anti-TB Ab) test and Interferon-gamma release assay (IGRA), evaluating humoral and cellular immune response to Mycobacterium tuberculosis, respectively. METHODS: Among patients tested for IGRA, 78 patients diagnosed as TB and treated with anti-TB drug and 80 non-TB patients were included in this study. We used QuantiFERON-TB GOLD (QFT, Cellestis limited, Australia) for IGRA and an immunochromatographic assay, Easy Test TB (ASAN PHARM, Korea), for anti-TB Ab test. RESULTS: The sensitivity, specificity, and positive and negative predictive values of Easy Test TB were 23.1%, 98.8%, 94.7% and 56.8%, respectively. QFT had a significantly higher sensitivity than Easy Test TB (67.9% vs. 23.1%; P<0.05). The agreement between the two assays was poor (69.6%, k=0.190). Of the 18 cases with positive Easy Test TB, six (33%) showed negative QFT results. The combination of Easy Test TB and QFT had a significantly higher sensitivity than single QFT (75.6%, vs. 67.9%; P=0.031). CONCLUSIONS: The combination of Easy Test TB and QFT could be used to aid in a rapid diagnosis and early treatment of TB.