Sensitivity Of Interferon-gamma Release Assays Research Articles

Disseminated, fatal reactivation of bovine tuberculosis in a patient treated with adalimumab: a case report and review of the literature.

Tumor necrosis factor inhibitors (TNFi) are known to increase the risk of tuberculosis (TB) reactivation, though cases involving Mycobacterium bovis are rarely reported. We describe a case of disseminated TB with M. bovis in a 78-year-old woman with a negative Interferon-Gamma-Release Assay (IGRA), taking adalimumab due to rheumatoid polyarthritis, which resulted in a fatal outcome. The atypical clinical and histopathological features were initially interpreted as sarcoidosis. The case occurred in Switzerland, an officially bovine tuberculosis-free country. The whole genome sequence of the patient's cultured M. bovis isolate was identified as belonging to the animal lineage La1.2, the main genotype in continental Europe, but showed significant genetic distance from previously sequenced Swiss cattle strains. In a literature review, four cases of bovine tuberculosis reactivation under TNFi treatment were identified, with pulmonal, oral and intestinal manifestations. Similar to our patient, two cases presented a negative IGRA before TNFi initiation, which later converted to positive upon symptomatic presentation of M. bovis infection. This case highlights the diagnostic challenges of TB in immunosuppressed patients, the limited sensitivity of IGRA, and the importance of considering TB reactivation even in regions declared free of bovine tuberculosis. Detailed patient histories, including potential exposure to unpasteurized dairy products, are essential for guiding preventive TB treatment before TNFi initiation.

Utility of interferon-gamma releasing assay for the diagnosis of active tuberculosis in children: A systematic review and meta-analysis

IntroductionThe accurate diagnosis of tuberculosis (TB) in children is essential for its effective management and control. Reliable diagnostic tools that are currently available for identifying TB infection include the in vivo tuberculosis skin test (TST) and ex vivo interferon-gamma release assays (IGRAs). This systematic review and meta-analysis aimed to evaluate the diagnostic accuracy of IGRAs in children. MethodsOf the 768 screened studies, 47 met the eligibility criteria. Data from 9065 patients, including 1086 (12.0 %) with confirmed TB, were included in the analysis. The overall quality of the included studies, assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, was unclear. ResultsThe calculated pooled sensitivity and specificity of IGRAs in children were 0.85 (95 % confidence interval [CI]: 0.79–0.89) and 0.94 (95 % CI: 0.88–0.97), respectively. Subpopulation analysis revealed that the sensitivities and specificities were as follows: QuantiFERON tests: 0.83 (95 % CI: 0.74–0.89) and 0.93 (95 % CI: 0.87–0.96), T-SPOT: 0.87 (95 % CI: 0.79–0.91) and 0.99 (95 % CI: 0.85–1.00), IGRAs in children under 15 years: 0.77 (95 % CI: 0.43–0.94) and 0.96 (95 % CI: 0.84–0.97), and IGRAs in children under 5 years: 0.85 (95 % CI: 0.52–0.97) and 0.94 (95 % CI: 0.90–0.99), respectively. ConclusionsThis study demonstrated that the sensitivity and specificity of the IGRAs in children were moderate and high, respectively. Therefore, the IGRAs may be useful for detecting TB infection in children. Clinical trial registrationThe review protocol was prospectively registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN000046737).

Use of Interferon-Gamma Release Assays in Children

While interferon-gamma release assays (IGRAs) are widely used for detecting tuberculosis (TB) infection, tuberculin skin tests (TSTs) remain preferred for children under the age of 2 years. The preference for TST stems from concern over IGRA sensitivity in young children. However, TSTs are susceptible to false-positive results following Bacille Calmette-Guérin (BCG) vaccination, which is common in infancy, and exposure to nontuberculous mycobacteria. We reviewed available data for IGRA performance in children under age 2 years. Across four cohorts of high-risk children under age 2 (mostly case contacts or those born in tuberculosis endemic regions), 0 of 575 untreated children with negative IGRA test results progressed to tuberculosis disease-including 0 of 70 who were TST positive but IGRA negative. While neither TSTs nor IGRAs are perfectly sensitive for the diagnosis of tuberculosis infection, IGRAs are an acceptable alternative to TST in children <2 years of age.

Diagnostic accuracy of interferon-gamma release assays for diagnosis of smear-negative pulmonary tuberculosis: a systematic review and meta-analysis

IntroductionThe diagnosis of smear-negative pulmonary tuberculosis (SNPTB) is challenging. Interferon gamma-release assays (IGRAs) may be helpful in early diagnosis among these patients resulting in prompt treatment and favorable outcomes.MethodsWe performed a comprehensive search from each databases’ inception to April 5, 2021. The studies that provided sufficient data regarding the sensitivity and specificity of IGRAs included QuantiFERON-TB Gold In-Tube (QFT-GIT), T-SPOT.TB, or QuantiFERON-TB Gold Plus for diagnosis of SNPTB were included.ResultsOf 1,312 studies screened, 16 studies were included; 11 QFT-GIT, 2 T-SPOT.TB, and 3 QFT-GIT and T-SPOT.TB. For diagnosis of SNPTB, QFT-GIT had sensitivity of 0.77 (95% CI 0.71–0.82), specificity of 0.70 (95% CI 0.58–0.80), diagnostic odds ratio (DOR) of 8.03 (95% CI 4.51–14.31), positive likelihood ratio (LR) of 2.61 (95% CI 1.80–3.80), negative LR of 0.33 (95% CI 0.25–0.42), and area under receiver operating characteristic (AUROC) of 0.81 (95% CI 0.77–0.84). T-SPOT.TB had sensitivity of 0.74 (95% CI 0.71–0.78), specificity of 0.71 (95% CI 0.49–0.86), DOR of 6.96 (95% CI 2.31–20.98), positive LR of 2.53 (95% CI 1.26–5.07), negative LR of 0.36 (95% CI 0.24–0.55), and AUROC of 0.77 (95% CI 0.73–0.80). The specificity seemed lower in the subgroup analyses of studies from high tuberculosis burden counties compared to the studies from low tuberculosis burden.ConclusionIGRAs do have insufficient diagnostic performance for SNPTB. However, the tests are still helpful to exclude tuberculosis among patients with low pre-test probability.Registry: PROSPERO: CRD42021274653.

A Bayesian analysis of a Test and Vaccinate or Remove study to control bovine tuberculosis in badgers (Meles meles).

A novel five year Test and Vaccinate or Remove (TVR) wildlife research intervention project in badgers (Meles meles) commenced in 2014 in a 100km2 area of Northern Ireland. It aimed to increase the evidence base around badgers and bovine TB and help create well-informed and evidence-based strategies to address the issue of cattle-to-cattle spread and spread between cattle and badgers. It involved real-time trap-side testing of captured badgers and vaccinating those that tested negative for bTB (BadgerBCG–BCG Danish 1331) and removal of those that tested bTB positive using the Dual-Path Platform VetTB test (DPP) for cervids (Chembio Diagnostic Systems, Medford, NY USA). Four diagnostic tests were utilised within the study interferon gamma release assay (IGRA), culture (clinical samples and post mortem), DPP using both whole blood and DPP using serum. BCG Sofia (SL222) was used in the final two years because of supply issues with BadgerBCG. Objectives for this study were to evaluate the performance of the DPP in field conditions and whether any trend was apparent in infection prevalence over the study period. A Bayesian latent class model of diagnostic test evaluation in the absence of a gold standard was applied to the data. Temporal variation in the sensitivity of DPP and interferon gamma release assay (IGRA) due to the impact of control measures was investigated using logistic regression and individual variability was assessed. Bayesian latent class analysis estimated DPP with serum to have a sensitivity of 0.58 (95% CrI: 0.40–0.76) and specificity of 0.97 (95% CrI: 0.95–0.98). The DPP with whole blood showed a higher sensitivity (0.69 (95% CrI: 0.48–0.88)) but similar specificity (0.98 (95% Crl: 0.96–0.99)). The change from BCG Danish to BCG Sofia significantly impacted on DPP serum test characteristics. In addition, there was weak evidence of increasing sensitivity of IGRA over time and differences in DPP test sensitivity between adults and cubs. An exponential decline model was an appropriate representation of the infection prevalence over the 5 years, with a starting prevalence of 14% (95% CrI: 0.10–0.20), and an annual reduction of 39.1% (95% CrI: 26.5–50.9). The resulting estimate of infection prevalence in year 5 of the study was 1.9% (95% CrI: 0.8–3.8). These results provide field evidence of a statistically significant reduction in badger TB prevalence supporting a TVR approach to badger intervention. They give confidence in the reliability and reproducibility in the DPP Whole Blood as a real time trap-side diagnostic test for badgers, and describe the effect of vaccination and reduced infection prevalence on test characteristics.

Evaluation of role of interferon gamma release assays in the diagnosis of latent tuberculosis in human immunodeficiency virus-infected patients.

Introduction:Tuberculosis (TB) is the most common opportunistic infection in human immunodeficiency virus (HIV)-infected individuals. The risk of eventually developing active TB from latent TB infection (LTBI) is about 10% per year in HIV-positive patients in contrast to 10% lifetime risk in HIV-negative patients. Until recently, the tuberculin skin test (TST) was the only tool available for diagnosing LTBI. Interferon-gamma release assays (IGRAs) were recently developed and address many of the limitations of TST test, especially in immunocompromised state.Aims and Objectives:(1) To determine the prevalence of latent, active pulmonary, and multidrug-resistant (MDR)-TB among HIV-positive patients in and around Aligarh region; (2) sensitivity and specificity of TST and IGRAs for diagnosis of LTBI in HIV positive patients; and (3) to assess drug resistance and mutational patterns of the clinical isolates of MDR-TB in HIV-TB co-infection.Materials and Methods:A cross-sectional study was done on all the patients attended the ICTC centre, JNMC, AMU Aligarh, seropositive for HIV, i.e. 469 (sample size) for the study period of 2 years from October 2015 to October 2017. All 469 HIV-positive patients were screened for latent and active pulmonary TB. Diagnosis of TB (active and latent) was made using clinical, radiological, and microbiological tests. TST and IGRA testing along with CD4 cell counts were also determined. Line probe assay was also done to assess drug resistance and mutational patterns of MDR-TB in HIV patients.Results:In our study, prevalence of HIV infection was 5.04%. Sixty-seven (14.28%) patients were as active TB (HIV-TB co-infection), out of which only one patient (1.49%) was confirmed as MDR-TB, 117 (24.94%) were diagnosed as LTBI. It was also evaluated that IGRA has more sensitivity (75%) and specificity (76%) than TST with sensitivity of 71.7% and specificity 66%.Conclusion:As there is no gold standard test for latent TB, longitudinal follow-up is needed to interpret discordant test results. There is a need to interpret negative QFT results with caution and to test for latent TB at higher CD4 counts, if possible. Interferon gamma assays can become better tool for diagnosis of especially for latent TB. However, more research study required for establish their relevance, especially in immunocompromised states.

Childhood tuberculosis in Vienna between 2010 and 2016.

Tuberculosis (TB) has become arare disease in developed countries. Austria is alow incidence country for TB with an incidence rate of 7.2/100,000 in 2016. The incidence of TB has shown aconstant decline in Austria from 2008 (9.8/100,000) to 2015 (6.7/100,000) but recently stagnated in 2016 (7.2/100,000). In recent years migration to Austria from countries with high TB incidence rates has increased. Therefore, this study aimed to describe the recent epidemiology of childhood TB in Vienna. Data of pediatric patients with active TB infections, who were hospitalized for further investigations or isolation precautions between 2010 and 2016 at the Wilhelminenspital, Austria's reference center for childhood tuberculosis, were retrospectively analyzed. Demographic and clinical data (symptoms, microbiology, radiology, immunology) were collected, compared and evaluated. A total of 127 patients with active tuberculosis were included in the study. The number of admissions varied between n = 7 in 2010 and n = 26 in 2016. There were two age peaks of infected children (0-5years: n = 41 and 15-18years: n = 45). In 35% of the cases one parent had active TB and was suspected to be the index case. In 36% the source of infection remained unknown. Compared to young children (<5years), adolescents (15-18years) showed proportionally more TB-related symptoms, such as cough (41% vs. 24%), fever (15% vs. 14%) and weight loss (22% vs. 0%). At the time of admission 51% of the young children and 33% of the adolescents were free of symptoms. Intrathoracic disease was found in 80.8%, extrathoracic disease in 19.2% and 11% of the cases were tuberculous lymphadenitis. Of the patients with intrathoracic TB 54% (n = 64) had apositive microbiological result (auramine staining, bacteriological culture, PCR). In young children hilar lymphadenopathy was the most frequent radiological finding (50%), whereas in adolescents lung infiltrates were most common (36%). The sensitivity of interferon-gamma release assays (IGRA) was 0.94 compared to 0.88 of the tuberculin skin test (TST). Both test methods showed moderate concordance (ϕ-coefficient = 0.48). A high number of asymptomatic children and adolescents with active TB were observed, which underlines the importance of efficient screening measures. Thorough history taking in all patients with TB is essential to maximize the effect of contact tracing. Overall, infection rates remained consistently low during the observation period.

Clinical application value of γ-IFN release assay combined with CA-125 in diagnosis of active pulmonary tuberculosis

Objective: To evaluate the diagnosis of interferon gamma release assay (IGRA) combined with tumor marker carbohydrate antigen-125 (CA-125) in active pulmonary tuberculosis (PTB). Methods: One hundred and three patients with active PTB (48 definite and 55 clinical diagnosed), 646 patients with non-PTB pulmonary disease and 60 normal controls hospitalized in Beijing Tongren Hospital, Capital Medical University between January 2014 and December 2016 were retrospectively investigated. Blood samples were collected to determine the IGRA and CA-125 level by enzyme-linked immunosorbent assay and electrochemiluminescence, respectively. The CA-125 level of patients with active PTB, non-PTB pulmonary disease and normal controls were compared. Subsequently, the best cut-off value of CA-125 for diagnosing PTB was calculated based on 60 active PTB cases and 60 normal controls. Methodological evaluation of IGRA, CA-125 and combination of these two tests (both positive) for active PTB diagnosing were performed based on 43 active PTB cases and all the non-PTB pulmonary disease cases. Results: The median values of CA-125 among definite and clinical diagnosis groups of active PTB were 55.00 (25.35, 156.90) U/ml and 81.50 (39.40, 138.00) U/ml, respectively. There was no difference between the two groups (U=1 093.00, P>0.05). And the CA-125 level of male and female PTB patients were also undifferentiated (U=1 124.00, P>0.05). There were statistically significant differences in CA-125 levels between the active PTB group and all other non-PTB groups (all P<0.001), including those who had ever closely contacted with TB patients. The area under the ROC curve constructed by CA-125 for diagnosing active PTB was 0.933. And the best cut-off value of CA-125 was 22.00 U/ml. Based on this cut-off value, the accuracy, sensitivity and specificity of CA-125 for diagnosing active PTB were 70.5% (486/689), 86.0% (37/43) and 69.5% (449/646). The accuracy, sensitivity and specificity of IGRA for diagnosing active PTB were 73.3% (480/689), 90.7% (39/43) and 68.3%(441/64). The accuracy, sensitivity and specificity of IGRA combined with CA-125 for diagnosing active PTB were 90.6% (624/689), 76.7% (33/43), 91.5% (591/646). Both of the accuracy and the false positive ratio of this combinational method (8.5%, 55/646) were significantly lower than two indexes individually used (χ(2)=94.461, 88.261, P<0.001). However, the false negative ratio was increased to 23.3% (10/43) by combinational method. Conclusion: IGRA combined with CA-125 has a certain clinical value in diagnosis of active PTB, especially when the evidences of bacterial is not available.

Recent Innovations in Diagnosis and Treatment of Pediatric Tuberculosis.

Tuberculosis is leading cause of global morbidity and mortality and a significant proportion of the burden of disease occurs in children. In the past 5years, a number of innovations have improved the diagnosis and treatment for children with both latent tuberculosis infection and active disease. This review discusses three key areas of innovation. First, we assess utilization and performance of interferon-gamma release assays (IGRAs) in different clinical and epidemiologic scenarios. Recent literature has demonstrated good performance of IGRAs for diagnosis of latent tuberculosis infection, particularly in low-incidence settings such as TB control programs in North America. For high-incidence populations, or when testing is done for possible active TB disease, IGRA performance has some important limitations, but IGRA sensitivity when measured against culture proven disease may be better than earlier studies suggested. The second area of innovation is in increased uptake of nucleic acid amplification (NAA) tests and broader application in non-sputum samples for both pediatric pulmonary and extrapulmonary tuberculosis. Finally, recent studies have provided solid evidence in support of shorter treatment courses for pediatric latent tuberculosis infection, such as 12weeks of weekly isoniazid and rifapentine or 4months daily rifampin, that improve compliance and may reduce resources required for TB control. Many recent innovations in pediatric tuberculosis relate to an improved understanding of how to optimally use existing tests and treatments. Until diagnostic tests and interventions such as vaccination are developed that can dramatically alter the paradigm of pediatric TB management and control, it is important for stakeholders to have a nuanced understanding of tools currently available.

Screening for latent tuberculosis infection prior to biologic therapy in patients with chronic immune-mediated inflammatory diseases (IMID): Interferon-gamma release assay (IGRA) versus tuberculin skin test (TST)

BackgroundThe screening for latent tuberculosis infection (LTBI) is mandatory before initiating biologics in patients with chronic immune-mediated inflammatory disease (IMID). The recommendations are based on the tuberculin skin test (TST) and interferon-gamma release assay (IGRA). Aim of the workTo evaluate the agreement between the two tests in the diagnosis of LTBI and to identify risk factors associated with positive TST and IGRA results. Patients and methodsMedical records of 105 IMID patients going to receive a biologic agents were extracted in a cross sectional study (2015–2017). No biologics was undertaken before LTBI screening. All patients underwent IGRA and chest radiography. TST was performed in 94 cases. ResultsThe mean age of the patients was 47.7 ± 14.4 years and disease duration of 11.2 ± 7.6 years. Agreement between the 2 tests results was low (κ coefficient = 0.08). The sensitivity of TST and IGRA was equally low but the specificity of IGRA was higher. Replacing TST results by positive IGRA showed that number of patients who would take anti-tuberculous chemoprophylaxis will be significantly reduced by 46.5% (from 40.9% to 21.9%; p = 0.0002). TST results were significantly less positive for patients receiving immunosuppressives than for those receiving no treatment (35.1% vs 42.5%, p = 0.031). IGRA results were associated with absence of Bacilli Calemtte-Guérin vaccination. Age was the only risk factor for LTBI associated with both IGRA and TST positivity (p = 0.031, p = 0.011 respectively). ConclusionsTST and IGRA have a low agreement. Both tests should be included in the strategy to diagnose LTBI prior to biologic therapy in IMID patients.

Interferon-gamma release assay for the diagnosis of latent tuberculosis infection: A latent-class analysis.

BackgroundAccurate diagnosis and subsequent treatment of latent tuberculosis infection (LTBI) is essential for TB elimination. However, the absence of a gold standard test for diagnosing LTBI makes assessment of the true prevalence of LTBI and the accuracy of diagnostic tests challenging. Bayesian latent class models can be used to make inferences about disease prevalence and the sensitivity and specificity of diagnostic tests using data on the concordance between tests. We performed the largest meta-analysis to date aiming to evaluate the performance of tuberculin skin test (TST) and interferon-gamma release assays (IGRAs) for LTBI diagnosis in various patient populations using Bayesian latent class modelling.MethodsSystematic search of PubMeb, Embase and African Index Medicus was conducted without date and language restrictions on September 11, 2017 to identify studies that compared the performance of TST and IGRAs for LTBI diagnosis. Two IGRA methods were considered: QuantiFERON-TB Gold In Tube (QFT-GIT) and T-SPOT.TB. Studies were included if they reported 2x2 agreement data between TST and QFT-GIT or T-SPOT.TB. A Bayesian latent class model was developed to estimate the sensitivity and specificity of TST and IGRAs in various populations, including immune-competent adults, immune-compromised adults and children. A TST cut-off value of 10 mm was used for immune-competent subjects and 5 mm for immune-compromised individuals.FindingsA total of 157 studies were included in the analysis. In immune-competent adults, the sensitivity of TST and QFT-GIT were estimated to be 84% (95% credible interval [CrI] 82–85%) and 52% (50–53%), respectively. The specificity of QFT-GIT was 97% (96–97%) in non-BCG-vaccinated and 93% (92–94%) in BCG-vaccinated immune-competent adults. The estimated figures for TST were 100% (99–100%) and 79% (76–82%), respectively. T-SPOT.TB has comparable specificity (97% for both tests) and better sensitivity (68% versus 52%) than QFT-GIT in immune-competent adults. In immune-compromised adults, both TST and QFT-GIT display low sensitivity but high specificity. QFT-GIT and TST are equally specific (98% for both tests) in non-BCG-vaccinated children; however, QFT-GIT is more specific than TST (98% versus 82%) in BCG-vaccinated group. TST is more sensitive than QFT-GIT (82% versus 73%) in children.ConclusionsThis study is the first to assess the utility of TST and IGRAs for LTBI diagnosis in different population groups using all available data with Bayesian latent class modelling. Our results challenge the current beliefs about the performance of LTBI screening tests, and have important implications for LTBI screening policy and practice. We estimated that the performance of IGRAs is not as reliable as previously measured in the general population. However, IGRAs are not or minimally affected by BCG and should be the preferred tests in this setting. Adoption of IGRAs in settings where BCG is widely administered will allow for a more accurate identification and treatment of LTBI.

Identification of novel Mycobacterium tuberculosis peptides as diagnostic reagents for tuberculosis among human immunodeficiency virus infected population

Objective To screen and validate the major histocompatibility complex class-Ⅰ(MHC-Ⅰ) restricted tuberculosis peptides as potential diagnostic reagents in tuberculosis interferon-gamma release assay (IGRA) used among human immunodeficiency (HIV)-infected population. Methods Candidate peptides were encoded by Mycobacterium tuberculosis (TB) RD (Region of difference). Computer software was used to predict and select CD8+ T cell epitopes restricted by MHC-Ⅰ molecules with high frequency and high affinity among HIV-infected people. Then peptides containing CD8+ T cell epitope were synthesized and screened in vitro. The sensitivity and specificity of IGRA using the above mixed peptides as stimulants were compared with those of IGRA using early secretory antigen target-6 (ESAT-6, molecular weight of 6 000) and culture filtrate protein-10 (CFP-10, molecular weight of 10 000) as stimulants among HIV-infected population. Results Eight overlapping peptides, including Rv0222176-191, Rv1980c122-138, Rv1985c105-120, Rv3425141-165, Rv3873133-151, Rv3873158-166, Rv387878-86, Rv3879c673-690, were obtained finally, which were able to stimulate the production of interferon-gamma from peripheral CD8+ T cells of tuberculosis patients, but not from peripheral blood mononuclear cells (PBMC) of healthy controls. Among the 25 patients with HIV/TB co-infection, the sensitivities of IGRA using the combination peptides (CP) and that using rESAT-6/CFP-10 (CE) were low (68% vs 48%, χ2=2.052, P=0.152). However, the sensitivity increased to 92% by using the combination of CP and CE, which was significantly higher than that using rESAT-6/CFP-10 alone (χ2=11.523, P<0.01), and the specificity was not affected. Conclusion These RD peptides with CD8+ T cell epitopes can increase the sensitivity of IGRA in detecting HIV/TB co-infection, which may improve the detection rate of tuberculosis in HIV infected population. Key words: TB/HIV coinfection; CD8-positive T-lymphocytes; Major histocompatibility complex class-Ⅰ; Epitope prediction; M. tuberculosis RD; Interferon gamma release assay

Multiplex analysis of plasma cytokines/chemokines showing different immune responses in active TB patients, latent TB infection and healthy participants

Interferon gamma release assays (IGRAs) have been widely used to diagnose Mycobacterium tuberculosis (MTB) infection. However, IGRAs cannot discriminate between active TB patients and latent TB infection (LTBI), and the sensitivity of IGRAs for MTB infection is suboptimal. Here, we analyzed cytokines/chemokines in MTB antigen-stimulated and -unstimulated plasma samples to identify host biomarkers that are associated with active TB and MTB infection. Active TB patients, subjects with LTBI and healthy participants were recruited. Seventy-one soluble cytokines and chemokines were tested using Luminex liquid array-based multiplexed immunoassays. For the 71 examined factors, our results indicated that the unstimulated levels of IL-8 Nil, IP-10 Nil, MIP-1a Nil, and sIL-2Ra Nil and the antigen stimulated levels of IL-8 (Ag-Nil), VEGF (Ag-Nil), and MCP-3 (Ag-Nil) were potential biomarkers for differentiating between active TB and LTBI, with AUCs of 0.8, 0.86, 0.755, 0.845, 0.825, 0.812 and 0.75, respectively. The G-CSF (Ag-Nil), GM-CSF (Ag-Nil), IL-1a (Ag-Nil), IL-2 (Ag-Nil), IP-10 (Ag-Nil), BCA-1 (Ag-Nil) and Eotaxin-1 (Ag-Nil) responses were significantly higher in patients with active TB and LTBI compared with healthy participants (p < 0.05), with AUCs of 0.922, 0.902, 0.908, 1.0, 0.937, 0.919 and 0.935, respectively. Our preliminary data suggest that unstimulated or stimulated levels of cytokines and chemokines could be used as host biomarkers for diagnosing active TB as well as additional biomarkers, except IFN-γ, for MTB infection.

Impact of diabetes mellitus on indeterminate results of the QuantiFERON TB Gold In-Tube test: A propensity score matching analysis.

BackgroundThe sensitivity of interferon-gamma release assays (IGRAs) in the detection of Mycobacterium tuberculosis infection could be affected by conditions of immune dysregulation. For this reason, diabetes mellitus (DM) may increase the frequency of indeterminate results of IGRAs. However, there have been inconsistent reports of role of DM on indeterminate IGRA results.MethodsWe retrospectively reviewed all patients who underwent QuantiFERON-TB Gold In-Tube testing (QFT-GIT) at Chonnam National University Hospital. We collected the clinical and laboratory data of these patients.ResultsOf all 3,391 subjects, 1,265 (37.3%) had a positive QFT-GIT result, 266 (7.8%) had an indeterminate result, and 1,860 (54.9%) had a negative result. The mean age was 54.8 ± 18.1 years and 55.0% of the patients were male. There were 512 (15.1%) patients with DM. Multivariable analysis revealed that systemic corticosteroid use, tuberculosis, lymphocytopenia, low serum albumin, and high serum C-reactive protein (CRP) levels were significantly associated with indeterminate QFT-GIT results. However, DM was not associated with indeterminate QFT-GIT results (adjusted odds ratio, 0.98; 95% confidence interval, 0.69–1.41; P = 0.939). After propensity score matching, DM was not associated with indeterminate results of QFT-GIT.ConclusionIn this large cohort study, DM does not affect the incidence of indeterminate results of QFT-GIT.

Application of molecular, microbiological, and immunological tests for the diagnosis of bone and joint tuberculosis.

To evaluate the application of interferon gamma release assay (IGRA), rifampicin resistant real-time fluorescence quantitative PCR technique Xpert Mycobacterium tuberculosis/rifampicin (Xpert MTB/RIF), and the levels of TNF-α and TGF-β in the diagnosis of bone and joint tuberculosis. Eighty-six patients with bone and joint tuberculosis, diagnosed by pathology or microbiology, were examined by Xpert MTB/RIF and IGRA (T-SPOT. TB) for Mycobacterium tuberculosis infection, and the TNF-α and TGF-β levels of the patients were measured. The sensitivity of IGRA in diagnosing bone and joint tuberculosis was 81.4%; Xpert MTB/RIF's sensitivity was 70.9%. The combined sensitivity of the two methods was 91.9%. The combined detection sensitivity of the two methods was higher than individual IGRA or Xpert MTB/RIF detection sensitivity. The TNF-α and TGF-β levels in bone and joint tuberculosis patients were higher than those in the control group. Xpert MTB/RIF, IGRA, TNF-α, and TGF-βs expression have value in the rapid diagnosis of bone and joint tuberculosis, and the sensitivity and accuracy of bone and joint tuberculosis diagnosis by combining them can improve it.

Interferon Gamma Release Assay in response to PE35/PPE68 proteins: a promising diagnostic method for diagnosis of latent tuberculosis.

Tuberculosis control relies on the identification and preventive treatment of people who are latently infected with Mycobacterium tuberculosis (Mtb). PE/PPE proteins have been reported to elicit CD4 and/or CD8 responses either in the form of whole recombinant proteins or as individual peptides. Very few of the PE and PPE proteins have been previously tested for responses in patients with TB and healthy donors. This is the first study to evaluate the Interferon Gamma Release Assay (IGRA) after stimulation with PE35 and PPE68. The antigen-specific levels of IFN-γ following stimulation with QuantiFERON-TB gold in-tube (QFT-G-IT) antigens, and PE35 and PPE68 recombinant proteins were evaluated in 79 children and 102 adults, respectively. Using QFT-G-IT kit, latent tuberculosis infection (LTBI) was detected in 26 children (33%) and 41 adults (40%); IGRA following stimulation with PE35 and PPE68 recombinant proteins, was positive, respectively, in 36 (46%) and 32 (40.5%) children, respectively. In addition, 53 adults (52%) had positive results following stimulation with these two proteins. The sensitivity and specificity of IGRA following stimulation with recombinant PE35 in children were 76% and 80%, and following stimulation with recombinant PPE68 in this group, it was 73% and 75%, respectively. Meanwhile, there is no gold standard test for LTBI. Our designed tests using PE35 and PPE68 PE/PPE proteins, two PE/PPE proteins not present in BCG vaccins, which elicit CD4 and/or CD8 responses, might be helpful for rapid diagnosis of TB and improve the detection of LTBI. However, further validation studies to determine the advantage of IGRAs using these proteins, alone or combined, are highly recommended.

Diagnostic utility of interferon-gamma release assay in extrapulmonary tuberculosis

Early diagnosis of extrapulmonary tuberculosis (EP-TB) is essential. However, diagnosis of EP-TB is difficult. We evaluated the diagnostic utility of an interferon-gamma release assay (IGRA) in diagnosing active EP-TB among suspected patients in Korea. We retrospectively reviewed the clinical records of all patients with suspected EP-TB at Gangnam Severance Hospital in Seoul, Korea. Of the 418 patients with suspected EP-TB, 324 had active EP-TB. The tuberculosis (TB) group had a higher percentage of positive IGRAs (70.2%, 33/47) than the non-TB group (33.3%, 3/9) (P=0.034). The IGRA sensitivity and specificity were 70.2% (63.7–74.8%) and 66.7% (32.9–90.6%), respectively. The sensitivity and specificity of IGRAs in patients with TB lymphadenitis were 81.8% (61.4–90.4%) and 80.0% (35.1–98.9%), but 38.5% (31.2–45.7%) and 50.0% (2.7–97.3%) in patients with TB pleurisy. The diagnostic performance of IGRAs may vary depending on the site of EP-TB involvement. IGRA was potentially valuable for diagnosis of active EP-TB in TB lymphadenopathy.

The usefulness of interferon-gamma release assay for diagnosis of tuberculosis-related uveitis in Korea.

PurposeTo evaluate the usefulness of the interferon-gamma release assay (IGRA) for diagnosing tuberculosis (TB)-related uveitis (TRU).MethodsRecords from 181 patients with ocular signs and symptoms suggestive of TRU and intraocular inflammation of unknown etiology were reviewed. All subjects underwent clinical and laboratory testing, including IGRA, to rule out presence of underlying disease. A diagnosis of presumed TRU was made based on an internist's TB diagnosis and a patient's response to anti-TB therapy. Sensitivity, specificity, and positive predictive values of IGRA for TRU diagnosis were calculated. Clinical characteristics were compared between patients with positive and negative IGRA results.ResultsThe sensitivity and specificity of IGRA for TRU were 100% and 72.0%, respectively. Mean age, percentage of patients with retinal vasculitis, and the anatomic type of uveitis were significantly different between patients with positive and negative IGRA results (all p ≤ 0.001). Positive IGRA rates and false-positive rates were significantly different between age and anatomic type groups (both p = 0.001). The positive predictive value of the IGRA among patients with intraocular inflammation was high (70%) when all of younger age (≤40 years), posterior uveitis, and retinal vasculitis were present.ConclusionsThe IGRA is useful for diagnosing TRU in the Korean population, especially when it is used as a screening test. Clinical characteristics, including younger age (≤40 years), posterior uveitis, and retinal vasculitis in IGRA-positive patients, increase the likelihood of the patient having TRU.

Screening for TB in high school adolescents in a high burden setting in South Africa

Screening for tuberculosis (TB) disease is important for TB control and TB vaccine efficacy trials but this has not been evaluated in adolescents. We conducted a study to determine the prevalence of active TB and performance of specific screening tests for TB in adolescents in a high burden setting. Adolescents aged 12-18 years were recruited from high schools in a rural town in South Africa. Participants were screened for active TB using symptoms, household TB contact, positive interferon gamma release assay (IGRA) and positive tuberculin skin test (TST). Of 6363 adolescents recruited, 21 were newly diagnosed with TB of whom 19 were culture positive. After exclusions, the derived prevalence of smear positive TB was 16/5682 = 3/1000 (95% confidence interval (CI) 1-4/1000). The sensitivity of TST and IGRA for active TB were 85% (95% CI 62-100%) and 94% (95% CI 79-100%) respectively. None of the methods alone or in combination had positive predictive values greater than 2%. The screening tools evaluated in this study may not be practical for routine use owing to low positive predictive values but may be useful in TB vaccine clinical trials.

Interferon-gamma Release Assays in der klinikbasierten Tuberkulose-Diagnostik bei Kindern und Jugendlichen - eine retrospektive Analyse

Interferon-gamma release assays (IGRA) are well established for diagnosing latent tuberculosis infection in adults. Evidence for their diagnostic relevance in children is still insufficient. The aim of this study was to evaluate the sensitivity and specificity of IGRA compared to the tuberculin skin test (TST) in a local population of children and adolescents presenting to our lung clinic with a specialised outpatient department. Records from all patients evaluated for tuberculosis at our centre between 2009 and 2011 were analysed retrospectively. Complete data sets were available for 80 children and adolescents (age 3 months to 17 years) in the following diagnostic groups: active pulmonary tuberculosis (MTB, n = 13), latent tuberculosis infection (LTBI, n = 15) and controls with tuberculosis exposure (n = 40), non-tuberculous mycobacterial disease (NTM, n = 2) or other lung diseases (n = 10). All 13 patients with MTB were positive on both IGRA and TST. Among the LTBI patients, 14 /15 had a positive IGRA and 14 /15 a positive TST result. In the control group 0 /52 exceeded the IGRA cut-off, while three patients had a positive TST due to a cross reaction with BCG or NTM. IGRA and TST results are highly correlated in paediatric patients with active or latent tuberculosis. IGRA sensitivity was comparable to that of the TST with a higher specificity as expected. The importance of IGRA in the hospital setting to guide diagnostic algorithms in an unselected population should be further evaluated in prospective studies.