Specificity Of Interferon-gamma Release Assays Research Articles

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).

Diagnosis and biomarkers for ocular tuberculosis: From the present into the future.

Tuberculosis is an airborne disease caused by Mycobacterium tuberculosis (Mtb) and can manifest both pulmonary and extrapulmonary disease, including ocular tuberculosis (OTB). Accurate diagnosis and swift optimal treatment initiation for OTB is faced by many challenges combined with the lack of standardized treatment regimens this results in uncertain OTB outcomes. The purpose of this study is to summarize existing diagnostic approaches and recently discovered biomarkers that may contribute to establishing OTB diagnosis, choice of anti-tubercular therapy (ATT) regimen, and treatment monitoring. The keywords ocular tuberculosis, tuberculosis, Mycobacterium, biomarkers, molecular diagnosis, multi-omics, proteomics, genomics, transcriptomics, metabolomics, T-lymphocytes profiling were searched on PubMed and MEDLINE databases. Articles and books published with at least one of the keywords were included and screened for relevance. There was no time limit for study inclusion. More emphasis was placed on recent publications that contributed new information about the pathogenesis, diagnosis, or treatment of OTB. We excluded abstracts and articles that were not written in the English language. References cited within the identified articles were used to further supplement the search. We found 10 studies evaluating the sensitivity and specificity of interferon-gamma release assay (IGRA), and 6 studies evaluating that of tuberculin skin test (TST) in OTB patients. IGRA (Sp = 71-100%, Se = 36-100%) achieves overall better sensitivity and specificity than TST (Sp = 51.1-85.7%; Se = 70.9-98.5%). For nuclear acid amplification tests (NAAT), we found 7 studies on uniplex polymerase chain reaction (PCR) with different Mtb targets, 7 studies on DNA-based multiplex PCR, 1 study on mRNA-based multiplex PCR, 4 studies on loop-mediated isothermal amplification (LAMP) assay with different Mtb targets, 3 studies on GeneXpert assay, 1 study on GeneXpert Ultra assay and 1 study for MTBDRplus assay for OTB. Specificity is overall improved but sensitivity is highly variable for NAATs (excluding uniplex PCR, Sp = 50-100%; Se = 10.5-98%) as compared to IGRA. We also found 3 transcriptomic studies, 6 proteomic studies, 2 studies on stimulation assays, 1 study on intraocular protein analysis and 1 study on T-lymphocyte profiling in OTB patients. All except 1 study evaluated novel, previously undiscovered biomarkers. Only 1 study has been externally validated by a large independent cohort. Future theranostic marker discovery by a multi-omics approach is essential to deepen pathophysiological understanding of OTB. Combined these might result in swift, optimal and personalized treatment regimens to modulate the heterogeneous mechanisms of OTB. Eventually, these studies could improve the current cumbersome diagnosis and management of OTB.

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.

1377. Use of Interferon-Gamma Release Assays (IGRAs) Reduced Latent Tuberculosis Infection (LTBI) Diagnosis in Refugee and Immigrant Children

BackgroundFor foreign-born children from countries with high tuberculosis (TB) burden, positive tuberculin skin test (TST) results, associated with Bacillus Calmette Guerin (BCG) vaccination, paradoxically increase the risk for overdiagnosis and overtreatment of latent TB infection (LTBI) during immigration. The higher specificity of interferon-gamma release assays, such as QuantiFERON-TB (QFT), may help distinguish LTBI from positive TSTs due to BCG or non-TB Mycobacteria. However, data on QFT usage in pediatric populations, particularly refugee and immigrant children, are sparse. Our objective was to assess the impact of QFT on LTBI diagnosis and treatment in the vulnerable child refugee and immigrant population.MethodsWe initiated a retrospective study of children (≤15 years) seen in Santa Clara County Refugee/Immigrant Clinic for post-immigration TB re-evaluation in 2017. We collected information from the Electronic Disease Notification system and post-immigration clinic records, including laboratory studies, imaging, and clinical impression. The primary outcome was post-immigration LTBI diagnosis in patients with positive pre-immigration TB screening. Patients with prior active TB or LTBI treatment were excluded.Results102/135 clinic encounters examined to date were post-immigration encounters. Median age was 9 years (range 14mo to 15y). Most (82.5%) were from Asia, primarily the Philippines (n = 48), Afghanistan (n = 10), Iran (n = 9), and Vietnam (n = 8). Sixty-six (64.7%) had documented BCG vaccination. Among 102 encounters, 71 (69.6%) were of children diagnosed pre-immigration with LTBI based on positive TST and normal chest radiograph. After post-immigration evaluation with retesting by QFT, 13/71 (18%) were diagnosed with LTBI (Table 1). There were no active TB cases among 102 patients, though long-term follow-up varied (mean 5.5 ± 6.5 months).ConclusionQFT use for post-immigration LTBI re-evaluation reduced LTBI diagnosis by 82% in children as young as 2 years old. Preliminary data suggest the preferential use of QFT over TST in non-United States-born children, in accordance with new California Department of Public Health TB screening recommendations for children ≥2 years, could reduce unnecessary diagnosis and treatment of LTBI in refugee and immigrant children. Disclosures All authors: No reported disclosures.

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.

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

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.

P12 Role of Interferon gamma release assay (QuantiFERON–TB Gold In Tube) in blood in the diagnostic work up of active tuberculosis in a high TB prevalence region

ObjectiveTo study the role of Interferon gamma release assay (IGRA) (QuantiFERON–TB Gold In Tube) in blood in the diagnostic work up of active tuberculosis (TB) in a high TB prevalence...

Specificity of a whole blood IGRA in German nursing students

BackgroundInterferon-gamma release assays (IGRA) are used for tuberculosis (TB) screening in healthcare workers (HCWs). However, data on specificity of IGRA in serial testing of HCWs is sparse. Therefore the specificity and the negative predictive value of the IGRA - QuantiFERON-TB Gold In-Tube (QFT) - in German nursing students was investigated.Methods194 nursing students at the start of their professional career were tested with the QFT. 14 nursing students were excluded from the specificity analysis, due to exposure to mycobacterium tuberculosis. Two of these subjects were QFT- positive. None of them developed disease during the year of follow-up. A study group of 180 students, all with very low risk of prior TB infection, remained in the specificity analysis. Subjects were monitored for at least two years with respect to the development of active TB disease. IGRA was performed at the start of the training and after one year.ResultsThe mean age of the study group (n = 180) was 23 years (range 18-53) with 70.9% female and 99.4% German born. The specificity of QFT was 98.9% (178/180; 95% CI 0.96-0.99); lowering the cut-off from 0.35 IU/ml to 0.1 IU/ml would have decreased specificity only slightly to 97.8% (176/180; 95% CI 0.94-0.99). Of the 154 nursing students available for re-testing, one student who initially scored positive reverted to negative, and one student initially negative converted to positive. None of the monitored group with initially negative QFT results developed TB disease, indicating a high negative predictive value of the IGRA in this population.ConclusionsFollowing our data, QFT can serve as an effective tool in pre-employment TB screenings for HCWs. As its negative results were stable over time, specificity of the QFT in serial testing of HCWs is high. As the risk of acquiring TB infection in the German healthcare system appears to be low, our data supports the recommendation of performing TB screening only in those HCWs with known contact to TB patients or infectious materials.

Interferon gamma release assay in diagnosis of pediatric tuberculosis: a meta-analysis

Although interferon gamma release assays (IGRAs) have been widely used for the diagnosis of latent and active tuberculosis in adults, a relative lack of validation studies in children has led to caution in their clinical interpretation. This meta-analysis systematically evaluated two IGRAs (ELISA and ELISPOT) and the tuberculin skin test (TST). We searched databases (PubMed, MEDLINE, Ovid) between January 2000 and January 2011 using search terms of latent tuberculosis infection or tuberculosis and interferon gamma release assay, or T-SPOT.TB test, or QuantiFERON-TB Gold, or ESAT-6, or CFP-10, and child, or childhood, or pediatrics. We also collected data by performing a manual search of references from relevant articles and communicating with selected authors. The meta-analysis was conducted with random effects models to account for heterogeneity between selected studies. The sensitivities of all three tests in active tuberculosis were similar. The pooled sensitivity was 70% for ELISA studies, 62% for ELISPOT studies and 71% for TST. Calculated sensitivities for IGRAs and the TST differ in culture-confirmed tuberculosis [ELISA (85%) vs. ELISPOT (76%) vs. TST (85%)] and clinical diagnosed cases [ELISA (64%) vs. ELISPOT (58%) vs. TST (66%)]. The pooled specificity was 100% for ELISA and 90% for ELISPOT, but was much lower for TST [56% in all included studies and 49% in children with bacillus Calmette-Guerin (BCG) vaccination]. The agreement between the TST and IGRAs in non-BCG-vaccinated children is higher than that in BCG-vaccinated children. In the diagnosis of active tuberculosis in children, the TST and IGRAs have similar sensitivity. By contrast, the specificity of IGRAs is far greater than the TST, particularly in children with previous BCG vaccination.

Role of QuantiFERON-TB Gold, Interferon Gamma Inducible Protein-10 and Tuberculin Skin Test in Active Tuberculosis Diagnosis

BackgroundThe measurement of Interferon gamma or Interferon gamma inducible protein (IP)-10 in antigen stimulated blood samples is suggested as an alternative method for latent tuberculosis (TB) diagnosis. Nonetheless, their role in active TB diagnosis, particularly in TB endemic settings is yet to be defined. In this study, the sensitivities and specificities of Interferon gamma release assay (IGRA), IP-10 assay and tuberculin skin test (TST) in detecting active TB cases were assessed in human immunodeficiency virus (HIV) sero-negative TB patients and healthy controls respectively.Methods/Principal FindingsA total of 177 adult TB patients and 100 healthy controls were included for this study. QuantiFERON-TB Gold In-tube (QFT-IT) method was used to analyze the sensitivity and specificity of IGRA. QFT-IT, IP-10 and TST yielded the diagnostic sensitivities of 90.6% (95%CI: 86.3%–94.9%), 92.5% (95%CI: 88.6%–96.4%) and 68.9% (95%CI: 60.6%–77.2%) and specificities of 55% (95% CI: 35.2%–54.8%), 48% (95% CI: 38.2%–57.8%) and 75.5% (95% CI: 66.8%–84.2%), respectively. The extent of pulmonary involvement or presence of diabetes mellitus did not appear to influence the sensitivities of any of these tests. The combination of any of the two tests among QFT-IT, IP-10 and TST showed >98% sensitivity among smear negative cases and particularly the combination of IP-10, TST and smear microscopy showed 100% sensitivity, however, the specificity was decreased to 44.8%.Conclusions/SignificanceQFT-IT and IP-10 were highly sensitive in detecting active TB cases. The combination with TST improved the sensitivity of QFT-IT and IP-10 significantly. Although the higher sensitivity of combination of QFT-IT/IP-10 and TST may be useful in active TB diagnosis, they are limited by their poor specificity due to the high prevalence of latent TB in our settings.