QuantiFERON-TB Gold In-Tube Test Research Articles

The QuantiFERON-TB Gold In-Tube Assay in Neuro-Ophthalmology

Although QuantiFERON-TB Gold In-Tube (QFT-GIT) testing is regularly used to detect infection with Mycobacterium tuberculosis, its utility in a patient population with a low risk for tuberculosis (TB) has been questioned. The following is a cohort study analyzing the efficacy of QFT-GIT testing as a method for detection of active TB disease in low-risk individuals in a neuro-ophthalmologic setting. Ninety-nine patients from 2 neuro-ophthalmology centers were identified as having undergone QFT-GIT testing between January 2012 and February 2016. Patients were divided into groups of negative, indeterminate, and positive QFT-GIT results. Records of patients with positive QFT-GIT results were reviewed for development of latent or active TB, as determined by clinical, bacteriologic, and/or radiographic evidence. Of the 99 cases reviewed, 18 patients had positive QFT-GIT tests. Of these 18 cases, 12 had documentation of chest radiographs or computed tomography which showed no evidence for either active TB or pulmonary latent TB infection (LTBI). Four had chest imaging which was indicative of possible LTBI. None of these 18 patients had symptoms of active TB and none developed active TB within the follow-up period. Based on our results, we conclude that routine testing with QFT-GIT in a low-risk cohort did not diagnose active TB infection. We do not recommend routine QFT-GIT testing for TB low-risk individuals, as discerned through patient and exposure history, ocular examination, and clinical judgment, in neuro-ophthalmology practice.

High rates of latent TB infection in contacts and the wider community in South India.

We aimed to compare TB transmission rates between case and community households in Vellore, South India. 359 household contacts (HHC) and 363 community contacts (CC) were assessed with tuberculin skin test (TST) and QuantiFERON TB Gold In-Tube test (QFT) between August 2010 and September 2011. Concordance test and multivariate risk factor assessment were conducted using logistic regression adjusted for clustering. Latent TB infection (LTBI) positivity was similar between the two groups using both tests, with only moderate concordance observed between QFT and TST. Children of HHC (<15 years) were at a higher risk for LTBI (odds of 2.37 [1.15-4.89] and 3.02 [1.22-7.45] for TST and QFT respectively). Among adults, both age in decades (odds of 1.33 [1.14-1.15] and 1.16 [1.02-1.32] for TST and QFT, respectively) and the interaction of male gender, smoking and alcohol consumption (odds of 4.06 [1.38-11.93] and 2.59 [1.19-5.64] for TST and QFT, respectively), were associated with increased risk of LTBI. This study provides estimates of TB infection rates accounting for both community and household exposure that contribute to understanding of TB transmission in this setting. We suggest that assessment of risk factors for infection need increased examination as prophylactic treatment of LTBI are being considered.

Utility of QuantiFERON tuberculosis gold-in-tube test for detecting latent tuberculosis infection among close household contacts of confirmed tuberculosis patients in Accra, Ghana.

Introduction of the interferon gamma (IFN-γ) release assays with their higher sensitivity and specificity over the traditional tuberculin skin test has improved testing for latent tuberculosis infection (LTBI). None of the IFN-γ release assays has ever been used to screen for LTBI in Ghana. This study set out to determine the utility of the QuantiFERON TB Gold-in-Tube (QFT-GIT) test for the diagnosis of LTBI among close household contacts of newly diagnosed sputum smear-positive tuberculosis (TB) patents in Accra, Ghana, and the associated risk factors for a positive QFT-GIT test. Close household contacts of newly diagnosed sputum smear-positive patients receiving anti-TB therapy from three hospitals in Accra were recruited, after providing written informed consent, between April 2012 and December 2014. In addition to demographic details, 2 mL of blood was collected from all participants for the QFT-GIT test for LTBI diagnosis. Out of 112 eligible consenting participants, the QFT-GIT test was performed for 100 participants. The prevalence of LTBI (QFT-GIT positive) was 65%, with 32% being QFT-GIT negative and 3% indeterminate results. Contacts aged >15 years were more likely to be QFT-GIT positive than those aged >15 years, regardless of their Bacillus Calmette-Guerin status. There was significantly higher QFT-GIT test positivity in adult contacts who were parents, siblings, or spouses to index cases than in child contacts (P = 0.0016, P = 0.04, and P = 0.0003, respectively). The QFT-GIT test will be a useful tool for screening of TB contacts for LTBI in Ghana.

QuantiFERON-TB Gold In-Tube Test in the Diagnosis of Latent Tuberculosis Infection in Arthritis Patients Treated with Tumor Necrosis Factor Antagonists.

The aim of this study was to investigate the role of the QuantiFERON-TB Gold In-Tube test (QFT-GIT) in detecting latent tuberculosis in immunocompromised patients before introducing tumor necrosis factor (TNF-α) antagonists. The study included 300 subjects of similar age. The study group comprised of 150 QuantiFERON (QFT) positive subjects with rheumatoid arthritis, Crohn's disease, ulcerative colitis, ankylosing spondylitis and psoriatic arthritis, while control group comprised of 150 QFT negative respondents with the same diseases. Exhaustive medical history was documented for all patients. Screening tests were performed including QFT-GIT, tuberculin skin test (TST), chest radiography and detection of Mycobacterium tuberculosisin sputum culture 2 times. A positive QFT-GIT test result, regardless of TST result, was considered as an indication for latent tuberculosis infection (LTBI) treatment. Results of this study showed good correlation between the conclusive results of QFT-GIT and TST. All study group patients had normal clinical findings, normal radiologic findings and negative results of sputum microbiological analysis during the course of prophylaxis and after its completion and during the course of biological therapy. Conversion of positive QFT-GIT test to negative was observed in 4% of study group patients, while QFT negative respondents remained negative. There was a statistically significant positive correlation between QFTGIT, TST results and patient age, smoking habit and contact with tuberculosis. Study results showed that along with good clinical evaluation and detailed medical history, it is important to conduct testing in order to avoid disease progression or unnecessary isoniazid prophylaxis.

QuantiFERON-TB Gold In-Tube Test for Tuberculosis Prevention in HIV-Infected Patients.

Optimal testing strategies for diagnosing latent tuberculosis infection and the administration of isoniazid preventive therapy (IPT) remain uncertain among human immunodeficiency virus (HIV)-infected patients. A 4-year prospective study was conducted among Thai HIV-infected patients who underwent simultaneous tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube Test (QFT-IT) at care entry. Based on baseline test results, patients were categorized into the following 4 groups: i) QFT-IT-positive, TST-reactive; ii) QFT-IT-positive, TST-non-reactive; iii) QFT-IT-negative, TST-reactive; and iv) QFT-IT-negative, TST-non-reactive. The QFT-IT-positive patients were offered 9-month IPT and were QFT-IT tested annually. Of the 150 enrolled patients, 8, 12, 16, and 114 patients were assigned to groups 1, 2, 3, and 4, respectively. Sixteen of 19 QFT-IT-positive patients (84%) completed IPT. The incidence of tuberculosis was significantly higher in patients who declined IPT than in those underwent treatment (11.11 vs. 0 case/100 patient-year; P ＜ 0.001). Among the 16 patients completing IPT, 11 (69%) and 2 (12%) had QFT-IT reversion at 1 and 2 years after IPT, respectively. The remaining 3 (19%) did not demonstrate any reversion, and their baseline interferon-γ (IFN-γ) levels were above 1.2 IU/mL. Initial QFT-IT-guided IPT was effective in preventing tuberculosis. Serial QFT-IT for evaluating IPT effectiveness had limitations because of delayed or lack of reversion, especially for patients with high baseline IFN-γ levels.

Immunodiagnostic Potential of an In-Vitro Interferon-Gamma Release Assay for Latent Tuberculosis Infection Among Apparently Healthy Individuals in Okada Community, Nigeria

A major challenge in the global Tuberculosis (TB) control is the diagnosis and treatment of Latent Tuberculosis Infection (LTBI). In the absence of any reference standard test for the diagnosis of LTBI, this study set out to compare the performance of the two current immune-based tests, Tuberculin Skin Test (TST) and Quantiferon–TB Gold In–Tube (QFT-GIT) ELISA in the diagnosis of LTBI. Two sets of diagnostic results for 196 apparently healthy volunteers from a cross-section of Okada Community, Edo State, Nigeria were compared in terms of age, occupation, BCG-vaccination status, prior TST and cigarette smoking history. Overall, 56 (28.6%) and 81 (41.3%) of the subjects were diagnosed with LTBI by the QFT-GIT test and TST respectively. The LTBI prevalence as assessed by the QFT-GIT test was significantly higher among the non-BCG-vaccinated, compared to the BCG-vaccinees (X²=18.79, df=1, p=0.0001). The highest concordance (QFT-GIT+ve/TST+ve) was found in the occupation categories (Ʀ=-0.009, p=0.747) and the highest discordance(QFT-GIT –ve/TST +ve) was with respect to the BCG-vaccination status (Ʀ=-0.194, p=0.046).The disparity in the performance of the two tests is attributable to the high false – positive TST results, which is a direct reflection of high (90.8%) BCG vaccination level among the study population. It is advocated that the two-step testing approach, using the QFT-GIT assay as a confirmatory test for LTBI after initial positive screening by the TST, be introduced into the TB control strategy in TB – laden communities with high BCG vaccination coverage.

Utility of the QuantiFERON-TB Gold In-Tube assay for the diagnosis of tuberculosis in Moroccan children.

The utility of interferon-gamma release assays (IGRAs), such as the QuantiFERON-TB Gold In-Tube (QFT-GIT) test, in diagnosing active tuberculosis (TB) in children is unclear and depends on the epidemiological setting. To evaluate the performance of QFT-GIT for TB diagnosis in children living in Morocco, an intermediate TB incidence country with high bacille Calmette-Gurin vaccination coverage. We prospectively recruited 109 Moroccan children hospitalised for clinically suspected TB, all of whom were tested using QFT-GIT. For 81 of the 109 children, the final diagnosis was TB. The remaining 28 children did not have TB. QFT-GIT had a sensitivity of 66% (95%CI 5277) for the diagnosis of TB, and a specificity of 100% (95%CI 88100). The tuberculin skin test (TST) had lower sensitivity, at 46% (95%CI 3360), and its concordance with QFT-GIT was limited (69%). Combining QFT-GIT and TST results increased sensitivity to 83% (95%CI 6992). In epidemiological settings such as those found in Morocco, QFT-GIT is more sensitive than the TST for active TB diagnosis in children. Combining the TST and QFT-GIT would be useful for the diagnosis of active TB in children, in combination with clinical, radiological and laboratory data.

Performance of the QuantiFERON-TB Gold In-Tube test to Monitor Treatment of Active Pulmonary Tuberculosis in Taiwan

Performance of the QuantiFERON-TB Gold In-Tube test to Monitor Treatment of Active Pulmonary Tuberculosis in Taiwan

Predictors of low prevalence of latent tuberculosis infection among Egyptian health care workers at intensive care and bronchoscopy units.

Aim: Latent tuberculosis infections (LTBI) contain a significant reservoir for future epidemics. Screening of health care workers (HCWs) in a high-risk tuberculosis (TB) environment is an important strategy in TB control. The study aimed to assess the prevalence of LTBI among high risk Egyptian HCWs and to assess infection associated risk factors.Methods: Fifty-two HCWs who work at intensive care unit (ICU), bronchoscopy unit, and chest diseases department were tested for LTBI using both tuberculin skin test (TST) and Quantiferon TB Gold in-tube test (QFT). Risk factors for infection, knowledge of HCWs towards different aspects of TB infection and agreement between TST and QFT were also evaluated.Results: Prevalence of LTBI in this study was 13.5% by QFT and TST. It was 13.6% by TST alone and 10.3% by QFT alone. There was good concordance between both tests (Kappa=0.713). There was a statistically significant association between prevalence of LTBI and age of staff ≥30 yr (p=0.002), period of working experience (p=0.006) and working at the Bronchoscopy Unit (p=0.001). The total knowledge of HCWs towards different aspects of TB infection was generally good. Conclusion: Although the participants in the current study were among high risk HCWs, the prevalence of LTBI was low. Bacille Calmette-Guerin (BCG) vaccination, young age, short employment duration, good knowledge and a good infection control were the predictors of low risk of contracting TB at our hospitals. The risk of TB infection in resource-limited countries can be reduced with simple continuous educational and administrative infection control programmes.

First characterization of the CD4 and CD8 T-cell responses to QuantiFERON-TB Plus

QuantiFERON®-TB Gold Plus (QFT-Plus) is the new generation of QuantiFERON-TB Gold In-Tube test to identify latent tuberculosis infection (LTBI). QFT-Plus includes TB1 and TB2 tubes which contain selected Mycobacterium tuberculosis (Mtb) peptides designed to stimulate both CD4 and CD8 T-cells. Aim of this study is the flow cytometric characterization of the specific CD4 and CD8 T-cell responses to Mtb antigens contained within QFT-Plus. We enrolled 27 active tuberculosis (TB) patients and 30 LTBI individuals. Following stimulation with TB1 and TB2, antigen-specific T-cells were characterized by flow cytometry. Data were also correlated with the grade of TB severity. TB1 mainly elicited a CD4 T-cell response while TB2 induced both CD4 and CD8 responses. Moreover, the TB2-specific CD4 response was detected for both active TB and LTBI patients, whereas the TB2-specific CD8 response was primarily associated with active TB (p=0.01). To our knowledge, we report the first characterization of the CD4 and CD8 T-cell response to QFT-Plus. CD8 T-cell response is mainly due to TB2 stimulation which is largely associated to active TB. These results provide a better knowledge on the use of this assay.

Latent Tuberculosis Infection Test Agreement in the National Health and Nutrition Examination Survey.

Latent tuberculosis infection (LTBI) test discordance is poorly understood. To determine the frequency and predictors of tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube test (QFT) discordance in the U.S. We analyzed data from a representative sample of the U.S. population ages 6 years and older who participated in the 2011-2012 National Health and Nutrition Examination Survey. We determined prevalence estimates of test positivity, calculated test agreement and kappa statistics, and performed multivariable logistic regression to determine predictors of discordance. LTBI prevalence among the U.S. born ranged from 0.6% to 2.8%, depending on how LTBI was defined, with test agreement 97.0% and kappa 0.27 (95% confidence interval, 0.18-0.36). Prevalence among the foreign born ranged from 9.1% to 20.3%, depending on how LTBI was defined, with test agreement 81.6% and kappa 0.38 (95% confidence interval, 0.33-0.44). TST(+)/QFT(-) discordance was associated with age, male sex, black race, Mexican-American ethnicity, previous TB exposure, and past LTBI treatment in U.S.-born participants, but only with higher lymphocyte count in foreign-born participants. TST(-)/QFT(+) discordance was associated with older age, previous TB exposure, and past LTBI treatment in U.S.-born participants and with older age, male sex, and past LTBI treatment in foreign-born participants. In the largest population-based sample of concurrently performed TST and QFT tests in a low tuberculosis incidence population, prevalence estimates depended heavily on how LTBI was defined and test agreement was only fair. We identified several predictors of discordance warranting further study.

The Prevalence of Latent Tuberculosis Infection in the United States.

Individuals with latent tuberculosis infection (LTBI) represent a reservoir of infection, many of whom will progress to tuberculosis (TB) disease. A central pillar of TB control in the United States is reducing this reservoir through targeted testing and treatment. To estimate the prevalence of LTBI in the United States using the tuberculin skin test (TST) and an IFN-γ release assay. We used nationally representative data from the 2011-2012 National Health and Nutrition Examination Survey (n = 6,083 aged ≥6 yr). LTBI was measured by both the TST and QuantiFERON-TB Gold In-Tube test (QFT-GIT). Weighted population, prevalence, and multiple logistic regression were used. The estimated prevalence of LTBI in 2011-2012 was 4.4% as measured by the TST and 4.8% by QFT-GIT, corresponding to 12,398,000 and 13,628,000 individuals, respectively. Prevalence declined slightly since 2000 among the U.S. born but remained constant among the foreign born. Earlier birth cohorts consistently had higher prevalence than more recent ones. Higher risk groups included the foreign born, close contact with a case of TB disease, and certain racial/ethnic groups. After years of decline, the prevalence of LTBI remained relatively constant between 2000 and 2011. A large reservoir of 12.4 million still exists, with foreign-born persons representing an increasingly larger proportion of this reservoir (73%). Estimates and risk factors for LTBI were generally similar between the TST and QFT-GIT. The updated estimates of LTBI and associated risk groups can help improve targeted testing and treatment in the United States.

The tuberculin skin test still matters for the screening of latent Tuberculosis infections among Inflammatory Bowel Disease patients

Background and aimsThere is a high risk of Tuberculosis among patients medicated with anti-tumour necrosis factor α (anti-TNFα) that can be mitigated by treating latent Tuberculosis infections (LTI). This study aimed to evaluate the performance of Tuberculin Skin test (TST) and Quantiferon-TB Gold in Tube (QFT-GIT) in a population of patients suffering from Inflammatory Bowel Diseases. MethodsThe cohort analyzed in this study consisted of 250 patients, of whom 15% were therapy-naïve and 85% were medicated: 70% under immunosuppressive therapy and 30% on anti-TNFα. A LTBI was diagnosed following a positive result in either of the tests and their performance and concordance were evaluated. ResultsFifty-eight and 24 patients had a positive TST and QFT-GIT, respectively. In 72 (29%) patients LTBI was diagnosed, of whom 8 (21%) were therapy-naïve. TST had an overall higher sensitivity (81% vs. 35%) and a higher Negative Predictive Value (93% vs. 80%) when compared to QFT-GIT test; this superiority was consistently maintained irrespective of the presence and kind of backbone immunosuppressive therapies. The concordance between both tests was weak. ConclusionsOur results underscore the need to maintain the TST on LTBI diagnosis in patients about to start or switch anti-TNFα therapy in an intermediate Tuberculosis incidence context.

Serial testing for latent tuberculosis using QuantiFERON-TB Gold In-Tube: A Markov model

Healthcare workers (HCWs) in low-incidence settings are often serially tested for latent TB infection (LTBI) with the QuantiFERON-TB Gold In-Tube (QFT) assay, which exhibits frequent conversions and reversions. The clinical impact of such variability on serial testing remains unknown. We used a microsimulation Markov model that accounts for major sources of variability to project diagnostic outcomes in a simulated North American HCW cohort. Serial testing using a single QFT with the recommended conversion cutoff (IFN-g > 0.35 IU/mL) resulted in 24.6% (95% uncertainty range, UR: 23.8–25.5) of the entire population testing false-positive over ten years. Raising the cutoff to >1.0 IU/mL or confirming initial positive results with a (presumed independent) second test reduced this false-positive percentage to 2.3% (95%UR: 2.0–2.6%) or 4.1% (95%UR: 3.7–4.5%), but also reduced the proportion of true incident infections detected within the first year of infection from 76.5% (95%UR: 66.3–84.6%) to 54.8% (95%UR: 44.6–64.5%) or 61.5% (95%UR: 51.6–70.9%), respectively. Serial QFT testing of HCWs in North America may result in tremendous over-diagnosis and over-treatment of LTBI, with nearly thirty false-positives for every true infection diagnosed. Using higher cutoffs for conversion or confirmatory tests (for initial positives) can mitigate these effects, but will also diagnose fewer true infections.

Using IFN-gamma release assay to confirm tuberculin skin test improves the screening of latent tuberculosis infection in Italian healthcare workers.

BackgroundHealthcare workers (HCWs) represent a tuberculosis (TB) risk group for a wide range of tasks in healthcare, even in countries with low TB incidence, like Italy. Latent Tuberculosis Infection (LTBI) screening programs are an important tool for TB prevention in these setting.MethodsA retrospective study under a LTBI screening program among HCWs at the Siena University Hospital (Italy), was conducted between September 2011 and July 2015. Tuberculin Skin Test (TST) was used as a first level examination; all TST-positive cases were tested with QuantiFERON-TB Gold In-Tube (QFT-GIT) test, together with a group of TST-negative subjects.ResultsAmong the 2136 HCWs screened, 144 (6.7 %) were TST-positive and therefore tested with QFT-GIT, confirming a positive result in 36 cases (25 %). Agreement between two tests was poor (k = 0.092; 95 %, Confidence Interval [CI]- 0.048–0.136, p = 0.002). Among TST-positive cases, discordant results occurred more frequently in BCG vaccinated than unvaccinated HCWs (86.3 %, p < 0.001). The probability of a QFT-GIT-positive result increased according to the TST diameter (p = 0.001). No putative risk factor was associated with LTBI occurrence.ConclusionsThe use of QFT-GIT test as a second step in TST-positive cases offers an appropriate tool for LTBI detection, especially among BCG-vaccinated HCWs.

Interferon Gamma Release Assay versus Tuberculin Skin Testing among Healthcare Workers of Highly Diverse Origin in a Moderate Tuberculosis Burden Country.

Health care workers (HCW’s) are always at an increased risk of contracting tuberculosis (TB) infection. In Saudi Arabia, Interferon Gamma Release Assay (IGRA) has not been evaluated as a screening tool for latent TB infection (LTBI) among HCW’s considering their high demographic diversity. During February 2012 to January 2015 a cross sectional study has been conducted in a tertiary care center with maximum demographically diverse staff population in the capital city-Riyadh. After a short interview and consenting, all the candidates were subjected to tuberculin skin test (TST) and QuantiFERON TB gold In-tube test (QFT). A logistic regression analysis was carried out for establishing the associations between putative risk factors and the diagnostic tests. The candidates were classified according to geographical origin and a detailed analysis was conducted on the impact of their origin towards the results of TST and QFT. Of the 1595 candidates enrolled, 90.6% were BCG vaccinated, female (67.9%) and mainly nurses (53.2%). Candidates with high risk of suspected or confirmed TB patient exposure were 56.1% and 76.5% of them had <10 year’s work experience. TST positivity was observed in 503 (31.5%) candidates, while QFT was positive among 399 (25%). Majority of the candidates were non-Saudi (83%) and predominantly (52.4%) from Western Pacific region. Concordant results were obtained in 14.2% of positive cases and 57.7% negative cases. The disagreements between the two tests were relatively high (kappa co-efficient-0.312±0.026, p value- <0.00001) as TST positive/QFT negative discordance was 54.8% while TST negative/QFT positive discordance was 15.7%. Age of the candidates, BCG vaccination, and South East Asian origin were associated with TST positivity while Occupational TB exposure and geographical origin of the candidates were associated with QFT positivity. A regular follow up on recently TST converted candidates showed no progression to active TB. The putative factors associated with the discordance were origin of the candidate (p value <0.001), profession (p value-0.001), BCG vaccination (p value-0.001) and occupational TB exposure level (P value-0.001). The study demonstrated high level prevalence of LTBI among the demographically diverse study candidates. The agreement between QFT and TST was poor, thus QFT alone cannot be recommended in our setting for a routine LTBI screening. Origin of the candidates has strong association with the results of TST and QFT. The discordant results particularly TST negative and QFT positive needs more detailed analysis.

Host immune responses to antigens derived from a predominant strain of Mycobacterium tuberculosis

Beijing strain of Mycobacterium tuberculosis (M. tb) is characterized by a high incidence of transmission, relapse, and drug resistance. This study aimed to determine host immune responses to antigens derived from the Beijing/K strain which has been highly prevalent in tuberculosis (TB) outbreaks in South Korea. We recruited 52TB patients and 96 healthy subjects comprising 31 individuals with latent TB infection (LTBI) and 65TB-naïve controls based on QuantiFERON-TB Gold In-Tube (QFT-IT) tests. Blood samples were obtained for diluted whole-blood assays, multiplex bead arrays, ELISpot assays, and HLA typing. Molecular genotyping of M. tb was performed using clinical isolates. Active TB and LTBI groups were differentiated by TNF-α concentrations induced by the Beijing/K strain-derived antigens, MTBK_24790 and MTBK_24800 (P<0.001). MTBK_24800-induced IFN-γ and CXCL10 concentrations discriminated the TB-infected groups from TB-naïve controls (P<0.001). IFN-γ-producing T cells were generated in 87.2% of TB patients in response to MTBK_24800 peptide antigens. The major immunogenic epitope was at C-terminal of the antigen, and predominantly recognized by HLA-DR4 and -DQ4. Measurement of IFN-γ, CXCL10, and TNF-α concentrations induced by MTBK_24790 and MTBK_24800 may contribute to improved diagnosis of TB and vaccine development in regions where the Beijing/K strain is endemic.

Multidrug-resistant tuberculosis outbreak in an Italian prison: tolerance of pyrazinamide plus levofloxacin prophylaxis and serial interferon gamma release assays.

The optimal treatment for latent tuberculosis infection (LTBI) in subjects exposed to multidrug-resistant (MDR) tuberculosis (TB) remains unclear, and the change in response of the QuantiFERON-TB Gold In-Tube (QTB-IT) test during and after treatment is unknown. Between May 2010 and August 2010, 39 prisoners at the ‘Casa Circondariale’ of Modena, Italy, were exposed to a patient with active pulmonary MDR TB. All contacts were tested with the tuberculin skin test and QTB-IT. Upon exclusion of active TB, subjects positive to both tests were offered 6 months' treatment with pyrazinamide (PZA) and levofloxacin (LVX). QTB-IT testing was repeated at 3 and 6 months after initial testing in all subjects who were offered LTBI treatment. Seventeen (43.5%) of 39 subjects tested positive to both tuberculin skin test and QTB-IT test, and 12 (70.5%) agreed to receive therapy with PZA and LVX at standard doses. Only five (41.6%) of 12 subjects completed 6 months' treatment. Reasons for discontinuation were asymptomatic hepatitis, gastritis and diarrhoea. The QTB-IT values decreased in all subjects who completed the treatment, in two (33%) of six of those who received treatment for less than 3 months and in one (50%) of two patients who discontinued therapy after 3 months. The QTB-IT test results never turned negative. Despite the small number of subjects, the study confirmed that PZA plus LVX is a poorly tolerated option for MDR LTBI treatment. We observed a large degree of variation in the results of the QTB-IT test results among participants. The study confirmed that the interferon gamma release assay is not a reliable tool for monitoring the treatment of MDR LTBI in clinical practice.

Utility of the QuantiFERON-TB Gold In-tube test (QFT) compared with the Tuberculin Skin Test (TST) in diagnosing tuberculosis in Indian children with malnutrition: A prospective study

Utility of the QuantiFERON-TB Gold In-tube test (QFT) compared with the Tuberculin Skin Test (TST) in diagnosing tuberculosis in Indian children with malnutrition: A prospective study

Prognostic value of interferon-γ release assays, a population-based study from a TB low-incidence country

BackgroundThe ability of interferon-γ release assays to predict the development of TB has been investigated in many studies, but few cases develop TB during follow-up limiting the generalisation of results.MethodsWe...