QuantiFERON TB-2G Test Research Articles

Quantiferon in the Diagnosis of Tuberculosis

Quantiferon test (QFT) is an indirect diagnostic test for latent tuberculosis (TB) infection and active TB. Objectives: The aim of this study is to investigate the role of Quantiferon-TB Gold test as one of the interferon-gamma release assays (IGRAs) in detecting LTBI. Research Methodology: This study was conducted at private lab in Tripoli during the period from October 2022 to January 2023, Diagnosis of 254 sample recorded. QFT was performed in accordance with the manufacturer’s instructions. Results: The study include (n= 254 cases), (58 sample 22.8 %) show positive results by Quantiferon test while (196 sample 77.1%) show negative test. Females constituted 118 (46.4%) of the total cases, while the males constituted 136 (53.6%). the age (31-40 years) for the negative include (35 cases 13.7%) while (41-50 years and (61-70 years) for positive include (11cases 4.3%). Discussion: This study confirmed previous reports that the QFT test had greater sensitivity for detecting active TB than the 100-year-old TST. Conclusion: It was concluded that the quantiferon TB-2G test is a more useful diagnostic method for tuberculosis infection. QFT-Plus assay showed good sensitivity for active TB and was particularly useful for the evaluation of children with suspected LTBI, giving a low rate of indeterminate results in this group. More studies are needed to properly evaluate QFT-Plus ability in discriminating active disease from latent infection.

Quantiferon in the Diagnosis of Tuberculosis

Quantiferon test (QFT) is an indirect diagnostic test for latent tuberculosis (TB) infection and active TB. Objectives: The aim of this study is to investigate the role of Quantiferon-TB Gold test as one of the interferon-gamma release assays (IGRAs) in detecting LTBI. Research methodology: This study was conducted at private lab in Tripoli during the period from October 2022 to January 2023, Diagnosis of 254 sample recorded. QFT was performed in accordance with the manufacturer’s instructions. Results: The study include (n= 254 cases), (58 sample 22.8 %) show positive results by Quantiferon test while (196 sample 77.1%) show negative test. Females constituted 118 (46.4%) of the total cases, while the males constituted 136 (53.6%). the age (31-40 years) for the negative includes (35 cases 13.7%) while (41-50 years and (61-70 years) for positive include (11cases 4.3%). Discussion: This study confirmed previous reports that the QFT test had greater sensitivity for detecting active TB than the 100-year-old TST. Conclusion: It was concluded that the quantiferon TB-2G test is a more useful diagnostic method for tuberculosis infection. QFT-Plus assay showed good sensitivity for active TB and was particularly useful for the evaluation of children with suspected LTBI, giving a low rate of indeterminate results in this group. More studies are needed to properly evaluate QFT-Plus ability in discriminating active disease from latent infection.

PWE-018 Predictive Factors for An Indeterminate Result on Interferon-Gamma Release Assay

Introduction Interferon-gamma (IFN-γ) release assay is used to identify patients with latent tuberculosis prior to biological treatment initiation. A lack of stimulation capacity of lymphocytes by the test control results in an indeterminate result. This is not uncommon in inflammatory bowel disease (IBD) patients receiving immunosuppressive agents. 1,2,3 The aim of this study is to compare the clinical and laboratory characteristics of patients with indeterminate results to those with determinate results. Methods The national database of IBD patients receiving biological agents was accessed. IFN-γ release assay (QuantiFERON-TB Gold) results were noted. Parameters at the time of testing were collected, namely age, diagnosis, disease activity, blood results and drug treatment. Comparisons between the indeterminate group and determinate group were made using IBM® SPSS® Statistics Version 20. The study was approved by the University and Research Ethics Committee of Malta. Results Data from 136 subjects was analysed. 8.8% ( n = 12) had an indeterminate IFN-γ release assay result, 2.2% ( n = 3) had a positive result, while 89% ( n = 121) had a negative result. The indeterminate group had a significantly lower lymphocyte count ( p = 0.041), globulin level ( p = 0.042), immunoglobulin A (IgA) ( p = 0.031) and haemoglobin ( p = 0.016). C-reactive protein was higher in the indeterminate group ( p = 0.024). No significant differences were recorded for age, gender, diagnosis, disease activity, white cell count, neutrophils, platelets, renal/liver function, albumin levels, IgM, IgG, or drug treatment. Critically, only 25% of indeterminate result subjects had a repeat test, all reported as negative. Conclusion Indeterminate results are common in IBD patients, affecting nearly 1 in 10 patients. Patients with low lymphocyte counts, low globulin, low haemoglobin, low IgA and high CRP levels are more likely to have an indeterminate result when tested. The potential of a false negative result is likely to be higher in these patients. One must exert caution when requesting IFN-γ release assays in such IBD patients since the probability of a determinate result may be low. We advise test repetition in all patients with indeterminate results and screening with chest x-ray. References 1 Helwig U, Muller M, Hedderich J, et al, Corticosteroids and immunosuppressive therapy influence the result of QuantiFERON TB Gold testing in inflammatory bowel disease patients . J Crohns and Colitis 2012; 6 :419–424. 2 Jeong SJ, Han SH, Kim CO, et al, Predictive factors for indeterminate result on the QuantiFERON test in an intermediate tuberculosis-burden country . J Infect . 2011; 62 :347–354. 3 Kobashi Y, Sugiu T, Mouri Y, et al , Indeterminate results of QuantiFERON TB-2G test performed in routine clinical practice . Eur Respir J 2009; 33 :812–815. Disclosure of Interest None Declared

Serial QuantiFERON TB-2G testing over a four-year period in healthcare workers at a city hospital.

To evaluate the performance and practicality of QuantiFERON TB-2G (QFT-2G) testing for screening healthcare workers (HCWs) at a city hospital in Japan without a tuberculosis (TB)-specific ward. We performed a chart review of 951 HCWs (251 men and 700 women) who underwent QFT-2G testing as a part of their pre-employment or annual employee screening between April 2007 and March 2010. The initial QFT-2G test was interpreted as positive in 28 (2.9%) HCWs, negative in 884 HCWs (92.9%) and indeterminate in 39 HCWs (4.1%). During the four-year study period, 37 HCWs were diagnosed as being positive at least once. Nine (0.98%) of the 923 HCWs with indeterminate or negative results on the initial testing converted to a positive status, including 6/479 (1.25%) nurses, 2/100 (2.0%) office staff members and 1/147 (0.68%) physicians. No HCWs with a positive result had a history of tuberculosis (TB) or any apparent contact with active TB patients and did not opt for treatment of latent TB. Seven (25%) of the 28 HCWs who were determined to be positive on the initial testing reverted to an indeterminate or negative status. In a series of annual serial QFT-2G tests, some HCWs exhibited conversion and/or reversion. Therefore, caution is required when interpreting mild fluctuations in interferon-γ responses.

AB0698 Latent tuberculosis: a potential extrinsic factor for IGG4-related disease

BackgroundIgG4-related disease (IgG4-RD) is an inflammatory systemic disease, whose lachrymal and salivary gland involvement is known as Mikulicz’s disease and resembles that of primary Sjogren’s syndrome (pSS)1). In IgG4-RD, increased...

Analysis of tuberculosis infection among foreigners using QuantiFeron TB-2G test

The purpose of this study was to investigate contacts of a tuberculosis patient among foreigners using QuantiFERON TB-2G (QFT-2G) test. Three index cases in this study were all foreigners. Contacts, who were mostly foreigners and some Japanese, were investigated by a chest X-ray examination, tuberculin skin test (TST) and QFT-2G, and all data were compared. Among 48 subjects (30 Vietnamese and 18 Japanese) in case 1, 8 Vietnamese and 2 Japanese were QFT-2G positive. One contacts among 3 most close contacts who lived in the same room with the index case was QFT-2G positive. In case 2, three Chinese among 22 contacts were QFT-2G positive, and a very close contact who lived in the next door to the index case was QFT-2G negative. Seven QFT-2G positive Chinese were identified among 24 contacts in case 3. However, four very close contacts among them were QFT-2G negative. Although it was unclear whether QFT-2G positives in cases 1 and 2 were infected with M. tuberculosis through the index cases, it is possible to speculate that these QFT-2G positives were already infected with M. tuberculosis while they live in their own country based on the prevalence of TB in their countries and the fact that many very close contacts were QFT-2G negative. Also, it was suggested that QFT-2G positives in case 3 may not be infected through the index case, but infected in their country, since all close contacts were QFT-2G negative. The results of this study suggested that using the QFT-2G test for foreigners prior to or soon after their entry to Japan and recommending chemoprophylaxis for those who are QFT-2G positive would be a very efficient control measures against immigrant foreigners with TB infection.

Usefulness of QuantiFERONTB-2G in a suspected case of drug resistant tuberculosis outbreak in a university

To diagnose M. tuberculosis infection and select subjects for chemoprophylaxis in a contact investigation, we used the whole blood interferon-gamma response test, QuantiFERONTB-2G (QFT), and examined the usefulness of QFT. The index case (heavily positive for sputum smear, at grade 6 by Gaffky system, the duration of coughing being 8 months; hence the infectious risk index is 48) was found at a periodic mass health examination before proceeding to the second grade in a university. Since TB outbreak was suspected based on the results of tuberculin skin test (TST) in the contact investigation, QFT test was carried out to determine the subjects for chemoprophylaxis and to define the target of further contact investigations. In the first TST, 57 contacts showed erythema of more than 30 mm in diameter, and these contacts would have been indicated for chemoprophylaxis based on TST results. Thus, this case would have been designated as a TB outbreak, and further investigation should be necessary for less close contacts. However, twice QFT tests revealed that only five contacts were positive for QFT (three showed erythema diameter of more than 30 mm, and two less than 29 mm). These five contacts were indicated chemoprophylaxis. Thus, the number of the secondary infections did not fulfill the criterion defined as a TB outbreak, and therefore an extended contact investigation was stopped. No contact has developed TB so far. QFT test was shown to be useful for determining subjects for chemoprophylaxis and selecting the range of the contact investigation.

Use of QuantiFeron TB-2G test on high-risk groups for tuberculosis infection at our hospital

To investigate the infection rate of tuberculosis in high-risk employees at our hospital. We measured interferon gamma levels in 40 employees and evaluated the infection rate in doctors working in the Tuberculosis Ward (D group), nurses in the Tuberculosis Ward (N group), and other high-risk employees (O group). The overall infection rate including probable infection was 6/40 (15.0%). The infection rate in the N group was 0%, while those in the D and O groups were 27.3% and 20.0% respectively. No new infection of tuberculosis was observed after the introduction of tuberculosis infection measure manual of our hospital. Our hospital's tuberculosis infection measure manual was effective in decreasing the new tuberculosis infection despite a high infection rate in high-risk employees at our hospital.

Comparison of T-Cell Interferon-γ Release Assays for Mycobacterium tuberculosis-Specific Antigens in Patients with Active and Latent Tuberculosis

Through the use of QuantiFERON-TB Gold, a commercial IFN-γ assay, we compared differences in quantitative T-cell responses to Mycobacterium tuberculosis (MTB)-specific antigens [QuantiFERON TB-2G (QFT-2G)] between patients with active tuberculosis (TB) disease and those with latent TB infection (LTBI). The patient group consisted of 180 patients with active TB disease (culture-positive for MTB) and 50 screening contacts with LTBI-positive response to the QFT-2G test. We prospectively performed a tuberculin skin test (TST) and a QFT-2G test for all subjects. The median IFN-γ levels upon the application of both antigens, ESAT-6 and CFP-10, were significantly higher in patients with active TB disease than in those with LTBI. A combined positive response to both antigens occurred at a higher rate in patients with active TB disease than in those with LTBI. There were no significant relationships between the quantitative responses of IFN-γ to both antigens and the maximum induration on TST in both patient groups. We demonstrated significant differences in the quantitative responses of IFN-γ to MTB between patients with active TB disease and those with LTBI in this study. However, there was an overlap in the IFN-γ levels between active TB disease and LTBI groups. Therefore, it would be difficult to use the QFT-2G test to completely discriminate active TB disease from LTBI.

Improvement in Symptoms and QuantiFERON TB-2G Test Results after Isoniazid Administration in a Patient with Normal Routine Tests Results

Improvement in Symptoms and QuantiFERON TB-2G Test Results after Isoniazid Administration in a Patient with Normal Routine Tests Results

RAPID DIAGNOSIS OF ACTIVE PULMONARY TUBERCULOSIS IN THE ELDERLY USING ENZYME‐LINKED IMMUNOSPOT ASSAY FOR INTERFERON‐GAMMA

RAPID DIAGNOSIS OF ACTIVE PULMONARY TUBERCULOSIS IN THE ELDERLY USING ENZYME‐LINKED IMMUNOSPOT ASSAY FOR INTERFERON‐GAMMA

Diagnostic accuracy of Quantiferon TB test for patients with SLE and miliary tuberculosis

The mortality rate of patients with miliary tuberculosis is almost 20%. The sensitivity of acid-fast staining method does not exceed 50% for diagnosis of miliary tuberculosis. Nevertheless, the time required for mycobacterium culture results may lead to signiWcant delay in diagnostic procedure. The tuberculin skin test is negative in more than 50% of patients with miliary tuberculosis. This is more distinct in patients who received steroid treatment. The sensitivity (86–89%) and speciWcity (94–98%) of QuantiFERON TB2G (QFT-TB) test is high for the diagnosis of tuberculosis infection and the test is introduced to the clinical applica

Clinical utility of a T cell‐based assay in the diagnosis of extrapulmonary tuberculosis

The aim of this study was to evaluate the QuantiFERON TB-2G (QFT-2G) results in patients with active extrapulmonary tuberculosis (E-TB) to determine whether QFT-2G test might be a reliable diagnostic method for detecting active E-TB infection compared with the tuberculin skin test (TST). TST and QFT-2G tests were performed for 35 patients with confirmed E-TB, 30 with probable E-TB and 45 who did not have E-TB. For patients with confirmed E-TB, the positive rate of the TST was 57% and that of the QFT-2G test was 86%. For patients with probable E-TB, the positive rate of the TST was 60%, whereas that of the QFT-2G test was 80%. However, the positive rate of the TST was 51% and that of QFT-2G test was 9% for patients that did not have E-TB. The QFT-2G test showed a significantly lower percentage of false-negative results compared with the TST. The sensitivity and specificity of the TST for the diagnosis of active E-TB were 57% and 49%, respectively. By comparison, the sensitivity and specificity of the QFT-2G test were 86% and 84%, respectively. When the results of the TST and QFT-2G tests were separated by the site of E-TB, the positive rates for both tests in patients with miliary tuberculosis were lower than those in patients with other E-TB disease, although the difference was not significant. The QFT-2G appears to be a reliable diagnostic test and in the appropriate clinical context QFT-2G may be more useful than the TST to support a diagnosis of E-TB. Studies are needed to evaluate its value also in situations of low clinical probability.

Indeterminate results of QuantiFERON TB-2G test performed in routine clinical practice

The present authors assessed risk factors that can promote indeterminate results of QuantiFERON TB-2G (QFT-2G; Cellestis Ltd, Carnegie, Australia) tests. The subjects were 704 patients with suspected tuberculosis (TB) and latent TB infection between January 2005 and December 2007. The QFT-2G test and the tuberculin skin test (TST) were performed for all subjects. If the results of the QFT-2G test were indeterminate, the test was repeated within 1 month. In total, 72 (10.2%) patients showed indeterminate results on the QFT-2G test. Indeterminate results were due to positive control failure in 68 (88.9%) patients and negative control failure in four patients. The results of the TST were negative for 64 patients showing indeterminate results, the remaining eight patients showed a positive response to the TST. Indeterminate results were significantly associated with elderly and immunocompromised patients. Lymphocytopaenia and hypoalbuminaemia were significantly associated with indeterminate laboratory findings. When the QFT-2G test was repeated for all patients showing indeterminate results, 12 (16.7%) patients demonstrated determinate results on the subsequent test. Indeterminate results of the QuantiFERON TB-2G test under routine clinical practice are not infrequent. When scoring QuantiFERON TB-2G test results for elderly and immunocompromised patients, one must be careful because the possibility of obtaining determinate results may be low even if the test is repeated.

Clinical evaluation of QuantiFERON TB-2G test in patients with healed pulmonary tuberculosis

We evaluated the response to the QuantiFERON TB-2G (QFT-2G) test in patients with healed pulmonary tuberculosis (TB) compared to the response in those with active pulmonary TB. The subjects were 208 patients with healed pulmonary TB and 155 patients with active pulmonary TB. The QFT-2G test results were analyzed by stratifying them into 5- or 10-year periods after the completion of antituberculosis treatment. Of the 208 patients with healed pulmonary TB, 63% had a positive tuberculin skin test (TST) and 34% had a positive QFT-2G test result. There was no significant difference in the positive response rate for the QFT-2G test, or in the positive test result rate for only the early secretory antigenin target 6-kD protein (ESAT-6) antigen, only the culture filtrate protein 10 (CFP-10) antigen, or both the ESAT-6 and CFP-10 antigens among any subgroups stratified by 5- or 10-year periods after the completion of antituberculosis treatment. The positive rate for the QFT-2G test was significantly higher in patients with active pulmonary TB (83%) than in patients with healed pulmonary TB (34%). Regarding the combined and separate responses to both the ESAT-6 and CFP-10 antigens, the positive response rate for both antigens was significantly lower in patients with healed pulmonary TB than in those with active pulmonary TB. Because many patients continued to show a positive response to the QFT-2G test even when a long period had passed after the completion of the antituberculosis treatment, it is suggested that, in patients with a previous history of TB, particular attention must be paid to the relapse of TB or reinfection with TB.

QuantiFERON TB-2G test for patients with active tuberculosis stratified by age groups

We evaluated the usefulness of the QuantiFERON TB-2G (QFT-2G) test and the tuberculin skin test (TST) in patients with active tuberculosis (TB) disease stratified by age in 10-year increments. Although the positive rate on TST was over 80% in younger patients aged < or =9 years, it decreased to 55% in patients of aged 70-79 years and 33% in patients aged over 80 years. However, the positive rate on QFT-2G test was over 80% for the age groups between 10-19 and 60-69 years, excluding younger patients aged < or =9 years. Furthermore, the rate was 79% in patients aged 70-79 years and 75% in patients over 80 years of age. The positive response rate of the QFT-2G test was significantly higher than that of the TST in patients over 50 years of age. The indeterminate result of the QFT-2G test increased with age and it is suggested that this result is concerned with the severity of underlying diseases in patients with active TB disease. Although the positive rate on QFT-2G test decreased with age in adults, it is thought to be a useful supportive diagnostic method for active TB disease compared to the TST, except in younger patients aged < or =9 years old.

Clinical Evaluation of the T-SPOT.TB Test for Patients with Indeterminate Results on the QuantiFERON TB-2G Test

To evaluate the clinical utility of the T-SPOT.TB test for patients with indeterminate results on the QFT-2G test. Forty patients (10.6%) showed indeterminate results among 378 patients who underwent QFT-2G test because active TB disease was clinically suspected. T-SPOT.TB test was performed for these 40 patients before the initiation of antituberculous treatment. Forty patients (10.6%) were judged as showing indeterminate results on QFT-2G test because the positive control presented a lower IFN-gamma level. Elderly patients (68.2 versus 57.7) or immunocompromised patients receiving immunosuppressive treatments and patients with a decrease in lymphocyte count, serum protein and albumin were more frequently recognized in the patients with indeterminate results compared to those with determinate results on QFT-2G test. T-SPOT.TB test could clearly demonstrate the results in 26 of the 40 patients (65.0%) with indeterminate results of QFT-2G test; these were divided into six patients with positive results and 20 with negative results of T-SPOT.TB test. Elderly patients (73.5 versus 64.3) or patients with underlying diseases such as malignant disease and those receiving immunosuppressive treatment and patients with hyponutritional conditions were more frequently recognized in the patients with indeterminate results compared to patients with determinate results on both tests. We think it may be necessary to introduce T-SPOT.TB test to increase the diagnostic rate of TB disease including latent tuberculosis infection because indeterminate results of QFT-2G test might be further decreased using T-SPOT.TB test. Although 14 patients showed indeterminate results on both tests, the lymphocytes of these patients may not possess functional cytokine production activity.

QuantiFERON TB-2G test for patients with active tuberculosis stratified by age groups

QuantiFERON TB-2G test for patients with active tuberculosis stratified by age groups

Transitional changes in T-cell responses to Mycobacterium tuberculosis-specific antigens during treatment

Currently, there is no available test for monitoring the clinical effect of active tuberculosis (TB) disease treatment. Therefore, we studied the usefulness of two commercial IFN-gamma assays (QuantiFERON TB-2G (QFT-2G) and T-SPOT.TB tests) for monitoring clinical efficacy. The subjects were 40 patients with active TB disease. These two commercial IFN-gamma assays were carried out every three months during active TB disease treatment. While the positive response rate of QFT-2G test significantly decreased from 83% at treatment initiation to 58% at treatment completion, that of T-SPOT.TB decreased from 90% at treatment initiation to 63% at treatment completion. Although there was a significant decrease in patients with TB infection showing positive responses for ESAT-6 only or CFP-10 only antigens on both IFN-gamma assays, there was no significant decrease in patients showing positive responses for both ESAT-6 and CFP-10 antigens on both IFN-gamma assays. On both QFT-2G test and T-SPOT.TB test, the mean values of the IFN-gamma levels in the pre- and post-treatment responses showed significantly decreased responses to CFP-10. On the other hand, smear conversion results of clinical specimens were obtained in all patients at treatment completion. Antituberculous treatment induced a significant decrease in T-cell responses to separate ESAT-6 and CFP-10 antigens as measured by both IFN-gamma assays. Although IFN-gamma assays might be later than smear conversion results of clinical specimens, the quantitative responses especially to CFP-10 may be one of the useful monitoring markers of clinical efficacy for active TB disease treatment.

Effects of prophylaxis on QuantiFERON TB-2G responses among children

To study the effect of treatment of latent tuberculosis infection (LTBI) on QuantiFERON TB-2G (QFT-2G) test results. QFT-2G was used for a contact investigation in a junior high school and those positive or doubtful positive (TB Antigen-Nil response > or = 0.1 and < 0.35 IU/ml) were indicated for treatment of LTBI with INH. All subjects who completed treatment of LTBI were re-tested with QFT-2G approximately 1 month after completion of treatment and a subset were again re-tested 8 to 11 months after the completion of treatment. The levels of IFN-gamma response in each QFT-2G test were compared. Initially, 43 subjects (28 QFT-2G positive and 15 doubtful positive) were indicated treatment of LTBI, and 41 (95%) completed 6-months treatment. These 41 subjects were re-tested with QFT-2G approximately 1 month after the completion of treatment. Among 28 pre-treatment positives, 19 remained positive, 6 became doubtful positive, and 3 reverted to negative. Among 13 pre-treatment doubtful positives, 1 converted to positive, 5 remained doubtful positive, and 7 reverted to negative. The QFT-2G responses after the completion of treatment significantly declined compared with the pre-treatment level (geometric means; before treatment ESAT-6: 0.30 IU/ml, CFP-10: 0.09 IU/ml, after treatment ESAT-6:0.18 IU/ml, CFP-10: 0.05 IU/ml, dependent t-test; ESAT-6: p = 0.020, CFP-10: p = 0.005). At 8 to 11 months after the completion of treatment, 30 randomly selected subjects received the third QFT-2G test. Among 19 positives at the completion of treatment, 14 remained positive, 4 become doubtful positive, and 1 reverted to negative. Among 8 doubtful positives at completion of treatment, 4 converted to positive, 3 remained doubtful positive, and 1 reverted to negative. A further decline of QFT-2G responses was not observed. Three subjects negative at the completion of treatment were re-tested and remained negative at the third test. QFT-2G responses significantly declined after the treatment of LTBI, despite the rate of reversion in QFT-2G being low. This low reversion rate suggests QFT-2G would not be useful as a marker to evaluate the success of treatment for LTBI. However, the finding that QFT-2G responses significantly decline after the treatment of LTBI suggests the possibility that this decline could be used as a marker of the susceptibility of the infective M. tuberculosis strain to the prophylactic drug used. The outbreak investigation has been carried out for over two years, and none of 229 students who were TST positive, but QFT-2G negative and because of this result not indicated treatment of LTBI, have developed TB, suggesting that QFT-2G reflects TB infection more accurately than the TST, even in school children.