Value Of Tuberculin Skin Test Research Articles

QuantiFERON Supernatant-Based Host Biomarkers Predicting Progression to Active Tuberculosis Disease Among Household Contacts of Tuberculosis Patients.

The positive predictive value of tuberculin skin test and current generation interferon gamma release assays are very low leading to high numbers needed to treat. Therefore, it is critical to identify new biomarkers with high predictive accuracy to identify individuals bearing high risk of progression to active tuberculosis (TB). We used stored QuantiFERON supernatants from 14 household contacts of index TB patients who developed incident active TB during a 2-year follow-up and 20 age and sex-matched non-progressors. The supernatants were tested for an expanded panel of 45 cytokines, chemokines, and growth factors using the Luminex Multiplex Array kit. We found significant differences in the levels of TB-antigen induced production of several analytes between progressors and non-progressors. Dominance analysis identified 15 key predictive biomarkers based on relative percentage importance. Principal component analysis revealed that these biomarkers could robustly distinguish between the 2 groups. Receiver operating characteristic analysis identified interferon-γ inducible protein (IP)-10, chemokine ligand (CCL)19, interferon (IFN)-γ, interleukin (IL)-1ra, CCL3, and granulocyte-macrophage colony-stimulating factor (GM-CSF) as the most promising predictive markers, with area under the curve (AUC) ≥90. IP-10/CCL19 ratio exhibited maximum sensitivity and specificity (100%) for predicting progression. Through Classification and Regression Tree analysis, a cutoff of 0.24 for IP-10/CCL19 ratio was found to be ideal for predicting short-term risk of progression to TB disease with a positive predictive value of 100 (95% confidence interval [CI] 85.8-100). The biomarkers identified in this study will pave way for the development of a more accurate test that can identify individuals at high risk for immediate progression to TB disease for targeted intervention.

Comparison of Interferon Gamma Release Assay and Tuberculin Skin Test for Diagnosis of Latent Tuberculosis in Psoriasis Patients Planned for Systemic Therapy.

Background:Latent tuberculosis infection (LTBI) is a common yet difficult problem to diagnose in tuberculosis endemic countries. Both tuberculin skin test (TST) and interferon-gamma release assay (IGRA) are used for the diagnosis of LTBI.Aims:The aim of the study is to compare TST and IGRA in patients planned for systemic treatment of psoriasis.Methods:It was a diagnostic study conducted in a tertiary care centre during the study period from January 20 to December 20. Patients more than 18 years of age with chronic plaque psoriasis planned for systemic therapy were included. Psoriasis area severity index (PASI), history of tuberculosis in past or family and BCG vaccination were recorded. Complete blood count, radiograph of the chest, tuberculin skin test and interferon-gamma release assay were performed in all patients. Statistical analysis was performed using statistical package for social sciences (SPSS version 20, Chicago).Results:A total of 75 patients, including 48 males and 27 females, were included in the study. The mean age and mean duration of disease were 46.08 (±12.16) and 4.59 (±3.8) years, respectively. Seventy-one (94.6%) patients had BCG scar, and two (2.6%) had a history of tuberculosis in a family member. The TST and IGRA were positive (>10 mm) in 23 (30.6%) and 16 (21.3%) patients, respectively. Either TST or IGRA was positive in 28 (37.3%) patients. Out of these 28 patients, concordance was seen in 11 (39.2%) and discordance in 17 (60.7%). Discordance was TST+/IGRA − in 12 (42.8%) and TST−/IGRA + in five (17.8%) patients. Abnormality in radiograph of the chest and computed tomography (CT) scan of the chest were seen in five (6.6%) and nine (12%) patients, respectively. The patients with either TST or IGRA + were more likely to have abnormal chest radiographs than those who were TST−/IGRA− (OR: 11.3, 95% CI: 1.24–102.3, P = 0.03). The TST and IGRA showed fair agreement ( = 0.364, P = 0.003). ROC curve was plotted for the absolute value of TST in mm considering IGRA as the gold standard. The area under the curve was 0.805 (95%CI: 0.655–0.954). For the TST positivity cut-off of 10 and 15 mm, specificity was 77.3% and 95.5%, respectively; the sensitivity was 68.8% irrespective of the cut-off value.Limitation:Small sample size and lack of follow-up are the biggest limitations of the study. The lack of a gold standard in the diagnosis of LTBI is an inherent yet unavoidable flaw in the study.Conclusion:Reactivation of LTBI is a concern in a patient planned for immunosuppressive therapy. We suggest the use of both TST and IGRA rather than two-step testing (TST followed by IGRA) or IGRA alone for the diagnosis of LTBI, especially in patients with a high risk of reactivation. The positivity on either test should prompt further evaluation and treatment decisions should be taken considering the risk-benefit ratio of treatment rather than test results alone.

Isoniazid treatment in children and comparison of tuberculin skin test values before and after treatment

Isoniazid treatment in children and comparison of tuberculin skin test values before and after treatment

Prognostic value of interferon-γ release assays and tuberculin skin test in predicting the development of active tuberculosis (UK PREDICT TB): a prospective cohort study

SummaryBackgroundTackling tuberculosis requires testing and treatment of latent tuberculosis in high-risk groups. The aim of this study was to estimate the predictive values of the tuberculin skin test (TST) and two interferon-γ release assays (IGRAs) for the development of active tuberculosis in high-risk groups—ie, people in recent contact with active tuberculosis cases and from high-burden countries.MethodIn this prospective cohort study, we recruited participants from 54 centres (eg, clinics, community settings) in London, Birmingham, and Leicester in the UK. Participants were eligible if they were aged 16 years or older and at high risk for latent tuberculosis infection (ie, recent contact with someone with active tuberculosis [contacts] or a migrant who had arrived in the UK in the past 5 years from—or who frequently travelled to—a country with a high burden of tuberculosis [migrants]). Exclusion criteria included prevalent cases of tuberculosis, and participants who were treated for latent tuberculosis after a positive test result in this study. Each participant received three tests (QuantiFERON-TB Gold-In Tube, T-SPOT.TB, and a Mantoux TST). A positive TST result was reported using three thresholds: 5 mm (TST-5), 10 mm (TST-10), and greater than 5 mm in BCG-naive or 15 mm in BCG-vaccinated (TST-15) participants. Participants were followed up from recruitment to development of tuberculosis or censoring. Incident tuberculosis cases were identified by national tuberculosis databases, telephone interview, and review of medical notes. Our primary objective was to estimate the prognostic value of IGRAs compared with TST, assessed by the ratio of incidence rate ratios and predictive values for tuberculosis development. The study was registered with ClinicalTrials.gov, NCT01162265, and is now complete.FindingsBetween May 4, 2010, and June 1, 2015, 10 045 people were recruited, of whom 9610 were eligible for inclusion. Of this cohort, 4861 (50·6%) were contacts and 4749 (49·4%) were migrants. Participants were followed up for a median of 2·9 years (range 21 days to 5·9 years). 97 (1·0%) of 9610 participants developed active tuberculosis (77 [1·2%] of 6380 with results for all three tests). In all tests, annual incidence of tuberculosis was very low in those who tested negatively (ranging from 1·2 per 1000 person-years, 95% CI 0·6–2·0 for TST-5 to 1·9 per 1000 person-years, 95% CI 1·3–2·7, for QuantiFERON-TB Gold In-Tube). Annual incidence in participants who tested positively were highest for T-SPOT.TB (13·2 per 1000 person-years, 95% CI 9·9–17·4), TST-15 (11·1 per 1000 person-years, 8·3–14·6), and QuantiFERON-TB Gold In-Tube (10·1 per 1000 person-years, 7·4–13·4). Positive results for these tests were significantly better predictors of progression than TST-10 and TST-5 (eg, ratio of test positivity rates in those progressing to tuberculosis compared with those not progressing T-SPOT.TB vs TST-5: 1·99, 95% CI 1·68–2·34; p<0·0001). However, TST-5 identified a higher proportion of participants who progressed to active tuberculosis (64 [83%] of 77 tested) than all other tests and TST thresholds (≤75%).InterpretationIGRA-based or BCG-stratified TST strategies appear most suited to screening for potential disease progression among high-risk groups. Further work will be needed to assess country-specific cost-effectiveness of each screening test, and in the absence of highly specific diagnostic tests, cheap non-toxic treatments need to be developed that could be given to larger groups of people at potential risk.FundingNational Institute for Health Research Health Technology Assessment Programme 08-68-01.

Evaluation of Treatment Indications, Tuberculin Skin Test, and Bacillus Calmette-Guerin Vaccination Scars in the Cases of Latent Tuberculosis Infection Treatment

The aim of our study was to evaluate the latent tuberculosis infection (LTBI) treatment application and to investigate if there is change between tuberculin skin test (TST) results according to bacillus Calmette-Guerin (BCG) scar numbers after LTBI treatment with isoniazid (INH). Data were collected from the LTBI treatment files from the dispensary of 2006. The results were statistically evaluated. Latent tuberculosis infection was administered to 253 cases in 2006. The male/female case rate was 51/49. The age of most patients was under 15 years out of 14 cases. The mean age was 8.92±6.87 years (range, 0-84 years). One case had liver function test abnormality and INH was stopped in the first month of treatment. The completion rate of LTBI treatment was 95%. BCG vaccination rate was 93%. Active tuberculosis did not develop during the LTBI treatment in our study. Of all the cases, 221 scar numbers and TST were full. Of all cases 221 the scar numbers and TST value were full.TST of the 221 cases according to BCG vaccine scar numbers and indications were compared pre- and post-treatment with INH. Indications for LTBI treatment in these cases were close contact with smear-positive active pulmonary tuberculosis cases (n=77, 35%), TST-positive children aged <15 years (n=138, 62%), and the other (n=6, 3%) immunosuppressed patient cases. After treatment with INH, TST values decreased in the TST-positive children aged <15 years with one and 2 scars, with a statistically significant this result were found statistically significant (p<0.05). The age of patients in most cases with LTBI treatment was under 15 years. The treatment completion rate and BCG vaccination rate were high. One case had liver function test abnormality. Active tuberculosis did not develop during the LTBI treatment. In the group with TST-positive children aged <15 years with one and 2 BCG vaccine scars, the decrease between pre- and post-treatment TST results showed a statistically significant difference.

Household tuberculosis contact investigation in a tuberculosis-prevalent country: Are the tuberculin skin test and interferon-gamma release assay enough in elderly contacts?

The high background rates of positive results on the tuberculin skin test (TST) and interferon-gamma release assay (IGRA) sometimes confuse the investigation of tuberculosis (TB) contact in TB-prevalent countries, particularly in elderly contacts. The aim was to investigate the predictive value of TST and IGRA for diagnosing latent TB infection (LTBI) in elderly household contacts in South Korea.In this retrospective study, TST and IGRA results of household contacts of suspected pulmonary TB patients were reviewed according to the index patient's final diagnosis (TB group: culture-confirmed pulmonary TB, non-TB group: pulmonary disease other than TB).A total of 249 contacts were included in the analysis (188 in the TB group and 61 in the non-TB group). In the TB group, TST and IGRA were positive in 42.6% and 45.7% of contacts, respectively. In the non-TB group, TST and IGRA were positive in 32.8% and 23.0% of contacts, respectively. TST did not show any differences between the TB and non-TB groups for any age group, whereas IGRA showed differences between the 2 groups for those ages 18 to 39 and 40 to 59 years. However, there were no significant differences between the groups for the ≥60 years old group.In elderly contacts, neither TST nor IGRA showed clear discrimination of positivity between the groups. Further studies are needed to predict which elderly contacts are at risk for progression to active TB as well as to accurately detect recent Mycobacterium tuberculosis infection in this vulnerable population.

Prevalence and Diagnosis of Latent Tuberculosis Infection in Young Children in the Absence of a Gold Standard.

IntroductionFor adequate disease control the World Health Organization has proposed the diagnosis and treatment of latent tuberculous infection (LTBI) in groups of risk of developing the disease such as children. There is no gold standard (GS) test for the diagnosis of LTBI. The objective of this study was to estimate the prevalence of LTBI in young children in contact with a household case of tuberculosis (TB-HCC) and determine the accuracy and precision of the Tuberculin Skin Test (TST) and QuantiFERON-TB Gold in-tube (QFT) used in the absence of a GS.MethodsWe conducted a cross-sectional study in children up to 6 years of age in Manaus/Brazil during the years 2009–2010. All the children had been vaccinated with the BCG and were classified into two groups according to the presence of a TB-HCC or no known contact with tuberculosis (TB). The variables studied were: the TST and QFT results and the intensity and length of exposure to the index tuberculosis case. We used the latent class model to determine the prevalence of LTBI and the accuracy of the tests.ResultsFifty percent of the children with TB-HCC had LTBI, with the prevalence depending on the intensity and length of exposure to the index case. The sensitivity and specificity of TST were 73% [95% confidence interval (CI): 53–91] and 97% (95%CI: 89–100), respectively, versus 53% (95%CI: 41–66) and 81% (95%CI:71–90) for QFT. The positive predictive value of TST in children with TB-HCC was 91% (95%CI: 61–99), being 74% for QFT (95%CI: 47–95).ConclusionsThis is one of the first studies to estimate the prevalence of LTBI in children and the parameters of the main diagnostic tests using a latent class model. Our results suggest that children in contact with an index case have a high risk of infection. The accuracy and the predictive value of the two tests did not significantly differ. Combined use of the two tests showed scarce improvement in the diagnosis of LTBI.

Mycobacterium tuberculosis-specific CD4 T cells are the principal source of IFN-γ in QuantiFERON assays in healthy persons

More than two billion people are estimated to be infected with the etiological agent of tuberculosis (TB) disease, Mycobacterium tuberculosis (M.tb). The tuberculin skin test (TST) has traditionally been used to identify people with M.tb infection, some of whom may develop TB disease. Isoniazid preventive therapy (IPT) reduces this risk markedly, especially in individuals with a positive tuberculin skin test (TST) [1]. However, vaccination with Bacille Calmette-Gu erin (BCG) may result in a positive TST and the predictive value of TST for incident TB disease is poor. Blood-based interferong release assays (IGRAs), such as QuantiFERON TB Gold In-Tube (QFT, Cellestis, Carnegie, Australia) and T-SPOT.TB (Oxford Immunotec, Oxford, UK), provide alternative tests for M.tb infection. These tests measure sensitization to the region of difference-1 (RD1) antigens, ESAT-6 and CFP-10, and are therefore not affected by BCG vaccination. The QFT assay has been used extensively in TB endemic and non-endemic countries [1], and detects soluble levels of IFN-g after whole blood culture with ESAT-6, CFP-10 and a peptide from TB7.7.

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

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

Tuberculin skin test versus interferon-gamma release assays for the diagnosis of tuberculosis infection

Objective:Accurate detection of latent tuberculosis infection (LTBI) is becoming increasingly important due to the increasing use of immunosuppressive medications and the human immunodeficiency epidemic, which have increased the risk for reactivation to active tuberculosis (TB) infection. LTBI is detected by tuberculin skin test (TST) and interferon-gamma release assays (IGRAs). The latter include T-SPOT®.TB (Oxford Immunotec) and QuantiFERON®-TB Gold In-Tube (QFT-GIT; Cellestis). We examined the value of TST versus IGRAs in the diagnosis of TB infection by meta-analysis based on data derived from a systematic literature review.Methods:PubMed was searched for articles in English published between January 2010 and July 2012 in which TST and IGRA were performed simultaneously in individuals with and without active TB infection. A random effect model meta-analysis was performed to determine pooled sensitivity and specificity values for TST, T-SPOT.TB, and QFT-GIT. Owing to the absence of a gold standard for the diagnosis of LTBI, active TB infection was used as a surrogate for LTBI.Results:Nineteen studies were included. T-SPOT.TB was significantly more sensitive [90% (95% confidence interval: 85–95) versus 64% (46–81)] than TST. The specificity of T-SPOT.TB was higher than the specificity of TST, but there was overlap between confidence intervals [77% (68–85) versus 57% (41–72)]. QFT-GIT seemed to be more sensitive than TST [75% (61–86) versus 64% (48–78)] but similarly specific [71% (62–86) versus 70% (57–81)].Conclusions:IGRAs, especially T-SPOT.TB, are more effective at detecting TB infection than TST. Despite their higher cost, they have added value and can be requested in addition to TST.

Tuberculin skin test and interferon-gamma release assay values are associated with antimicrobial peptides expression in polymorphonuclear cells during latent tuberculous infection.

It has been reported that patients with progressive tuberculosis (TB) express abundant amounts of the antimicrobial peptides (AMPs) cathelicidin (LL-37) and human neutrophil peptide-1 (HNP-1) in circulating cells, whereas latent TB infected donors showed no differences when compared with purified protein derivative (PPD) and QuantiFERON®-TB Gold (QFT)-healthy individuals. The aim of this study was to determine whether LL-37 and HNP-1 production correlates with higher tuberculin skin test (TST) and QFT values in TB household contacts. Twenty-six TB household contact individuals between 26-58 years old TST and QFT positive with at last two years of latent TB infection were recruited. AMPs production by polymorphonuclear cells was determined by flow cytometry and correlation between TST and QFT values was analysed. Our results showed that there is a positive correlation between levels of HNP-1 and LL-37 production with reactivity to TST and/or QFT levels. This preliminary study suggests the potential use of the expression levels of these peptides as biomarkers for progression in latent infected individuals.

SAT0154 Screening Latent Tuberculosis Infection with Tuberculin Skin Test and Quantiferon-Tb Gold Test in Patients with BehÇEt’S Disease and Takayasu’S Arteritis

BackgroundTumor Necrosis Factor-α (TNF-α) inhibitors have increased risk of reactivation of latent tuberculosis infection (LTBI). Screening for LTBI before initiating anti-TNF therapy is recommended.(1) Tuberculin skin test (TST) and in...

Negative predictive value of TST and IGRA in anti-TNF treated patients

To the Editors: Anti-tumour necrosis factor (TNF) therapy is increasingly used in chronic inflammatory diseases. These agents are related to an increased risk of tuberculosis (TB) depending on the clinical setting and the anti-TNF agent used, so screening is mandatory before its start [1]. Inhibition of TNF-α and TNF-regulated chemokine networks is the presumed biological basis [2]. Though patients with chronic inflammatory diseases and suspected latent TB infection (LTBI) who are candidates for anti-TNF therapy are at higher risk of TB reactivation, they are prone to false-negative tuberculin skin test (TST) and interferon-γ release assay (IGRA) results due to T-cell hyporesponsiveness, either because of illness or immunosuppressive medications [3]. The reliability of these tests in this population is therefore of interest, but currently unclear. The negative predictive value (NPV) of TST and IGRA is still not defined in this group of patients. National guidelines for diagnosis and treatment of LTBI require screening of any candidate on anti-TNF therapy, prior to starting it, through assessment of …

Tuberculin reactivity in bacille calmette-guerin vaccinated individuals with sputum positive pulmonary tuberculosis

The study was carried out to assess the value of tuberculin skin test for the diagnosis of Tuberculosis (TB) in BCG vaccinated individuals and to find out the sensitivity rate of tuberculin skin test (TST) in comparison to acid fast bacilli positive pulmonary TB. Similar population with high BCG vaccination coverage having both pulmonary TB patients (n=150) and apparently healthy individuals (n=150) in eastern Nepal were enrolled in this comparative study. Sputum from all the subjects was subjected to Z-N microscopy. TST was performed on these subjects by standard Mantoux method. Among the patients (mean age 36.18±14.15 yrs) and controls (mean age 35.61±13.44 yrs), 55.33 % and 47.33 % respectively have been found to be positive PPD reactors (&gt;10mm) which is statistically not significant (P&gt;0.05). About 23% of the patients &amp; 27% of controls failed to react (anergic) to 5 TU PPD. PPD reactivity rate was high in the patients whose sputum smears were graded as 1+ in Z-N microscopy. The sensitivity of TST was highest for the induration of &gt;5mm (77.3%). Specificity increased with increasing size of induration and was highest (73.3%) with induration of &gt;15 mm. Tuberculin skin test is an all or none phenomenon. In Nepal, tuberculin test has a limited value in the diagnosis of pulmonary TB as both the apparently healthy individuals and patients with sputum smear positive pulmonary TB who had been immunized with BCG, showed almost similar rate of tuberculin reactivity. DOI: http://dx.doi.org/10.3126/jcmsn.v7i1.5970 JCMSN 2011; 7(1): 28-35

The clinical utility of tuberculin skin test and interferon-γ release assay in the diagnosis of active tuberculosis among young adults: a prospective observational study

BackgroundThe roles of the tuberculin skin test (TST) and QuantiFERON®-TB Gold In-Tube assay (QFT-IT) in the diagnosis of active tuberculosis (TB) are not clear in young adults. We evaluated the diagnostic accuracy of the TST and QFT-IT in smear-negative TB among young adults with no underlying disease.MethodsWe prospectively enrolled 166 young participants 20-29 years of age with suspected active TB in a military hospital of South Korea. The TST and QFT-IT were performed for all participants.ResultsOf the 143 patients included in the analysis, active TB was diagnosed in 100 (69.9%). There were 141 male patients, none of whom had immunosuppressive disease. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TST were 94% (95% CI, 87-98%), 88% (95% CI, 74-96%), 95% (95% CI, 88-98%), and 86% (95% CI, 72-94%), respectively. The sensitivity, specificity, PPV, and NPV of the QFT-IT were 93% (95% CI, 86-97%), 95% (95% CI, 81-99%), 98% (95% CI, 92-99%), and 84% (95% CI, 69-93%), respectively. No significant differences were found between the TST and QFT-IT in any statistic.ConclusionsBoth the TST and QFT-IT showed high sensitivity and specificity in differentiating active TB from other diseases. The diagnostic accuracy of these two tests did not differ significantly when applied to this clinical population of young, immunocompetent adults in whom neonatal BCG vaccination was common, there was no history of previous TB and in whom suspicion of TB was high.Trial registrationClinicalTrials.gov: NCT00982969

A T-cell-based enzyme-linked immunospot assay for tuberculosis screening in Chinese patients with rheumatic diseases receiving infliximab therapy

Anti-tumour necrosis factor-α (TNF-α) therapy brought new hopes for treating rheumatic diseases but also increased the risk of infection, including mycobacterium tuberculosis (MTb). Conventional screening tools, such as tuberculin skin test (TST), lack sensitivity or specificity. Recently, T-SPOT.TB has been introduced to detect tuberculosis infection. Reports have proved its superior performance in detecting tuberculosis infection in various patient populations than the TST. To compare the value of a T-cell-based enzyme-linked immunospot assay (ELISPOT) T-SPOT.TB and conventional (TST) in screening and monitoring tuberculosis in patients with rheumatic diseases during infliximab therapy in China. Fifty-eight patients with various rheumatic diseases who received infliximab therapy were enrolled in the trial. Freshly isolated peripheral blood mononuclear cells were stimulated with MTb-specific antigens (ESAT-6 and CFP10), and IFN-γ-producing cells were counted. TST was performed with 1 TU PPD injected intradermally into the volar aspect of forearm. A cutaneous induration with diameter ≥5mm was considered as positive TST, and an increment≥5mm of cutaneous induration was considered as TST conversion. TST and T-SPOT.TB test were carried out at baseline and repeated 12months after infliximab therapy (if no active TB occurs) or at times when TB occurred. Moreover, all patients were initially evaluated for latent tuberculosis infection (LTBI) with clinical examination and chest radiograph. The McNemar test was used for TST and T-SPOT.TB concordance analysis. Cohen's kappa coefficient was used to assess strength of the agreement. Among the 58 patients evaluated, 25 (43.1%) had ankylosing spondylitis, 24 (41.4%) had rheumatoid arthritis, 4 (6.9%) had undifferentiated spondyloarthropathy, 3 (5.2%) had psoriatic arthritis and 2 (3.4%) had reactive arthritis. A total of 52 patients (89.7%) had previously received vaccination with Bacille Calmette-Guerin. All of the patients received either single or combination of disease modifying anti-rheumatic drug (DMARDs) therapy, and 16 (27.4%) had previously or presently received glucocorticoid therapy. Before infliximab therapy, 12 patients (20.7%) had positive and 46 (79.3%) had negative TST results, and only 1 (1.7%) had positive T-SPOT.TB. Among 51 patients completing the repeated TST and T-SPOT.TB assay, 7 patients (13.7%) had TST conversion and 4 (7.8%) had positive T-SPOT.TB results. Of 7 patients with TST conversion, 2 patients (28.6%) developed active TB and also had positive T-SPOT.TB results; of 44 patients with no TST conversion, 2 patients (4.5%) had positive T-SPOT.TB and 1 (2.3%) had active TB. If 5mm was used as the cut-off value of TST, TST and T-SPOT.TB, had an agreement value of 68.6% with a kappa value of 0.166. If 10mm was used as the cut-off value, the agreement between TST and T-SPOT.TB was 88.2% with a kappa value of 0.338. T-SPOT.TB was more specific than TST in detecting tuberculosis during infliximab therapy in China with high BCG vaccination and high prevalence of TB. It can be used as a reliable tool for TB monitoring during infliximab therapy in Chinese patients with rheumatic diseases. Finally, it is recommended to repeat the TST and T-SPOT.TB periodically during biological treatment.

Assessment of latent tuberculosis infection in Takayasu arteritis with tuberculin skin test and Quantiferon-TB Gold test

A possible relationship between Takayasu arteritis (TA) and tuberculosis (TB) has been suggested. An increased frequency of tuberculin skin test (TST) was observed in TA patients. Quantiferon-TB Gold test (QFT) is a new in vitro assay measuring interferon-gamma response to M. tuberculosis antigens and helpful in diagnosing latent TB infection. The aim of this study was to investigate latent TB infection among TA patients by the use of both TST and QFT Gold test. Ninety-four (male/female: 7/87) TA patients fulfilling ACR 1990 TA criteria from three different university hospitals in Turkey and 107 control subjects without inflammatory diseases were included in the study. Data about medical history (TA and TB) were collected for both groups. TST and QFT were performed. TST values > or =5 mm for TA patients and > or =15 mm for controls was accepted as TST positivity. Even though TA group was older (40 +/- 12 vs. 32 +/- 8, P < 0.001), there was no significant difference between TA patients and controls regarding demographic characteristics. Six TA patients and one control had a history of previous TB infection (P = 0.054). Although TST positivity was higher in TA group [55 patients (62.5%) vs. 24 controls (41.4%), P = 0.008], QFT positivity was similar between two groups [21 patients (22.3%) vs. 24 controls (22.4%), P > 0.05]. QFT was negative in two of six TA patients with previous TB history. Rate of latent TB infection in TA patients measured with QFT is no more than controls. QFT seems to be a good and favorable test compared with TST in detecting LTBI in TA.

Otopsi Çalışanlarında Tüberkülin Deri Testi ve Tüberküloz Riski

Objective: Tuberculosis (TB) is a disease that arises due to M. tuberculosis complex and usually involves the lungs but can also affect other organs or organ systems. The number of people who died in Turkey was 210146 in 2006 and 0.11% (n=249) of them died because of pulmonary tuberculosis. During autopsy, many microparticles (aerosols) can be generated while taking the organ out of the body, washing the body, or using the oscillating saw. If these aerosols may contain bacilli that can easily infect the health workers. Tuberculin skin test (TST) determines delayed type hypersensitivity reactions to some antigenic components of microorganism. The only sign of latent tuberculosis infection is positive TST. In our study, we aimed to calculate the exposure rate of the autopsy workers to TB bacillus by evaluating TST measurements and chest radiograms. Material and Methods: The study group was composed of 25 physicians and five autopsy technicians. The control group was composed of 30 physicians, residents and specialists of basic medical sciences except of Microbiology. Both groups were evaluated by TST and chest X-rays from TB point of view. We used TST reaction evaluation criteria that was suggested by Ministry of Health of Republic of Turkey while evaluating TST measurements. All measurements were analyzed statistically. Results: TST positivity ratio is determined as 83.3% in the study group and 33.3% in the control group. The mean of TST measurement value is determined as 13.8±4.7 mm in the study group and 8.6±2.2 mm in the control group. There were no statistically significant differences between two groups concerning age, height, marital status, occupational experience or smoking habits (p>0.05). There was a statistically significant difference between study and control groups for the TST values were (F=11.786; p=0.001). There were no statistically significant differences for gender, smoking and interaction between gender-group and smoking-group (p>0.05). Established ANOVA model (univariate ANOVA); explained the =0.903 of TST change and it was statistically significant (F=71.159; p<0.001). There was a statistically significant correlation between TST results and time spent in the autopsy room (r=0.553; p=0.002). Conclusion: Our study shows that autopsy workers have a high risk of TB exposure. We suggest that autopsy workers should be examined for occupational TB exposure. Furthermore, morgue buildings and autopsy rooms of our country should be designed in accordance with the international standards, and measures should be taken in this regard without delay.

Vergleich von Tuberkulin-Hauttests und Interferon-Gamma-Tests im Rahmen einer Umgebungsuntersuchung in einer JVA

After the occurrence of a multidrug-resistant tuberculosis in a prison of Lower Saxony (Germany), 223 contact persons (178 inmates, 45 staff members) were identified. To detect latent tuberculosis infections, all contact persons were tested with the tuberculin skin test (TST) and the interferon-gamma release assay (IGRA). An additional standardised questionnaire on anamnestic information and risk factors was completed by the participants. The statistical analysis included 149 male inmates with a mean age of 39 years. 61.1% of the inmates were born in Germany, 14.8% were born in the USSR or, respectively, its follow-up states. With the TST 29.5% of the inmates were tested positive, whereas with the IGRA the positive rate was 18.1%. For 7 inmates there was a positive IGRA despite a negative TST. The positive predictive value of TST with respect to IGRA was 45.5%, agreement was 79.2% (kappa=0.44). The agreement found in this study is comparable to studies within populations with lower incidence. Numerous investigations outside Europe indicate a high risk of tuberculosis infection among inmates.

Value of the Tuberculin Skin Test in Screening for Tuberculosis in Dialysis Patients

Background Hemodialysis patients are at high risk for tuberculosis, and a tuberculin skin test (TST) is not usually helpful in detecting tuberculosis infection because of anergic reactions. Prophylactic therapy against tuberculosis in dialysis patients is important to enhance transplantation success. Herein we evaluated the value of TST in screening for tuberculosis and analyzed any compounding factors that might affect the results of the test in hemodialysis patients in an endemic area of Turkey. Methods A total of 187 (96 female, 91 male) patients were screened using a 2-step TST. Test results were compared with clinical, radiologic, and laboratory data. Results None of the patients had active tuberculosis during the study and 55% had been vaccinated against tuberculosis. After the first purified protein derivative (PPD) test, 55.1% of the patients showed a positive reaction, ultimately reaching a total of 68.4% following the second test. Cumulative positive TST results were significantly correlated with male gender ( P = .001, r = .352), previous tuberculosis history ( P = .013, r = .183) positively, whereas with the ferritin level ( P = .001, r = −.233) negatively; but there were no significant relationships between TST results and other data. Conclusions Impairment of delayed-type hypersensitivity reaction is frequent in dialysis patients, but we observed high rates of positivity with the two-step TST which could be attributed to tuberculosis being endemic in Turkey. Further comparative studies with more specific diagnostic methods will be helpful to evalute the importance of TST positivity in identifying tuberculosis-infected HD patients.