Sensitivity Of Tuberculin Skin Test Research Articles

Selection of the cutoff value of the tuberculin skin test for diagnosing students who need preventive treatment: A school-based cross-sectional study

ObjectiveTuberculosis outbreaks in schools are common in China. This study aimed to introduce and evaluate a new screening process to help control outbreaks.MethodsScreening information of students in three schools with tuberculosis outbreaks was collected. QuantiFERON-TB gold in-tube (QFT) results were used as the reference standard to determine the cutoff value of the tuberculin skin test (TST) for diagnosing students who need to have preventive medication.ResultsA total of 1,232 students and teachers from three different schools that all had more than three student patients with tuberculosis were included in this study. In total, 308 (25.0%) students had an induration diameter ≥10 mm; among students in a class different from the index case, the infection rate was 24.4% (264/1,084), which was lower than the rate among students in the same class (29.7%) (P = 0.157). Students in the same class as the index tuberculosis case had a much higher QFT positivity compared to those in a different class (58.1% vs. 7.7%, P < 0.0001). Diagnostic agreement between TST ≥10 mm and QFT was 36.6%. The diagnostic value reached the highest when the induration diameter of TST was ≥9 mm, with a sensitivity and specificity of 94.1% (95% CI: 89.4%–97.1%) and 27.6% (95% CI: 24.9%–30.4%), respectively. The area under the curve (AUC) was 0.664 (95% CI: 0.637–0.690, P < 0.0001).ConclusionIn tuberculosis outbreaks in schools, if there are three or more cases of students with tuberculosis in a class or if the moderate or strong TST positivity rate is much higher than the normal range in the region, attention should be paid to those with moderately positive TST results. Interferon-gamma release assays (IGRAs) are recommended to be conducted following TST on the day of reading the results, especially among students sharing the same class with the index case. In resource-poor areas lacking IGRAs, the induration diameter of TST can be appropriately reduced from 15 to 9 mm to enhance the sensitivity of TST.

What Tool for Diagnosis of Latent Tuberculosis Infection in Developing Country with Tuberculosis High Burden: Interferon Gamma Release Assays &amp;lt;i&amp;gt;versus&amp;lt;/i&amp;gt; Tuberculin Skin Test in Burkina Faso

Background: The diagnosis and treatment of active tuberculosis and the detection/management of latent tuberculosis infection (LTBI) cases are the two main strategies for the TB control, particularly in endemic countries. Tuberculin skin test (TST) and Interferon Gamma Release Assays (IGRAs) are tools for detection of LTBI. The objective of this study was to evaluate the performance of the TST and QuantiFERON-TB Gold Plus® (QTF-Plus) and to identify a threshold for TST in best agreement with QTF-Plus for LTBI detection in a high TB burden setting. Methods: In July 2020, a cross-sectional analytical study was performed for QFT-Plus using blood samples and TST in 101 individuals with a high risk of TB living in Bobo-Dioulasso, Burkina Faso. A crude comparison between both tests was done and receiver operating characteristic curve was generated to determine TST’s threshold. TST sensitivity, specificity, predictive values and accuracy were calculated. Adjusted agreement between TST and QFT-Plus was evaluated. Results: With the minimum threshold of positivity set at 5 mm for TST, the overall agreement between the latter and QFT-Plus was poor with a Kappa coefficient (κ) rated at 0.319 (95% CI: 0.131 - 0.508). This cut-off yielded a sensitivity of 94.12% (95% CI: 88.53 - 99.71), and very poor specificity of 36.4% (95% IC: 25.0 - 47.80). However, an adjusted cut-off set at 11 mm gave a better specificity of 72.73% (95% CI: 62.1 - 83.30) of TST and improved the PPV (86%). Moreover, concordance between both tests was improved with κ at 0.56 (95% CI: 0.385 - 0.728) and 80.20% of accuracy. Factors associated with discordance between TST (11 mm) and QFT-Plus results were BCG vaccination, OR = 7.53 (95% CI: 1.43 - 139.25), p = 0.05 and chronic cough, OR = 5.07 (95% CI: 1.27 - 20.43), p = 0.01. Conclusions: This study showed that using a minimal cut-off of 11mm for TST significantly improved the concordance between QTF-Plus (IGRA) and TST. Using the cut-off TST of 11 mm would be ideal in low-income countries with a high TB burden, taking into account factors that could contribute to the discrepancy of results.

Interpretation of tuberculin skin test in bacillus calmette–guerin-vaccinated children

Objective: The objective was to determine the sensitivity and specificity of tuberculin skin test (TST) in Bacillus Calmette–Guerin (BCG)-vaccinated children for diagnosis of tuberculosis (TB). Materials and Methods: This observational study was conducted at a single tertiary care center over a period of 32 months from March 2012 to November 2014. All children up to 15 years of age who had received BCG at birth, suspected of TB, and referred to pediatric TB clinic were enrolled in the study. All patients were given TST by 5 Tuberculin Unit Purified Protein Derivative-Standard. The diagnosis of TB was based on either clinical, histopathological, or bacteriological grounds. Results: Out of 371 patients, 341 (91.91%) had TB. TST was positive in 227 (61.2%) and negative in 144 (38.8%) patients. The sensitivity of TST to detect active TB was 62.8% and specificity was 56.7%. TST cutoff as ≥15 mm increased specificity of TST to 73.3%, but sensitivity decreased to 25.8%. Age, gender, and contact with TB patients did not affect TST results. Conclusion: The accuracy of TST for the diagnosis of TB is low with low sensitivity and specificity. By increasing the cutoff for positive TST to >15 mm, the number of false-positive TST can be reduced.

Tuberculin skin test and predictive host factors for false-negative results in patients with pulmonary and extrapulmonary tuberculosis.

Tuberculin skin test (TST) has been the standard test for screening for Mycobacterium tuberculosis infection for decades. Identifying persons with latent tuberculosis infection (LTBI) is crucial, as they constitute a reservoir that sustains the global tuberculosis (TB) epidemic. However, different factors, such as HIV infection, can lower the sensitivity of the test. The aim of this study was to determine the TST sensitivity in active TB patients and to ascertain risk factors that could be associated with false-negative results. Retrospective cohort study of all active TB notifications with a TST result (n=8833), from 2008 to 2015. TST results were interpreted using a 5mm and 10mm cutoff. Bivariate and multivariate logistic regression analysis were used to evaluate the association of sociodemographic and clinical factors with false-negative TST results and to develop predictive risk models. TST presented an overall sensitivity of 63.8% (5mm) and 56.1% (10mm). HIV infection was the risk factor with the strongest association with false-negative results (aOR 4.65-5mm; aOR 5.05-10mm). Other factors such as chronic renal failure (CRF) (aOR 1.55-5mm; aOR 1.73-10mm), alcohol abuse (aOR 1.52-5mm; aOR 1.31-10mm), drug abuse (aOR 1.90-5mm; aOR 1.76-10mm) or age ≥65years (OR 1.69-5mm and 10mm) were also associated with a probability of false-negative results. These results highlight the importance of knowing which factors influence TST results, such as HIV status, substance abuse or age, thus improving its usefulness as a screening method for LTBI.

Evaluation of QuantiFERON tuberculosis Gold In-Tube assay for diagnosis of active tuberculosis in children.

Tuberculin skin test (TST) is still used in diagnostic algorithms of childhood tuberculosis (TB). QuantiFERON TB Gold In-Tube assay (QFT-GIT) is an alternative test to TST based on the detection of interferon-gamma release upon in vitro induction of peripheral mononuclear cells by TB antigens. In this study, we aimed to determine the diagnostic value and performance of QFT-GIT for active childhood TB. This retrospective study was conducted between January 2005 and December 2011 in three referral hospitals in Turkey with 124 children who were diagnosed with definite active TB. Sensitivity values of TST and QFT-GIT were determined by accepting the microbiological confirmation as the gold standard of diagnosis of TB. In our study, sensitivity of QFT-GIT and TST was found to be 65 and 66% respectively. However, combined usage of QFT-GIT and TST was found to be more sensitive (85%) than TST or QFT-GIT alone (P < 0.0001). Although negative results of QFT-GIT or TST did not exclude the diagnosis of active TB in children, their positivity supported the diagnosis. Specificity could not be measured as only microbiologically confirmed cases of Mycobacterium tuberculosis disease were enrolled in the study. Although sensitivities of TST and QFT-GIT are too low to exclude active TB, their positivity supports diagnosis of active TB in children concomitant with signs and symptoms. QFT-GIT and TST should be used together to enhance diagnostic sensitivity and could help exclude a diagnosis of TB if the pretest probability is low.

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

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

Tuberculin skin test and QuantiFERON-Gold In Tube assay for diagnosis of latent TB infection among household contacts of pulmonary TB patients in high TB burden setting.

BackgroundWorld Health Organization (WHO) recommends systematic screening of high-risk populations, including household contacts (HHCs) of adult pulmonary tuberculosis (TB) patients, as a key strategy for elimination of TB. QuantiFERON-TB Gold In-Tube (QFT-GIT) assay and tuberculin skin test (TST) are two commonly used tools for the detection of latent tuberculosis infection (LTBI) but may yield differential results, affecting eligibility for TB preventive therapy.Materials and methodsA prospective cohort study of adult pulmonary TB patients and their HHCs were recruited in 2 cities of India, Pune and Chennai. HHCs underwent QFT-GIT (QIAGEN) and TST (PPD SPAN 2TU/5TU). A positive QFT-GIT was defined as value ≥0.35 IU/ml and a positive TST as an induration of ≥5 mm. A secondary outcome of TST induration ≥10mm was explored. Proportion positive by either or both assays, discordant positives and negatives were calculated; test concordance was assessed using percentage agreement and kappa statistics; and risk factors for concordance and discordance including age categories were assessed using logistic regression. Sensitivity and specificity was estimated by latent class model.ResultsOf 1048 HHCs enrolled, 869 [median (IQR) age: 27 years (15–40)] had both TST and QFT-GIT results available and prevalence of LTBI by QFT-GIT was 54% [95% CI (51, 57)], by TST was 55% [95% CI (52, 58)], by either test was 74% [95% CI (71, 77) and by both tests was 35% [95% CI (31, 38)]. Discordance of TST+/QFT-GIT- was 21% while TST-/QFT-GIT+ was 26%. Poor to fair agreement occurred with TST 5mm or 10mm cutoff (60 and 61% agreement with kappa value of 0.20 and 0.25 respectively). Test agreement varied by age, TST strength and induration cut-off. In multivariate analysis, span PPD was a risk factor for QFT-GIT+ and TST- while absence of BCG scar was for TST+ and QFT-GIT-. Being employed and exposure to TB case outside the household case were associated with positivity by both the tests. Sensitivity of TST and QFT-GIT to diagnose LTBI was 77% and 69%. Probability of having LTBI was >90% when both tests were positive irrespective of exposure gradient.ConclusionPrevalence of LTBI among HHCs of adult pulmonary TB patients in India is very high and varies by test type, age, and exposure gradient. In our high TB burden setting, a strategy to treat all HHCs or a targeted strategy whereby an exposure index is used should be assessed in future preventive therapy and vaccine studies as HHCs have several factors that place them at high risk for progression to TB disease.

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

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

Comparison of the Quantiferon tb gold assay and tuberculin skin test to detect tuberculosis infection among tuberculosis patient contact

Introduction: Tuberculosis is a communicable disease and therefore TB patient contacts are at higher risk of developing TB infection. So screening and diagnosis of latent TB is done by QFT Gold assay and Tuberculin skin test (TST). Methodology: A total of 100 TB patient contacts were taken for study, blood was drawn and processed by using the QFT G assay followed by immediate administration of TST solution in subjects forearm. Data were analyzed and results were compared. Results: QFT G assay detect LTBI with sensitivity of 88.88% and specificity of 90%. TST Sensitivity 68%, Specificity 16%. Conclusions: QFT G Assay have higher detection rate among TB contact patient. Keywords: QFT G quantiferon TB Gold, LTBI- Latent tuberculosis infection, TST – Tuberculin skin test

Evaluation of QuantiFERON®-TB Gold in Tube Test and Tuberculin Skin Test in the Diagnosis of Mycobacterium tuberculosis Infection

The aims of this study were to evaluate the sensitivity of QuantiFERON®-TB Gold in Tube (QFT) test and its agreement with the tuberculin skin test (TST), to investigate possible factors associated with indeterminate QFT test results and to explore the relationship between latent tuberculosis infection (LTBE) prevalence and the rate of tuberculosis (TB) cases in our region. 1455 cases with QFT test performed in Ege University Faculty of Medicine Hospital between 2013 and 2015 were included in the study and simultaneously TST results of 268 of 1455 cases were reached. TST results were evaluated according to both ≥ 10 mm and ≥ 15 mm cut-off values. The QFT results of the cases were compared according to their gender, age groups and clinical characteristics with chi-square test. Stratified analyses were also conducted according to age groups. Multivariate logistic regression was used to analyse factors associated with QFT positivity and indeterminate QFT results. Cohen's kappa was used to test the agreement between QFT and TDT, overall and stratified according to age groups. Among 1455 cases, 396 (27.2%) were QFT positive and 120 (8.2%) had an indeterminate QFT result. When the indeterminate results were excluded, QFT positivity was found as 29.7%. The highest indeterminate results were determined among 0-4 year-old and ≥ 65 year-old groups as 17.6% and 12.1%, respectively and lowest among the 55-64 age group as 4%. The comparison of the cases without any cellular immunity defect and the patients with hematologic malignancies or immune deficiency and patients under immunosuppressive treatment had two and 2.44 times more indeterminate QFT results, respectively. Among 268 cases with TST results reached, QFT positivity was 30.6%; 38.1% for TST ≥ 10 mm and 25.7% for TST ≥ 15. After the exclusion of indeterminate results, the agreement between QFT and TST ≥ 10 mm was 71.3% for positive cases and 75.5% for negative cases. The highest agreement between QFT and TST ≥ 10 mm was in the age group 35-64 and lowest in the age group ≥ 65. Among 43 culture-positive cases, 32 had QFT positive, six negative and five indeterminate results. When indeterminate results were excluded, the sensitivity of thetest was 84.2% (32/38) among culture-positive active TB cases. TST results were available for 17 of the culture-positive cases, among them QFT sensitivity was 76.5% (13/17), TST sensitivity 70.6% (12/17) and the sensitivity of both tests was 88.2% (15/17). The ratio of QFT positivity has increased as the age increased. Interestingly, QFT positivity was higher among females than males in the 15-34 age group and higher among males in the 35-64 age group. The rates of QFT positivity were lower among immunocompromised patients. When QFT and TST positivities were compared with the rate of TB cases among age groups, QFT positivity was observed as parallel to the rate of TB cases. In conclusion, although the sensitivity of QFT was higher than TST, it was found that it could not be considered as a gold standard in LTBE diagnosis. As active TB cases originate from the LTBE pool, QFT test results might be considered a better indicator of active TB development risk.

Early Tuberculin Skin Test for the Diagnosis of Latent Tuberculosis Infection in Patients with Inflammatory Bowel Disease.

Sensitivity of tuberculin skin test [TST] during screening for latent tuberculosis infection [LTBI] is affected by steroid and/or immunosuppressant therapy. The aim of this study was to compare performance of the two-step TST in inflammatory bowel disease patients immediately before anti-tumour necrosis factor [TNF] therapy as part of routine screening for LTBI vs control patients when the TST was carried out at an early stage. In this multicentre prospective controlled study, we evaluated the performance of two-step TST with 5-mm threshold. Factors associated with TST results were determined by logistic regression. We evaluated 243 candidates for anti-TNF therapy and 337 control patients. Overall, 105 patients [18.1%] had an induration ≥ 5 mm in the first TST or in TST retest. LTBI was diagnosed in 25% of patients by TST retest. Twenty-eight [11.5%] anti-TNF group patients vs 77 [22.8%] control patients had a positive TST (odds ratio [OR] 0.44, 95% confidence interval [CI] 0.28-0.70; P < 0.001]. In multivariate analysis, positive TST was associated with higher age [OR 2.63, 95% CI 1.21-5.72; P < 0.001] and 5-aminosalicylate therapy [OR 1.86, 95% CI 1.14-3.05; P = 0.013]. Negative TST was associated with steroid therapy [OR 0.36, 95% CI 0.16-0.83; P = 0.016], immunosuppressant therapy [OR 0.36, 95% CI 0.21-0.62; P < 0.001], or steroids + immunosuppressant therapy [OR 0.20, 95% CI 0.07-0.59; P = 0.004]. The sensitivity of routine TST performed just before starting anti-TNF therapy is low. TST performed at an early stage enables screening in the absence of immunosuppressive treatment and thus maximises the diagnostic yield of TST for detecting LTBI.

Immunomodulator effect of topical zinc oxide application in tuberculin skin test.

OBJECTIVE:We aimed to evaluate the sensitivity of tuberculin skintest (purified protein derivative-PPD) by topical zinc application on test site to improve diagnostic reliability.METHODS:We performed this study in 100 children aged 6–14 years, and plasma zinc levels were analyzed after 10–12 hours fasting. After PPD, we applied 40% zinc oxide cream on one forearm and placebo on the other forearm. PPD indurations were measured 72 hours later.RESULTS:In this study, 26% of the children showed increases in PPD induration following local zinc applications. There was no correlation between indurations size and serum zinc levels.CONCLUSION:We concluded that topical zinc cream application can enhance sensitivity of tuberculin reactivityin the diagnosis of tuberculosis.

Hodgkin lymphoma initially misdiagnosed as tuberculosis: Clinical case report

Given clinical similarities it can be difficult to differentiate between tuberculosis (TB) and Hodgkin lymphoma. The diagnosis of tuberculosis is often difficult in children due to its non-specific clinical and radiological findings, lower sensitivity of the Mantoux tuberculin skin test (TST), low bacterial load and difficulties in mycobacterium isolation in children.Consequently, a trial of anti-TB treatment is often started in children. Careful monitoring and lymph node biopsy is highly recommended in order to avert a misdiagnosis of Hodgkin’s Lymphoma.

T-SPOT. TB assay and tuberculin skin test for diagnosis and screening of tuberculosis: First report in a Sri lankan population

Objective: Guidelines encourage evaluation of an Interferon Gamma Release Assay (IGRA) in the local setting, particularly in low/ middle income, Bacillus Calmette Guerin (BCG) vaccinated populations where the assays have shown variable utility. The TSPOT.TB assay and the Tuberculin Skin Test (TST) were compared in diagnosis of active tuberculosis (TB) and in contact screening in an adult Sri Lankan population.Methods: A prospective study including confirmed TB cases (n=75), controls (n-74) and close contacts of smear positive cases (n=27) was carried out at the regional Chest clinic in Kandy district. Clinical history and investigation findings, including TST results were recorded and the TSPOT.TB (Oxford Immunotec) performed.Results: The presence of diabetes and cavitation were significant predictors of TSPOT.TB positivity, while TST had no significant clinical predictors. In the diagnosis of active TB, TSPOT.TB sensitivity was 73.3% (95% CI, 58.6-84.6%) and a specificity was 72% (95% CI, 62.0-85.5%) while the TST sensitivity was 70.7% (95% CI, 54.2-83.3%) and specificity was 64.1% (95% CI, 49.7-76.5%). In contact investigation neither test showed an association with exposure level. Cost estimate was LKR 9400.00 per TSPOT.TB test compared to LKR 200.00 per TST. A high (21%) indeterminate result rate was seen with the TSPOT.TB assayConclusions: This study did not show any advantage in using TSPOT.TB over TST in this setting.Asian Journal of Medical Sciences Vol.7(1) 2015 14-19

Comparison of tuberculin skin test and QuantiFERON®-TB Gold In-Tube for the diagnosis of childhood tuberculosis.

Tuberculosis (TB) is an important worldwide ongoing health issue. To be able to control TB, one should not only cure active TB but also identify childhood TB patients who have the possibility to develop active disease in the future. The aim of this study was to compare a century-old tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube (QFT-GIT) test, developed as an alternative to TST and which has been claimed to be superior to TST in several ways, in the diagnosis of childhood TB. Fifty-three children with TB between 5 months and 17.5 years of age and 92 healthy children from the same age group with no risk factors for TB were recruited into the study. All children underwent TST and QFT-GIT test and their demographic, clinic and laboratory data were recorded. Data were analyzed using SPSS 14. A total of 53 patients were diagnosed with TB. Mean patient age was 8.5 ± 4.3 years (range, 5 months-17.5 years). A total of 41.7% of the patients were female. Sixteen of 53 patients had confirmation on culture. QFT-GIT test was positive in 16 and TST was positive in 15 among 16 children with culture-confirmed TB. The sensitivity of TST and QFT-GIT were 93.8% and 100.0%, and the specificity of TST and QFT-GIT were 100.0% and 97.8%, respectively. With regard to the 53 TB children including those without bacteriological confirmation, QFT-GIT was positive in 33 children, and TST was positive in 44 children. The sensitivity of TST and QFT-GIT was then 83.0% and 62.3%, and the specificity, 100.0% and 97.8%, respectively. Although positive QFT-GIT test is very significant for TB, negative results will not exclude TB infection. TST and QFT-GIT used together may provide more efficient results.

Comparison of Tuberculin Skin Test, IFN-γ Assay, Real Time PCR and Lateral Flow Rapid Test in Diagnosis of Field Outbreaks of Bovine Tuberculosis

Bovine tuberculosis is an important zoonotic disease transmitted by direct contact, respiratory pathway, ingestion of unpasteurised milk and milk product, raw or undercooked meat. Tuberculosis can be difficult to diagnose based only on the clinical signs. Tuberculosis is usually diagnosed in the field with the tuberculin skin test. Sputum and other body fluids may be collected for microbiological examination. Polymerase chain reaction (PCR) methods have also been described. Diagnostic blood tests include the lymphocyte proliferation assay, the interferon gamma (IFN-γ) assay, and enzyme-linked immunosorbent assays (ELISA). In this study a total of 50 animals were tested by using tuberculin skin test (TST), lateral flow rapid test, IFN-γ assay and real time PCR. The animals were selected randomly among 178 cattle in dairy farms with the aged between 3-5 years and suspected of having tuberculosis. Forty five cattle were positive out of 50 for TST while 31 for reactive by the IFN-γ assay and 28 for rapid test and 9 for real time PCR. The purpose behind such variable as age was to compare sensitivity of tuberculin skin test, the IFN-γ assay and TB lateral flow rapid test and real time PCR examination for the diagnosis of field outbreaks of bovine tuberculosis in Turkey.

Performance of Tuberculin Skin Test Measured against Interferon Gamma Release Assay as Reference Standard in Children

Objectives. International guidelines differ in the threshold of tuberculin skin test (TST) induration regarded as indicating Mycobacterium (M.) tuberculosis infection. Interferon gamma release assay (IGRA) results were used as reference to assess performance of TST induration thresholds for detection of M. tuberculosis infection in children. Design. Systematic review which included studies containing data on TST, IGRA, and Bacillus Calmette-Guérin (BCG) status in children. Data bases searched were PubMed, EMBASE, and the Cochrane library. Specificities and sensitivities were calculated for TST thresholds 5, 10, and 15 mm and correlated with age and geographical latitude. Results. Eleven studies with 2796 children were included. For BCG immunised children diameters of 5, 10, and 15 mm had median sensitivities of 87, 70, and 75% and specificities of 67, 93, and 90%, respectively. In non-BCG immunised children median sensitivities were 94, 95, and 83% and specificities 91, 95, and 97%. At the 10 mm threshold age correlated negatively with sensitivity of TST (r = −0.65, P = 0.04) and latitude correlated positively (r = 0.71, P = 0.02). Conclusions. For the 10 mm threshold the sensitivity of the TST is lower in BCG immunised children. Younger age and higher geographical latitude were associated with higher sensitivity of the TST.

Systematic review and meta-analysis on the utility of Interferon-gamma release assays for the diagnosis of Mycobacterium tuberculosis finfection in children: a 2013 update

BackgroundPrevious meta-analyses regarding the performance of interferon-gamma release assays (IGRAs) for tuberculosis diagnosis in children yielded contrasting results, probably due to different inclusion/exclusion criteria.MethodsWe systematically searched PubMed, EMBASE and Cochrane databases and calculated pooled estimates of sensitivities and specificities of QuantiFERON-TB Gold In Tube (QFT-G-IT), T-SPOT.TB, and tuberculin skin test (TST). Several sub-analysis were performed: stratification by background (low income vs. high income countries); including only microbiological confirmed TB cases; including only studies performing a simultaneous three-way comparison of the three tests, and including immunocompromised children.ResultsOverall, 31 studies (6183 children) for QFT-G-IT, 14 studies (2518 children) for T-SPOT.TB and 34 studies (6439 children) for TST were included in the analyses. In high income countries QFT-G-IT sensitivity was 0.79 (95%IC: 0.75-0.82) considering all the studies, 0.78 (95%CI:0.70-0.84) including only studies performing a simultaneous three-way comparison and 0.86 (95%IC 0.81-0.90) considering only microbiologically confirmed studies. In the same analyses T-SPOT.TB sensitivity was 0.67 (95%IC 0.62-0.73); 0.76 (95%CI: 0.68 to 0.83); and 0.79 (95%IC 0.69-0.87), respectively. In low income countries QFT-G-IT pooled sensitivity was significantly lower: 0.57 (95%IC:0.52-0.61), considering all the studies, and 0.66 (95%IC 0.55-0.76) considering only microbiologically confirmed cases; while T-SPOT.TB sensitivity was 0.61 (95%IC 0.57-0.65) overall, but reached 0.80 (95%IC 0.73-0.86) in microbiologically confirmed cases. In microbiologically confirmed cases TST sensitivity was similar: 0.86 (95%IC 0.79-0.91) in high income countries, and 0.74 (95%IC 0.68-0.80) in low income countries. Higher IGRAs specificity with respect to TST was observed in high income countries (97-98% vs. 92%) but not in low income countries (85-93% vs. 90%).ConclusionsBoth IGRAs showed no better performance than TST in low income countries.

우리나라 잠복결핵감염 검진전략의 경제성 분석

Background: Although interferon-gamma release assay (IGRA) is now available alternatives to tuberculin skin test (TST) for detection of latent tuberculosis infection (LTBI), the cost of IGRA test is much higher than TST. So economic analysis of LTBI screening strategies have been done in many countries, but there are few reports in Korea. This study examined cost analysis of LTBI screening strategies in Korea.Methods: The economic outcomes were evaluated by five strategies. These were 1) TST alone, 2) IGRA alone, 3) combination of TST and IGRA (TST followed by IGRA) and 4) no testing no prevention, 5) no testing all prevention. Last two strategies were added to compare with three main LTBI screening strategies. Decision analysis model were used to perform economic analysis. A cohort study of Korean Institute of Tuberculosis and the data of published literatures were used to estimate the cost analysis.Results: In a base-case scenario which was assumed that TST specificity was 80%, TST alone was the least expensive strategy. In a al-ternative scenario which was assumed that TST specificity was 97%, the combination of TST and IGRA was the least expensive strat-egy. Sensitivity analysis shows that patients adherent rate to LTBI treatment, TST sensitivity, IGRA sensitivity and IGRA specificity did not have a significant impact on the outcomes.Conclusion: In Korea, for the diagnosis of LTBI at the time of child and adolescent, TST alone reduces medical costs compared with IGRA alone or combination of TST and IGRA.Keywords: Costs and cost analysis; Latent tuberculosis infection; Tuberculosis

Role of the QuantiFERON®-TB Gold In-Tube test in the diagnosis of intrathoracic childhood tuberculosis

Tertiary care hospitals in India. To compare the performance of the QuantiFERON®-TB Gold In-Tube test (QFT-GIT) with that of the tuberculin skin test (TST) in the diagnosis of intrathoracic childhood tuberculosis (TB). Children with intrathoracic TB were enrolled in a randomised controlled trial studying micronutrient supplementation in intrathoracic TB. They underwent TST and QFT-GIT before starting daily anti-tuberculosis treatment. Of 362 children (median age 115.5 months, IQR 73-144, 55% girls) enrolled in the study, microbiological confirmation of TB was obtained in 128 (35%). The TST was positive in 337 (93%, 95%CI 90-95.5) and QFT-GIT in 297 (82%, 95%CI 77.8-85.6). Sensitivity of TST and QFT-GIT in culture-confirmed TB cases was respectively 90.5% (95%CI 84.1-94.5) and 82.6% (95%CI 74.9-88.4). QFT-GIT positivity rate correlated with TST induration (P < 0.001). TST was influenced by the disease spectrum (P = 0.004) and the age of the children (P = 0.002); QFT-GIT remained unaffected by these factors. Bacille Calmette-Guérin immunisation status, weight-for-age Z-scores and microbiological confirmation of Mycobacterium tuberculosis did not influence the performance of either test. In high-burden countries, QFT-GIT is comparable to TST and offers no added advantage in the diagnosis of childhood intrathoracic TB.