A meta-analysis of the effect of Bacille Calmette Guérin vaccination on tuberculin skin test measurements

Predictors of positive tuberculin skin test in neonates exposed to pulmonary tuberculosis

BACKGROUND

Neonates are at risk of nosocomial tuberculosis (TB) infection from health care workers (HCWs) in neonatal care facilities, which can progress to severe TB diseases. Tuberculin skin test (TST) is commonly used for TB diagnosis, but its accuracy in neonates is influenced by various factors, including bacilli Calmette-Guérin (BCG) vaccination. This study aimed to identify predictors of positive TSTs in neonates exposed to HCWs with pulmonary TB.

METHODS

A retrospective observational study was conducted to compare the frequency of predictors between TST-positive and TST-negative neonates. Demographic, epidemiological, and clinical data of neonates exposed to TB, along with that of HCW and household contacts, were collected retrospectively through contact investigations with the Korean National TB Surveillance System (KNTSS) database. TSTs using 2 tuberculin units of purified protein derivative RT23 were performed on exposed neonates at the end of preventive TB treatment. Firth logistic regression was performed to identify predictors of TST positivity.

RESULTS

Contact investigations revealed that 152 neonates and 54 HCWs were exposed to infectious TB index cases in 3 neonatal care facilities. Of 152 exposed neonates, 8 (5.3%) had positive TST results. Age of 6 days or more at the initial exposure is a statistically significant predictor of positive TST (Firth coefficient 2.1, 95% confidence interval 0.3-3.9, P = 0.024); BCG vaccination showed no statistical significance in both univariable and multivariable analysis. Sex, prematurity, exposure duration, duration from initial exposure to contact investigation, and isoniazid preventive treatment duration were not significant predictors.

CONCLUSION

Age at the initial exposure is a significant predictor of positive TST in neonates exposed to active pulmonary TB. Given the complexities of TST interpretation, including false positives due to BCG vaccination, careful risk assessment is necessary for appropriate decision-making and resource allocation in the management of neonatal TB exposure.

Tuberculin responses after BCG vaccination predict amyotrophic lateral sclerosis risk

Background

T cell infiltration around dying motor neurons is a hallmark of amyotrophic lateral sclerosis (ALS). It is not known if this immune response represents a cause or a consequence of the disease. We aimed to establish whether individual variation in regulation of a T cell driven immune response is associated with long-term ALS risk.

Methods

Tuberculin skin test (TST) following BCG vaccination represents a standardized measure of a secondary T cell driven immune response. During a Norwegian tuberculosis screening program (1963-1975) Norwegian citizens born from 1910 to 1955 underwent TST. In those previously BCG vaccinated (median 7 years prior to TST), we related tuberculin skin tests to later ALS disease identified through validated Norwegian health registers. We fitted Cox proportional hazard models to investigate the association between tuberculin reactivity and ALS risk.

Results

Among 324,629 participants (52 % women) with median age 22 (IQR 10) years at tuberculosis screening, 496 (50 % women) later developed ALS. Hazard ratio for ALS was 0.74 (95% CI 0.57-0.95) for those who remained TST negative compared to those who mounted a positive TST. The association was strongest when time between BCG immunization and TST was short. The associations observed persisted for more than four decades after TST measurement.

Conclusions

Negative TST responses after BCG vaccination is associated with decreased long-term risk for ALS development, supporting a primary role for adaptive immunity in ALS development.

Association of Mycobacterium tuberculosis infection test results with risk factors for tuberculosis transmission

Background

Close contacts infected with Mycobacterium tuberculosis are at high risk of tuberculosis (TB) disease and a priority for preventive treatment. Three tests measure infection: two interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST). The objective of our study was to assess the association of positive test results in contacts with infectiousness of the presumed TB source case.

Methods

Contacts in a cohort study at 10 United States sites received both IGRAs (QuantiFERON-TB Gold In-Tube (QFT-GIT) and T-SPOT.TB (T-SPOT)) and TST. We defined test conversion as negative for all tests at baseline and positive for at least one on retest. Risk ratios (RR) and 95% confidence intervals (CI) assessed association of positive test results with increased infectiousness of the TB case-defined as acid-fast bacilli (AFB) on sputum microscopy or cavities on chest radiographs- and contact demographics.

Results

Adjusted for contacts' age, nativity, sex, and race, IGRAs (QFT-GIT RR = 6.1, 95% CI 1.7-22.2; T-SPOT RR = 9.4, 95% CI 1.1-79.1), but not TST (RR = 1.7, 95% CI 0.8-3.7), were more likely to convert among contacts exposed to persons with cavitary TB disease.

Conclusions

Because IGRA conversions in contacts are associated with infectiousness of the TB case, their use may improve efficiency of health department contact investigations by focusing efforts on those likely to benefit from preventive treatment in the United States.

Postvaccination immune responses and risk of primary total hip arthroplasty-A population-based cohort study

OBJECTIVE

To investigate the relationship between individual postvaccination immune responses and subsequent risk of total hip arthroplasty (THA) due to idiopathic osteoarthritis (OA) or rheumatoid arthritis (RA).

METHOD

Results of tuberculin skin tests (TSTs) following the Bacille Calmette-Guerin (BCG) vaccination were used as a marker of individual immune responses. TST results from the mandatory mass tuberculosis screening program 1948-1975 (n = 236 770) were linked with information on subsequent THA during 1987-2020 from the Norwegian Arthroplasty Register. The multivariable Cox proportional hazard regression was performed.

RESULTS

A total of 10 698 individuals received a THA during follow-up. In men, there was no association between TST and risk of THA due to OA (Hazard ratio [HR] 1.01, 95% confidence interval [CI] 0.92-1.12 for positive versus negative TST and HR 1.06, 95% CI 0.95-1.18 for strong positive vs negative TST), while the risk estimates increased with increasingly restrictive sensitivity analyses. In women, there was no association with THA due to OA for positive versus negative TST (HR 0.98, 95% CI 0.92-1.05), while a strong positive TST was associated with reduced risk of THA (HR 0.90, 95% CI 0.84-0.97). No significant associations were observed in the sensitivity analysis for women or for THA due to RA.

CONCLUSION

Our results suggest that an increased postvaccination immune response is associated with a nonsignificant trend of increased risk of THA among men and a decreased risk among women, although risk estimates were small.

The Collaborative Ocular Tuberculosis Study (COTS) calculator-a consensus-based decision tool for initiating antitubercular therapy in ocular tuberculosis

OBJECTIVE

To introduce the Collaborative Ocular Tuberculosis Study (COTS) Calculator, an online clinical scoring system for initiating antitubercular therapy (ATT) in patients with ocular tuberculosis (TB).

METHOD

The COTS Calculator was derived from COTS Consensus (COTS CON) data, which has previously published consensus guidelines. Using a two-step Delphi method, 81 experts evaluated 486 clinical scenario-based questions, ranking their likelihood of initiating ATT in each specific scenario. Each scenario was a permutation of the results and/or availability of five following components-clinical phenotype, endemicity, two immunological (tuberculin skin test, interferon-γ release assay) and one radiological (chest X-Ray) test results-and a sixth component further stratifying three of the clinical phenotypes. The median scores and interquartile ranges (IQR) of each scenario were tabulated, representing the expert consensus on whether to initiate ATT in that scenario. The consensus table was encoded to develop the COTS Calculator.

RESULTS

The COTS Calculator can be accessed online at: https://www.oculartb.net/cots-calc . The attending physician can select the conditions present in the patient, which will generate a median score from 1 to 5. 114 out of 486 scenarios (24%) deliberated had a median score of 5 indicating expert consensus to initiate ATT.

CONCLUSION

The COTS Calculator is an efficient, low-cost, evidence and experience-based clinical tool to guide ATT initiation. While it holds substantial promise in improving standard-of-care for ocular-TB patients, future validation studies can help to as certain its clinical utility and reliability.

Efficacy and Risk Factors of Interferon-Gamma Release Assays among HIV-Positive Individuals

Latent tuberculosis is prevalent in HIV-infected people and has an impact on the progression of AIDS. The aim of this study is to match a more accurate IGRA method for the better detection of latent tuberculosis infection in HIV patients. All 2394 patients enrolled were tested using three IGRA methods. The positive rate consistency of pairwise comparison and risk factors were analyzed. Receiver operator characteristic (ROC) curve analysis was applied to evaluate the diagnostic value of T-SPOTTB. The positive rates of the three methods were statistically different (p < 0.001). The CD4⁺ T cell number statistically impacted the QuantiFERON and Wan Tai tests after the analysis with univariate logistic regression, while no statistical difference was observed in T-SPOT.TB. Additionally, there was a better sensitivity and specificity of T-SPOT.TB if the positive cut-off value of ESAT-6 and CFP-10 was 4.5 and 5.5, respectively. This study provides an insight into the IGRA methods and demonstrated that the positive response detected via QuantiFERON declined with decreased CD4⁺ T cells in the HIV-infected population; T-SPOT.TB functions independently of the CD4⁺ T cell level and Wan Tai was affected in some cases. This will be useful in the diagnosis of LTBI in the HIV-infected population, which will be a key step toward TB elimination in China.

Comparison of IGRA and TST in the diagnosis of latent tuberculosis among women of reproductive age in South India

BACKGROUND

Latent tuberculosis infection (LTBI) is a mycobacterial infection defined on the basis of cellular immune response to mycobacterial antigens. The tuberculin skin test (TST) and the Interferon-Gamma Release Assay (IGRA) are the two tests currently used to establish the diagnosis of LTB. Literature suggests that a study regarding tuberculosis (TB) infection among women of reproductive age group is limited.

METHODS

Female household contact, married, aged 18-49 years underwent written consent form and are screened for LTBI using the TST and IGRA. Participants are injected with TST [5 tuberculin unit (TU), purified protein derivative (PPD)] and IGRA [QuantiFERON®-TB Gold Plus kit (QFT-Plus)]. All the household contacts were followed-up for one year for incident TB cases. Statistical analysis was done using STATA version 14 (StataCorp., Texas, USA). Cohen's kappa test was used to determine the agreement between two tests.

RESULTS

The prevalence of LTBI was found to be 69% (either TST or IGRA positive). Positivity rate of IGRA was higher when compared to that of TST. Out of 139 participants, 68 (49%) tested positive for TST, 80 (57.6%) tested positive for IGRA and 52 (37.4%) tested positive for both. Discordant results were observed in about two fifth of the study population and there was poor agreement between the two tests.

CONCLUSION

Longitudinal studies are required to detect incident TB cases to evaluate the usefulness of these tests. The study was found that IGRA is more consistent to diagnosis of latent tuberculosis infection than the TST. Such studies can also be performed in varied settings among different populations which would help us to improve the diagnosis of LTBI and consequently help in TB control.

Skin thickness affects the result of tuberculin skin test in systemic sclerosis

Background

Skin thickness is a prominent clinical feature of systemic sclerosis (SSc), but there is no consensus on the cut-off for a positive tuberculin skin test (TST) size and the limitation of the TST for a diagnosis of tuberculosis in SSc. We aimed to identify the cut-off size of an indurated TST and the sensitivity and specificity of the test for the diagnosis of tuberculosis in SSc patients.

Methods

A cross-sectional study of 168 adult Thai SSc patients was conducted. The TST was done using 0.1 ml of purified protein derivatives via intradermal injection. The test was interpreted 72 h after testing.

Results

The median age was 57.2 years. The majority (71.8%) had the diffuse cutaneous SSc subset. All the patients had a BCG vaccination at birth, and 17 (10.1%) had a tuberculosis infection. An indurated skin reaction size of 20 mm had the highest specificity for tuberculosis (99.3%: 95%CI 96.4–100) (ROC 0.53). The skin thickness—assessed using the modified Rodnan skin score (mRSS)—had a significant negative correlation with the reaction size (Rho -0.23; p = 0.003).

Conclusion

The TST is not sufficiently sensitive for detecting TB infection in SSc patients, albeit a skin induration of ≥ 15 mm indicates a high specificity for tuberculosis infection. A high mRSS resulted in a smaller skin reaction size when using the TST, which has limited utility as a diagnostic for tuberculosis among SSc patients with severe skin thickness.

The manuscript was presented as a poster presentation at the Annual European Congress of Rheumatology EULAR 2019 Madrid 12–15 June 2019. (Ann Rheum Dis. 2019;78(suppl 2): abstract FRI0347) http://dx.doi.org/10.1136/annrheumdis-2019-eular.1456

Supplementary Information

The online version contains supplementary material available at 10.1186/s41927-022-00278-8.

The effect of BCG vaccination and risk factors for latent tuberculosis infection among college freshmen in China

OBJECTIVES

In this study, we aimed to verify whether Bacillus Calmette-Guérin (BCG) can protect first-year college students against Mycobacterium tuberculosis (MTB) infection by the recombinant fusion protein ESAT6-CFP10 skin test (ECST) or the tuberculin skin test (TST).

METHODS

We conducted a cross-sectional study to assess risk factors for latent tuberculosis infection (LTBI). Vaccine effectiveness of BCG against LTBI, measured by ECST and TST separately, was assessed using multivariable logistic regression.

RESULTS

A total of 7351 college freshmen accepted ECST, whereas 7228 accepted TST. A total of 263 (3.58%) tested positive with ECST and 581 (8.04%) tested positive with TST. BCG was significantly associated with LTBI (ECST: adjusted odds ratio (aOR) = 0.26; 95% CI 0.09 to 0.73; TST: aOR = 0.25; 95% CI 0.13 to 0.49). The BCG protective effect on freshmen living in rural areas (ECST: aOR = 0.16; 95% CI 0.04 to 0.55; TST: aOR = 0.12; 95% CI 0.04 to 0.33) is better than that of freshmen living in cities (ECST: aOR = 0.53; 95% CI 0.07 to 4.03; TST: aOR = 0.44; 95% CI 0.17 to 1.16).

CONCLUSIONS

Protection against LTBI was strongly associated with BCG vaccination. A novel skin test (ECST) may underestimate the protective effects of BCG in college freshmen. BCG has better protection in areas with a slightly higher incidence of LTBI.

Strong tuberculin response after BCG vaccination is associated with low multiple sclerosis risk: a population-based cohort study

Background

Multiple sclerosis (MS) is characterized by inflammatory lesions in the central nervous system involving pro-inflammatory T-cells. Immune dysregulation is well described in prevalent disease, but it is not known whether this precedes disease development. Bacillus Calmette–Guérin (BCG) vaccination ameliorates MS-like disease in mice. In people vaccinated with BCG, the tuberculin skin test (TST) offers a standardized measure of a T-cell-mediated immune response. We therefore hypothesized that the strength of the TST response after BCG vaccination is associated with subsequent MS risk.

Methods

Using data from a Norwegian tuberculosis screening programme (1963–1975), we designed a population-based cohort study and related the size of TST reactions in individuals previously vaccinated with BCG to later MS disease identified through the Norwegian MS registry. We fitted Cox proportional hazard models and flexible parametric survival models to investigate the association between TST reactivity, MS risk and its temporal relationship.

Results

Among 279 891 participants (52% females), 679 (69% females) later developed MS. Larger TST reactivity was associated with decreased MS risk. The hazard ratio for MS per every 4-mm increase in skin induration size was 0.86 (95% confidence interval 0.76–0.96) and similar between sexes. The strength of the association persisted for &gt;30 years after the TST.

Conclusion

A strong in vivo vaccine response to BCG is associated with reduced MS risk &gt;30 years later. The immunological mechanisms determining TST reactivity suggest that skewed T-cell-mediated immunity precedes MS onset by many decades.

Assessment of Interferon Gamma-Induced Protein 10 mRNA Release Assay for Detection of Latent Tuberculosis Infection in Egyptian Pediatric Household Contacts

OBJECTIVES

Current diagnostic tests for tuberculosis (TB) in children living in low-endemic countries are limited by low specificity and the inability of the current tests to differentiate between active TB and latent TB infection (LTBI). This study aimed to evaluate the blood IP-10 mRNA expression level to detect LTBI in Egyptian pediatric household contacts (PHC).

METHODS

TB-specific IP-10 and IFN-γ mRNA levels were assessed by real-time quantitative PCR (RT-qPCR) in 72 Egyptian PHC of active pulmonary TB cases. All study participants were also assessed by Tuberculin Skin Test (TST) and Quantiferon gold in tube (QFN-GIT) assay.

RESULTS

IP-10 and IFN-γ mRNA expression levels were significantly higher in PHC with active TB or LTBI than TB negative (p < 0.0001). The level of IP-10 mRNA expression was significantly higher in PHC with active TB than LTBI (p = 0.0008). In contrast, there was no significant differences in the IFN-γ mRNA expression between PHC with active TB compared to LTBI (p = 0.49). The sensitivity and specificity of the IP-10 RT-qPCR were 94.2% and 95.2%, respectively, in PHC with active TB compared to 85.7% and 81.8% in PHC with LTBI. The negative and positive predictive values and accuracy of IP-10 RT-qPCR for distinguishing active TB from LTBI were 85.2%, 58.3%, and 72.6% respectively.

CONCLUSION

Blood IP-10 mRNA expression level may be a potential diagnostic marker to help distinguish active TB from LTBI in PHC.

Screening for latent tuberculosis before starting TNF-alpha inhibitors in a population with high BCG vaccination rates

It is assumed that in candidates for TNF-alpha inhibitor (TNFi) treatment, tuberculin skin test (TST) may be unreliable, since BCG vaccination causes false positive and drugs cause false negative results, favoring the use of Quantiferon or T-spot assays. However, these tests may not be readily available in all parts of the world. We aimed to determine the reliability of TST with respect to BCG vaccination and drugs in candidates for TNFi treatment, and how isoniazid is tolerated, assuming that the use of TST would result in increased isoniazid use. We included 1031 adult patients who were prescribed a TNFi for the first time. We analysed the association of BCG and drugs with TST and Quantiferon results, the determinants of a positive TST, and evaluated the tolerability of isoniazid. BCG vaccination and male sex were associated with positive TST (OR 3.56, 95% CI 1.98-6.41 and OR 2.54, 95% CI 1.75-3.68, respectively), while prednisolone and azathioprine were associated with negative TST (OR 0.63, 95% CI 0.43-0.91 and OR 0.40, 95% CI 0.11-0.76). Isoniazid was prescribed to 684 (66.3%) patients and had to be discontinued in 12.2% of these before 9 months, most commonly due to hepatotoxicity (44%). One patient developed tuberculosis despite isoniazid use. BCG vaccination may be associated with false positive TST, despite a long time since vaccination in candidates for TNFi treatment. Prednisolone and azathioprine use were associated with negative TST. Despite the high frequency of isoniazid use associated with using TST instead of QTF, isoniazid was generally well tolerated.

Predictors of Discordant Tuberculin Skin Test and QuantiFERON-TB Gold In-tube Results in Eastern China: A Population-based, Cohort Study

BACKGROUND

Discordance between the QuantiFERON-TB Gold In-tube (QFT) and tuberculin skin test (TST) is not well understood. We aimed to identify the factors that determine discordance between the TST and QFT when compared to either TST+QFT+ or TST-QFT- results in a medium tuberculosis (TB) burden setting.

METHODS

We conducted a population-based study in Eastern China and administered TSTs and QFTs to participants. We calculated kappa values while constructing multivariable logistic regression models to evaluate predictors of test discordance. We analyzed the predictive value of discordant and concordant test results for progression to TB over 6 years of follow-up.

RESULTS

Overall, 5405 participants were enrolled; 2043 (37.8%) and 1104 (20.4%) were TST and QFT positive, respectively. There was fair agreement between the TST and the QFT (kappa values between 0.30-0.39 at different TST cutoffs). Agreement was lower among participants vaccinated with Bacillus Calmette-Guerin (BCG; κ, 0.17 versus 0.47 in nonvaccinated participants). TST+QFT- results were associated with decreasing age, smoking, undiagnosed diabetes, and BCG vaccination (adjusted odds ratio, 1.45; 95% confidence interval [CI], 1.11-1.90). TST-QFT+ results were associated with increasing age, male sex, smoking, and diagnosed diabetes. Compared to participants with TST-QFT- results, QFT+ and TST+QFT+ participants were 6.3 (95% CI, 1.9-20.4) and 7.5 (95%CI, 2.3-25.1) times more likely to progress to TB, respectively.

CONCLUSIONS

In this population-based study of over 5000 participants from a medium TB burden region, the test agreement between QFT and TST was fair overall and we found multiple novel predictors of discordant QFT/TST results. QFT provides a substantial improvement to the TST among these populations and was multi-fold better at predicting progression to TB.

Usefulness of screening tests for diagnosis of latent tuberculosis infection in children

BACKGROUND

The aim of this study is to provide a basis for the development of appropriate screening strategies and evaluate the indications of the interferon-gamma release assay (IGRA) in Bacillus Calmette-Guérin (BCG)-vaccinated children.

METHODS

Children who were examined with both IGRA (QuantiFERON®-TB Gold Plus) and tuberculin skin test (TST) for tuberculosis infection were included in the study. Underlying medical conditions of the patients were recorded. Cohen's κ was run to determine if there was an agreement between TST and IGRA.

RESULTS

A total of 220 patients with a mean age of 11.05 ± 4.43 years (2.5-18 years) were analyzed. Ninety-nine patients were immunocompromised and 121 patients were immunocompetent. TSTs and IGRA showed none to the slight agreement in both of the immunocompromised and immunocompetent patients. In the immunocompromised group, 43/99 (43.4%) and the immunocompetent group 35/121 (28.9%) of the tests did not show any correlation.

CONCLUSION

In a high-risk setting where the BCG vaccine is mandatory, it may be beneficial to use IGRA primarily in immunocompetent patients. In immunocompromised patients, the use of both the TST and IGRA could increase the efficacy of screening for latent tuberculosis infection.

Safety Evaluation of Recombinant Fusion Protein RP22 as a Skin Test Reagent for Tuberculosis Diagnosis: A Phase I Clinical Trial

INTRODUCTION

This phase I clinical trial was conducted to evaluate the safety of RP22 as a skin test reagent for tuberculosis (TB) diagnosis and to explore the appropriate dosage.

METHODS

We used a randomized, double-blind, placebo-controlled identification allergen (IA) skin test. A total of 72 healthy adult volunteers with negative chest X-ray results were randomized into six groups and given a QuantiFERON-TB Gold (QFT) test. Of the 12 participants in each group, eight received RP22 and four received placebo. The doses of RP22 in the six experimental groups ranged from 0.1 to 4.0 μg in a single intradermal injection of 0.1 ml. Skin reactions and adverse events were recorded at intervals.

RESULTS

All doses of RP22 except the highest were well tolerated and safe. No serious adverse events associated with the injection were observed in all groups. There were 11 participants who had positive QFT results, eight had a skin reaction with a redness or induration area diameter of greater than 10 mm at 48-72 h, one had no skin reaction. Among the 60 negative-QFT participants, none had a reaction area diameter of greater than 10 mm.

CONCLUSION

The RP22 skin test was well tolerated and safe, it could play a key role in screening for latent tuberculosis infection (LTBI) by providing a much-wanted alternative to the tuberculin skin test (TST) and interferon-γ release assays (IGRAs).

Re: The Bacillus Calmette-Guerin (BCG) Vaccine: Is it a better choice for the treatment of viral warts?

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Evaluation of a lateral flow assay-based IFN-γ release assay as a point-of-care test for the diagnosis of latent tuberculosis infection

INTRODUCTION

We compared the performance of a fluorescence lateral flow assay (ichroma™ IGRA-TB) with the QuantiFERON-TB Gold PLUS (QFT-PLUS) for the diagnosis of latent tuberculosis infection (LTBI) in patients with immune-mediated inflammatory diseases (IMID) prior to receiving biologics therapy.

METHOD

The comparability of the ichroma™ IGRA-TB assay with the QFT-PLUS assay for the diagnosis of LTBI was determined in prospectively enrolled patients with IMID prior to receiving biologics between August 2018 and October 2019. To determine the best cut-off value of the ichroma™ IGRA-TB, an ROC curve analysis was performed.

RESULTS

Patients with IMID (n = 145) had inflammatory bowel disease (n = 83; 57.2%), rheumatoid arthritis (n = 44; 30.3%), or spondyloarthropathy (n = 18; 12.4%). The median age was 40.5 (interquartile range: 27.0-56.0), 72 (49.7%) were men, and 140 (96.6%) received BCG vaccination. With the manufacturer-recommended cut-off values, 11 (7.6%) and 20 (13.8%) patients showed positive results with the ichroma™ IGRA-TB and QFT-PLUS tests, respectively. The overall agreement between the two tests was 91.0% with a Cohen's kappa value of 0.535 (95% confidence interval: 0.317-0.754). ROC curve analysis of the QFT-PLUS results showed that a cut-off value of > 0.21 IU/mL would improve the performance of the ichroma™ IGRA-TB. Using the new cut-off value, the concordance rate was improved to 93.1% with a Cohen's kappa value of 0.668 (95% confidence interval: 0.478-0.858).

CONCLUSIONS

The ichroma™ IGRA-TB could be used as a point-of-care test for LTBI screening in IMID patients before starting biologics, especially in resource-limited settings. Key Points • The ichroma™ IGRA-TB is an automated fluorescence lateral flow assay-based IGRA. • The test has advantages like short turn-around time, low-cost, and ease of use. • The ichroma™ IGRA-TB showed high agreement with the QuantiFERON-TB Gold In-Tube in patients with chronic immune-mediated inflammatory diseases before starting biologics.

Prevalence and Risk Factors of Latent Tuberculosis Infection (LTBI) in Patients with Type 2 Diabetes Mellitus (T2DM)

Type 2 diabetes mellitus (T2DM) and tuberculosis (TB) together impose a high disease burden in terms of both mortality and health economics worldwide. The objective of this study was to estimate the prevalence and risk factors of latent TB infection (LTBI) in patients with T2DM in Malaysia. A cross-sectional study was performed, and adult T2DM patients (n = 299) were included. Simple and multiple logistic regression analyses were performed to identify the LTBI-associated risk factors in patients with T2DM. Multiple logistic regression was used to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CIs) between T2DM and LTBI and was adjusted for potential confounders. The prevalence of LTBI in patients with T2DM was 11.4% (95% CI: 8.0-15.0%). There was no significant difference in the socio-demographic characteristics between LTBI and non-LTBI subjects. No significant difference in the smoking status, the duration of smoking, and the duration of T2DM, HbA1c, or treatments was observed. Interestingly, a higher level of education was observed to be associated with a lower prevalence of LTBI in T2DM patients (aOR: 0.08, 95% CI: 0.01-0.70, p = 0.02). Although the prevalence of LTBI in T2DM was low, it is important to screen for it in T2DM patients due to the risk of developing severe active TB.

Individual Variation in Adaptive Immune Responses and Risk of Hip Fracture-A NOREPOS Population-Based Cohort Study

Immune-mediated bone loss significantly impacts fracture risk in patients with autoimmune disease, but to what extent individual variations in immune responses affect fracture risk on a population level is unknown. To examine how immune responses relate to risk of hip fracture, we looked at the individual variation in a post-vaccination skin test response that involves some of the immune pathways that also drive bone loss. From 1963 to 1975, the vast majority of the Norwegian adult population was examined as part of the compulsory nationwide Norwegian mass tuberculosis screening. These examinations included standardized tuberculin skin tests (TSTs). Our study population included young individuals (born 1940 to 1960 and aged 14 to 30 years at examination) who had all received Bacille Calmette-Guerin (BCG) vaccination after a negative TST at least 1 year prior and had no signs of tuberculosis upon clinical examination. The study population ultimately included 244,607 individuals, whose data were linked with a national database of all hospitalized hip fractures in Norway from 1994 to 2013. There were 3517 incident hip fractures during follow-up. Using a predefined Cox model, we found that men with a positive or a strong positive TST result had a 20% (hazard ratio [HR] = 1.20, 95% confidence interval [CI] 1.01-1.44) and 24% (HR = 1.24, 95% CI 1.03-1.49) increased risk of hip fracture, respectively, compared with men with a negative TST. This association was strengthened in sensitivity analyses. Total hip bone mineral density (BMD) was available for a limited subsample and similarly revealed a non-significantly reduced BMD among men with a positive TST. Interestingly, no such clear association was observed in women. An increased immune response after vaccination is associated with an increased risk of hip fracture decades later among men, possibly because of increased immune-mediated bone loss. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Utility of the monocyte to lymphocyte ratio in diagnosing latent tuberculosis among HIV-infected individuals with a negative tuberculosis symptom screen

BACKGROUND

Latent Tuberculosis Infection (LTBI) remains a major driver of the TB epidemic, and individuals with Human Immuno-deficiency Virus (HIV) are particularly at a heightened risk of developing LTBI. However, LTBI screening among HIV-infected individuals in resource limited setting is largely based on a negative symptom screen, which has low specificity.

METHODS

In a cross sectional diagnostic study, 115 HIV infected participants with a negative symptom screen will be consented and enrolled. They will be requested to donate 5 ml of blood for complete blood count (CBC) and interferon gamma release assay (IGRA) testing. In a nested prospective study, the 115 participants will be initiated on Tuberculosis Preventive Therapy and the CBC testing repeated after 3 months. In the analysis of study finding, the monocyte to lymphocyte ratio (MLR) will be derived from the dividend of the absolute monocyte and lymphocyte counts. The optimal MLR positivity cut-off for elevated or normal MLR will be the highest value of Youden's index, J (sensitivity + specificity-1). The MLR will be cross tabulated with the IGRA status to determine the sensitivity, specificity, negative and positive predictive values of the MLR. The area under the receiver operating characteristic (ROC) curve will be determined to give the overall diagnostic accuracy of MLR. The baseline and 3 month CBC will be used to determine the change in MLR, and a random effect logistic regression will be used to determine factors associated with the change in the MLR.

DISCUSSION

If positive results are realized from this study, the MLR could become an inexpensive alternative biomarker with potential to improve the specificity of the negative symptom screen in identifying individuals that should be targeted for TB preventive therapy.

Effect of pregnancy and HIV infection on detection of latent TB infection by Tuberculin Skin Test and QuantiFERON-TB Gold In-Tube assay among women living in a high TB and HIV burden setting

OBJECTIVE

To investigate the effect of pregnancy and Human immunodeficiency virus (HIV) infection on detection performances of tuberculin skin test (TST) and QuantiFERON-TB Gold In-Tube (QFTGIT) for the diagnosis of latent tuberculosis infection (LTBI) among women living in high TB and HIV endemic setting.

METHOD

A cross-sectional study was conducted among women with and without pregnancy and HIV infection. Three-hundred twenty women were enrolled in this study and were diagnosed using TST and QFTGIT for the detection of LTBI.

RESULTS

Overall prevalence of LTBI among the enrolled women was 55.6%, 46.3% and 51.1% as determined by TST, QFTGIT and concordant TST/QFTGIT results, respectively. Our study revealed that pregnancy or HIV infection reduced the rate of detection of LTBI by TST and QFTGIT tests, with the utmost effect observed in HIV-positive pregnant women. Additionally, we observed that the concordance between TST and QFTGIT among women increased with the presence of pregnancy and/or HIV infection. A history of contact with TB patients was significantly associated with positivity of TST and QFTGIT.

CONCLUSION

This study demonstrated that both pregnancy and HIV infection profoundly affected the detection performance of TST and QFTGIT, which may be associated with immunosuppression of anti-mycobacterial immunity in women with pregnancy and/or HIV infection.

Diagnostic Accuracy of Interferon Gamma-Induced Protein 10 mRNA Release Assay for Tuberculosis

Interferon gamma (IFN-γ) release assays (IGRAs) are increasingly used to test for latent tuberculosis (TB) infection. Although highly specific, IGRAs have a relatively high false-negative rate in active TB patients. A more sensitive assay is needed. IFN-γ-induced protein 10 (IP-10) is an alternative biomarker with a 100-fold-higher expression level than IFN-γ, allowing for different analysis platforms, including molecular detection. The PCR technique is already an integrated tool in most TB laboratories and, thus, an obvious platform to turn to. In this case-control study, we investigated the diagnostic sensitivity and specificity of a molecular assay detecting IP-10 mRNA expression following antigen stimulation of a blood sample. We included 89 TB patients and 99 healthy controls. Blood was drawn in QuantiFeron-TB gold in-tube (QFT) assay tubes. Eight hours poststimulation, IP-10 mRNA expression was analyzed, and 20 h poststimulation, IP-10 and IFN-γ protein plasma levels were analyzed using an in-house IP-10 enzyme-linked immunosorbent assay (ELISA) and the official QFT ELISA, respectively. The IP-10 mRNA assay provided high specificity (98%), sensitivity (80%), and area under the concentration-time curve (AUC) (0.97); however, the QFT assay provided a higher overall diagnostic potential, with specificity of 100%, sensitivity of 90%, and AUC of 0.99. The IP-10 protein assay performed on par with the QFT assay, with specificity of 98%, sensitivity of 87%, and AUC of 0.98. We have provided proof of high technical performance of a molecular assay detecting IP-10 mRNA expression. As a diagnostic tool, this assay would gain from further optimization, especially on the kinetics of IP-10 mRNA expression.

Interferon gamma release assays for Diagnostic Evaluation of Active tuberculosis (IDEA): test accuracy study and economic evaluation

BACKGROUND

Interferon gamma release assays (IGRAs) are blood tests recommended for the diagnosis of tuberculosis (TB) infection. There is currently uncertainty about the role and clinical utility of IGRAs in the diagnostic workup of suspected active TB in routine NHS clinical practice.

OBJECTIVES

To compare the diagnostic accuracy and cost-effectiveness of T-SPOT.TB ^® (Oxford Immunotec, Abingdon, UK) and QuantiFERON^® TB GOLD In-Tube (Cellestis, Carnegie, VIC, Australia) for diagnosis of suspected active TB and to estimate the diagnostic accuracy of second-generation IGRAs.

DESIGN

Prospective within-patient comparative diagnostic accuracy study.

SETTING

Secondary care.

PARTICIPANTS

Adults (aged ≥ 16 years) presenting as inpatients or outpatients at 12 NHS hospital trusts in London, Slough, Oxford, Leicester and Birmingham with suspected active TB.

INTERVENTIONS

The index tests [T-SPOT.TB and QuantiFERON GOLD In-Tube (QFT-GIT)] and new enzyme-linked immunospot assays utilising novel Mycobacterium tuberculosis antigens (Rv3615c, Rv2654, Rv3879c and Rv3873) were verified against a composite reference standard applied by a panel of clinical experts blinded to IGRA results.

MAIN OUTCOME MEASURES

Sensitivity, specificity, predictive values and likelihood ratios were calculated to determine diagnostic accuracy. A decision tree model was developed to calculate the incremental costs and incremental health utilities [quality-adjusted life-years (QALYs)] of changing from current practice to using an IGRA as an initial rule-out test.

RESULTS

A total of 363 patients had active TB (culture-confirmed and highly probable TB cases), 439 had no active TB and 43 had an indeterminate final diagnosis. Comparing T-SPOT.TB and QFT-GIT, the sensitivities [95% confidence interval (CI)] were 82.3% (95% CI 77.7% to 85.9%) and 67.3% (95% CI 62.1% to 72.2%), respectively, whereas specificities were 82.6% (95% CI 78.6% to 86.1%) and 80.4% (95% CI 76.1% to 84.1%), respectively. T-SPOT.TB was more sensitive than QFT-GIT (relative sensitivity 1.22, 95% CI 1.14 to 1.31; p < 0.001), but the specificities were similar (relative specificity 1.02, 95% CI 0.97 to 1.08; p = 0.3). For both IGRAs the sensitivity was lower and the specificity was higher for human immunodeficiency virus (HIV)-positive than for HIV-negative patients. The most promising novel antigen was Rv3615c. The added value of Rv3615c to T-SPOT.TB was a 9% (95% CI 5% to 12%) relative increase in sensitivity at the expense of specificity, which had a relative decrease of 7% (95% CI 4% to 10%). The use of current IGRA tests for ruling out active TB is unlikely to be considered cost-effective if a QALY was valued at £20,000 or £30,000. For T-SPOT.TB, the probability of being cost-effective for a willingness to pay of £20,000/QALY was 26% and 21%, when patients with indeterminate test results were excluded or included, respectively. In comparison, the QFT-GIT probabilities were 8% and 6%. Although the use of IGRAs is cost saving, the health detriment is large owing to delay in diagnosing active TB, leading to prolonged illness. There was substantial between-patient variation in the tests used in the diagnostic pathway.

LIMITATIONS

The recruitment target for the HIV co-infected population was not achieved.

CONCLUSIONS

Although T-SPOT.TB was more sensitive than QFT-GIT for the diagnosis of active TB, the tests are insufficiently sensitive for ruling out active TB in routine clinical practice in the UK. Novel assays offer some promise.

FUTURE WORK

The novel assays require evaluation in distinct clinical settings and in immunosuppressed patient groups.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and the NIHR Health Protection Research Unit in Respiratory Infections, Imperial College London, London, UK.

Diagnostic Potential of a PPE Protein Derived from Mycobacterium tuberculosis Beijing/K Strain

PURPOSE

The prevalence of Mycobacterium tuberculosis (M. tb) and the status of M. bovis BCG vaccination may affect host immune responses to M. tb antigens. Understanding of the predominant local M. tb strain and immune signatures induced by its strain-specific antigens may contribute to an improved diagnosis of tuberculosis (TB). The aim of this study was to determine immune responses to M. tb antigen which was identified from the hyper-virulent Beijing/K strain in South Korea.

MATERIALS AND METHODS

Pulmonary TB patients (n=52) and healthy subjects (n=92) including individuals with latent TB infection (n=31) were recruited, and QuantiFERON-TB Gold In-Tube tests were performed. The Beijing/K-antigen specific immune signatures were examined by diluted whole blood assays and multiplex bead arrays in a setting where nationwide BCG vaccination is employed.

RESULTS

Statistical analyses demonstrated that three [C-X-C motif chemokine (CXCL10), interleukin (IL)-6, interferon (IFN)-α] of 17 cytokines/chemokines distinguished active cases from healthy controls following stimulation with the Beijing/K-specific antigen. IFN-α also differentiated between active diseases and latent TB infection (p<0.01), and the detection rate of TB was dramatically increased in combination with IL-6 and CXCL10 at the highest levels of specificity (95-100%).

CONCLUSION

Our data indicate that immune signatures to the M. tb Beijing/K-specific antigen can provide useful information for improved TB diagnostics. The antigen may be developed as a diagnostic marker or a vaccine candidate, particularly in regions where the M. tb Beijing/K strain is endemic.

Prevalence of and risk factors associated with latent tuberculosis infection in a Latin American region

Tuberculosis (TB) represents a health problem in Colombia, and its control is focused on the search for contacts and treatment of TB cases underscoring the role of latent tuberculosis infection (LTBI) as a reservoir of Mycobacterium tuberculosis. The burden of LTBI in Colombia is unknown. We aimed to estimate the prevalence of LTBI and identify the associated risk factors. In this cross-sectional study, we recruited participants from four health care centers in Cali, Colombia. The participants were eligible if they were aged between 14 and 70 years, and all participants answered a survey evaluating their medical history and sociodemographic and lifestyle factors. LTBI status was based on tuberculin skin test (TST) positivity using two thresholds: ≥10 mm (TST-10) and ≥15 mm (TST-15). The magnitude of the associations between independent factors and dependent outcomes (LTBI status and TST induration) were evaluated by logistic regression and generalized linear models, respectively. A total of 589 individuals were included with TST positivity rates of 25.3% (TST-10) and 13.2% (TST-15). Logistic regression showed that being between age 40 and 69 years (OR = 7.28, 95% CI [1.62–32.7]), being male (OR = 1.71, 95% CI [1.04–2.84]), being employed (OR = 1.56, 95% CI [1.02–2.38]), and having a low intake of alcohol (OR = 2.40, 95% CI [1.13–5.11]) were risk factors for TST positivity, while living in the north zone (OR = 0.32, 95% CI [0.18–0.55]), living in the suburb zone (OR = 0.28, 95% CI [0.15–0.52]) and having a secondary education (OR = 0.49 95% CI [0.29–0.83]) lowered the risk of TST positivity. The generalized linear model showed that the previous predictors, as well as a low body mass index, had an effect on TST reaction size. The LTBI prevalence found in the population was moderate, reflecting the continuous transmission of M. tuberculosis. Social factors seem to play a decisive role in the risk of LTBI. Employed males, who are over 40 years of age, are overweight, have a lower level of education and have a low intake of alcohol (50–100 mL, once/week) should be a priority group for prophylactic treatment as a strategy for TB control in this city.

Effectiveness of BCG Vaccination Against Mycobacterium tuberculosis Infection in Adults: A Cross-sectional Analysis of a UK-Based Cohort

BACKGROUND

BCG appears to reduce acquisition of Mycobacterium tuberculosis infection in children, measured using interferon-gamma release assays (IGRAs). We explored whether BCG vaccination continues to be associated with decreased prevalence of M. tuberculosis infection in adults.

METHODS

We conducted a cross-sectional analysis of data from adult contacts of tuberculosis cases participating in a UK cohort study. Vaccine effectiveness (VE) of BCG, ascertained based on presence of a scar or vaccination history, against latent tuberculosis infection (LTBI), measured via IGRA, was assessed using multivariable logistic regression. The effects of age at BCG and time since vaccination were also explored.

RESULTS

Of 3453 recent tuberculosis contacts, 27.5% had LTBI. There was strong evidence of an association between BCG and LTBI (adjusted odds ratio = 0.70; 95% confidence interval, .56-.87; P = .0017) yielding a VE of 30%. VE declined with time since vaccination but there was evidence that LTBI prevalence was lower amongst vaccinated individuals even >20 years after vaccination, compared with nonvaccinated participants.

CONCLUSIONS

BCG is associated with lower prevalence of LTBI in adult contacts of tuberculosis. These results contribute to growing evidence that suggests BCG may protect against M. tuberculosis infection as well as disease. This has implications for immunization programs, vaccine development, and tuberculosis control efforts worldwide.

CLINICAL TRIALS REGISTRATION

NCT01162265.

Reece S, R. Martineau A, P. Kateete D. Detection of Mycobacterium tuberculosis DNA in CD34 + peripheral blood mononuclear cells of Ugandan adults with latent infection: a cross-sectional and nested prospective study

Background: Tuberculin skin test and interferon gamma release assay (IGRA) show limitations in diagnosing latent tuberculosis infection (LTBI) and poorly predict progression to active tuberculosis. This study will explore detection of Mycobacterium tuberculosis ( M.tb) DNA in CD34 + peripheral blood mononuclear cells (PBMCs) as a biomarker for LTBI and monitoring chemoprophylaxis response. Methods: In a cross-sectional study, 120 household contacts (60 HIV positive and 60 HIV negative) will be recruited. Also, 10 patients with sputum positive pulmonary tuberculosis and 10 visitors from low incidence countries with no history of TB treatment will be recruited as positive and negative controls, respectively. Participants will donate 100 ml (50 ml for TB patients) of blood to isolate PBMCs using density gradient centrifugation. Isolated PBMCs will be separated into CD34 + and CD34 - enriched cellular fractions. DNA from each fraction will be purified, quantified and subjected to droplet digital PCR targeting IS6110 (a M.tb Complex multi-copy gene) and rpoB, a single copy gene. Also, 4 ml of blood will be drawn for IGRA. In a nested prospective study, 60 HIV positive participants will be given 300 mg of Isoniazid Preventive Therapy (IPT) daily for six months, after which they will donate a second 100 ml blood sample that will be processed as described above. Data from the cross-sectional study will be analysed to determine the proportion of individuals in whom M.tb DNA is detectable in CD34 + and CD34 - fractions and number of M.tb genomes present. Data from the prospective study will be analysed to compare the proportion of individuals with detectable M.tb DNA in CD34 + and CD34 - fractions, and median M.tb genome copy number, post vs pre-IPT. Discussion: This study will determine whether detection of M.tb DNA in CD34 + PBMCs holds promise as a biomarker for LTBI and monitoring chemoprophylaxis response.

Tuberculosis Skin Test Screening in the National Tuberculosis Program of Trinidad and Tobago

Globally, a quarter of the population is infected with tuberculosis (TB), caused by Mycobacterium tuberculosis. About 5–10% of latent TB infections (LTBI) progress to active disease during the lifetime. Prevention of TB and treating LTBI is a critical component of the World Health Organization’s (WHO) End TB Strategy. This study aims to examine the screening practices for prevention and treatment employed by the National Tuberculosis Program of Trinidad and Tobago in comparison to the WHO’s standard guidelines. A cross-sectional retrospective study was conducted from the TB registers (2018–2019) for persons aged 18 years and above with recorded tuberculin skin test reactions (TST). Bivariate comparisons for categorical variables were made using Chi-square or Fisher’s exact test. Binary logistic regression was used for exploring predictors of TST positivity with adjustment for demographic confounders in multivariable models. Of the total 1972 eligible entries studied, 384 (19.4%) individuals were tested positive with TST. TB contact screening (aOR 2.49; 95% CI 1.65, 3.75) and Bacillus Calmette–Guerin (BCG) vaccination status (aOR 1.66; 95% CI, 1.24 to 2.22) were associated with a positive TST reaction, whereas, preplacement screening failed to show such association when compared to those screened as suspect cases. The findings suggest that TB contact screening and positive BCG vaccination status are associated with TST positivity independent of age and gender.

Significance of Mantoux Test and Its Correlation with Erythrocyte Sedimentation Rate in Pediatric Cleft Lip and Palate Patients: An Institutional Perspective

Aims and Objective

This retrospective study evaluates the importance of Mantoux test and Erythrocyte Sedimentation Rate (ESR) levels in pediatric tuberculosis and also signifies the impact of this test in treatment planning and implementation in pediatric cleft lip and palate patients.

Methodology

Retrospective analyses of the records of 2010 pediatric cleft lip and palate patients below 5 years age were performed, and patients with elevated ESR subjected to Mantoux test were identified. The parameters included were age, sex, ESR levels, type of cleft, history of contact with TB & BCG vaccination, Mantoux conversion, chest X-ray findings, number of smear-positive pulmonary tuberculosis.

Results

Out of 2010 patients with cleft lip and palate, 180 patients were subjected to Mantoux test due to high ESR levels. Among these, 54 (30%) patients found as Mantoux positive, in which 45 patients were identified as smear-positive pulmonary tuberculosis patients; as a result, surgery was deferred and they underwent antituberculous therapy. Most of the Mantoux-positive cases were found in patients with ESR range of 20-30 mm, i.e., 38 patients (71%), and common age group was 6 months-1 year. The most commonly involved cleft type was: unilateral cleft lip and palate having 36 patients (66.7%). The overall incidence of tuberculosis was 2%.

Conclusion

Although the correlation of Mantoux test with elevated ESR was not significant in our study, it could be of value as a screening tool along with the Mantoux test, which is sensitive but nonspecific in the diagnosis of active tuberculosis. Together, they could be a valuable screening tool in any community or hospital for diagnosis of the disease.

Neonatal BCG vaccination and child survival in TB-exposed and TB-unexposed children: a prospective cohort study

OBJECTIVES

To assess the association between neonatal BCG vaccination and mortality between 28 days and 3 years of age among tuberculosis (TB)-exposed and TB-unexposed children.

DESIGN

Prospective cohort study.

SETTING

Bandim Health Project runs an urban Health and Demographic Surveillance site in Guinea-Bissau with registration of mortality, vaccination status and TB cases.

PARTICIPANTS

Children entered the analysis when their vaccination card was inspected after 28 days of age and remained under surveillance to 3 years of age. Children residing in the same house as a TB case were classified as TB-exposed from 3 months prior to case registration to the end of follow-up.

METHODS

Using Cox-proportional hazards models with age as underlying time scale, we compared mortality of children with and without neonatal BCG between October 2003 and September 2017.

MAIN OUTCOME MEASURE

HR for neonatal BCG compared with no neonatal BCG by TB-exposure status.

RESULTS

Among the 39 421 children who entered the analyses, 3022 (8%) had observation time as TB-exposed. In total, 84% of children received neonatal BCG. Children with neonatal BCG had lower mortality both in TB-exposed (adjusted HR: 0.57 (0.26 to 1.27)) and in TB-unexposed children (HR: 0.57 (95% CI 0.47 to 0.69)) than children without neonatal BCG. Children exposed to TB had higher mortality than TB-unexposed children if they had not received neonatal BCG.

CONCLUSION

Neonatal BCG vaccination was associated with lower mortality among both TB-exposed and TB-unexposed children, consistent with neonatal BCG vaccination having beneficial non-specific effects. Interventions to increase timely BCG vaccination are urgently warranted.

Comparison of tuberculin skin test and QuantiFERON-TB Gold In-Tube test in Bacillus Calmette-Guerin-vaccinated children

Objectives:

The aim of this study is to determine the concordance between QuantiFERON-TB Gold In-Tube (QFT-GIT) and tuberculin skin test (TST) in children vaccinated with Bacillus Calmette–Guerin (BCG).

Methods:

This cross-sectional study was done at a pediatric tertiary care center in 33 BCG-vaccinated children aged 6 months–15 years suspected of Mycobacterium tuberculosis infection or in contact with a patient with open tuberculosis (TB). All patients were tested for TST with purified protein derivative-S 5 tuberculin units and QFT-GIT assays. Concordance was evaluated between TST and QFT assay by kappa coefficient (k). Agreement between the tests was classified into categories: poor if k < 0.20, fair (k = 0.21–0.40), moderate (k = 0.41–0.60), good (k = 0.61–0.80), and very good (k = 0.81–1.00).

Results:

Both the TST and QFT assay were positive in 13 and negative in eight children, respectively, resulting in an agreement of 63% (κ = 0.31). Eight children were <4 years of age of which only one patient had a positive TST and QFT-GIT, and TST and QFT-GIT were negative in two patients resulting in an agreement of 37.5% (κ = 0.063). Among children 4 years of age and older, 12 patients had a positive TST and QFT-GIT and 6 patients had a negative TST and QFT-GIT resulting in an agreement of 72% (κ = 0.41). Among 12 children who had been in contact with an adult having open TB, both the TST and QFT-GIT were positive in 6 patients and negative in two patients, respectively, resulting in an agreement of 66% (κ = 0.41). TST specificity was only 29.6% with a positive predictive value of 42.4% as compared to QFT-GIT. Among children <4 years of age, TST specificity was only 28.6% with a positive predictive rate of 16.7%, and among children >4 years of age, TST specificity was 50% with a positive predictive value of 66.7%. In patients with contact with a patient having TB, TST specificity was 33.3%. Considering TST of 15 mm and above as positive, TST specificity increased to 63.2% and a positive predictive value was 56.3%.

Conclusion:

The concordance of TST and QFT-GIT is low in children with previous BCG vaccination and especially in children <4 years of age. QFT-GIT may help to rule out false-positive TST.

QuantiFERON-TB Gold In-Tube test performance in a large pediatric population investigated for suspected tuberculosis infection

BACKGROUND

The performance of QuantiFERON-TB Gold In-Tube (QTF-IT) in children is under debate, especially in those under 5 years of age. Moreover, interpretation of discordant QFT-IT/Tuberculin-Skin-Test (TST) results remains controversial. This study aims at studying the sensitivity of QFT-IT and TST in children with active TB cases and exploring risk factors associated with discordant TST+/QFT-IT-.

METHODS

Children consecutively referred to one single pediatric center between 2010 and 2017 for suspected tuberculosis infection (TB) were enrolled. All children underwent clinical evaluation, TST and QFT-IT. Sensitivity of QFT-IT and TST in active TB cases and risk factors associated with discordant TST+/QFT-IT- results were assessed. Uni- and multi-variate logistic regression analyses were performed.

RESULTS

Overall, 4631 children (median age 5.67 years) were enrolled, and 205 active TB cases were diagnosed (83 microbiologically confirmed). A high QFT-IT sensitivity was observed in children between 2 and 4 years of age (95.0%; 95%CI: 85.4-100) and in those between 5 and 18 years (89.1%; 95%CI:79.2-99.2) with microbiologically confirmed active TB. However, sensitivity was suboptimal in children younger than 2 years (84.6%; 95%CI: 65.0-100). Independent risk factors associated with discordant TST+/QFT-IT- results in children with latent tuberculosis infection (LTBI) were previous BCG vaccination (aOR:2.18; 95%CI:1.33-3.58; p = 0.002), age <2 years vs. 5-18 years (aOR:7.54; 95%CI:2.52-22.59; p < 0.0001), age 2-4 years vs. 5-18 years (aOR:4.63; 95%CI:2.66-8.06; p < 0.0001), and investigation for screening rather than for contact with a suspected or confirmed case (aOR:3.58; 95%CI:2.30-5.59; p < 0.0001).

CONCLUSION

Our data suggest that QFT-IT might be used as unique assay in children over 2 years of age investigated for recent immigration/adoption screening and in cases of recent low risk TB contact. This approach could considerably reduce the number of children undergoing pharmacological treatment. Conversely, both tests are recommended in cases of strong clinical suspicion or high risk TB contact in children less than 5 years of age, in order to avoid misdiagnosis.

Comparing QuantiFERON-TB Gold Plus with Other Tests To Diagnose Mycobacterium tuberculosis Infection

The fourth-generation QuantiFERON test for tuberculosis infection, QuantiFERON-TB Gold Plus (QFT-Plus) has replaced the earlier version, QuantiFERON-TB Gold In-Tube (QFT-GIT). A clinical need exists for information about agreement between QFT-Plus and other tests. We conducted this study to assess agreement of test results for QFT-Plus with those of QuantiFERON-TB Gold In-Tube (QFT-GIT), T-SPOT.TB (T-SPOT), and the tuberculin skin test (TST). Persons at high risk of latent tuberculosis infection (LTBI) and/or progression to tuberculosis (TB) disease were enrolled at the 10 sites of the Tuberculosis Epidemiologic Studies Consortium from October 2016 through May 2017; each participant received all four tests. Cohen's kappa (κ) and Wilcoxon signed-rank test compared qualitative and quantitative results of QFT-Plus with the other tests. Test results for 506 participants showed 94% agreement between QFT-Plus and QFT-GIT, with 19% positive and 75% negative results. When the tests disagreed, it was most often in the direction of QFT-GIT negative/QFT-Plus positive. QFT-Plus had similar concordance as QFT-GIT with TST (77% and 77%, respectively) and T-SPOT (92% and 91%, respectively). The study showed high agreement between QFT-GIT and QFT-Plus in a direct comparison. Both tests had similar agreement with TST and T-SPOT.

QuantiFERON-TB Performs Better in Children, Including Infants, than in Adults with Active Tuberculosis: a Multicenter Study

Immunological tests, including the QuantiFERON-TB Gold In-Tube (QFT-IT) assay, represent an important aid for diagnosing active tuberculosis (TB) and latent TB infections in children, but concerns about their use in children <5 years of age persist. This is a multicenter retrospective study comparing a population of 226 children to 521 adults with pulmonary or extrapulmonary TB. The aim was to evaluate the QFT-IT performance, analyzing both qualitative and quantitative results, according to age, birthplace, and disease localization. Compared to culture, QFT-IT sensitivity was 93.9%, 100%, and 94.4% in children ≤2, 2 to 5, and 5 to 16 years of age, respectively, and was significantly higher than that in adults (81.0%) (P < 0.0001). The rate of indeterminate test results for children (2.2%) was significantly lower than that for adults (5.2%) (P < 0.0001). In children, QFT-IT sensitivity was not affected by disease localization or birthplace (Italy born versus foreign born). Interferon gamma (IFN-γ) values in response to TB antigen and mitogen were significantly higher in children than in adults (TB antigen, median of 10 versus 1.66 IU IFN-γ/ml; mitogen, median of 10 versus 6.70 IU IFN-γ/ml; P < 0.0001). In summary, this study supports the use of QFT-IT as a complementary test for the diagnosis of pediatric TB even under 2 years of age. Our observations could be applicable to the new version of the test, QuantiFERON-TB Gold Plus, which has recently been shown to have similar sensitivity in active TB, although data in children are still lacking.

Diagnostic value of the interferon-γ release assay for tuberculosis infection in patients with Behçet's disease

Background

To investigate the diagnostic value of the interferon-γ release assay (IGRA) for detecting tuberculosis (TB) infection in patients with Behçet’s disease (BD).

Methods

We retrospective analyzed the data collected from 173 BD patients hospitalized between 2010 and 2015. Ninety-nine healthy volunteers were enrolled as a control group. IGRA was performed using T-SPOT.TB. The diagnosis of active TB (ATB) was based on clinical, radiological, microbiological, histopathological information and the response to anti-TB therapy. Latent TB (LTB) infection was defined as asymptomatic patients with positive T-SPOT.TB.

Results

TB infection was documented in 59 BD patients (34.1%). The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio of T-SPOT.TB for the diagnosis of ATB were 88.9%, 74.8%, 29.1%, 98.3%, 3.53 and 0.15, respectively. The receiver-operating-characteristic curve demonstrated that spot-forming cells (SFCs) of 70/10⁶ PBMC was the optimal cutoff for diagnosing ATB, with an area under the curve of 0.891. Furthermore, the median SFCs in ATB group was significantly higher than those in LTB infection (466/10⁶ PBMC vs. 68/10⁶ PBMC, p = 0.007) or previous TB infection (466/10⁶ PBMC vs. 96/10⁶ PBMC, p = 0.018). A significant discrepancy between T-SPOT.TB and tuberculin skin test was noted (kappa coefficient = 0.391, p = 0.002).

Conclusions

T-SPOT.TB, an IGRA, may assist in the diagnosis of ATB in BD patients, and the higher SFCs suggest ATB in BD patients.

Global Variations and Challenges With Tubercular Uveitis in the Collaborative Ocular Tuberculosis Study

Purpose

The aim of this study was to examine regional variation management practices and outcomes for tubercular uveitis (TBU).

Methods

In this retrospective multinational cohort study, patients from 25 international eye care centers diagnosed with TBU with a minimum follow-up of 1 year were included. The geographic variation in treatment outcomes on survival analysis in patients with TBU were analyzed. Treatment failure is defined as a persistence or recurrence of inflammation within 6 months of completing antitubercular therapy, the inability to taper oral corticosteroids to less than 10 mg/d or topical corticosteroid drops to less than 2 drops daily, and/or recalcitrant inflammation necessitating corticosteroid-sparing immunosuppressive therapy.

Results

Records of 945 patients (1485 eyes) with TBU were analyzed. The mean age was 41.3 ± 15.0 years (range, 4-90 years), with more males (52.9%, n = 500/945) and predominant Asian ethnicity (74.4%, n = 690/927). Most patients had no symptoms (92.0%, n = 655/712) or history (76.7%, n = 604/787) suggestive of pulmonary tuberculosis (TB). Some patients had evidence of inactive pulmonary TB on chest X-rays (26.9%, n = 189/702) or chest computed tomography (68.6%, n = 109/159). Patients with western geographic origin (log-rank = 6.47, P = 0.010), African or Hispanic ethnicity (log-rank = 19.9, P < 0.001), and positive immigrant status (log-rank = 4.89, P = 0.027) had poorer survival outcomes.

Conclusions

This is a first-ever multinational analysis of TBU that highlights regional differences in treatment outcomes for this elusive form of extrapulmonary TB. Our findings will help in the design of future collaborative studies together with internists to develop best practice guidelines for this early opportunity to address TB infection and strategies to target at-risk groups such as immigrants.

Latent tuberculosis infection in transplant candidates: a systematic review and meta-analysis on TST and IGRA

INTRODUCTION

The diagnostic accuracy of interferon-gamma release assays (IGRAs) and the tuberculin skin test (TST) for latent tuberculosis infection (LTBI) in transplant candidates is uncertain.

METHODS

Pubmed, Embase and Cochrane library were searched to identify relevant studies. Quality of included studies was assessed with RevMan5 software (via GUADAS2 checklist). Accuracy measures of IGRAs and TST assays (sensitivity, specificity and others) were pooled with random effects model. Data were analyzed by STATA and Meta-DiSc.

RESULTS

Twenty-eight studies were selected for full review, and 16 were included in the final analysis. The pooled sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) for TST were 46% [95% confidence interval (CI) 38-54%], 86% (95% CI 75-93%), 46.3% (95% CI 40-52), 88.7% (95% CI 87-89), 3.3 (95% CI 1.6-6.4), 0.63 (95% CI 0.52-0.77) and 5 (95% CI 2-12), respectively. For QFT-G, the pooled sensitivity, specificity, PPV, NPV, PLR, NLR, and DOR were 58% (95% CI 41-73%), 89% (95% CI 77-95%), 72.7% (95% CI 68-76), 80.6% (95% CI 78-82), 5.3 (95% CI 2.0-14.0), 0.47 (95% CI 0.30-0.75) and 11 (95% CI 3-46), respectively. Likewise, for T-SPOT.TB, the pooled sensitivity, specificity, PPV, NPV, PLR, NLR, and DOR were 55% (95% CI 40-70%), 92% (95% CI 87-95%), 60.4% (95% CI 47-72), 90.2% (95% CI 86-92), 6.7 (95% CI 4.0-11.1), 0.52 (95% CI 0.31-0.85) and 16 (95% CI 7-37), respectively.

CONCLUSIONS

IGRAs were more sensitive and specific than the TST with regard to the diagnosis of LTBI in the transplant candidates. They have added value and can be complementary to TST.

Predictors of discordant latent tuberculosis infection test results amongst South African health care workers

BACKGROUND

The tuberculin skin test (TST) and interferon-gamma-release-assays (IGRAs) are utilized in screening programmes for presumed latent tuberculosis infection (LTBI) in health care workers (HCWs). However, inter-test comparison yields high rates of discordance, which is poorly understood. The aim of the study was therefore to identify factors associated with discordance amongst HCWs in a TB and HIV endemic setting.

METHODS

505 HCWs were screened for LTBI in South Africa using the TST and two IGRA assays (QuantiFERON-TB-Gold-In-Tube (QFT-GIT) and TSPOT.TB). Factors associated with discordance were analyzed using a multinomial logistic regression model.

RESULTS

TST-IGRA discordance was negatively associated with longer duration of employment for both TSPOT.TB (OR = 0.92; 95% confidence interval (CI) 0.85-0.99) and QFT-GIT (OR = 0.90; 95% CI 0.84-0.96). Marked test discordance occurred in HIV-infected individuals who were more likely to have TSPOT.TB + ve / TST-ve discordance (OR 4.44; 95% CI 1.14-17.27) or TSPOT.TB + ve / QFT-GIT-ve test discordance (OR 5.72; 95% CI 1.95-16.78). Those engaged in home care were less likely to have QFT-GIT + ve/TSPOT.TB -ve / discordance (OR 0.32; 95% CI 0.10-0.95).

CONCLUSION

The marked TST-IGRA and IGRA-IGRA discordance in HIV-infected individuals suggest greater sensitivity of TSPOT.TB in immunocompromised persons or potential greater reactivity of TSPOT.TB in this population.

Infectious Diseases in Internationally Adopted Children and Intercountry Discrepancies Among Screening Protocols, A Narrative Review

Internationally adopted children (IAC) require thorough health assessments at time of arrival in the host country. As these children are at higher risk for infectious diseases, such as gastrointestinal parasites, tuberculosis, hepatitis, syphilis, and human immunodeficiency virus, early diagnosis of infectious diseases is fundamental for the optimal management of the child and, also, to reduce the risk of transmission to the adopting community. Comparative analysis of the screening protocols adopted in Europe, the United States, and Canada revealed different approaches to the adopted children. A homogeneous and internationally shared standard of care in the management of IAC should be provided.

Screening of healthcare workers for latent tuberculosis infection in the low tuberculosis burden country: QuantiFERON-TB gold in tube test or tuberculin skin test?

Healthcare workers (HCWs) are an important group at increased risk for exposure to various infectious agents including Mycobacterium tuberculosis. Unfortunately, there is very limited data on the prevalence of latent tuberculosis infection (LTBI) among HCWs in Iran. The aim of this study was to analyze the prevalence of LTBI among HCW's of Children Medical Center (CMC), an Iranian referral hospital, and to compare the feasibility of using tuberculin skin test (TST) and QuantiFERON-TB gold in tube test (QFT-GIT) to screen the LTBI among this population. Informed consent was obtained before the study questionnaire was completed. Participants were then evaluated for LTBI using QFT-GIT test followed immediately by TST. The prevalence of latent TB infection in the 101 HCWs, based on QFT-GIT positivity, was 47% (n = 47), while based on TST test a higher prevalence was observed (n = 57, 57%). Forty-five (45%) subjects were positive for both tests, whereas 14 (14%) were positive by either test. Among the TST positive cases, 21% (n = 12) were negative for QFT-GIT. The overall agreement of TST and QFT-GIT was 86% ([45 + 42]/101] and a moderate correlation between these two tests was observed (Kappa value 0.72). The use of QFT-GIT test as a second step in TST-positive cases offers an appropriate tool for LTBI detection in our country where all HCWs are BCG-vaccinated. To enable the effective control and prevention of TB in healthcare settings in Iran, specific and detailed guidelines for dealing with LTBI are highly required. All newly hired HCWs should receive baseline testing for LTBI before commencing employment. In addition, HCWs who work in high-risk departments should receive regular follow-up screening for LTBI.

Comparison of IFN-γ Levels in Children with Tuberculosis Disease (TB) and Latent Tuberculosis Infection (LTBI)

AIM:

This study aimed to evaluate the importance of IFN-γ in the diagnosis of pediatric TB and LTBI and to compare the IFN-γ levels.

METHODS:

We analysed 100 patients examined for possible M. tuberculosis infection or disease at the Institute of Respiratory Diseases in Children, Kozle, Skopje. Patients were divided into 2 groups: TB disease and LTBI. The following parameters were analyzed: demographic characteristics, history of previous exposure to active TB, BCG vaccination and presence of BCG scar, lung X-ray findings, tuberculin skin test by the Monteux method and the value of INF-γ according to the Quantiferon TB gold test, direct samples of acid-alcohol-resistant bacilli of sputum and Löwenstein Jensen cultures. Informed parental consent was obtained for each child included in the study.

RESULTS:

In the LTBI group 60.9% had a scar from the vaccination while in the TB group 50% had BCG scar. TST induration diameters in children with or without BCG scar were significantly larger in patients with active TB. Children with active TB had significantly higher IFN-γ levels than children with LTBI. The IFN-γ for the cut-off of 0.35 IU/ml, has 64% sensitivity for detection of LTBI, versus 80.6% sensitivity for active disease. Children with close TB contact had significantly higher IFN-γ levels. Correlation between TST induration diameter and IFN-γ levels was stronger in the TB group.

CONCLUSION:

IFN-γ levels are significantly higher in children with active TB, and children with close contact with TB patient. It has better sensitivity in active TB. Using both tests (IFN-γ and TST) can improve the diagnose of LTBI and TB in countries where vaccination with BCG is widespread.