Interferon-Gamma Release Assays versus Tuberculin Skin Testing for the Diagnosis of Latent Tuberculosis Infection: An Overview of the Evidence

Utility of interferon-gamma releasing assay for the diagnosis of active tuberculosis in children: A systematic review and meta-analysis

INTRODUCTION

The accurate diagnosis of tuberculosis (TB) in children is essential for its effective management and control. Reliable diagnostic tools that are currently available for identifying TB infection include the in vivo tuberculosis skin test (TST) and ex vivo interferon-gamma release assays (IGRAs). This systematic review and meta-analysis aimed to evaluate the diagnostic accuracy of IGRAs in children.

METHODS

Of the 768 screened studies, 47 met the eligibility criteria. Data from 9065 patients, including 1086 (12.0 %) with confirmed TB, were included in the analysis. The overall quality of the included studies, assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, was unclear.

RESULTS

The calculated pooled sensitivity and specificity of IGRAs in children were 0.85 (95 % confidence interval [CI]: 0.79-0.89) and 0.94 (95 % CI: 0.88-0.97), respectively. Subpopulation analysis revealed that the sensitivities and specificities were as follows: QuantiFERON tests: 0.83 (95 % CI: 0.74-0.89) and 0.93 (95 % CI: 0.87-0.96), T-SPOT: 0.87 (95 % CI: 0.79-0.91) and 0.99 (95 % CI: 0.85-1.00), IGRAs in children under 15 years: 0.77 (95 % CI: 0.43-0.94) and 0.96 (95 % CI: 0.84-0.97), and IGRAs in children under 5 years: 0.85 (95 % CI: 0.52-0.97) and 0.94 (95 % CI: 0.90-0.99), respectively.

CONCLUSIONS

This study demonstrated that the sensitivity and specificity of the IGRAs in children were moderate and high, respectively. Therefore, the IGRAs may be useful for detecting TB infection in children.

CLINICAL TRIAL REGISTRATION

The review protocol was prospectively registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN000046737).

M. tuberculosis Infection Attributable to Exposure in Social Networks of Tuberculosis Cases in an Urban African Community

Background

The persistence of tuberculosis today and its global disparity send a powerful message that effective tuberculosis control must respond to its regional epidemiology. Active case finding through contact investigation is a standard protocol used for tuberculosis control, but its effectiveness has not been established, especially in endemic areas.

Methods

To quantify the potential effectiveness of contact investigation in Kampala, Uganda, we used a cross-sectional design to evaluate the social networks of 123 tuberculosis index cases and 124 controls without tuberculosis.

Results

Tuberculous infection was present in 515 of 989 tuberculosis case contacts (52.1%) and 396 of 1026 control contacts (38.6%; adjusted prevalence ratio, 1.4; 95% CI, 1.3-1.6). The proportion of infected participants with known exposure within the social network of the tuberculosis case was 35%. The population-attributable fraction was 11.1% for any known exposure, with 7.3% attributable to household exposure and 3.4% attributable to extrahousehold exposure.

Conclusions

This low population-attributable fraction indicates that contact tracing in the social networks of index cases will have only a modest effect in reducing tuberculous infection in a community. New approaches to community-level active case finding are needed.

Challenges and Triumphs: Unusual Presentation of Tuberculosis in the Cuboid Bone Successfully Managed Through Surgical and Medical Intervention

This case report describes the unusual presentation of tuberculosis (TB) affecting the cuboid bone in a 16-year-old male patient. The patient presented with a one-year history of progressive foot pain, a discharging sinus, evening rise of temperature, weight loss, and loss of appetite. Clinical examination revealed soft tissue swelling and the presence of caseous material oozing from the sinus. Emergency debridement and curettage were performed, and bone cementing was carried out. An intraoperative sample was sent for a culture sensitivity test, histological analysis, and cartridge-based nucleic acid amplification test (CBNAAT). Histopathological examination, CBNAAT, and culture and sensitivity tests confirmed the diagnosis of Mycobacterium tuberculosis infection. Post-operatively, anti-tuberculous treatment was started. The patient fully recovered from TB of the cuboid.

Diagnostic performance of a novel ESAT6-CFP10 skin test for tuberculosis infection in school tuberculosis outbreak in China

Background

The ESAT6-CFP10 (EC) skin test is recommended by the World Health Organization for latent tuberculosis infection (LTBI). However, it is still unknown how the EC skin test performs in students during a school tuberculosis outbreak.

Methods

We conducted an epidemiological investigation to assess the performance of the EC skin test in this high-risk population.

Results

A total of 9 active student patients were confirmed in the same class as the index case, with an incidence rate of 18.0% (9/50). Among the 50 close contacts, 14 (28%) were over 15 years old and had a chest X-ray (CXR), and none of them had abnormal CXR findings. The rates of positive tuberculin skin test (TST) ≥ 5 mm and < 10 mm, ≥ 10 mm and < 15 mm, and ≥ 15 mm were 12.0% (6/50), 16.0% (8/50), and 10.0% (5/50), respectively. On the second screening, 44 students with the same class as the index case had the EC skin test, of which 31 (70.5%) had positive EC tests. All patients had negative sputum smear results, of whom 4 (44.4%) had positive Xpert results; three had a TST induration diameter between 5 mm and 10 mm, but all of them had an EC diameter > 15 mm; 5 (55.6%) had abnormal CXR results, but all the confirmed patients had abnormal CT results; Except for four cases that were diagnosed by Xpert, the remaining five were confirmed by CT scan.

Conclusion

The novel EC skin test performed well in students during the school tuberculosis outbreak. In some special conditions, such as when the index case is bacteriologically positive for tuberculosis and the rate of LTBI is higher than the average for the local same-age group, secondary screening is recommended 2-3 months after the first screening. Furthermore, we cannot ignore the role of CT in the diagnosis of early student tuberculosis.

Tuberculosis in older adults: challenges and best practices in the Western Pacific Region

The Western Pacific has one of the fastest-growing older adult populations globally, and tuberculosis (TB) remains one of the foremost infectious causes of disease and death in the region. Older adults are at higher risk of TB due to immunosenescence, comorbidities, and increased institutionalisation. Atypical symptoms and reduced access to health services may delay care-seeking and TB diagnosis, while co-morbidity and increased risk of adverse drug reactions complicate TB treatment. Post-TB sequelae and socioeconomic challenges may decrease the quality of life after TB treatment completion. Despite their high disease burden and special challenges, there is a lack of regionally coordinated policies and guidelines to manage TB among older adults. Routine TB screening at aged-care facilities, age-friendly infrastructure and services, awareness of atypical TB features, integration of TB and non-communicable diseases services, and person-centred approaches to treatment support could improve TB management among older adults. Addressing these challenges and adopting the best practices identified should inform policy formulation and implementation.

Funding

This project was funded by 1) the World Health Organization Regional Office for the Western Pacific, with financial contributions from the Government of the Republic of Korea through the Korean Disease Control and Prevention Agency and the Government of Japan through the Ministry of Health, Labour and Welfare, and 2) NUS Start-up Grant. The funders had no role in the paper design, collection, analysis, and interpretation of data and in writing of the paper.

Innovative Therapeutic Approaches Based on Nanotechnology for the Treatment and Management of Tuberculosis

Tuberculosis (TB), derived from bacterium named Mycobacterium tuberculosis, has become one of the worst infectious and contagious illnesses in the world after HIV/AIDS. Long-term therapy, a high pill burden, lack of compliance, and strict management regimens are disadvantages which resulted in the extensively drug-resistant (XDR) along with multidrug-resistant (MDR) in the treatment of TB. One of the main thrust areas for the current scenario is the development of innovative intervention tools for early diagnosis and therapeutics towards Mycobacterium tuberculosis (MTB). This review discusses various nanotherapeutic agents that have been developed for MTB diagnostics, anti-TB drugs and vaccine. Undoubtedly, the concept of employing nanoparticles (NPs) has strong potential in this therapy and offers impressive outcomes to conquer the disease. Nanocarriers with different types were designed for drug delivery applications via various administration methods. Controlling and maintaining the drug release might be an example of the benefits of utilizing a drug-loaded NP in TB therapy over conventional drug therapy. Furthermore, the drug-encapsulated NP is able to lessen dosage regimen and can resolve the problems of insufficient compliance. Over the past decade, NPs were developed in both diagnostic and therapeutic methods, while on the other hand, the therapeutic system has increased. These "theranostic" NPs were designed for nuclear imaging, optical imaging, ultrasound, imaging with magnetic resonance and the computed tomography, which includes both single-photon computed tomography and positron emission tomography. More specifically, the current manuscript focuses on the status of therapeutic and diagnostic approaches in the treatment of TB.

Management of Latent Tuberculosis Infection Based on T-SPOT.TB Assay in Patients with Hematological Malignancies

Background and objective

Patients with latent tuberculosis infection (LTBI) receiving chemotherapy for hematological malignancy (HM) are at high risk of developing active tuberculosis (TB) infection. The aim of this study is to show real-life data and results of the T-SPOT test and preventive isoniazid (INH) therapy in pre-chemotherapy LTBI screening in the HM patient group.

Methods

This retrospective study includes 209 HM patients who had T-SPOT test between 2016 and 2021 in Sultan 2. Abdulhamid Han Training and Research Hospital in Istanbul, Turkey.

Results

The prevalence of LTBI was 26.8% in 209 patients (n=56). Preventive INH therapy was initiated in 82.1% (n=46) of 56 patients with LTBI. 23.9% (n=11) of the 46 patients who received preventive INH therapy were unable to complete the treatment. Nine patients died due to malignancy; one was lost to follow-up, and only one had to stop INH treatment due to elevated liver enzymes. Elevated liver enzymes occurred in 4 (8.7%) patients using INH, while gastrointestinal symptoms occurred in 3 (6.5%) patients. Active TB infection emerged in none of the T-SPOT positive or indeterminate individuals but in one HIV(+) patient in the T-SPOT negative group. The active TB infection incidence rate was 217 cases/100.000hab/year (95% CI, 29-748).

Conclusions

INH treatment was generally well tolerated, and very few serious drug-related side effects were observed. Although LTBI cannot be demonstrated in patients with HIV(+) HM who are scheduled for chemotherapy, these patients should be closely monitored for the development of active TB infection.

Insight into diagnosis of pleural tuberculosis with special focus on nucleic acid amplification tests

INTRODUCTION

Pleural tuberculosis (TB) is the archetype of extrapulmonary TB (EPTB), which mainly affects the pleural space and leads to exudative pleural effusion. Diagnosis of pleural TB is a difficult task predominantly due to atypical clinical presentations and sparse bacillary load in clinical specimens.

AREA COVERED

We reviewed the current literature on the globally existing conventional/latest modalities for diagnosing pleural TB. Bacteriological examination (smear/culture), tuberculin skin testing/interferon-γ release assays, biochemical testing, imaging and histopathological/cytological examination are the main modalities. Moreover, nucleic acid amplification tests (NAATs), i.e. loop-mediated isothermal amplification, PCR/multiplex-PCR, nested-PCR, real-time PCR and GeneXpert® MTB/RIF are being utilized. Currently, GeneXpert Ultra, Truenat MTB^TM, detection of circulating Mycobacterium tuberculosis (Mtb) cell-free DNA by NAATs, aptamer-linked immobilized sorbent assay and immuno-PCR (I-PCR) have also been exploited.

EXPERT OPINION

Routine tests are not adequate for effective pleural TB diagnosis. The latest molecular/immunological tests as discussed above, and the other tools, i.e. real-time I-PCR/nanoparticle-based I-PCR and identification of Mtb biomarkers within urinary/serum extracellular vesicles being utilized for pulmonary TB and other EPTB types may also be exploited to diagnose pleural TB. Reliable diagnosis and early therapy would reduce the serious complications associated with pleural TB, i.e. TB empyema, pleural fibrosis, etc.

Comparative diagnosis of bovine tuberculosis using single intradermal cervical tuberculin technique, conventional methods, enzyme-linked immunosorbent assay, and the gamma-interferon assay

Background and Aim:

Bovine tuberculosis (TB) is a zoonotic disease that causes huge economic losses. This study aimed to compare the result obtained from the single intradermal test, conventional methods (culture and microscopy), gamma-interferon (IFN-γ) assay, and indirect enzyme-linked immunosorbent assay (ELISA) to diagnose bovine TB.

Materials and Methods:

This study evaluated 2913 animals from milk farms in Cairo, El-Sharkia, and El-Qalyubia Governorates by single intradermal cervical tuberculin technique (SICTT), ELISA, and IFN-γ assay.

Results:

Of the 2913 dairy cows surveyed, 3.7% yielded positive results. Culture prepared samples on Lowenstein-Jensen and Middlebrook 7H10 agar media yielded 52 (1.85%) isolates of Mycobacterium spp. from 2805 milk samples that yielded negative tuberculin reactions and 56 (51.85%) isolates of Mycobacterium spp. were recovered from 108 lymph node samples from positive cases. ELISA analysis of the sera of 108 positive SICTT reactors revealed that 94 (87.03%) and 97 (89.81%) animals were positive for bovine purified protein derivative (PPD-B) antigen and commercial polypeptide antigen, respectively. IFN-γ assays were performed on whole blood samples collected from positive SICTT reactors and showed that 103 (95.37%) animals were positive.

Conclusion:

M. tuberculosis complex may be isolated from raw milk and not all infected animals shed mycobacterial bacilli in their milk. The use of polypeptide antigen in ELISA provides better diagnostic efficacy than PPD-B antigen. The IFN-γ assay is more sensitive than both SICTT and ELISA. It should be used in parallel with SICTT to allow the detection of more positive animals before they become a source of infection to other animals and humans.

Framing the Detection of Incipient Tuberculosis Infection: a qualitative study of political prioritization

Objective

Incipient Tuberculosis (ITB) refers to Mycobacterium tuberculosis infection that is likely to progress to active disease in the absence of treatment, but without clinical signs, symptoms, radiographic or microbiological evidence of disease. Biomarker‐based tests to diagnose incipient TB hold promise for better prediction and, through TB preventive therapy, prevention of disease. This study explored current and future framing and prioritisation of ITB.

Methods

Twenty‐two interviews across eight countries were conducted. A modified Shiffman & Smith Framework, containing four categories—Ideas, Issue Characteristics, Actor Power, and Political Contexts—was used to analyse the current landscape and potential for prioritisation of diagnosis and treatment of ITB.

Results

Latent TB policy implementation has been slow due to technical, logistical and financial challenges, and because it has been framed in a manner non‐conducive to gaining political priority. Framing ITB testing as ‘early detection’ rather than ‘prediction’, and its management as ‘treatment’ rather than ‘preventive therapy’, may help raise its importance in policies, and its acceptance among actors.

Conclusion

Consensus surrounding the framing of ITB will be crucial for the successful adoption of ITB diagnostics and treatment. When designing ITB tools and policies, it will be important to address challenges that pertain to latent TB policies.

Comparison of the QuantiFERON-TB® Gold Plus on LIAISON® XL and T-SPOT.TB for the diagnosis of latent Mycobacterium tuberculosis infection in a low tuberculosis incidence population

The current study compared the QuantiFERON-TB® Gold Plus on LIAISON® XL to the T-SPOT.TB for the diagnosis of latent Mycobacterium tuberculosis infection on 125 patient samples. A high agreement of qualitative results (90%) was observed between both methods with 3% major discrepancies, half of which were false negative results with the T-SPOT.TB.

Association of Vitamin D Receptor Polymorphism (rs2228570, rs1544410, rs7975232, and rs731236) and Macrophage Migration Inhibitory Factor -173 G/C (rs755622) with the Susceptibility of Active Pulmonary Tuberculosis in Makassar, Indonesia

BACKGROUND: The study of Vitamin D Receptor (VDR) and Macrophage Migration Inhibitory Factor (MIF) polymorphisms, associated with active pulmonary tuberculosis (ATB) presents varying results. AIMS: This study aimed to investigate the association between VDR rs2228570, rs1544410, rs7975232, rs731236 and MIF -173 G/C (rs755622) single nucleotide polymorphism (SNP), with susceptibility of developing ATB, and positivity of Interferon Gamma Release Assay (IGRA) results (in household contact). METHODS AND MATERIAL: This study involved 83 ATB and 73 household contacts in Makassar. We checked IGRA based on ELISA in household contacts by using QuantiFERON TB Gold Plus test, and we found that 61.64% (n = 45) of household contacts had positive IGRA. Polymorphism examination was carried out by Sanger sequencing. RESULTS: VDR rs2228570 T/T and T/C-T/T were significantly associated with higher risk of active tuberculosis. VDR rs7975232 G/G genotype was associated with an increased risk of developing active TB compared to T/T-T/G. Haplotype analysis of VDR rs2228570, rs1544410, rs7975232, rs731236 and combination with MIF rs755622 demonstrated that TGGTG was observed to have a higher risk of tuberculosis. CONCLUSIONS: The combination of VDR and MIF variants may contribute to the susceptibility of active tuberculosis disease.

A simple protocol for tuberculin skin test reading certification

Although tuberculosis preventive therapy is one of the cornerstones for eliminating the disease, many barriers exist in the cascade of care for latent tuberculosis infection, including the need to certify healthcare professionals for reading tuberculin skin tests (TST). This paper proposes and evaluates a simple protocol for TST reading training. Primary care workers from different backgrounds received a 2-hour theoretical course, followed by a practical course on bleb reading. Blebs were obtained by injecting saline into sausages and then in volunteers. A certified trainer then evaluated the effectiveness of this protocol by analyzing the trainees' ability to read TST induration in clinical routine, blinded to each other's readings. Interobserver agreement was analyzed using the Bland-Altman test. The trainees' reading accuracy was calculated using two cut-off points - 5 and 10mm - and the effect of the number of readings was analyzed using a linear mixed model. Eleven healthcare workers read 53 saline blebs and 88 TST indurations, with high agreement for TST reading (0.07mm average bias). Sensitivity was 100% (94.6; 100.0) at 5mm cut-off and 87.3% (75.5; 94.7) at 10mm cut-off. The regression model found no effect of the number of readings [coefficient: -0.007 (-0.055; 0.040)]. A simple training protocol for reading TST with saline blebs simulations in sausages and volunteers was sufficient to achieve accurate TST induration readings, with no effect observed for the number of readings. Training with saline blebs injected into voluntary individuals is safer and easier than the traditional method.

Up-regulated long noncoding RNA AC007128.1 and its genetic polymorphisms associated with Tuberculosis susceptibility

Background

Tuberculosis (TB) remains a major public health problem. Long non-coding RNAs (lncRNAs) are important regulators of gene expression. In this study, we explored the association between the expression of lncRNA AC007128.1 and TB susceptibility.

Methods

Three single-nucleotide polymorphisms (SNPs) (rs12333784, rs6463794, and rs720964) of lncRNA AC007128.1 were selected using the 1000 Genomes Project database and offline software Haploview V4.2, and were genotyped by a customized 2×48-Plex SNPscan™ Kit.

Results

We identified two differentially expressed lncRNA including AC007128.1 and AP001065.3 in comparisons of expression profiles between ATB vs. LTBI, LTBI vs. HCs, and AC700128.1 expression was specifically and significantly up-regulated in TB patients by verification of external data. Gene Ontology functional enrichment analysis and co-expression network showed up-regulated mRNA was mainly involved in negative regulation of the G protein-coupled receptor (GPCR) signaling pathway, and FPR1 and CYP27B1 were involved in the co-expression of AC007128.1. Using the 1000 Genomes Project, software Haploview V4.2, and SNP genotype, we screened out SNP rs12333784 which locus at 7p21.3 in AC007128.1 associated with TB susceptibility. The G carrier of rs12333784 was then finally verified to be significantly associated with pulmonary TB (PTB) and extrapulmonary tuberculosis (EPTB) susceptibility (pBonferroni =0.03878), and a similar but more significant effect was observed under the dominant model analysis (pBonferroni =0.013, OR =1.349, 95% CI, 1.065–1.709). In addition, the GG + GA genotype of SNP rs12333784 was significantly correlated with higher glucose (GLU) (P=0.03), higher gamma-glutamyl transferase (GGT) (P=0.05), and higher erythrocyte sedimentation rate (ESR) (P=0.05).

Conclusions

Our findings show lncRNA AC007128.1 can be regarded as biomarkers discriminating between ATB and LTBI and may also be a diagnostic biomarker for LBTI. These findings may aid clinical decision making in the management of TB.

Sensitivity, specificity, and safety of a novel ESAT6-CFP10 skin test for tuberculosis infection in China: two randomized, self-controlled, parallel-group phase 2b trials

BACKGROUND

Diagnostics to identify tuberculosis infection are limited. We aimed to assess the diagnostic accuracy and safety of the novel ESAT6-CFP10 (EC) skin test for tuberculosis infection in Chinese adults.

METHODS

We conducted two randomized, parallel-group clinical trials in healthy participants and tuberculosis patients. All participants were tested with the T-SPOT.TB test, then received EC skin test and tuberculin skin test (TST). The diameter of skin indurations and/or redness at injection sites were measured at different time periods. A Bacillus Calmette Guerin (BCG) model was also established to assess the diagnosis of tuberculosis infection using EC skin test.

RESULTS

In total, 777 healthy participants and 96 tuberculosis patients were allocated to receive the EC skin test at 1.0μg/0.1ml or 0.5μg/0.1ml. The area under the curve was 0.95 (95% CI, 0.91-0.97) from the EC skin test at a dose of 1.0μg/0.1ml at 24-72 hours. Compared to the T-SPOT.TB test, the EC skin test demonstrated similar sensitivity (87.5, 95% CI 77.8-97.2 versus 86.5, 95% CI 79.5-93.4) and specificity (98.9, 95% CI 96.0-99.9 versus 96.1, 95% CI 93.5-97.8). Among BCG vaccinated participants, the EC skin test had high consistency with the T-SPOT.TB test (96.3, 95% CI, 92.0-100.0). No serious adverse events related to the EC skin test were observed.

CONCLUSIONS

The EC skin test demonstrated both high specificity and sensitivity at a dose of 1.0μg/0.1ml, comparable to the T-SPOT.TB test. The diagnostic accuracy of the EC skin test was not impacted by BCG vaccination.

Interferon-gamma release assay levels and risk of progression to active tuberculosis: a systematic review and dose-response meta-regression analysis

Background

Identifying and treating individuals with high risk of progression from latent tuberculosis infection to active tuberculosis (TB) disease is critical for eliminating the disease. We aimed to conduct a systematic review and meta-regression analysis to quantify the dose-response relationship between interferon-gamma release assay (IGRA) levels and the risk of progression to active TB.

Methods

We searched PubMed and Embase from 1 January 2001 to 10 May 2020 for longitudinal studies that reported the risk of progression from latent to active TB as a function of baseline IGRA values. We used a novel Bayesian meta-regression method to pool effect sizes from included studies and generate a continuous dose-response risk curve. Our modeling framework enabled us to incorporate random effects across studies, and include data with different IGRA ranges across studies. The quality of included studies were assessed using the Newcastle-Ottawa scale (NOS).

Results

We included 34 studies representing 581,956 person-years of follow-up with a total of 788 incident cases of TB in the meta-regression analysis. Higher levels of interferon-gamma were associated with increased risk of progression to active tuberculosis. In the dose-response curve, the risk increased sharply between interferon-gamma levels 0 and 5 IU/ml, after which the risk continued to increase moderately but at a slower pace until reaching about 15 IU/ml where the risk levels off. Compared to 0 IU/ml, the relative risk of progression to active TB among those with interferon-gamma levels of 0.35, 1, 5, 10, 15, and 20 IU/ml were: 1.64 (1.28–2.08), 2.90 (2.02–3.88), 11.38 (6.64–16.38), 19.00 (13.08–26.90), 21.82 (14.65–32.57), and 22.31 (15.43–33.00), respectively. The dose-response relationship remains consistent when limiting the analysis to studies that scored highest in the NOS.

Conclusion

The current practice of dichotomizing IGRA test results simplifies the TB infection disease continuum. Evaluating IGRA test results over a continuous scale could enable the identification of individuals at greatest risk of progression to active TB.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06141-4.

Behçet's disease with latent Mycobacterium tuberculosis infection

Objective

The aim of this study is to examine the clinical features of patients with Behçet's disease (BD) in the presence or absence of latent tuberculosis infection (LTBI).

Methods

This was a retrospective study of 232 consecutive patients with active BD hospitalized between October 2012 and June 2017. LTBI was diagnosed based on the positive T-SPOT.TB assay, negative clinical, and imaging examinations.

Results

Among the 232 patients, 68 (29.3%) had LTBI. The frequency, number, and scope of oral ulcers in the BD-LTBI group were significantly more serious than in the non-LTBI group (all P < 0.05). Genital ulcers and eye involvement in the LTBI group were significantly higher than in the non-LTBI group (both P < 0.01). No active TB was diagnosed during follow-up (median, 27.9 months; range, 3-58 months). The patients with LTBI had signs of liver damage compared with the non-LTBI group. In the LTBI group, the frequency of alanine transaminase >2.0, the upper limit of normal, was higher in the rifampicin subgroup compared with the non-rifampicin subgroup (P = 0.033).

Conclusion

Patients with BD and LTBI had worse clinical features than those with BD without LTBI. Rifampicin might be associated with the damage to liver in BD patients combined with latent TB.

Polymorphisms in TLR4 and TNFA and Risk of Mycobacterium tuberculosis Infection and Development of Active Disease in Contacts of Tuberculosis Cases in Brazil: A Prospective Cohort Study

BACKGROUND

The role of genetic polymorphisms in latent tuberculosis (TB) infection and progression to active TB is not fully understood.

METHODS

We tested the single-nucleotide polymorphisms (SNPs) rs5743708 (TLR2), rs4986791 (TLR4), rs361525 (TNFA), rs2430561 (IFNG) rs1143627 (IL1B) as risk factors for tuberculin skin test (TST) conversion or development of active TB in contacts of active TB cases. Contacts of microbiologically confirmed pulmonary TB cases were initially screened for longitudinal evaluation up to 24 months, with clinical examination and serial TST, between 1998 and 2004 at a referral center in Brazil. Data and biospecimens were collected from 526 individuals who were contacts of 177 active TB index cases. TST conversion was defined as induration ≥5 mm after a negative TST result (0 mm) at baseline or month 4 visit. Independent associations were tested using logistic regression models.

RESULTS

Among the 526 contacts, 60 had TST conversion and 44 developed active TB during follow-up. Multivariable regression analysis demonstrated that male sex (odds ratio [OR]: 2.3, 95% confidence interval [CI]: 1.1-4.6), as well as SNPs in TLR4 genes (OR: 62.8, 95% CI: 7.5-525.3) and TNFA (OR: 4.2, 95% CI: 1.9-9.5) were independently associated with TST conversion. Moreover, a positive TST at baseline (OR: 4.7, 95% CI: 2.3-9.7) and SNPs in TLR4 (OR: 6.5, 95% CI: 1.1-36.7) and TNFA (OR: 12.4, 95% CI:5.1-30.1) were independently associated with incident TB.

CONCLUSIONS

SNPs in TLR4 and TNFA predicted both TST conversion and active TB among contacts of TB cases in Brazil.

Performance of a household tuberculosis exposure survey among children in a Latin American setting

OBJECTIVE: To evaluate the performance of a survey that quantifies the intensity of household tuberculosis (TB) exposure among children.METHODS: Children aged 0-14 years in Lima, Peru, with ≥1 signs and/or symptoms of TB and a history of contact with an adult TB patient were included. The 10-question survey was administered to caregivers and addressed sleep proximity, frequency of exposure, and infectiousness of the contact. Infection status was determined using tuberculin skin tests (TSTs). The exposure scale was evaluated for association with TST positivity using mixed-effects regression analyses.RESULTS: The exposure score was significantly associated with TST positivity (age-adjusted odds ratio [aOR] 1.14, 95%CI 1.02-1.28). We observed a stronger association with TST positivity in children aged ≤5 years; (aOR 1.23, 95%CI 1.07-1.41) and no association in children 6-14 years of age (aOR 0.99, 95%CI 0.82-1.20).CONCLUSION: This survey was easy to use and modestly successful in predicting TST positivity in children aged ≤5 years. It may be a useful resource for clinicians for diagnosing TB in children, and for national TB programs aiming to scale up preventive therapy initiatives.

Comparison between the Interferon γ Release Assay-QuantiFERON Gold Plus (QFT-Plus)-and Tuberculin Skin Test (TST) in the Detection of Tuberculosis Infection in Immunocompromised Children

Background

Immunocompromised patients are at a higher risk of having latent tuberculosis infection (LTBI). QuantiFERON-TB Gold Plus (QFT-Plus) has been proven to perform effectively in LTBI detection among immunocompromised adults and can overcome the limitations of the tuberculin skin test (TST). However, the role of QFT-Plus in detecting LTBI in immunocompromised paediatric patients has not been well established. Therefore, the aim of this study was to assess the test agreement between QFT-Plus and the TST in LTBI detection among immunocompromised children.

Method

In this cross-sectional study, we enrolled immunocompromised paediatric patients, aged between 5 and 18 years, who were treated with corticosteroids and/or chemotherapy from June to November 2019. We categorized them into three groups based on the following diseases: hematologic malignancies and nephrological and immunological diseases. We recorded the patient characteristics and QFT-Plus and TST results, in which the positive result of the TST was induration ≥ 5 mm. Within the same group, comparisons between the two tests were performed using the McNemar test, and results were statistically significant for p values of <0.05. The kappa index was used to assess the agreement between the two test results.

Results

Among 71 patients (median age: 11.8 years) who underwent TST and QFT-Plus testing, 52% were females, and 69% had a normal nutritional status. Chemotherapy was the most common treatment modality for hematologic malignancy compared to other immunosuppressive treatments. The total number of patients with positive QFT-Plus and TST results was 11/71 (15.5%) and 4/71 (5.6%), respectively, among whom 3/11 patients had positive results in both tests, and one patient with positive TST results exhibited a discrepancy, as this was not followed by positive QFT-Plus results. QFT-Plus generated more positive results than the TST in immunocompromised children (McNemar, p = 0.039 (p < 0.05)). The diagnostic agreement between the tests was fair (K = 0.345, 95% CI: 0.05–0.745).

Conclusion

QFT-Plus detected LTBI more effectively than the TST in immunocompromised children.

Availability of culture filtrate protein-10 (CFP-10) secreted from Mycobacterium pseudoshottsii for mycobacteriosis diagnosis in ginbuna crucian carp Carrasius auratus langsdorfii

Mycobacteriosis in cultured fish is a challenge for the aquaculture industry worldwide. Treatment by chemical administration is difficult and no effective vaccine has been developed. Therefore, detection and isolation by early diagnosis are important for prevention of the spread of the disease. In mammals, interferon gamma release assays have been established for detection of tuberculosis; these tests are based on the delayed-type hypersensitivity (DTH) response against culture filtrate protein-10 (CFP-10) and the 6-kDa early secreted antigen target (ESAT-6) of Mycobacterium tuberculosis. On the other hand, little is known about the fish immune response against the ESAT-6 and CFP-10 proteins of mycobacteria, although these responses should find application in the diagnosis of mycobacteriosis in fish. In the present study, we identified ESAT-6 and CFP-10 from Mycobacterium pseudoshottsii and cloned the corresponding genes. Intraperitoneal injection of the corresponding DNA plasmid constructs in ginbuna crucian carp yielded increased expression of the fish interferon-γ1-1-encoding gene (IFN-γ1-1). In contrast, IFN-γ1-1 expression accompanied by DTH response was observed only in the CFP-10-DNA plasmid-injected fish. Furthermore, fish that had been prophylactically injected with CFP-10-DNA plasmid exhibited increased survival of M. pseudoshottsii infection. Taken together, these results suggested that CFP-10 may facilitate diagnosis of mycobacteriosis.

Good Agreement between an Interferon Gamma Release Assay and Tuberculin Skin Tests in Testing for Latent Tuberculosis Infection among HIV-Infected Patients in Indonesia

BACKGROUND

Latent tuberculosis infection is a condition where there is a persistent immune response to Mycobacterium tuberculosis without clinical manifestations of tuberculosis. Currently, there is no gold standard to diagnose latent tuberculosis infection. The tuberculin skin test and interferon-gamma release assay are currently used to diagnose latent tuberculosis infection. However, studies have shown inconsistencies regarding the level of agreement between these tests in different settings. In this study, we aimed to evaluate the agreement between these two tests for diagnosing latent tuberculosis infection in human immunodeficiency virus (HIV)-infected individuals.

METHODS

We screened HIV patients with no clinical symptoms of tuberculosis, a normal chest X-ray, and no history of tuberculosis or use of antituberculous drugs. Participants were tested with tuberculin skin test (TST) and T-SPOT.TB (an interferon gamma release assay) simultaneously. Participants' HIV stage was determined by measuring the level of CD4+ T-lymphocytes. Tuberculosis status was confirmed by sputum examination using GeneXpert. The level of agreement between the TST and T-SPOT.TB results was measured using Cohen's κ coefficient.

RESULTS

Of the 112 participants, 20 had a positive T-SPOT.TB test result, and 21 had a positive TST result. The TST and T-SPOT.TB test results showed a high level of agreement (κ = 0.648, P < 0.001). Performance of the tests did not vary with CD4+ level. However, in participants with CD4+ < 200 cells/mm³, T-SPOT.TB detected more latent tuberculosis infections than the TST.

CONCLUSION

There was good agreement between the TST and T-SPOT.TB results of latent tuberculosis infection in participants. TST is the preferred test for diagnosing latent tuberculosis infection in HIV-infected patients, especially in resource-limited settings, because it is simple and cost-effective. However, T-SPOT.TB may be useful to rule out latent tuberculosis infection in patients with severe immunodeficiency.

Diagnosis and management of latent tuberculosis infection in Asia: Review of current status and challenges

Asia has the highest burden of tuberculosis (TB) and latent TB infection (LTBI) in the world. Optimizing the diagnosis and treatment of LTBI is one of the key strategies for achieving the WHO 'End TB' targets. We report the discussions from the Asia Latent TubERculosis (ALTER) expert panel meeting held in 2018 in Singapore. In this meeting, a group of 13 TB experts from Bangladesh, Cambodia, Hong Kong, India, Indonesia, Malaysia, Myanmar, the Philippines, Singapore, Taiwan, Thailand and Vietnam convened to review the literature, discuss the barriers and propose strategies to improve the management of LTBI in Asia. Strategies for the optimization of risk group prioritization, diagnosis, treatment, and research of LTBI are reported. The perspectives presented herein, may help national programs and professional societies of the respective countries enhance the adoption of the WHO guidelines, scale-up the implementation of national guidelines based on the regional needs, and provide optimal guidance to clinicians for the programmatic management of LTBI.

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.

The value of transcriptomics in advancing knowledge of the immune response and diagnosis in tuberculosis

Blood transcriptomics analysis of tuberculosis has revealed an interferon-inducible gene signature that diminishes in expression after successful treatment; this promises improved diagnostics and treatment monitoring, which are essential for the eradication of tuberculosis. Sensitive radiography revealing lung abnormalities and blood transcriptomics have demonstrated heterogeneity in patients with active tuberculosis and exposed asymptomatic people with latent tuberculosis, suggestive of a continuum of infection and immune states. Here we describe the immune response to infection with Mycobacterium tuberculosis revealed through the use of transcriptomics, as well as differences among clinical phenotypes of infection that might provide information on temporal changes in host immunity associated with evolving infection. We also review the diverse blood transcriptional signatures, composed of small sets of genes, that have been proposed for the diagnosis of tuberculosis and the identification of at-risk asymptomatic people and suggest novel approaches for the development of such biomarkers for clinical use.

Interferon-Gamma Release Assay-Based Screening for Pediatric Latent Tuberculosis Infection in an Urban Primary Care Network

OBJECTIVE

To assess outcomes from a QuantiFERON-tuberculosis (TB) Gold (QFT)-based screening for pediatric latent TB infection (LTBI) in the Denver Health Community Health System (CHS), an urban primary-care network in the US.

STUDY DESIGN

We retrospectively analyzed all QFTs (n = 6685) performed on children aged 2-18 years between January 5, 2011, and August 18, 2014. Risk factors for positive testing in the CHS population were identified by logistic regression, and further assessed using a case-control comparison. Results from CHS were compared with higher-TB-risk populations (refugee and TB clinics) in our health system.

RESULTS

Positive QFT occurred in 79 of 3745 (2.1%) CHS patients. Positive rates increased with age (0.3% in age 2-5 years to 4.9% in age 13-18 years). Indeterminate results were uncommon (0.8%) including in children <5 (1.3%). Risk factors for positive tests in the CHS population included non-Medicaid insured/uninsured and non-English/Spanish preferred language. In the case-control analysis, birth/travel to/residence in a TB-endemic country was the only identified risk factor for positive testing (OR 5.2 [95% CI 1.04-25.5]). Rates of positive testing were lower in the CHS population than the refugee/TB clinic populations, including among children age 2-5.

DISCUSSION

QFT-based LTBI screening was successfully introduced in our pediatric primary-care health system, and supported our programmatic goals of identifying LTBI cases while limiting unnecessary LTBI treatment courses. Increasing positive rates with age, and higher rates in the refugee/TB populations compared with CHS, add indirect evidence of adequate test sensitivity, even among young children, for whom data on interferon-gamma release assay performance are limited.

Tuberculous Uveitis Presenting with a Bullous Exudative Retinal Detachment: A Case Report and Systematic Literature Review

Purpose: To describe tuberculous uveitis (TU) presenting as a bullous retinal detachment (RD) and to perform a comprehensive literature review on TU with similar features. Methods: Observational case report and systematic literature review. Results: An 84-year-old woman presented with bilateral granulomatous uveitis and bullous RD in the left eye. The interferon gamma release assay was strongly positive, but all other tests were unremarkable. The patient was diagnosed with TU and started on anti-tubercular therapy (ATT) and systemic steroids with excellent treatment response. Twenty-six articles (32 cases) reported TU with exudative RD. Choroidal tuberculoma was the most common clinical manifestation, followed by optic disc edema and retinal exudate. Systemic steroids with ATT improved vision in more patients (78.6%) than ATT alone (50.0%) or oral steroids followed by ATT (50.0%). Conclusion: Atypical presentations of TU make diagnosis and treatment difficult. A high level of suspicion for TU is needed to minimize ocular morbidity.

Interferon-gamma release assay performance in northeastern Brazil: influence of the IFNG+874 A>T polymorphism

Introduction

Latent tuberculosis infection diagnosis based on the release of interferon-gamma in cultures of peripheral blood cells stimulated with Mycobacterium tuberculosis antigens has replaced the tuberculin skin test in many countries with low tuberculosis prevalence. The IFN-γ production can be influenced by genetic polymorphisms, of which the IFNG + 874 (rs62559044) locus is the most studied. We investigated the possible influence of the IFNG + 874 A/T polymorphism on interferon-gamma test performance.

Methods

Patients diagnosed with pulmonary tuberculosis (75), volunteers with positive tuberculin skin test (70) and healthy volunteers with negative tuberculin skin test and no history of contact with tuberculosis (57) were evaluated regarding the IFNG + 874 genotype and the IFN-γ levels in whole blood cultures performed using an interferon-gamma commercial kit (QuantiFERON-TB^® Gold In-Tube).

Results

IFN-γ production was not influenced by the IFNG + 874 genotype, regardless of antigen or mitogen-based stimulation, which suggests that other genes may influence IFN-γ production in response to mycobacteria. The IFNG + 874 polymorphism was found to exert no influence over QFT-IT test sensitivity in our study.

Conclusions

The IFNG + 874 polymorphism was not shown to influence QuantiFERON-TB^® Gold In-Tube test performance in an admixed population from northeastern Brazil.

IGRA-Based Screening for Latent Tuberculosis Infection in Persons Newly Incarcerated in New York City Jails

In the United States, latent tuberculosis infection (LTBI) detection in correctional settings is a public health priority. Interferon gamma release assay (IGRA)-based LTBI screening was introduced in New York City jails in 2011 to 2012, replacing historically used tuberculin skin testing (TST), which was associated with substantial incomplete screening rates. This retrospective, cross-sectional study evaluated LTBI screening outcomes and correlates of positivity in 40,986 persons newly incarcerated in 2011 to 2013. Of 35,090 eligible patients tested (96.4%), final results were 6.3% positive, 93.4% negative, and 0.2% indeterminate. In multivariable regression modeling, sex, age, race/ethnicity, nativity, marital status, prior jail incarceration, and HIV status were correlated with positivity. IGRA-based screening yielded high screening and low indeterminate test rates and may be recommended in correctional and other settings where TST is currently used.

Accurate diagnosis of latent tuberculosis in children, people who are immunocompromised or at risk from immunosuppression and recent arrivals from countries with a high incidence of tuberculosis: systematic review and economic evaluation

BACKGROUND

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB) [(Zopf 1883) Lehmann and Neumann 1896], is a major cause of morbidity and mortality. Nearly one-third of the world's population is infected with MTB; TB has an annual incidence of 9 million new cases and each year causes 2 million deaths worldwide.

OBJECTIVES

To investigate the clinical effectiveness and cost-effectiveness of screening tests [interferon-gamma release assays (IGRAs) and tuberculin skin tests (TSTs)] in latent tuberculosis infection (LTBI) diagnosis to support National Institute for Health and Care Excellence (NICE) guideline development for three population groups: children, immunocompromised people and those who have recently arrived in the UK from high-incidence countries. All of these groups are at higher risk of progression from LTBI to active TB.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, The Cochrane Library and Current Controlled Trials were searched from December 2009 up to December 2014.

REVIEW METHODS

English-language studies evaluating the comparative effectiveness of commercially available tests used for identifying LTBI in children, immunocompromised people and recent arrivals to the UK were eligible. Interventions were IGRAs [QuantiFERON(®)-TB Gold (QFT-G), QuantiFERON(®)-TB Gold-In-Tube (QFT-GIT) (Cellestis/Qiagen, Carnegie, VA, Australia) and T-SPOT.TB (Oxford Immunotec, Abingdon, UK)]. The comparator was TST 5 mm or 10 mm alone or with an IGRA. Two independent reviewers screened all identified records and undertook a quality assessment and data synthesis. A de novo model, structured in two stages, was developed to compare the cost-effectiveness of diagnostic strategies.

RESULTS

In total, 6687 records were screened, of which 53 unique studies were included (a further 37 studies were identified from a previous NICE guideline). The majority of the included studies compared the strength of association for the QFT-GIT/G IGRA with the TST (5 mm or 10 mm) in relation to the incidence of active TB or previous TB exposure. Ten studies reported evidence on decision-analytic models to determine the cost-effectiveness of IGRAs compared with the TST for LTBI diagnosis. In children, TST (≥ 5 mm) negative followed by QFT-GIT was the most cost-effective strategy, with an incremental cost-effectiveness ratio (ICER) of £18,900 per quality-adjusted life-year (QALY) gained. In immunocompromised people, QFT-GIT negative followed by the TST (≥ 5 mm) was the most cost-effective strategy, with an ICER of approximately £18,700 per QALY gained. In those recently arrived from high TB incidence countries, the TST (≥ 5 mm) alone was less costly and more effective than TST (≥ 5 mm) positive followed by QFT-GIT or T-SPOT.TB or QFT-GIT alone.

LIMITATIONS

The limitations and scarcity of the evidence, variation in the exposure-based definitions of LTBI and heterogeneity in IGRA performance relative to TST limit the applicability of the review findings.

CONCLUSIONS

Given the current evidence, TST (≥ 5 mm) negative followed by QFT-GIT for children, QFT-GIT negative followed by TST (≥ 5 mm) for the immunocompromised population and TST (≥ 5 mm) for recent arrivals were the most cost-effective strategies for diagnosing LTBI that progresses to active TB. These results should be interpreted with caution given the limitations identified. The evidence available is limited and more high-quality research in this area is needed including studies on the inconsistent performance of tests in high-compared with low-incidence TB settings; the prospective assessment of progression to active TB for those at high risk; the relative benefits of two-compared with one-step testing with different tests; and improved classification of people at high and low risk for LTBI.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014009033.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

A systematic approach to diagnosing intra-thoracic tuberculosis in children

Children suffer a huge and often underappreciated burden of disease in tuberculosis (TB) endemic countries. Major hurdles include limited awareness among health care workers, poor integration of TB into maternal and child health approaches, diagnostic difficulties and a lack of child-friendly treatment options. Accurate disease diagnosis is particularly difficult in young and vulnerable children who tend to develop paucibacillary disease and are unable to produce an expectorated sputum sample. In addition, access to chest radiography is problematic in resource-limited settings. Differentiating between TB exposure and M. tuberculosis infection, and especially between M. tuberculosis infection and TB disease is crucial to guide clinical management. TB represents a dynamic continuum from well-contained "latent" infection to incipient and ultimately severe disease. The clinical spectrum of disease in children is broad and can be confused with a myriad of common infections. We provide a pragmatic 4-step approach to diagnose intra-thoracic TB in children and demonstrate how classifying clinical, radiological and laboratory findings into recognised clinical syndromes may provide a more refined diagnostic approach, even in resource-limited settings.

Prevalence and risk factors for latent tuberculosis infection among primary health care workers in Brazil

Health care workers (HCW) are at increased risk of latent tuberculosis infection (LTBI) from occupational exposure to Mycobacterium tuberculosis. The objective was to determine the prevalence of and risk factors for LTBI among primary HCW in five Brazilian cities. We conducted a cross-sectional study, from 2011 to 2013, among primary HCW, using a structured questionnaire and an evaluated for LTBI using the Quantiferon-TB Gold in-tube test. The magnitude of the associations was assessed using hierarchical logistic regression models. Among 708 HCW, the LTBI prevalence was 27% (n = 196; 95%CI: 24%-31%). We found that the following factors were positively associated with LTBI in primary HCW: age > 50 years (OR = 2.94; 95%CI: 1.44-5.99), absence of a BCG scar (OR = 2.10; 95%CI: 1.28-3.43), self-reported ex-smoker status (OR = 1.80; 95%CI: 1.04-3.11), being a nurse (OR = 2.97; 95%CI: 1.13-7.83), being a nurse technician (OR = 3.10; 95%CI: 1.26-7.60), being a community health agent (OR = 2.60; 95%CI: 1.06-6.40), and irregular use of N95 masks (OR = 2.51; 95%CI: 1.11-5.98). In contrast, HCWs who do not work in health care facilities with a TB control program were less likely to have LTBI (OR = 0.66; 95%CI: 0.45-0.97). This study demonstrated a substantial occupational risk of LTBI among primary HCW in Brazil. The Brazilian TB control program, as well as local programs, need to target these high-risk HCW with education, as well as with better personal protective equipment to prevent acquisition of new TB infection.

Challenges in the Estimation of the Annual Risk of Mycobacterium tuberculosis Infection in Children Aged Less Than 5 Years

Accurate estimates of Mycobacterium tuberculosis infection in young children provide a critical indicator of ongoing community transmission of M. tuberculosis. Cross-reactions due to infection with environmental mycobacteria and/or bacille Calmette-Guérin (BCG) vaccination compromise the estimates derived from population-level tuberculin skin-test surveys using traditional cutoff methods. Newer statistical approaches are prone to failure of model convergence, especially in settings where the prevalence of M. tuberculosis infection is low and environmental sensitization is high. We conducted a tuberculin skin-test survey in 5,119 preschool children in the general population and among household contacts of tuberculosis cases in 2012-2014 in a district in northern Malawi where sensitization to environmental mycobacteria is common and almost all children are BCG-vaccinated. We compared different proposed methods of estimating M. tuberculosis prevalence, including a method described by Rust and Thomas more than 40 years ago. With the different methods, estimated prevalence in the general population was 0.7%-11.5% at ages <2 years and 0.8%-3.3% at ages 2-4 years. The Rust and Thomas method was the only method to give a lower estimate in the younger age group (0.7% vs 0.8%), suggesting that it was the only method that adjusted appropriately for the marked effect of BCG-attributable induration in the very young.

Frequency of indeterminate results from an interferon-gamma release assay among HIV-infected individuals

Objective:

To evaluate the frequency of and factors associated with indeterminate interferon-gamma release assay (IGRA) results in people living with HIV/AIDS (PLWHA).

Methods:

We tested 81 PLWHA in the central-west region of Brazil, using the tuberculin skin test and an IGRA. Information on sociodemographic and clinical variables was gathered through the use of questionnaires and from medical records. The association of those variables with indeterminate results was analyzed by calculating the adjusted ORs in a multivariate logistic regression model. Concordance was evaluated by determining the kappa statistic.

Results:

Among the 81 patients evaluated, the tuberculin skin test results were positive in 18 (22.2%) of the patients, and the IGRA results were positive in 10 (12.3%), with a kappa of 0.62. The IGRA results were indeterminate in 22 (27.1%) of the patients (95% CI: 17.8-38.1%). The odds of obtaining indeterminate results were significantly higher in smokers (adjusted OR = 6.0; 95% CI: 1.4-26.7) and in samples stored for less than 35 days (adjusted OR = 14.0; 95% CI: 3.1-64.2). Patients with advanced immunosuppression (CD4+ T-cell count < 200 cells/mm³) were at a higher risk for indeterminate results (OR adjusted for smoking and inadequate duration of sample storage = 4.7; 95% CI: 0.91-24.0), although the difference was not significant.

Conclusions:

The high prevalence of indeterminate results can be a major limitation for the routine use of IGRAs in PLWHA. The need to repeat the test increases its costs and should be taken into account in cost-effectiveness studies. The processing of samples can significantly alter the results.

Tuberculosis Associated with HIV Infection

Tuberculosis (TB) has recently surpassed HIV as the primary infectious disease killer worldwide, but the two diseases continue to display lethal synergy. The burden of TB is disproportionately borne by people living with HIV, particularly where HIV and poverty coexist. The impact of these diseases on one another is bidirectional, with HIV increasing risk of TB infection and disease progression and TB slowing CD4 recovery and increasing progression to AIDS and death among the HIV infected. Both antiretroviral therapy (ART) and latent TB infection (LTBI) treatment mitigate the impact of coinfection, and ART is now recommended for HIV-infected patients independent of CD4 count. LTBI screening should be performed for all HIV-positive people at the time of diagnosis, when their CD4 count rises above 200, and yearly if there is repeated exposure. Tuberculin skin tests (TSTs) may perform better with serial testing than interferon gamma release assays (IGRAs). Any patient with HIV and a TST induration of ≥5 mm should be evaluated for active TB disease and treated for LTBI if active disease is ruled out. Because HIV impairs multiple aspects of immune function, progressive HIV is associated with lower rates of cavitary pulmonary TB and higher rates of disseminated and extrapulmonary disease, so a high index of suspicion is important, and sputum should be obtained for evaluation even if chest radiographs are negative. TB diagnosis is similar in patients with and without TB, relying on smear, culture, and nucleic acid amplification tests, which are the initial tests of choice. TSTs and IGRAs should not be used in the evaluation of active TB disease since these tests are often negative with active disease. Though not always performed in resource-limited settings, drug susceptibility testing should be performed on all TB isolates from HIV-positive patients. Urine lipoarabinomannan testing may also be helpful in HIV-positive patients with disseminated disease. Treatment of TB in HIV-infected patients is similar to that of TB in HIV-negative patients except that daily therapy is required for all coinfected patients, vitamin B6 supplementation should be given to all coinfected patients receiving isoniazid to reduce peripheral neuropathy, and specific attention needs to be paid to drug-drug interactions between rifamycins and many classes of antiretrovirals. In patients requiring ART that contains ritonavir or cobicistat, this can be managed by the use of rifabutin at 150 mg daily in place of rifampin. For newly diagnosed coinfected patients, mortality is lower if treatment is provided in parallel, rather than serially, with treatment initiation within 2 weeks preferred for those with CD4 counts of <50 and within 8 to 12 weeks for those with higher CD4 counts. When TB immune reconstitution inflammatory syndrome occurs, patients can often be treated symptomatically with nonsteroidal anti-inflammatory drugs, but a minority will benefit from steroids. Generally, patients who do not have space-occupying lesions such as occurs in TB meningitis do not require cessation of therapy.

Immunological characterization of latent tuberculosis infection in a low endemic country

The diagnosis of a latent tuberculosis infection (LTBI) is based on detection of immunity against Mycobacterium tuberculosis (Mtb). The tuberculin skin test (TST), the Quantiferon (QFT) and a prolonged lymphocyte stimulation test using either ESAT-6/CFP-10 (LST-EC) or PPD (LST-PPD) were evaluated in a cohort of 495 individuals, suspected to have LTBI, in a low endemic country. While the TST and LST-PPD were both positive in the majority (75%) of individuals, only one third responded in the LST-EC and in the QFT. The choice for LTBI treatment was significantly associated with ESAT6/CFP10 recognition, however the LST-EC detected considerably more individuals (21%) with immunity against Mtb, who might also be at risk for development of active TB, although none of them did during follow up. Follow-up for 2 years showed 7% conversions and 32% reversions for the QFT. The LST-EC showed higher conversion rates (∼45%), although the percentage of individuals positive in the LST-EC did not change significantly within the follow-up period. LTBI treatment did not alter immune recognition of Mtb antigens. In conclusion, the sensitivity of tests for detection of cellular immunity to Mtb specific antigens depends on test methodology and may vary considerably over time in a low endemic region.

Application of molecular, microbiological, and immunological tests for the diagnosis of bone and joint tuberculosis

BACKGROUND

To evaluate the application of interferon gamma release assay (IGRA), rifampicin resistant real-time fluorescence quantitative PCR technique Xpert Mycobacterium tuberculosis/rifampicin (Xpert MTB/RIF), and the levels of TNF-α and TGF-β in the diagnosis of bone and joint tuberculosis.

METHODS

Eighty-six patients with bone and joint tuberculosis, diagnosed by pathology or microbiology, were examined by Xpert MTB/RIF and IGRA (T-SPOT. TB) for Mycobacterium tuberculosis infection, and the TNF-α and TGF-β levels of the patients were measured.

RESULTS

The sensitivity of IGRA in diagnosing bone and joint tuberculosis was 81.4%; Xpert MTB/RIF's sensitivity was 70.9%. The combined sensitivity of the two methods was 91.9%. The combined detection sensitivity of the two methods was higher than individual IGRA or Xpert MTB/RIF detection sensitivity. The TNF-α and TGF-β levels in bone and joint tuberculosis patients were higher than those in the control group.

CONCLUSION

Xpert MTB/RIF, IGRA, TNF-α, and TGF-βs expression have value in the rapid diagnosis of bone and joint tuberculosis, and the sensitivity and accuracy of bone and joint tuberculosis diagnosis by combining them can improve it.

From Latent Tuberculosis Infection to Tuberculosis. News in Diagnostics (QuantiFERON-Plus)

It is estimated that one third of the world's population have latent tuberculosis infection and that this is a significant reservoir for future tuberculosis cases. Most cases occur within two years following initial infection. The identification of individuals with latent tuberculosis infection is difficult due to the lack of an ideal diagnostic assay and incomplete understanding of latent infection. Currently, there are three tests: the oldest tuberculin skin test, T-SPOT.TB and the latest QuantiFERON-Plus for the detection of Mycobacterium tuberculosis infection. The interpretation of the test results must be used in the conjunction with a patient's epidemiological history, risk assessment, current clinical status, radiography and microbiological methods to ensure accurate diagnosis.

Comparing interferon-gamma release assays with tuberculin skin test for identifying latent tuberculosis infection that progresses to active tuberculosis: systematic review and meta-analysis

BACKGROUND

Timely and accurate identification of people with latent tuberculosis infection (LTBI) is important for controlling Mycobacterium tuberculosis (TB). There is no gold standard for diagnosis of LTBI. Screening tests such as interferon gamma release assays (IGRAs) and tuberculin skin test (TST) provide indirect and imperfect information. This systematic review compared two types of IGRAs QuantiFERON®-TB Gold In-Tube test (QFT-GIT) and T-SPOT.TB with TST for identification of LTBI by predicting progression to a diagnosis of active TB in three subgroups: children, immunocompromised people, and those recently arrived from countries with high TB burden.

METHODS

Cohort studies were eligible for inclusion. We searched MEDLINE, EMBASE, the Cochrane Library and other databases from December 2009 to June 2015. One reviewer screened studies, extracted data, and assessed risk of bias with cross checking by a second reviewer. Strength of association between test results and incidence of TB was summarised using cumulative incidence ratios (CIRs with 95% CIs). Summary effect measures: the ratio of CIRs (R-CIR) with 95% CIs. R-CIRs, were pooled using a random-effects model. Heterogeneity was assessed using Chi-squared and I² statistics.

RESULTS

Seventeen studies, mostly of moderate or high risk of bias (five in children, 10 in immunocompromised people, and two in those recently arrived) were included. In children, while in two studies, there was no significant difference between QFT-GIT and TST (≥5 mm) (pooled R-CIR = 1.11, 95% CI: 0.71, 1.74), two other studies showed QFT-GIT to outperform TST (≥10 mm) in identifying LTBI. In immunocompromised people, IGRA (T-SPOT.TB) was not significant different from TST (≥10 mm) for identifying LTBI, (pooled R-CIR = 1.01, 95% CI: 0.65, 1.58). The forest plot of two studies in recently arrived people from countries with high TB burden demonstrated inconsistent findings (high heterogeneity; I² = 92%).

CONCLUSIONS

Prospective studies comparing IGRA testing against TST on the progression from LTBI to TB were sparse, and these results should be interpreted with caution due to uncertainty, risk of bias, and unexplained heterogeneity. Population-based studies with adequate sample size and follow-up are required to adequately compare the performance of IGRA with TST in people at high risk of TB.

Prevalence and associated risk factors of latent tuberculosis infection among undergraduate and postgraduate dental students: A retrospective study

To estimate the prevalence of latent tuberculosis (TB) infection (LTBI) in Italian dental students exposed to the same occupational risks as dental health care personnel and to evaluate potential risk factors, a cross-sectional study was conducted on undergraduate and postgraduate students. After clinical evaluation, students were given a tuberculin skin test; in those found positive, an interferon-γ release assay (IGRA) was conducted. Of the 281 students enrolled, 10 were only TST positive; 8 were TST or/and IGRA positive. We found that participants testing positive at TST and/or IGRA, a group in which the risk of false LTBI positives is minimal, were older and had been studying longer. Although the prevalence of LTBI among dental students in our study was low, a risk of acquiring a work-related infection exists even in a country with a low incidence of TB. Thus, dental students should be screened to catch LTBI early on.

Prevalence of tuberculosis infection in healthcare workers of the public hospital network in Medellín, Colombia: a Bayesian approach

A latent tuberculosis infection (LTBI) prevalence survey was conducted using tuberculin skin test (TST) and Quantiferon test (QFT) in 1218 healthcare workers (HCWs) in Medellín, Colombia. In order to improve the prevalence estimates, a latent class model was built using a Bayesian approach with informative priors on the sensitivity and specificity of the TST. The proportion of concordant results (TST+,QFT+) was 41% and the discordant results contributed 27%. The marginal estimate of the prevalence P(LTBI+) was 62·1% [95% credible interval (CrI) 53·0–68·2]. The probability of LTBI+ given positive results for both tests was 99·6% (95% CrI 98·1–99·9). Sensitivity was 88·5 for TST and 74·3 for QFT, and specificity was 87·8 for TST and 97·6 for QFT. A high LTBI prevalence was found in HCWs with time-accumulated exposure in hospitals that lack control plans. In a context of intermediate tuberculosis (TB) incidence it is recommended to use only one test (either QFT or TST) in prevalence surveys or as pre-employment tests. Results will be useful to help implement TB infection control plans in hospitals where HCWs may be repeatedly exposed to unnoticed TB patients, and to inform the design of TB control policies.

FOXO3 rs12212067: T > G Association with Active Tuberculosis in Han Chinese Population

It is well known that the human innate immune and adaptive immune response play important role in tuberculosis (TB) infection and progress. Emerging evidence shows that FOXO3 plays an important role in the human immune system. Recent research has shown that the FOXO3 genetic variants are associated malaria infection. In this study, 268 confirmed TB patients, 321 patients with latent tuberculosis infection (LTBI), and 475 TB-free controls were recruited; the single-nucleotide polymorphism (SNP) rs12212067: T > G in FOXO3 was genotyped using predesigned TaqMan® allelic discrimination assays. The results showed that the G allele of rs12212067 in FOXO3 was more common in health control and the latent TB group compared with the active TB group (p = 0.048, odds ratio (OR) 95 % confidence intervals (CI) = 1.37 (1.00-1.89); p = 0.042, OR 95 % CI = 1.42 (1.01-1.99), respectively); furthermore, within active TB patients, the G allele of rs12212067 in FOXO3 was more frequent in extra-pulmonary tuberculosis (EPTB) group compared to pulmonary tuberculosis (PTB) group (p = 0.035, OR 95 % CI = 0.57 (0.33-0.97). In conclusion, this study found that rs12212067 in FOXO3 was associated with increased risk of active TB. The minor G allele might be a protection factor which was found more common in latent TB patients and healthy controls than active TB patients.

Tuberculosis exposure, infection and disease in children: a systematic diagnostic approach

The accurate diagnosis of tuberculosis (TB) in children remains challenging. A myriad of common childhood diseases can present with similar symptoms and signs, and differentiating between exposure and infection, as well as infection and disease can be problematic. The paucibacillary nature of childhood TB complicates bacteriological confirmation and specimen collection is difficult. In most instances intrathoracic TB remains a clinical diagnosis. TB infection and disease represent a dynamic continuum from TB exposure with/without infection, to subclinical/incipient disease, to non-severe and severe disease. The clinical spectrum of intrathoracic TB in children is broad, and the classification of clinical, radiological, endoscopic, and laboratory findings into recognized clinical syndromes allows a more refined diagnostic approach in order to minimize both under- and over-diagnosis. Bacteriological confirmation can be improved significantly by collecting multiple, high-quality specimens from the most appropriate source. Mycobacterial testing should include traditional smear microscopy and culture, as well as nucleic acid amplification testing. A systematic approach to the child with recent exposure to TB, or with clinical and radiological findings compatible with this diagnosis, should allow pragmatic classification as TB exposure, infection, or disease to facilitate timely and appropriate management. It is important to also assess risk factors for TB disease progression and to undertake follow-up evaluations to monitor treatment response and ongoing evidence supporting a TB, or alternative, diagnosis.

Prevalence of latent tuberculosis infection in healthcare workers at a hospital in Naples, Italy, a low-incidence country

Background

Healthcare workers (HCWs) are at higher risk than the general population of contracting tuberculosis (TB). Moreover, although subjects with latent TB infection (LTBI) are asymptomatic and are not infectious, they may eventually develop active disease. Thus, a fundamental tool of TB control programs for HCWs is the screening and treatment of LTBI.

Methods

From January 2014 to January 2015, hospital personnel at Azienda Ospedaliera Universitaria, Naples, Italy, were screened for TB. To this end, a tuberculin skin test (TST) was administered as an initial examination, unless when contraindicated, in which case the QuantiFERON® TB-Gold (QFT) assay was performed. Moreover, QFT was carried out on all TST-positive cases to confirm the initial result.

Results

Of 628 personnel asked to participate, 28 (4.5%) denied consent, 533 were administered TST as the baseline examination, and 67 were tested only with QFT. In the TST group, 73 (13.2%) individuals were found positive, 418 (78.4%) were negative, and 42 (7.9%) were absent for the reading window; QFT confirmed the result in 39 (53.4%) TST-positive individuals. In the QFT-only group, 44 (65.7%) individuals were found positive. All TST- and/or QFT-positive subjects were referred for chest X-ray and examination by an infectious diseases specialist. None were found to have active TB, and were thus diagnosed with LTBI.

Conclusions

Although Italy is a low-incidence country regarding TB, our findings suggest that the prevalence of LTBI in HCWs may be relatively high. As a result, active screening for TB and LTBI is needed for these workers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12995-016-0141-6) contains supplementary material, which is available to authorized users.

Expert Recommendations on Treating Psoriasis in Special Circumstances (Part II)

BACKGROUND

There is insufficient information on how best to treat moderate to severe psoriasis in difficult clinical circumstances.

MATERIAL AND METHODS

We considered 5 areas where there is conflicting or insufficient evidence: pediatric psoriasis, risk of infection in patients being treated with biologics, psoriasis in difficult locations, biologic drug survival, and impact of disease on quality of life. Following discussion of the issues by an expert panel of dermatologists specialized in the management of psoriasis, participants answered a questionnaire survey according to the Delphi method.

RESULTS

Consensus was reached on 66 (70.9%) of the 93 items analyzed; the experts agreed with 49 statements and disagreed with 17. It was agreed that body mass index, metabolic comorbidities, and quality of life should be monitored in children with psoriasis. The experts also agreed that the most appropriate systemic treatment for this age group was methotrexate, while the most appropriate biologic treatment was etanercept. Although it was recognized that the available evidence was inconsistent and difficult to extrapolate, the panel agreed that biologic drug survival could be increased by flexible, individualized dosing regimens, continuous treatment, and combination therapies. Finally, consensus was reached on using the Dermatology Quality of Life Index to assess treatment effectiveness and aid decision-making in clinical practice.

CONCLUSIONS

The structured opinion of experts guides decision-making regarding aspects of clinical practice for which there is incomplete or conflicting information.

Systematic review of mathematical models exploring the epidemiological impact of future TB vaccines

Mathematical models are useful for assessing the potential epidemiological impact of future tuberculosis (TB) vaccines. We conducted a systematic review of mathematical models estimating the epidemiological impact of future human TB vaccines. PubMed, Embase and WHO Global Health Library were searched, 3-stage manual sifted, and citation- and reference-tracked, identifying 23 papers. An adapted quality assessment tool was developed, with a resulting median study quality score of 20/28. The literature remains divided as to whether vaccines effective pre- or post-infection would provide greatest epidemiological impact. However, all-age or adolescent/adult targeted prevention of disease vaccines achieve greater and more rapid impact than neonatal vaccines. Mass campaigns alongside routine neonatal vaccination can have profound additional impact. Economic evaluations found TB vaccines overwhelmingly cost-effective, particularly when targeted to adolescents/adults. The variability of impact by setting, age group and vaccine characteristics must be accounted for in the development and delivery of future TB vaccines.