Evidence-based comparison of commercial interferon-gamma release assays for detecting active TB: a metaanalysis

Transcriptional profiling of human peripheral blood mononuclear cells in household contacts of pulmonary tuberculosis patients provides insights into mechanisms of Mycobacterium tuberculosis control and elimination

Household contacts (HHCs) of patients with active tuberculosis (ATB) are at higher risk of Mycobacterium tuberculosis (M. tuberculosis) infection. However, the immune factors responsible for different defense responses in HHCs are unknown. Hence, we aimed to evaluate transcriptome signatures in human peripheral blood mononuclear cells (PBMCs) of HHCs to aid risk stratification. We recruited 112 HHCs of ATB patients and followed them for 6 years. Among the HHCs, only 2 developed ATB, while the remaining HHCs were classified into three groups: (1) HHC-1 group (n = 23): HHCs with consistently positive T-SPOT.TB test, negative chest radiograph, and no clinical symptoms or evidence of ATB during the 6-year follow-up period; (2) HHC-2 group (n = 15): HHCs with an initial positive T-SPOT result that later became negative without evidence of ATB; (3) HHC-3 group (n = 14): HHCs with a consistently negative T-SPOT.TB test and no clinical or radiological evidence of ATB. HHC-2 and HHC-3 were combined as HHC-23 group for analysis. RNA sequencing (RNA-seq) in PBMCs, with and without purified protein derivative (PPD) stimulation, identified significant differences in gene signatures between HHC-1 and HHC-23. Gene ontology analysis revealed functions related to bacterial pathogens, leukocyte chemotaxis, and inflammatory and cytokine responses. Modules associated with clinical features in the HHC-23 group were linked to the IL-17 signaling pathway, ferroptosis, complement and coagulation cascades, and the TNF signaling pathway. Validation using real-time PCR confirmed key genes like ATG-7, CXCL-3, and TNFRSF1B associated with infection outcomes in HHCs. Our research enhances understanding of disease mechanisms in HHCs. HHCs with persistent latent tuberculosis infection (HHC-1) showed significantly different gene expression compared to HHCs with no M. tuberculosis infection (HHC-23). These findings can help identify HHCs at risk of developing ATB and guide targeted public health interventions.

Cost-effectiveness of latent tuberculosis infection testing and treatment with 6-week regimen among key population in rural communities in China: a decision analysis study

PURPOSE

Several model studies suggested the implementation of latent tuberculosis infection (LTBI) testing and treatment could greatly reduce the incidence of tuberculosis (TB) and achieve the 2035 target of the "End TB" Strategy in China. The present study aimed to evaluate the cost-effectiveness of LTBI testing and TB preventive treatment among key population (≥ 50 years old) susceptible to TB at community level in China.

METHODS

A Markov model was developed to investigate the cost-effectiveness of LTBI testing using interferon gamma release assay (IGRA) and subsequent treatment with 6-month daily isoniazid regimen (6H) (as a standard regimen for comparison) or 6-week twice-weekly rifapentine and isoniazid regimen (6-week H2P2) in a cohort of 10,000 adults with an average initial age of 50 years.

RESULTS

In the base-case analysis, LTBI testing and treatment with 6H was dominated (i.e., more expensive with a lower quality-adjusted life year (QALY)) by LTBI testing and treatment with 6-week H2P2. LTBI testing and treatment with 6-week H2P2 was more effective than no intervention at a cost of $20,943.81 per QALY gained, which was below the willingness-to-pay (WTP) threshold of $24,211.84 per QALY gained in China. The one-way sensitivity analysis showed the change of LTBI prevalence was the parameter that most influenced the results of the incremental cost-effectiveness ratios (ICERs).

CONCLUSION

As estimated by a Markov model, LTBI testing and treatment with 6-week H2P2 was cost-saving compared with LTBI testing and treatment with 6H, and it was considered to be a cost-effective option for TB control in rural China.

Pulmonary tuberculoma-induced cyst formation leading to repeated pneumothorax: a case report

Most cases of secondary spontaneous pneumothorax in patients with active pulmonary tuberculosis are caused by rupturing of the visceral pleura caused by Mycobacterium tuberculosis. The check-valve airway mechanism in the lungs is generally involved in the formation of pulmonary cysts, which often cause spontaneous pneumothorax. Herein, we describe a rare case of repeated spontaneous pneumothorax suspected to have been caused by pulmonary cyst formation as a result of a tuberculoma. The patient was a man with a family history of pulmonary tuberculosis. Pulmonary cysts were gradually enlarged on the peripheral side of a lung mass in the upper lobe of the patient's right lung, who experienced two spontaneous pneumothoraxes in the area. Exploratory surgery was performed to diagnose the lung mass and treat the pneumothorax, resulting in a final diagnosis of pulmonary tuberculoma. A check-valve mechanism caused by the pulmonary tuberculoma was suspected based on the patient's clinical course.

Poor performance of paired tests of latent tuberculosis in highly immune-compromised individuals exposed to multidrug-resistant tuberculosis: time for new diagnostic markers

Guideline-based recommendations for diagnosis of latent TB in highly immune suppressed populations are difficult to interpret and poorly characterised. More accurate biomarkers independent of T-cell functions are urgently required. https://bit.ly/41P8vTa.

Sarcoidosis detected after COVID‑19 with T‑SPOT.TB positive: A case report

Sarcoidosis is an idiopathic multisystem disorder with unknown etiology. Due to clinical similarities among sarcoidosis, tuberculosis (TB) infection and malignant diseases (such as lymphoma, lung carcinoma and pituitary tumor), the diagnosis of sarcoidosis is challenging. The present report describes a case of sarcoidosis in a 48-year-old male with complaint of chest pain 1 month after Coronavirus disease 2019. The patient underwent whole-body 18F-fluorodeoxyglucose (18F-FDG) PET-CT imaging, which revealed multiple lymphadenopathies throughout the body without lung parenchyma involvement. Biochemical examinations such as T-SPOT.TB test and pathological examination of right supraclavicular lymph node revealed positive T-SPOT.TB but negative Ziehl-Neelsen staining. However, non-caseating epithelioid granulomas were observed in the mediastinal biopsy, indicating the diagnosis of sarcoidosis. The patient was clinically stable, and the symptom of chest pain was gradually relieved without any specific treatment. Outpatient follow-up continued every 3 months. The present case suggested a possible link between coronavirus infection and sarcoidosis, which suggests the advantages of 18F-FDG PET-CT for the detection of sarcoidosis. However, T-SPOT.TB is insufficient for differentiating between sarcoidosis and TB.

[Tuberculosis Infection Control & Hygiene - Recommendations of the DZK]

Preventing the spread of the disease is an essential goal in the care and treatment of tuberculosis. In addition to early diagnosis and effective therapies, isolation of infectious patients and adequate hygiene measures are of particular importance for infection prevention. The present recommendations replace the previous recommendations "tuberculosis infection control" from 2012 and take into account the current national and international recommendations and as well as new scientific findings. After a description of the infection and the transmission pathways, the necessary prevention and hygiene measures in health care facilities are comprehensively presented. Since the last revision of the recommendations on infection prevention, international recommendations and the KRINKO recommendation on ending isolation have been changed. In accordance with this, under certain conditions in the case of sensitive tuberculosis, de-isolation in health care facilities can take place after 14 days without taking the sputum findings into account. The second part of the recommendations explains in detail the measures to be taken in special situations and areas, such as general practitioners, ambulance services and care facilities. Here, the recommendations on respiratory protection have been simplified; for staff, an FFP2 mask is now generally considered sufficient.

Accuracy of QuantiFERON in active tuberculosis suspects with comorbidities and nontuberculous mycobacterial infection in Northern California

The QuantiFERON-TB Gold (QFT) is routinely utilized in North American health systems to detect a cellular immune response to Mycobacterium tuberculosis antigens in symptomatic and asymptomatic patients. The sensitivity of QFT in tuberculosis (TB) patients with comorbidities is not well established and the specificity of QFT in patients with nontuberculous mycobacteria (NTM) infections is incompletely understood. Between 2012 and 2023, all patients with culture-positive TB and patients with NTM infection per the expert diagnostic guidelines or biopsy-proven NTM infection who had a concurrent QFT test were included in this study. The sensitivity and specificity of QFT were measured in TB and NTM patients, respectively. In 109 patients with active TB, the overall sensitivity of QFT was 78.0% (85/109; 95% CI: 70.1, 85.7). The sensitivity was 86.0% (49/57; 95% CI: 76.6, 94.8) and 69.2% (36/52; 95% CI: 56.7, 81.8) in immunocompetent and immunocompromised patients, respectively. The overall specificity of QFT in 88 patients with NTM infection was 76.1% (67/88; 95% CI: 67.2, 85.0). After the exclusion of 17 NTM patients with risk factors for latent TB infection, the specificity was 94.4% (67/71; 95% CI: 89.1, 99.7). Two patients had NTM species known to cross-react with QFT. In two NTM patients infected with species (Mycobacterium intracellulare subsp. intracellulare and Mycobacterium intracellulare subsp. chimaera) not known to cross-react, whole genome sequencing did not detect ESAT-6 or CFP-10. In Northern California, the QFT assay demonstrated moderately low to moderately high sensitivity in TB patients and very high specificity in NTM patients, thus ruling out concerns for cross-reactivity with NTM.

Comparable cytokine release ex-vivo by whole blood from COVID-19 patients with and without non-invasive ventilation

T cells are key players in the resolution of the infection by SARS-CoV-2. A delay in their activation can lead to severe COVID-19. The present work aimed to identify differences in cytokine release by T cells ex-vivo between COVID-19 patients in the acute phase, showing diverse disease severity. Concentrations of IFNγ, Granzyme B, IL-6, IL-10, IL-17A, IL-18, IP-10, MCP-1, and TNFα were evaluated after stimulation ex-vivo of whole blood samples with peptides from SARS-CoV-2 spike protein and a mitogen as well as without stimulation. Samples derived from hospitalized COVID-19 patients and SARS-CoV-2 vaccinated controls (CTR). Patients were classified on disease severity considering the necessity of non-invasive ventilation (NIV). Samples from patients requiring NIV revealed a similar release of cytokines compared with patients without NIV. COVID-19 patients showed higher spontaneous production of IFNγ and IP-10, lower production of MCP-1 after SARS-CoV-2 peptide stimulation and lower production of IFNγ, IL-10, IL-17A, Granzyme B, IP-10 after mitogenic stimulus compared with CTR. In conclusion, differences in T cell responses evaluated ex-vivo by a whole blood-based cytokine release assay do not appear to explain the need for non-invasive ventilation in COVID-19 patients.

[Recommendations for Contact Tracing for Tuberculosis - Update 2023]

The aim of contact tracing for tuberculosis is in addition to active case finding the detection of chains of infection and the prevention of the further spread of the disease. In this context, a careful selection of contact persons is necessary, depending on the type and duration of contact, to identify persons who are recently infected and therefore to increase the benefit of a preventive therapy and to avoid unnecessary testing of persons who are not at risk of infection. Since the last update of the recommendations on contact tracing, data on the use of interferon-y release assays (IGRAs) in children has been improved markedly. These are the preferred test in contact tracing of adults. For children, both IGRAs and the tuberculin skin test can be used equivalently. Rifampicin for 4 months, rifampicin and isoniazid for 3 months, or isoniazid for 9 months are recommended as preventive therapy in cases of confirmed infection.The implementation of the contact tracing in different age groups as well as legal framework conditions and socio-medical aspects and challenges are dealt with in detail. In addition, special cases, such as environmental screening in day-care centers, schools, or other community facilities, are discussed separately.

[Recommendations for contact tracing for tuberculosis - update 2023]

The aim of contact tracing for tuberculosis is in addition to active case finding the detection of chains of infection and the prevention of the further spread of the disease. In this context, a careful selection of contact persons is necessary, depending on the type and duration of contact, to identify persons who are recently infected and therefore to increase the benefit of a preventive therapy and to avoid unnecessary testing of persons who are not at risk of infection. Since the last update of the recommendations on contact tracing, data on the use of interferon-y release assays (IGRAs) in children has been improved markedly. These are the preferred test in contact tracing of adults. For children, both IGRAs and the tuberculin skin test can be used equivalently. Rifampicin for 4 months, rifampicin and isoniazid for 3 months, or isoniazid for 9 months are recommended as preventive therapy in cases of confirmed infection.The implementation of the contact tracing in different age groups as well as legal framework conditions and socio-medical aspects and challenges are dealt with in detail. In addition, special cases, such as environmental screening in day-care centers, schools, or other community facilities, are discussed separately.

Indeterminate results of interferon gamma release assays in the screening of latent tuberculosis infection: a systematic review and meta-analysis

Objectives

We aimed to evaluate the indeterminate rate of interferon gamma release assays (IGRAs) in the detection of latent tuberculosis infection (LTBI).

Methods

On 15 November 2022, we searched the PubMed® (National Library of Medicine, Bethesda, MD, USA), Embase® (Elsevier, Amsterdam, the Netherlands), and Cochrane Library databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two investigators independently extracted the study data and assessed their quality using a modified quality assessment of diagnostic accuracy studies (i.e., QUADAS-2) tool. A random-effects model was used to calculate pooled results.

Results

We included 403 studies involving 486,886 individuals and found that the pooled indeterminate rate was 3.9% (95% CI 3.5%-4.2%). The pooled indeterminate rate for QuantiFERON®-TB (QFT) was similar to that for T-SPOT®.TB (T-SPOT) [odds ratio (OR) = 0.88, 95% CI 0.59-1.32]; however, the indeterminate rate for a new generation of QFT (QFT-plus) was lower than that of T-SPOT (OR = 0.24, 95% CI 0.16-0.35). The indeterminate rate in the immunocompromised population was significantly higher than that in healthy controls (OR = 3.51, 95% CI 2.11-5.82), and it increased with the reduction of CD4+ cell count in HIV-positive patients. Children's pooled indeterminate rates (OR = 2.56, 95% CI 1.79-3.57) were significantly higher than those of adults, and the rates increased as the children's age decreased.

Conclusion

On average, 1 in 26 tests yields indeterminate IGRA results in LTBI screening. The use of advanced versions of the QuantiFERON-TB assay (QFT-plus), may potentially reduce the occurrence of an indeterminate result. Our study emphasizes the high risk of immunosuppression and young age in relation to indeterminate IGRA, which should receive more attention in the management of LTBI.

Systematic review registration

PROSPERO https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020211363, CRD42020211363.

Screening for Latent Tuberculosis Infection in Adults: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force

Importance

Latent tuberculosis infection (LTBI) can progress to active tuberculosis disease, causing morbidity and mortality.

Objective

To review the evidence on benefits and harms of screening for and treatment of LTBI in adults to inform the US Preventive Services Task Force (USPSTF).

Data Sources

PubMed/MEDLINE, Cochrane Library, and trial registries through December 3, 2021; references; experts; literature surveillance through January 20, 2023.

Study Selection

English-language studies of LTBI screening, LTBI treatment, or accuracy of the tuberculin skin test (TST) or interferon-gamma release assays (IGRAs). Studies of LTBI screening and treatment for public health surveillance or disease management were excluded.

Data Extraction and Synthesis

Dual review of abstracts, full-text articles, and study quality; qualitative synthesis of findings; meta-analyses conducted when a sufficient number of similar studies were available.

Main Outcomes and Measures

Screening test accuracy; development of active tuberculosis disease, transmission, quality of life, mortality, and harms.

Results

A total of 113 publications were included (112 studies; N = 69 009). No studies directly evaluated the benefits and harms of screening. Pooled estimates for sensitivity of the TST were 0.80 (95% CI, 0.74-0.87) at the 5-mm induration threshold, 0.81 (95% CI, 0.76-0.87) at the 10-mm threshold, and 0.60 (95% CI, 0.46-0.74) at the 15-mm threshold. Pooled estimates for sensitivity of IGRA tests ranged from 0.81 (95% CI, 0.79-0.84) to 0.90 (95% CI, 0.87-0.92). Pooled estimates for specificity of screening tests ranged from 0.95 to 0.99. For treatment of LTBI, a large (n = 27 830), good-quality randomized clinical trial found a relative risk (RR) for progression to active tuberculosis at 5 years of 0.35 (95% CI, 0.24-0.52) for 24 weeks of isoniazid compared with placebo (number needed to treat, 112) and an increase in hepatotoxicity (RR, 4.59 [95% CI, 2.03-10.39]; number needed to harm, 279). A previously published meta-analysis reported that multiple regimens were efficacious compared with placebo or no treatment. Meta-analysis found greater risk for hepatotoxicity with isoniazid than with rifampin (pooled RR, 4.22 [95% CI, 2.21-8.06]; n = 7339).

Conclusions and Relevance

No studies directly evaluated the benefits and harms of screening for LTBI compared with no screening. TST and IGRAs were moderately sensitive and highly specific. Treatment of LTBI with recommended regimens reduced the risk of progression to active tuberculosis. Isoniazid was associated with higher rates of hepatotoxicity than placebo or rifampin.

Assessment of immune function and prediction of survival and infection in patients with severe alcoholic hepatitis: An exploratory study

Background and Aim

Alcoholic hepatitis (AH), a severe complication of long-term alcohol misuse, has a 30% 90-day mortality. Infections are common and associated with higher mortality. There is currently no accurate method to predict infection in these patients. We aimed to test a measure of immune function, the QuantiFERON Monitor (QFM), in predicting clinical outcomes in patients with severe AH.

Methods

Peripheral blood was taken at baseline, and QFM performed according to the manufacturer's instructions. In parallel, QFM samples were analyzed with a cytokine multiplex. Clinical outcomes of mortality at 28 and 90 days and development of infection were recorded prospectively.

Results

Forty-nine patients were recruited (mean age 51, 59% male and mean discriminant function 57.8). Interferon (IFN)-γ release measured by standard QFM was significantly higher in survivors compared to non-survivors at 28 (102 vs 16 IU/mL, P = 0.02) and 90 days (115 vs 32 IU/mL; P = 0.046). The area under the receiver operating characteristic curve (AUROC) was 0.79 for 28-day mortality. IFN-γ, IL-10, and IL-23 release measured by multiplex were significantly lower in patients who developed a subsequent infection compared to those who did not (115 vs 27 IU/mL, P = 0.037; 457 vs 202 pg/mL, P = 0.008; and 1039 vs 663 pg/mL, p = 0.01, respectively).

Conclusion

Immune dysfunction is associated with poorer outcomes in patients with severe AH. Measurement of IFN-γ release by standard QFM accurately predicts early mortality, which can be applied to clinical practice as a biomarker of survival. Adaptation of the test to measure IL-10 could be used as a biomarker of subsequent infection to guide clinical treatment decisions.

Management of Tuberculosis Infection: Current Situation, Recent Developments and Operational Challenges

Tuberculosis infection (TBI) is defined as a state of infection in which individuals host live Mycobacterium tuberculosis with or without clinical signs of active TB. It is now understood as a dynamic process covering a spectrum of responses to infection resulting from the interaction between the TB bacilli and the host immune system. The global burden of TBI is about one-quarter of the world’s population, representing a reservoir of approximately 2 billion people. On average, 5–10% of people who are infected will develop TB disease over the course of their lives, but this risk is enhanced in a series of conditions, such as co-infection with HIV. The End-TB strategy promotes the programmatic management of TBI as a crucial endeavor to achieving global targets to end the TB epidemic. The current development of new diagnostic tests capable of discriminating between simple TBI and active TB, combined with novel short-course preventive treatments, will help achieve this goal. In this paper, we present the current situation and recent developments of management of TBI and the operational challenges.

A systematic review of cost-utility analyses of screening methods in latent tuberculosis infection in high-risk populations

Background

The World Health Organisation (WHO) recommends that testing and treatment for latent tuberculosis infection (LTBI) should be undertaken in high-risk groups using either interferon gamma release assays (IGRAs) or a tuberculin skin test (TST). As IGRAs are more expensive than TST, an assessment of the cost-effectiveness of IGRAs can guide decision makers on the most appropriate choice of test for different high-risk populations. This current review aimed to provide the most up to date evidence on the cost-effectiveness evidence on LTBI testing in high-risk groups—specifically evidence reporting the costs per QALY of different testing strategies.

Methods

A comprehensive search of databases including MEDLINE, EMBASE and NHS-EED was undertaken from 2011 up to March 2021. Studies were screened and extracted by two independent reviewers. The study quality was assessed using the Bias in Economic Evaluation Checklist (ECOBIAS). A narrative synthesis of the included studies was undertaken.

Results

Thirty-two studies reported in thirty-three documents were included in this review. Quality of included studies was generally high, although there was a weakness across all studies referencing sources correctly and/or justifying choices of parameter values chosen or assumptions where parameter values were not available. Inclusions of IGRAs in testing strategies was consistently found across studies to be cost-effective but this result was sensitive to underlying LTBI prevalence rates.

Conclusion

While some concerns remain about uncertainty in parameter values used across included studies, the evidence base since 2010 has grown with modelling approaches addressing the weakness pointed out in previous reviews but still reaching the same conclusion that IGRAs are likely to be cost-effective in high-income countries for high-risk populations. Evidence is also required on the cost-effectiveness of different strategies in low to middle income countries and countries with high TB burden.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02149-x.

Diagnostic Performance of a Novel CXCL10 mRNA Release Assay for Mycobacterium tuberculosis Infection

One-fourth of the world’s population has been infected with Mycobacterium tuberculosis (M.tb). Although interferon-gamma release assays (IGRAs) have been shown to be valid methods for identifying M.tb infection and auxiliary methods for diagnosis of active tuberculosis (TB), lower sensitivity and higher indeterminate rate were often detected among immunosuppressed patients. IP-10 was an alternative biomarker due to the higher expression level after M.tb antigen stimulation, but whether CXCL10 mRNA (the gene that transcribes for the IP-10 protein) can be used as a target for M.tb infection diagnosis was limited. Therefore, we aimed to evaluate the performance of a novel M.tb-specific CXCL10 mRNA release assay in diagnosis of M.tb infection. Suspected TB patients and healthy controls were prospectively recruited between March 2018 and November 2019 from three hospitals in China. CXCL10 mRNA release assay and traditional interferon-gamma release assay (T-SPOT.TB) were simultaneously performed on peripheral blood. Of the 1,479 participants enrolled in the study, 352 patients with definite TB and 153 healthy controls were analyzed. CXCL10 mRNA release assay provided a sensitivity of 93.9% (95% CI = 90.8–96.2%) and a specificity of 98.0% (95% CI = 94.3–99.6%) in the diagnosis of M.tb infection, respectively, while T-SPOT.TB gave a sensitivity of 94.5% (95% CI = 91.5–96.6%) and a specificity of 100% (95% CI = 97.6–100.0%) in the diagnosis of M.tb infection, respectively. The diagnostic performance of CXCL10 mRNA release assay was consistent with T-SPOT.TB, with a total coincidence rate of 95.0% (95% CI = 93.0–96.9%) and a Cohen’s kappa value of 0.89 (0.84–0.93, p < 0.001). However, among TB patients with HIV co-infection (n = 14), CXCL10 mRNA release assay presented significantly higher positive rate [92.9% (66.1–99.8%) vs. 61.5% (31.6–86.1%), p = 0.029] than those of T-SPOT.TB. These results suggested that M.tb-specific CXCL10 mRNA was a novel and useful target in the diagnosis of M.tb infection.

Diagnostic Value of Interferon-Gamma Release Assays for Tuberculosis in the Immunocompromised Population

Interferon-gamma release assays (IGRAs) are widely used in the diagnosis of Mycobacterium tuberculosis (M. tuberculosis) infection by detecting interferon-γ released by previously sensitized T-cells in-vitro. Currently, there are two assays based on either enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunospot (ELISPOT) technology, with several generations of products available. The diagnostic value of IGRAs in the immunocompromised population is significantly different from that in the immunocompetent population because their results are strongly affected by the host immune function. Both physiological and pathological factors can lead to an immunocompromised situation. We summarized the diagnostic value and clinical recommendations of IGRAs for different immunocompromised populations, including peoplewith physiological factors (pregnant and puerperal women, children, and older people), as well as people with pathological factors (solid organ transplantation recipients, combination with human immunodeficiency virus infection, diabetes mellitus, end-stage renal disease, end-stage liver disease, and chronic immune-mediated inflammatory diseases). Though the performance of IGRAs is not perfect and often requires a combination with other diagnostic strategies, it still has some value in the immunocompromised population. Hopefully, the newly developed IGRAs could better target this population.

A Pilot TB Screening Model in a U.S. Prison Population Using Tuberculin Skin Test and Interferon Gamma Release Assay Based on Country of Origin

The objective of this study was to compare tuberculosis (TB) screening results before and after implementation of a stratified testing strategy screening pilot study, incorporating interferon gamma release assay (IGRA) and tuberculin skin test (TST), based on country of origin. In 2015, the Washington State Department of Corrections began screening people born outside of the United States for TB with IGRA, while U.S.-born people continued screening by TST. Of 405 (75%) foreign-born men screened with IGRA, 403 had valid test results and IGRA screening positivity was 10.4% (N = 42). In contrast, among 5,940 primarily U.S-born men screened with TST, 24 (0.4%) were positive. Overall positivity was 1.05%, similar to TST-only positivity in 2013 (1.05%) and 2014 (0.85%). Incorporating IGRA screening among foreign-born persons was feasible in this state prison system.

Gene Set Enrichment Analysis Reveals Individual Variability in Host Responses in Tuberculosis Patients

Group-aggregated responses to tuberculosis (TB) have been well characterized on a molecular level. However, human beings differ and individual responses to infection vary. We have combined a novel approach to individual gene set analysis (GSA) with the clustering of transcriptomic profiles of TB patients from seven datasets in order to identify individual molecular endotypes of transcriptomic responses to TB. We found that TB patients differ with respect to the intensity of their hallmark interferon (IFN) responses, but they also show variability in their complement system, metabolic responses and multiple other pathways. This variability cannot be sufficiently explained with covariates such as gender or age, and the molecular endotypes are found across studies and populations. Using datasets from a Cynomolgus macaque model of TB, we revealed that transcriptional signatures of different molecular TB endotypes did not depend on TB progression post-infection. Moreover, we provide evidence that patients with molecular endotypes characterized by high levels of IFN responses (IFN-rich), suffered from more severe lung pathology than those with lower levels of IFN responses (IFN-low). Harnessing machine learning (ML) models, we derived gene signatures classifying IFN-rich and IFN-low TB endotypes and revealed that the IFN-low signature allowed slightly more reliable overall classification of TB patients from non-TB patients than the IFN-rich one. Using the paradigm of molecular endotypes and the ML-based predictions allows more precisely tailored treatment regimens, predicting treatment-outcome with higher accuracy and therefore bridging the gap between conventional treatment and precision medicine.

Cross-sectional study of prevalence and risk factors, and a cost-effectiveness evaluation of screening and preventive treatment strategies for latent tuberculosis among migrants in Singapore

OBJECTIVES

WHO recommends that low burden countries consider systematic screening and treatment of latent tuberculosis infection (LTBI) in migrants from high incidence countries. We aimed to determine LTBI prevalence and risk factors and evaluate cost-effectiveness of screening and treating LTBI in migrants to Singapore from a government payer perspective.

DESIGN

Cross-sectional study and cost-effectiveness analysis.

SETTING

Migrants in Singapore.

PARTICIPANTS

3618 migrants who were between 20 and 50 years old, have not worked in Singapore previously and stayed in Singapore for less than a year were recruited.

PRIMARY AND SECONDARY OUTCOME MEASURES

Costs, quality-adjusted life-years (QALYs), threshold length of stay, incremental cost-effectiveness ratios (ICERs), cost per active TB case averted.

RESULTS

Of 3584 migrants surveyed, 20.4% had positive interferon-gamma release assay (IGRA) results, with the highest positivity in Filipinos (33.2%). Higher LTBI prevalence was significantly associated with age, marital status and past TB exposure. The cost-effectiveness model projected an ICER of S$57 116 per QALY and S$12 422 per active TB case averted for screening and treating LTBI with 3 months once weekly isoniazid and rifapentine combination regimen treatment compared with no screening over a 50-year time horizon. ICER was most sensitive to the cohort's length of stay in Singapore, yearly disease progression rates from LTBI to active TB, followed by the cost of IGRA testing.

CONCLUSIONS

For LTBI screening and treatment of migrants to be cost-effective, migrants from high burden countries would have to stay in Singapore for ~50 years. Risk-stratified approaches based on projected length of stay and country of origin and/or age group can be considered.

The TBAg/PHA ratio in T-SPOT.TB assay has high prospective value in the diagnosis of active tuberculosis: a multicenter study in China

Background

The positive rate of pathogenic examination about tuberculosis is low. It is still difficult to achieve early diagnosis for some TB patients. The value of Interferon-gamma release assays (IGRA) in the diagnosis of active tuberculosis remains controversial. The purpose of this multicenter prospective study was to verify and validate the role of TBAg/PHA ratio (TB-specific antigen to phytohaemagglutinin) of T-SPOT.TB assay in diagnosing ATB.

Methods

We prospectively enrolled 2390 suspected pulmonary tuberculosis patients with positive T-SPOT assay results from three tertiary hospitals.

Results

A total of 1549 ATB (active tuberculosis) patients (including 1091 confirmed and 458 probable ATB) and 724 non-tuberculosis (non-TB) patients with positive T-SPOT results were included. The results of this study showed that ESAT-6 and CFP-10 in the T-SPOT.TB assay were significantly higher in the ATB group compared with the non-TB group, while PHA was lower in the ATB group. Results of ESAT-6, CFP-10 and PHA show a certain diagnostic performance, but moderate sensitivity and specificity. The TBAg/PHA ratio, a further calculation of ESAT-6, CFP-10 and PHA in T-SPOT.TB assay showed improved performance in the diagnosis of active Tuberculosis. If using the threshold value of 0.2004, the specificity and sensitivity of TBAg/PHA ratio in distinguishing ATB from non-TB were 92.3% and 74.4%, PPV was 95.4, PLR was 9.6.

Conclusion

By recalculating the results of T-SPOT.TB Assay, the TBAg/PHA ratio shows high prospect value in the diagnosis of active tuberculosis in high prediction areas.

Analysis of 605 tuberculosis outbreaks in Japan, 1993-2015: time, place and transmission site

Since 1993, reports on tuberculosis (TB) outbreaks have been collected in Japan; however, there has never been an overall analysis of these TB outbreaks. We aim to provide one here. The TB outbreak data were obtained from the Ministry of Health, Labour and Welfare and are described in terms of time, place and transmission site. The average number of TB cases and latent tuberculosis infection (LTBI) were compared by the transmission site. Some 605 TB outbreaks with 3491 TB cases were reported in 1993-2015 with an increasing trend (r = 0.45), during which time 728 777 TB cases were reported nationwide. On an average, TB outbreaks occurred more often in April to May (5.5 outbreaks per 2 months) than in December to January (3.4). The most common transmission sites were workplaces (n = 255), followed by health facilities (n = 144), schools (n = 60) and welfare facilities (n = 48). Psychiatric hospitals and nursing homes had the highest average number of TB cases per outbreak (8.5 each), whereas schools and prisons had the highest numbers of LTBI cases (29.1 and 38.9, respectively). Countries, particularly those that have resources to investigate TB outbreaks, should collect and analyse findings of TB outbreaks, as it informs surveillance systems and eventually strengthens general health systems.

Machine Learning Algorithms Evaluate Immune Response to Novel Mycobacterium tuberculosis Antigens for Diagnosis of Tuberculosis

Rationale

Tuberculosis diagnosis in children remains challenging. Microbiological confirmation of tuberculosis disease is often lacking, and standard immunodiagnostic including the tuberculin skin test and interferon-γ release assay for tuberculosis infection has limited sensitivity. Recent research suggests that inclusion of novel Mycobacterium tuberculosis antigens has the potential to improve standard immunodiagnostic tests for tuberculosis.

Objective

To identify optimal antigen–cytokine combinations using novel Mycobacterium tuberculosis antigens and cytokine read-outs by machine learning algorithms to improve immunodiagnostic assays for tuberculosis.

Methods

A total of 80 children undergoing investigation of tuberculosis were included (15 confirmed tuberculosis disease, five unconfirmed tuberculosis disease, 28 tuberculosis infection and 32 unlikely tuberculosis). Whole blood was stimulated with 10 novel Mycobacterium tuberculosis antigens and a fusion protein of early secretory antigenic target (ESAT)-6 and culture filtrate protein (CFP) 10. Cytokines were measured using xMAP multiplex assays. Machine learning algorithms defined a discriminative classifier with performance measured using area under the receiver operating characteristics.

Measurements and main results

We found the following four antigen–cytokine pairs had a higher weight in the discriminative classifier compared to the standard ESAT-6/CFP-10-induced interferon-γ: Rv2346/47c- and Rv3614/15c-induced interferon-gamma inducible protein-10; Rv2031c-induced granulocyte-macrophage colony-stimulating factor and ESAT-6/CFP-10-induced tumor necrosis factor-α. A combination of the 10 best antigen–cytokine pairs resulted in area under the curve of 0.92 ± 0.04.

Conclusion

We exploited the use of machine learning algorithms as a key tool to evaluate large immunological datasets. This identified several antigen–cytokine pairs with the potential to improve immunodiagnostic tests for tuberculosis in children.

Advances in tuberculous meningitis diagnosis

Introduction: Tuberculous meningitis (TBM) is the most devastating form of central nervous system tuberculosis (TB) and causes high mortality worldwide. Nonspecific clinical manifestations and limited sensitivity of existing laboratory methods make the diagnosis elusive due to the paucibacillary nature of the infection. Areas Covered: We reviewed current literature on the adequacy and limitations of globally existing laboratory methods for diagnosing TBM. Expert opinion: TBM is deadliest among all TB forms, as the outcome may lead to death in 50% of cases, and survivors undergo irreversible neurological disorders. Therefore, early diagnosis and prompt treatment are cornerstones of effective disease management. Conventional microscopy and culture are widely used modalities but remain inadequate in most TBM cases. Although expanded use of rapid molecular tests such as real-time PCR and Xpert Ultra, even in resource-limited settings, hold promising results for TB diagnosis but need optimization for early detection of TBM. Moreover, CSF IGRA is also used but unable to differentiate between active and latent TB. Overall no single test for diagnosing TBM has adequate accuracy so, there is an urgent need to devise a point-of-care test.

Vaccination with Intradermal Bacillus Calmette-Guérin Provides Robust Protection against Extrapulmonary Tuberculosis but Not Pulmonary Infection in Cynomolgus Macaques

Recently, the efficacy of Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccination is being reassessed in accordance with the achievements of clinical tuberculosis (TB) vaccine research. However, the mechanisms ultimately determining the success or failure of BCG vaccination to prevent pulmonary TB remain poorly understood. In this study, we analyzed the protective effects of intradermal BCG vaccination by using specific pathogen-free cynomolgus macaques of Asian origin that were intradermally vaccinated with BCG (Tokyo strain) followed by Mycobacterium tuberculosis (Erdman strain) infection. Intradermal BCG administration generated TB Ag-specific multifunctional CD4 T cell responses in peripheral blood and bronchoalveolar lavage and almost completely protected against the development of TB pathogenesis with aggravation of clinical parameters and high levels of bacterial burdens in extrapulmonary organs. However, interestingly, there were no differences in bacterial quantitation and pathology of extensive granulomas in the lungs between BCG-vaccinated monkeys and control animals. These results indicated that the changes in clinical parameters, immunological responses, and quantitative gross pathology that are used routinely to determine the efficacy of TB vaccines in nonhuman primate models might not correlate with the bacterial burden and histopathological score in the lung as measured in this study.

Management and control of tuberculosis control in socially complex groups: a research programme including three RCTs

Background

Socially complex groups, including people experiencing homelessness, prisoners and drug users, have very high levels of tuberculosis, often complicated by late diagnosis and difficulty in adhering to treatment.

Objective

To assess a series of interventions to improve tuberculosis control in socially complex groups.

Design

A series of observational surveys, evaluations and trials of interventions.

Setting

The pan-London Find&Treat service, which supports tuberculosis screening and case management in socially complex groups across London.

Participants

Socially complex groups with tuberculosis or at risk of tuberculosis, including people experiencing homelessness, prisoners, drug users and those at high risk of poor adherence to tuberculosis treatment.

Interventions and main outcome measures

We screened 491 people in homeless hostels and 511 people in prison for latent tuberculosis infection, human immunodeficiency virus, hepatitis B and hepatitis C. We evaluated an NHS-led prison radiographic screening programme. We conducted a cluster randomised controlled trial (2348 eligible people experiencing homelessness in 46 hostels) of the effectiveness of peer educators (22 hostels) compared with NHS staff (24 hostels) at encouraging the uptake of mobile radiographic screening. We initiated a trial of the use of point-of-care polymerase chain reaction diagnostics to rapidly confirm tuberculosis alongside mobile radiographic screening. We undertook a randomised controlled trial to improve treatment adherence, comparing face-to-face, directly observed treatment with video-observed treatment using a smartphone application. The primary outcome was completion of ≥ 80% of scheduled treatment observations over the first 2 months following enrolment. We assessed the cost-effectiveness of latent tuberculosis screening alongside radiographic screening of people experiencing homelessness. The costs of video-observed treatment and directly observed treatment were compared.

Results

In the homeless hostels, 16.5% of people experiencing homelessness had latent tuberculosis infection, 1.4% had current hepatitis B infection, 10.4% had hepatitis C infection and 1.0% had human immunodeficiency virus infection. When a quality-adjusted life-year is valued at £30,000, the latent tuberculosis screening of people experiencing homelessness was cost-effective provided treatment uptake was ≥ 25% (for a £20,000 quality-adjusted life-year threshold, treatment uptake would need to be > 50%). In prison, 12.6% of prisoners had latent tuberculosis infection, 1.9% had current hepatitis B infection, 4.2% had hepatitis C infection and 0.0% had human immunodeficiency virus infection. In both settings, levels of latent tuberculosis infection and blood-borne viruses were higher among injecting drug users. A total of 1484 prisoners were screened using chest radiography over a total of 112 screening days (new prisoner screening coverage was 43%). Twenty-nine radiographs were reported as potentially indicating tuberculosis. One prisoner began, and completed, antituberculosis treatment in prison. In the cluster randomised controlled trial of peer educators to increase screening uptake, the median uptake was 45% in the control arm and 40% in the intervention arm (adjusted risk ratio 0.98, 95% confidence interval 0.80 to 1.20). A rapid diagnostic service was established on the mobile radiographic unit but the trial of rapid diagnostics was abandoned because of recruitment and follow-up difficulties. We randomly assigned 112 patients to video-observed treatment and 114 patients to directly observed treatment. Fifty-eight per cent of those recruited had a history of homelessness, addiction, imprisonment or severe mental health problems. Seventy-eight (70%) of 112 patients on video-observed treatment achieved the primary outcome, compared with 35 (31%) of 114 patients on directly observed treatment (adjusted odds ratio 5.48, 95% confidence interval 3.10 to 9.68; p < 0.0001). Video-observed treatment was superior to directly observed treatment in all demographic and social risk factor subgroups. The cost for 6 months of treatment observation was £1645 for daily video-observed treatment, £3420 for directly observed treatment three times per week and £5700 for directly observed treatment five times per week.

Limitations

Recruitment was lower than anticipated for most of the studies. The peer advocate study may have been contaminated by the fact that the service was already using peer educators to support its work.

Conclusions

There are very high levels of latent tuberculosis infection among prisoners, people experiencing homelessness and drug users. Screening for latent infection in people experiencing homelessness alongside mobile radiographic screening would be cost-effective, providing the uptake of treatment was 25–50%. Despite ring-fenced funding, the NHS was unable to establish static radiographic screening programmes. Although we found no evidence that peer educators were more effective than health-care workers in encouraging the uptake of mobile radiographic screening, there may be wider benefits of including peer educators as part of the Find&Treat team. Utilising polymerase chain reaction-based rapid diagnostic testing on a mobile radiographic unit is feasible. Smartphone-enabled video-observed treatment is more effective and cheaper than directly observed treatment for ensuring that treatment is observed.

Future work

Trials of video-observed treatment in high-incidence settings are needed.

Trial registration

Current Controlled Trials ISRCTN17270334 and ISRCTN26184967.

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full in Programme Grants for Applied Research; Vol. 8, No. 9. See the NIHR Journals Library website for further project information.

Comparison of biochemical parameters and chemokine levels in pleural fluid between patients with anergic and non-anergic tuberculous pleural effusion

Pleural fluid (PF) immune response in anergic tuberculous pleural effusion (TPE) patients is poorly understood. This study aimed to compare PF biochemical parameters and chemokine levels between anergic and non-anergic TPE patients. Chemokine arrays, cytokine measurements, and flow cytometry were performed in 58 patients (TPE [non-anergic (n = 32) and anergic (n = 10)] and malignant pleural effusion (MPE) [n = 16]). PF adenosine deaminase 2 (ADA2) levels were significantly lower in anergic TPE patients than in non-anergic TPE patients (p = 0.048). Among the 40 chemokines tested, PF CCL27 levels were significantly higher in anergic TPE patients than in non-anergic TPE and MPE patients (p < 0.001). The percentage of CD4⁺CCR10⁺T cells in PF was higher in anergic TPE patients than in non-anergic TPE and MPE patients (p = 0.001). We reported here that CCL27/CCR10 interactions might contribute to pathophysiology in anergic TPE. PF CCL27 and CD4⁺CCR10⁺T cells may help in diagnosing TPE in patients with moderate elevation of PF ADA levels.

A retrospective study on Xpert MTB/RIF for detection of tuberculosis in a teaching hospital in China

BACKGROUND

The Xpert MTB/RIF assay is an automated molecular test that is designed to simultaneously detect Mycobacterium tuberculosis (MTB) complex and rifampin resistance. However, there are relatively few studies on this method in China. Xpert has been routinely used at Peking University People's Hospital (PKUPH) since November 2016. Thus, the aim of this study was to evaluate the performance of Xpert, and provide a reference and guidance for the detection and diagnosis of TB in non-TB specialized hospitals.

METHODS

The medical records of inpatients simultaneously tested with Xpert, acid-fast bacilli (AFB) smear microscopy, and interferon-gamma release assay (IGRA, by T-SPOT®.TB) at PKUPH from November 2016 to October 2018 were reviewed. Active TB cases were considered according to a composite reference standard (CRS). Then, the three methods were evaluated and compared.

RESULTS

In total, 787 patients simultaneously tested with Xpert, AFB, and IGRA were enrolled; among them 11.3% (89/787) were diagnosed and confirmed active pulmonary TB (PTB, 52 cases), extrapulmonary TB (EPTB, 17 cases), and tuberculous pleurisy (TP, 20 cases). The sensitivity of Xpert in detecting PTB, EPTB, and TP was 88.5, 76.5, and 15.0%, respectively, which was slightly lower than IGRA (96.2, 82.4, and 95.0%, respectively), but higher than AFB (36.5, 11.8, and 0%, respectively); IGRA showed the highest sensitivity, but its specificity (55.9, 67.1, and 45.2%, respectively) was significantly lower than Xpert (99.6, 99.4, and 100%, respectively) and AFB (99.0, 99.4, and 100%, respectively) (P < 0.001). The sensitivity of Xpert in detecting lung tissue, cerebrospinal fluid, lymph nodes, and joint fluid was 100%, followed by sputum (88.5%), alveolar lavage (85.7%), and bronchoscopy secretion (81.2%); the pleural fluid sensitivity was the lowest, only 15.0%. For AFB negative patients, the sensitivity of Xpert in detecting PTB, EPTB, and TP was 84.9, 73.3, and 15.0%, respectively.

CONCLUSIONS

Xpert showed both high sensitivity and high specificity, and suggested its high value in TB diagnosis; however, the application of pleural fluid is still limited, and should be improved. Owing to the high sensitivity of IGRA, it is recommended for use as a supplementary test, especially for assisting in the diagnosis of TP and EPTB.

A tuberculosis outbreak at an insecure, temporary housing facility, manga café, Tokyo, Japan, 2016-2017

In November 2016, a woman in her 30s who stayed at an insecure, temporary housing facility, a manga café in Tokyo, Japan, for a year was diagnosed with sputum smear-positive tuberculosis (TB). Since the café had 31 staff members and provided with accommodation to many people, the local health office initiated a contact investigation. This study aims to characterise the cases found in the outbreak. A TB case was defined as a person tested bacteriologically positive for TB, or was determined to have TB by a physician. A latent TB infection case was defined as a person tested positive by interferon-γ release assay. From January 2016 through November 2017, there were 31 staff members at the manga café, of which, six developed TB disease (one smear-negative, culture-positive and five smear- and culture-negative) in addition to seven LTBI. Another long-term customer was found having sputum smear-positive TB. Variable numbers tandem repeat (VNTR) test revealed that the index patient and the long-term customer had the identical type of VNTR; however, one staff member had a different VNTR. Local health authorities should intensify screening long-term customers of such facilities for TB regularly as well as once a TB outbreak occurs.

Protection of healthcare workers against transmission of Mycobacterium tuberculosis in hospitals: a review of the evidence

Background

Employees in contact with infectious tuberculosis (TB) patients in healthcare facilities of low-incidence countries are still at considerable risk of acquiring TB infections. However, formal precautions recommended on the protection of healthcare workers may not only vary from country to country but also within a single country. The objective of this study was to compare current guidelines with respect to hospital infection control of TB, focusing on common shared priorities and discrepancies between sets of recommendations.

Methods

Five types of procedures captured in guidelines of the World Health Organization, the United States of America, the United Kingdom and Germany are compared and the underlying evidence is discussed.

Results

Uncontroversially, personal protection by respirators in the TB ward and during aerosol-generating procedures is key to reducing Mycobacterium tuberculosis exposure. However, there is no consensus on the types of masks that should be worn in different situations. Closely connected to this, there is considerable uncertainty with respect to the optimal date of removing sputum smear-negative and multidrug-resistant TB patients from isolation. Indeed, the use of notable new tools for this purpose, such as the highly sensitive PCR tests recommended by the World Health Organization for detecting TB/multidrug-resistant TB, have yet to be sufficiently incorporated into TB guidelines. Perceptions differ, too, as to whether long-term control measures for M. tuberculosis infections in healthcare workers by serial testing for latent TB infection should be established and, if so, how testing results should be interpreted.

Conclusions

Although the current recommendations on protection of healthcare workers are otherwise homogeneous, there are considerable discrepancies that have important implications for daily practice.

Current @WHO, US, UK and German recommendations on protecting employees in healthcare facilities against M. tuberculosis transmission show considerable practical discrepancies. Harmonisation and practical amendments of such guidelines is most desirable.http://bit.ly/2EzGlBN

A tuberculosis outbreak in a psychiatric hospital: Kanagawa, Japan, 2012

In January 2012, an inpatient in a ward of a psychiatric hospital with nearly 300 beds in Kanagawa, Japan, was diagnosed with sputum smear-positive pulmonary tuberculosis (TB). Here we characterise the TB outbreak cases and identify the population at risk. TB was diagnosed when a person tested bacteriologically positive for TB or was determined to have TB by a physician. A latent TB infection (LTBI) case was defined as a person tested positive by interferon-gamma release assay (IGRA). A total of 125 contacts were screened via IGRA and chest X-ray. In all, 15 TB and 15 LTBI cases were found by the end of October 2012, and thereafter no additional TB case was found. Of the 15 TB cases, eight were culture-positive and all the isolates had identical variable number tandem repeat patterns. Twenty-four of the 56 (42.9%, 95% confidence interval (CI) 29.7-56.8) inpatients in the ward had either TB or LTBI with a relative risk of 8.6 (95% CI 1.2-59.3), compared to the staff members who did not work full-time in the ward (one of 20 (5.0%, 95% CI 0.0-24.9)). We recommend that psychiatric hospitals conduct periodic screening of staff members and inpatients for TB to prevent nosocomial TB outbreaks.

Serial anti-tuberculous immune responses during the follow-up of patients with tuberculous pleurisy

Little is known about the decay kinetics of interferon (IFN)-γ response and its influencing factors in tuberculous pleurisy. We enrolled thirty-two patients with tuberculous pleurisy prospectively and followed up at month 0, 6, and 9, at which time peripheral venous blood was drawn for interferon gamma release assay (IGRA) by means of QuantiFERON-TB Gold In-Tube (QFT-GIT). Demographic and clinical data were captured. To identify significant predictive factors influencing the IFN-γ response, multiple linear regression analyses were performed. Percentage of CD4+, CD8+, Vγ2Vδ2 T cells and Treg cells were measured by flow cytometry. The percentage of QFT-GIT-positive patients at baseline, month 6 and month 9 were 96.9% (30/32), 90.6% (29/32) and 84.4% (27/32), respectively. Quantitative IFN-γ response at baseline were significantly correlated with symptom duration (P = .003, R = 0.261) and age (P = .041, R = 0.132). Besides, the decreases of the IFN-γ response at month 6 and month 9 were positively correlated with the IFN-γ level at baseline. The dynamic tendency of the percentages of Treg cells was similar to the IFN-γ responses at each time-point. Quantitative IFN-γ response could be influenced by host immune status, instead of disease burden and anti-tuberculosis treatment. IGRA is probably not a useful biomarker of treatment efficacy in tuberculous pleurisy.

Cost-effectiveness of QuantiFERON-TB Gold In-Tube versus tuberculin skin test for diagnosis and treatment of Latent Tuberculosis Infection in primary health care workers in Brazil

Objectives

The goal of this study was to perform a cost-effectiveness analysis from the public health system perspective, comparing five strategies for Latent Tuberculosis Infection (LTBI) diagnosis in primary health care workers in Brazil.

Design

Analytical model for decision making, characterized by cost-effectiveness analysis.

Setting

Primary Care Level, considering primary health care workers in Brazil.

Participants

An analytical model for decision making, characterized by a tree of probabilities of events, was developed considering a hypothetical cohort of 10,000 primary health care workers, using the software TreeAge Pro^™ 2013 to simulate the clinical and economic impacts of new diagnostic technology (QuantiFERON^®-TB Gold in-Tube) versus the traditional tuberculin skin test.

Methods

This model simulated five diagnostic strategies for LTBI in primary health care workers (HCW) in Brazil: tuberculin skin testing using ≥5 mm cut-off, tuberculin skin testing ≥10 mm cut-off, QuantiFERON^®-TB Gold in-Tube, tuberculin skin testing using ≥5 mm cut-off confirmed by QuantiFERON^®-TB Gold In-Tube if TST positive, tuberculin skin testing using ≥10 mm cut-off confirmed by QuantiFERON^®-TB Gold In-Tube if TST positive.

Primary and secondary outcome measures

The outcome measures are the number of individuals correctly classified by the test and the number of Tuberculosis cases avoided.

Results

The most cost-effective strategy was the tuberculin skin test considering ≥10mm cut-off. The isolated use of the QuantiFERON^®-TB Gold In-Tube revealed the strategy of lower efficiency with incremental cost-effectiveness ratio (ICER) of US$ 146.05 for each HCW correctly classified by the test.

Conclusions

The tuberculin skin test using ≥10 mm cut-off was the most cost-effective strategy in the diagnosis of Latent Tuberculosis Infection in primary health care works in Brazil.

Diagnosis of mycobacterial skin infections

The diagnosis of cutaneous mycobacterial infections may be challenging. Owing to the broad spectrum of their clinical presentations, mycobacterioses have to be considered as differential diagnoses to many inflammatory dermatoses. Diagnostic measures comprise histology including special staining, cultures and molecular microbiological examinations as well as the detection of cellular immune reactions of the patient by means of interferon-γ release assays and skin testing. Clinicians should know the appropriate use and combination of procedures to diagnose mycobacterioses quickly and correctly and to avoid costs and delays caused by unnecessary examinations. This mini review summarizes advantages, limitations, and pitfalls of diagnostic methods for mycobacterial skin infections.

Correlation between the tuberculin skin test and T-SPOT.TB in patients with suspected tuberculosis infection: A pilot study

T-SPOT.TB is a novel screening method for Mycobacterium tuberculosis infection. However, it is controversial whether T-SPOT.TB should become an alternative method to the tuberculin skin test (TST) for screening M. tuberculosis infections. The present study aimed to evaluate this issue based on the retrospective analysis of clinical cases. TST and T-SPOT.TB tests were used on patients with suspected M. tuberculosis infection on admission. Demographic data and clinical information, including previous history of M. tuberculosis infection, were collected. A total of 118 patients were included in the analysis, among whom 30 (25.4%) were diagnosed with active M. tuberculosis infection, and seven patients (5.9%) were currently receiving immunosuppressive treatment. The overall sensitivity and specificity of the TST were 76.7 and 77.3%, respectively, while they were 88.3 and 68.1%, respectively, for the T-SPOT.TB test. Patients with large TST indurations had a higher number of gamma interferon-producing T cells among peripheral blood mononuclear cells compared with those of TST-negative patients. In conclusion, the T-SPOT.TB test had a higher sensitivity than the TST, but the difference was not statistically significant. Neither the T-SPOT.TB test nor the TST was sufficiently accurate to detect active M. tuberculosis infection.

Comparative performance of QuantiFERON-TB Gold versus skin test with tuberculosis recombinant allergen (Diaskintest) among patients with suspected pulmonary tuberculosis in Russia

BACKGROUND

The early identification of Mycobacterium tuberculosis infection can prevent tuberculosis (TB) transmission. A skin test with a tuberculosis recombinant allergen (Diaskintest) is a new method for identification that has been implemented in Russia. This study was performed to compare the performances of Diaskintest and QuantiFERON-TB Gold (QFT) in adults and children with suspected TB in Moscow, Russia.

METHODS

Adults (n=85) and children (n=96) were tested using Diaskintest and QFT. Concordance and comparative analyses were performed.

RESULTS

Diaskintest and QFT were concordant in 84% of adults and 90% of children (overall concordance 87%, κ>0.6, K_c>0.5). The concordance between QFT, Diaskintest, and the final diagnosis was good in adults (86% and 81%, respectively) and moderate in children (77% and 79%, respectively). In adults, QFT had a higher sensitivity for detecting TB than Diaskintest (82% and 68%, respectively); in children, Diaskintest was more sensitive (73% and 65%, respectively). In patients with a confirmed TB diagnosis, negative Diaskintest/QFT results were associated with low disease activity. Combined Diaskintest/QFT results identified TB patients with higher sensitivity and specificity than each test separately.

CONCLUSIONS

Diaskintest is a low-cost diagnostic tool that shows a test positivity rate similar to QFT and can be used in combination with QFT as an adjunctive test for TB diagnosis.

Clinical value of interferon-γ release assay in the diagnosis of active tuberculosis

Sensitivity and specificity of the interferon-γ release test for active tuberculosis screening were evaluated. Due to the high-test cost of imported IGRAs, QFT-GIT and T-SPOT.TB, we applied a cheaper domestic TB-IGRA which was approved in China recently. We recruited 740 patients and performed tuberculosis interferon release test (IGRAs), detection of Mycobacterium tuberculosis IgG antibody (TB-IgG) and tuberculin skin test (TST). The sensitivity of the three methods are 90.8, 40.0 and 75.45%, with specificity of 76.62, 74.47 and 72.27%. The area under the ROC curve according to the value of T-N detected by IGRAs was 0.878 (95% CI, 0.839–0.917), with the area under the curve for the diagnosis of active pulmonary tuberculosis and extrapulmonary tuberculosis being 0.839 and 0.841 respectively. The interferon-γ release test seems to be superior to TST and TB-IgG as a screening tool for the detection of active tuberculosis in China.

The effect of combining QuantiFERON-TB Gold In-Tube test with tuberculin skin test on the detection of active tuberculosis

Background

Interferon-γ release assays (IGRAs) and tuberculin skin tests (TSTs) play an important role in the detection of tuberculosis (TB) infection. However, the interaction between these tests in detecting active pulmonary TB in adults has never been researched.

Methods

A matched case-control study was conducted in Taiwan from 1 March 2012 to 31 December 2013 by enrolling 150 confirmed TB cases and 852 matched controls dwelling at the same area (stratified by low, medium and high incidence).

Results

Compared with a negative QuantiFERON-TB Gold In-Tube (QFT-GIT) test and a negative tuberculin skin test (TST), the effect size for detecting active pulmonary TB was highest for both a positive QFT-GIT and positive TST (adjusted odds ratio [aOR] 8.77 [95% confidence interval {CI} 4.51 to 17.05]), but the detectability was substantially attenuated in the absence of either a positive TST (aOR 1.59 [95% CI 0.70 to 3.63]) or positive QFT-GIT (aOR 1.15 [95% CI 0.48 to 2.71]) after controlling for age and gender. The joint effect of detecting active TB was positively synergistic according to a large positive value of relative excess risk due to interaction (7.05 [95% CI 2.48 to 11.61]).

Conclusions

The administration of both the IGRA and TST for enhancing the detectability of active pulmonary TB in an area with a moderate prevalence of TB such as Taiwan is strongly suggested.

Interferon-Gamma Release Assay is Not Appropriate for the Diagnosis of Active Tuberculosis in High-Burden Tuberculosis Settings: A Retrospective Multicenter Investigation

Background:

Interferon-gamma release assay (IGRA) has been used in latent tuberculosis (TB) infection and TB diagnosis, but the results from different high TB-endemic countries are different. The aim of this study was to investigate the value of IGRA in the diagnosis of active pulmonary TB (PTB) in China.

Methods:

We conducted a large-scale retrospective multicenter investigation to further evaluate the role of IGRA in the diagnosis of active PTB in high TB-epidemic populations and the factors affecting the performance of the assay. All patients who underwent valid T-SPOT.TB assays from December 2012 to November 2015 in six large-scale specialized TB hospitals in China and met the study criteria were retrospectively evaluated. Patients were divided into three groups: Group 1, sputum culture-positive PTB patients, confirmed by positive Mycobacterium tuberculosis sputum culture; Group 2, sputum culture-negative PTB patients; and Group 3, non-TB respiratory diseases. The medical records of all patients were collected. Chi-square tests and Fisher's exact test were used to compare categorical data. Multivariable logistic analyses were performed to evaluate the relationship between the results of T-SPOT in TB patients and other factors.

Results:

A total of 3082 patients for whom complete information was available were included in the investigation, including 905 sputum culture-positive PTB cases, 914 sputum culture-negative PTB cases, and 1263 non-TB respiratory disease cases. The positive rate of T-SPOT.TB was 93.3% in the culture-positive PTB group and 86.1% in the culture-negative PTB group. In the non-PTB group, the positive rate of T-SPOT.TB was 43.6%. The positive rate of T-SPOT.TB in the culture-positive PTB group was significantly higher than that in the culture-negative PTB group (χ² = 25.118, P < 0.01), which in turn was significantly higher than that in the non-TB group (χ² = 566.116, P < 0.01). The overall results were as follows: sensitivity, 89.7%; specificity, 56.37%; positive predictive value, 74.75%; negative predictive value, 79.11%; and accuracy, 76.02%.

Conclusions:

High false-positive rates of T-SPOT.TB assays in the non-TB group limit the usefulness as a single test to diagnose active TB in China. We highly recommend that IGRAs not be used for the diagnosis of active TB in high-burden TB settings.

Immigrant screening for latent tuberculosis infection: numbers needed to test and treat, a Norwegian population-based cohort study

OBJECTIVES

To estimate the number needed to screen (NNS) and the number needed to treat (NNT) to prevent one tuberculosis (TB) case in the Norwegian immigrant latent tuberculosis infection (LTBI) screening programme and to explore the effect of delay of LTBI treatment initiation.

DESIGN

Population-based, prospective cohort study.

PARTICIPANTS

Immigrants to Norway.

OUTCOME

Incident TB.

METHODS

We obtained aggregated data on immigration to Norway in 2008-2011 and used data from the Norwegian Surveillance System for Infectious Diseases to assess the number of TB cases arising in this cohort within 5 years after arrival. We calculated the average NNS and NNT for immigrants from the top 10 source countries for TB in Norway and by estimated TB incidence rates in source countries. We explored the sensitivity of these estimates with regard to test performance, treatment efficacy and treatment adherence using an extreme value approach, and assessed the effects of emigration, time to TB diagnosis (to define incident TB) and intervention timing.

RESULTS

NNS and NNT were overall high, with substantial variation. NNT showed numerically stronger negative correlation with TB notification rate in Norway (-0.75 [95% CI -1.00 to -0.44]) than with the WHO incidence rate (IR) (-0.32 [95% CI -0.93 to 0.29]). NNT was affected substantially by emigration and the definition of incident TB. Estimates were lowest for Somali (NNS 99 [70-150], NNT 27 [19-41]) and highest for Thai immigrants (NNS 585 [413-887], NNT 111 [79-116]). Implementing LTBI treatment in immigrants sooner after arrival may improve the effectiveness of the programme.

CONCLUSION

Using TB notifications in Norway, rather than IR in source countries, would improve targeting of immigrants for LTBI management. However, the overall high NNT is a concern and challenges the scale-up of preventive LTBI treatment for significant public health impact. Better data are urgently needed to monitor and evaluate NNS and NNT in countries implementing LTBI screening.

Current Medical Management of Pulmonary Tuberculosis

Tuberculosis (TB) remains a common cause of infection and disease in much of the world. The majority of disease occurs from reactivation months or years after initial infection and most often involves the lungs. Sputum smears for acid-fast bacilli remain the initial diagnostic test but have limited sensitivity and specificity. Nucleic acid amplification tests are more sensitive and specific and can detect some mutations that cause drug resistance. Treatment of TB resistant to rifamycins alone or in combination with isoniazid and other drugs remains difficult and should be done in consultation with an expert in treating drug-resistant disease.

Risk Factors for Indeterminate Interferon-Gamma Release Assay for the Diagnosis of Tuberculosis in Children-A Systematic Review and Meta-Analysis

Background: Interferon-gamma release assays (IGRA) are well-established immunodiagnostic tests for tuberculosis (TB) in adults. In children these tests are associated with higher rates of false-negative and indeterminate results. Age is presumed to be one factor influencing cytokine release and therefore test performance. The aim of this study was to systematically review factors associated with indeterminate IGRA results in pediatric patients. Methods: Systematic literature review guided by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) searching PubMed, EMBASE, and Web of Science. Studies reporting results of at least one commercially available IGRA (QuantiFERON-TB, T-SPOT.TB) in pediatric patient groups were included. Random effects meta-analysis was used to assess proportions of indeterminate IGRA results. Heterogeneity was assessed using the I² value. Risk differences were calculated for studies comparing QuantiFERON-TB and T-SPOT.TB in the same study. Meta-regression was used to further explore the influence of study level variables on heterogeneity. Results: Of 1,293 articles screened, 133 studies were included in the final analysis. These assessed QuantiFERON-TB only in 77.4% (103/133), QuantiFERON-TB and T-SPOT.TB in 15.8% (21/133), and T-SPOT.TB only in 6.8% (9/133) resulting in 155 datasets including 107,418 participants. Overall 4% of IGRA results were indeterminate, and T-SPOT.TB (0.03, 95% CI 0.02-0.05) and QuantiFERON-TB assays (0.05, 95% CI 0.04-0.06) showed similar proportions of indeterminate results; pooled risk difference was-0.01 (95% CI -0.03 to 0.00). Significant differences with lower proportions of indeterminate assays with T-SPOT.TB compared to QuantiFERON-TB were only seen in subgroup analyses of studies performed in Africa and in non-HIV-infected immunocompromised patients. Meta-regression confirmed lower proportions of indeterminate results for T-SPOT.TB compared to QuantiFERON-TB only among studies that reported results from non-HIV-infected immunocompromised patients (p < 0.001). Conclusion: On average indeterminate IGRA results occur in 1 in 25 tests performed. Overall, there was no difference in the proportion of indeterminate results between both commercial assays. However, our findings suggest that in patients in Africa and/or patients with immunocompromising conditions other than HIV infection the T-SPOT.TB assay appears to produce fewer indeterminate results.

Tuberculous coxitis with trochanteric bursitis manifesting a year after immigration to Germany: a case report

Background

Osteoarticular tuberculosis is rare in Germany. In particular, trochanteric bursitis is an extremely rare manifestation of osteoarticular tuberculosis. We describe a case of tuberculous coxitis with trochanteric bursitis, successfully treated with a fourfold tuberculostatic therapy.

Case presentation

We report the case of a 43-year-old human immunodeficiency virus-negative Sudanese man with osteoarticular tuberculosis, who was originally admitted with the suspected diagnosis of ankylosing spondylitis. Low grade fever together with the positive result of an interferon-gamma release assay test as well as findings from magnetic resonance imaging provided clues to the diagnosis. A definitive diagnosis could be set after a computed tomography-guided biopsy.

Conclusions

Apart from a rare involvement pattern of osteoarticular tuberculosis, including trochanteric bursitis, this case highlights the increasing importance of osteoarticular tuberculosis as a differential diagnosis of rheumatic disorders. With the growing migration flows from tuberculosis-endemic African countries, clinicians in central and northern Europe may be more frequently confronted with atypical involvement patterns of osteoarticular tuberculosis.

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.

Ocular Autoimmune Systemic Inflammatory Infectious Study (OASIS) - Report 2: Pattern of Uveitis Investigations in Singapore

Purpose: To analyze the pattern of laboratory investigations of uveitis at a tertiary referral eye care center in Singapore.Methods: Retrospective analysis of 2040 uveitis cases from the Ocular Autoimmune Systemic Inflammatory Infectious Study (OASIS) database over a 12-year period (2004 - 2015).Results: Patients with retinal vasculitis (RV) had the most tests utilized per patient (6.79), followed by intermediate uveitis (IU) (5.25), panuveitis (Pan) (5.12), posterior uveitis (PU) (4.17), anterior uveitis (AU) (2.75), and keratouveitis (KU) (1.10). The most frequently utilized test for infective etiology were the VDRL (41.3%), Syphilis IgG (29.5%), and T-SPOT.TB (24.6%). For autoimmune tests, ANA was most utilized (18.2%), followed by anti-dsDNA (14.8%), and HLA-B27 (12.4%).Conclusion: There was high utilization of autoimmune tests such as ANA, anti-dsDNA, RF, and ANCA, despite its limited yield. Rationalization of investigations in patients with ocular inflammation via a stepladder approach may help optimize the use of limited resources.

Tuberculosis-associated hemophagocytic lymphohistiocytosis with subsequent unmasking cryptococcal immune reconstitution inflammatory syndrome (IRIS) in an HIV-negative man

A 22-year-old HIV-negative man from Ghana was diagnosed with severe hemophagocytic lymphohistiocytosis (HLH) induced by multiorgan tuberculosis with peritoneal, hepatic, pericardial, myocardial, pleural, pulmonary, and bone manifestation. His body mass index was 12.9 m²/kg. Bioptic material of a peritoneal biopsy grew M. tuberculosis, sensitive to all first-line antituberculous drugs. HLH resolved with antituberculous therapy, without additional anti-inflammatory therapy being given. The initial CT scan of his brain was normal. After 5 months of antituberculous treatment, he developed a paralysis of the left arm. A cerebral MRT showed ring-enhanced lesions. Blood cultures and lumbar puncture revealed Cryptococcus neoformans var. grubi. The HIV test was repeatedly negative. Antituberculous treatment was continued for a total of 9 months, and additional treatment with antifungal therapy was established. He recovered fully after 14 months of antifungal treatment.