Diagnosis of tuberculosis infection using interferon-γ-based assays

A nomogram to predict lung cancer in pulmonary lesions for tuberculosis infection patients

Similar clinical features make the differential diagnosis difficult, particularly between lung cancer and pulmonary tuberculosis (TB), without pathological evidence for patients with concomitant TB infection. Our study aimed to build a nomogram to predict malignant pulmonary lesions applicable to clinical practice. We retrospectively analyzed clinical characteristics, imaging features, and laboratory indicators of TB infection patients diagnosed with lung cancer or active pulmonary TB at Xiangya Hospital of Central South University. A total of 158 cases from January 1, 2018 to May 30, 2019 were included in the training cohort. Predictive factors for lung cancer were screened by a multiple-stepwise logistic regression analysis. A nomogram model was established, and the discrimination, stability, and prediction performance of the model were analyzed. A total of 79 cases from June 1, 2019, to December 30, 2019, were used as the validation cohort to verify the predictive value of the model. Eight predictor variables, including age, pleural effusion, mediastinal lymph node, the number of positive tumor markers, the T cell spot test for TB, pulmonary lesion morphology, location, and distribution, were selected to construct the model. The corrected C-statistics and the Brier scores were 0.854 and 0.130 in the training cohort, and 0.823 and 0.163 in the validation cohort. Calibration plots showed good performance, and decision curve analysis indicated a high net benefit. In conclusion, the nomogram model provides an effective method to calculate the probability of lung cancer in TB infection patients, and it has excellent discrimination, stability, and prediction performance in detecting a malignant diagnosis of undiagnosed pulmonary lesions.

Amino acid profiling as a screening and prognostic biomarker in active tuberculosis patients

BACKGROUND

Tuberculosis (TB) is one of the world's most deadly chronic infectious diseases; early diagnosis contributes to reducing disease transmission among populations. However, discovering novel diagnostic and prognostic biomarkers is still an important topic in the field of TB. Amino acid is the basic unit of protein composition, and its structure and physicochemical characteristics are more stable. Therefore, it is a potential target for TB diagnosis and the prediction of TB development.

METHODS

In this study, the blood of healthy people (HC), TB patients (TB), cured TB (RxTB), and other non-TB pneumonia patients (PN) were collected to detect the levels of amino acids in whole blood and plasma using ultra-high performance liquid chromatography coupled with mass spectrometry.

RESULTS

We detected that the amino acid levels correlated with participants status (TB, HC, RxTB, or PN) and the degree of lung damage. The results showed that phenylalanine had a good effect on the screening of TB (AUC = 0.924). We then built a TB prediction model. The model, which was based on the ratio of plasma amino acid content to whole blood amino acid content, showed good performance for the screening of TB, with 84% (95% CI = 60-97) sensitivity and 97% (95% CI = 83-100) specificity. The result of correlation between the HRCT score and amino acid level indicated that the glutamine content of plasma was significantly inversely associated with disease severity. Additionally, ornithine levels in the plasma of RxTB group reduced and four amino acids of which the ratio in plasma to whole blood showed significantly changed.

CONCLUSIONS

Taken together, amino acid profiling can be used for TB screening, and a multiparameter profiling model is better. The profiling can also reflect the severity of lung damage. Moreover, the amino acid profile is useful for reflecting the efficacy of TB treatment.

Miliary Tuberculosis in a Crohn's Disease Patient: The Risk beyond the Screening

Tumor necrosis factor alpha (TNFα) antagonist is recognized as an effective treatment to achieve clinical remission and healing mucosal in patients with moderate to severe active Crohn's disease. Considering that it plays a central role in immune-mediated modulation, there are some obvious concerns about its long-term safety. There is evidence that it may increase the risk of opportunistic infections such as tuberculosis, particularly reactivation of previous latent infection. Due to the global high incidence of tuberculosis and its frequent severity in immunocompromised patients, the exclusion of latent infection is currently part of the screening prior to anti-TNFα therapy. Only a few cases of life-threatening disseminated tuberculosis have been reported in immunocompromised patients probably related to widespread use of higher-accuracy screening tests, such as interferon-γ release assays. However, despite negative screening, the risk of active tuberculosis infection remains during treatment. In that instance, tuberculosis infection becomes considerably more difficult to diagnose due to its altered pattern presentation (extrapulmonary and disseminated infection) and is harder to treat because of the high rate of resistance and its associated relevant morbidity and mortality. We report an enigmatic case of a miliary tuberculosis despite negative latent infection screening, using interferon-γ release assays, in a Crohn's disease patient undergoing treatment with infliximab and azathioprine, focusing on the screening and diagnostic and therapeutic challenge. This case enhances the awareness of anti-TNFα therapy management and the need for strategies to diagnose and treat tuberculosis in this context.

Evaluation of Varicella-zoster virus-specific cell-mediated immunity by interferon-γ Enzyme-Linked Immunosorbent Assay in adults ≥50 years of age administered a herpes zoster vaccine

Varicella-zoster virus (VZV)-specific cell-mediated immunity (CMI) is critical for preventing and controlling the onset of herpes zoster (HZ). To assess VZV CMI, an interferon-γ (IFN-γ) enzyme-linked immunosorbent assay (ELISA) was validated by examining the influence of VZV-specific antigen content, incubation time, and interval from whole blood collection on the assay. In phase II clinical trial, VZV-specific CMI in adults ≥50 years of age administered an HZ vaccine were evaluated by IFN-γ ELISA, as determined by measuring IFN-γ production in the whole blood in response to stimulation with ultraviolet light-inactivated VZV. The VZV-specific IFN-γ levels varied among individuals from prevaccination (baseline) to 6 weeks postvaccination. In most subjects, VZV-specific CMI was increased at 6 weeks postvaccination. The HZ vaccine elicited a significant increase in the VZV-specific CMI response as measured by ELISA; the geometric mean fold-rises from baseline to 6 weeks postvaccination were 3.50, 4.22, and 5.24 in the 4.3, 4.7, and 4.9 log plaque-forming unit vaccine groups, respectively, which was significantly higher than in the placebo group (P < 0.05). These results indicate that vaccination enhances the VZV-specific CMI responses in subjects; IFN-γ ELISA is an effective method for evaluating the CMI response and may be useful for identifying individuals at a high risk of HZ infection.

QuantiFERON-TB Gold In-tube test for the diagnosis of active and latent tuberculosis in selected health facilities of Addis Ababa, Ethiopia

Objective

To determine the performance of QuantiFERON-TB IN-Gold for the diagnosis active tuberculosis and latent tuberculosis.

Results

A total of 213 participants (136 tuberculosis suspects, 66 latently infected) were enrolled. Of 213, 21 (15.4%) of the tuberculosis suspects and 3 (4.5%) of the latent tuberculosis groups were human immunodeficiency virus infected. The sensitivity, specificity, positive and negative predictive value of QuantiFERON-TB IN-Gold for the diagnosis of active tuberculosis was 70.3% (26/37), 49.5% (49/99), 34.7% (26/75) and 83.1% (49/59) respectively. A kappa value of 0.316 (p = 0.001, 95% CI 1.605–1.609) between QuantiFERON-TB IN-Gold and tuberculin skin test were found.

Evaluation of interferon-gamma release assays in extrasanguinous body fluids for diagnosing tuberculosis: A systematic review and meta-analysis

AIMS

In this study, we conducted a meta-analysis to systematically compare the diagnostic accuracy of IGRAs performed for extrasanguinous body fluids with that performed for blood in the diagnosis of TB.

MAIN METHODS

Multiple English and Chinese databases were searched up to November 2017. Studies that complied with the guidelines for the Quality Assessment of Diagnostic Accuracy Studies and used QuantiFERON-TB Gold In-Tube and/or T-SPOT.TB (ELISPOT) assays on both blood and extrasanguinous body fluids were included. Statistical analysis was performed using Stata 12.0 software. Since publication bias is a concern in the meta-analysis of diagnostic studies, we tested for this using Begg's funnel plots.

KEY FINDING

Among the 1332 articles searched from the databases, 24 articles met the inclusion criteria, which included 1040 samples in the patient group and 1044 samples in the control group. For extrasanguinous body fluids, the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) area under the curve (AUC) were 87% (95% CI: 0.81-0.91), 89% (95% CI: 0.84-0.93), 8.22 (95% CI 5.38-12.56), 0.15 (95% CI: 0.10-0.21), 44.92 (95% CI: 25.61-78.81), and 0.94 (95% CI: 0.92-0.96), respectively. For peripheral blood, these values were 83% (95% CI: 0.79-0.87), 74% (95% CI: 0.68-0.79), 3.17 (95% CI 2.63-3.84), 0.23 (95% CI: 0.19-0.29), 12.99 (95% CI: 10.19-16.57), and 0.86 (95% CI: 0.82-0.89), respectively.

SIGNIFICANCE

IGRAs performed on extrasanguinous body fluids exhibited a better diagnostic accuracy compared with IGRAs performed on peripheral blood for diagnosing TB.

How Can Elispot Add Information to Improve Knowledge on Tropical Diseases?

Elispot has been used as an important tool for detecting immune cells' products and functions and has facilitated the understanding of host-pathogen interaction. Despite the incredible diversity of possibilities, two main approaches have been developed: the immunopathogenesis and diagnosis/prognosis of infectious diseases as well as cancer research. Much has been described on the topics of allergy, autoimmune diseases, and HIV-Aids, however, Elispot can also be applied to other infectious diseases, mainly leishmaniasis, malaria, some viruses, helminths and mycosis usually classified as tropical diseases. The comprehension of the function, concentration and diversity of the immune response in the infectious disease is pointed out as crucial to the development of infection or disease in humans and animals. In this review we will describe the knowledge already obtained using Elispot as a method for accessing the profile of immune response as well as the recent advances in information about host-pathogen interaction in order to better understand the clinical outcome of a group of tropical and neglected diseases.

Tuberculosis and Transplantation

Mycobacterium tuberculosis is a major opportunistic pathogen in transplant recipients. Compared to that in the general population, the frequency of tuberculosis (TB) is 10 to 40 times higher in hematopoietic stem cell transplant (HSCT) recipients and 20 to 74 times higher in solid-organ transplant (SOT) recipients. Transplant recipients with TB are also more likely to develop disseminated disease, have longer time to definitive diagnosis, require more invasive diagnostic procedures, and experience greater anti-TB treatment-related toxicity than the general population. Specific risk factors for TB in SOT recipients include previous exposure to M. tuberculosis (positive tuberculin skin tests and/or residual TB lesions in pretransplant chest X ray) and the intensity of immunosuppression (use of antilymphocyte antibodies, type of basal immunosuppression, and intensification of immunosuppressive therapy for allograft rejection). Risk factors in HSCT recipients are allogeneic transplantation from an unrelated donor; chronic graft-versus-host disease treated with corticosteroids; unrelated or mismatched allograft; pretransplant conditioning using total body irradiation, busulfan, or cyclophosphamide; and type and stage of primary hematological disorder. Transplant recipients with evidence of prior exposure to M. tuberculosis should receive treatment appropriate for latent TB infection. Optimal management of active TB disease is particularly challenging due to significant drug interactions between the anti-TB agents and the immunosuppressive therapy. In this chapter, we address the epidemiology, clinical presentation, diagnostic considerations, and management strategies for TB in SOT and HSCT recipients.

Guidelines for the use of interferon-γ release assays in the diagnosis of tuberculosis infection

INTRODUCTION

Interferon-gamma release assays are widely used for the diagnosis of tuberculosis infection in low-prevalence countries. However, there is no consensus on their application. The objective of this study was to develop guidelines for the use of interferon-gamma release assays in specific clinical scenarios in Spain.

METHODS

A panel of experts comprising specialists in infectious diseases, respiratory diseases, microbiology, pediatrics and preventive medicine, together with a methodologist, formulated the clinical questions and outcomes of interest. They conducted a systematic literature search, summarized the evidence and rated its quality, and prepared the recommendations following the GRADE (Grading of Recommendations of Assessment Development and Evaluations) methodology.

RESULTS

The panel prepared recommendations on the use of interferon-gamma release assays for the diagnosis of tuberculosis infection in the contact-tracing study (both adults and children), health care workers, immunosuppressed patients (patients infected with human immunodeficiency virus, patients with chronic immunomediated inflammatory diseases due to start biological therapy and patients requiring organ transplant) and for the diagnosis of active tuberculosis. Most recommendations were weak, mainly due to the lack of good quality evidence to balance the clinical benefits and disadvantages of the interferon-gamma release assays as compared with the tuberculin skin test.

CONCLUSION

This document provides evidence-based guidance on the use of interferon-gamma release assays for the diagnosis of tuberculosis infection in patients at risk of tuberculosis or with suspicion of active disease. The guidelines will be applicable in specialist and primary care and in public health settings.

Toxicity and adherence to treatment for latent tuberculosis infection in patients with hematologic malignancies

PURPOSE

Oncohematological patients undergoing chemotherapy who have latent tuberculosis infection (LTBI) are at a high risk of developing active tuberculosis (TB). The identification and treatment of these patients can prevent LTBI progressing to active TB. This study analyzed the degree of adherence with and safety of the treatment of latent tuberculosis infection (TLTBI) in oncohematological patients undergoing antineoplastic chemotherapy.

METHODS

This is a retrospective study of a cohort of oncohematological patients receiving TLTBI and antineoplastic chemotherapy simultaneously, between January 2007 and June 2010. The proportions of toxicity and adherence to TLTBI in these patients were compared with a non-oncohematological control group, matched for age, sex, and year in which the TLTBI was started. In addition, a minimum 2-year follow-up was carried out for all patients.

RESULTS

A total of 105 patients who received TLTBI were included, 21 of whom had received antineoplastic chemotherapy simultaneously. The mean age of the patients was 63 years. There were no significant baseline differences in transaminase values. The percentages of patients completing treatment were 76.2% in the control group and 71.4% in the oncohematological group [risk ratio (RR): 1.07, 95% confidence interval (CI): 0.79-1.43]. The voluntary dropout proportion was similar in both groups (12.3 vs. 11.8%, RR: 1.05, 95% CI: 0.25-4.42). Treatment was discontinued because of toxicity in three oncohematological patients and in 11 patients from the control group (RR: 1.14; 95% CI: 035-3.66). No patient developed TB during the follow-up period.

CONCLUSION

The safety of TLTBI is not influenced by simultaneous antineoplastic chemotherapy in oncohematological patients.

Preclinical study and phase I clinical safety evaluation of recombinant Mycobacterium tuberculosis ESAT6 protein

BACKGROUND

To investigate the ability of rESAT6 to identify different mycobacteria-sensitized guinea pigs and its safety in preclinical and phase I clinical study.

MATERIAL AND METHODS

Guinea pigs were sensitized with different Mycobacteria. After sensitization, all animals were intradermally injected with rESAT6 and either PPD or PPD-B. At 24 h after the injection, the erythema of the injection sites were measured using a double-blind method. For the preclinical safety study, different doses of rESAT6 and BSA were given 3 times intramuscularly to guinea pigs. On day 14 after the final immunization, the guinea pigs were intravenously injected with the same reagents in the hind legs and the allergic reactions were observed. A single-center, randomized, open phase I clinical trial was employed. The skin test was conducted in 32 healthy volunteers aged 19-65 years with 0.1 µg, 0.5 µg, and 1 µg rESAT6. Physical examination and laboratory tests were performed before and after the skin test and adverse reactions were monitored. The volunteers' local and systemic adverse reactions and adverse events were recorded for 7 days.

RESULTS

Positive PPD or PPD-B skin tests were observed in all Mycobacteria-sensitized guinea pigs; the diameters of erythema were all >10 mm. The rESAT6 protein induced a positive skin test result in the guinea pigs sensitized with MTB, M. bovis, M. africanum and M. kansasii; the diameters of erythema were 14.7±2.0, 9.3±3.8, 18.7±2.4, and 14.8±4.2 mm, respectively. A negative skin test result was detected in BCG-vaccinated and other NTM-sensitized guinea pigs. The rESAT6 caused no allergic symptoms, but many allergic reactions, such as cough, dyspnea, and even death, were observed in the guinea pigs who were administered BSA. During the phase I clinical trial, no adverse reactions were found in the 0.1 µg rESAT6 group, but in the 0.5 µg rESAT6 group 2 volunteers reported pain and 1 reported itching, and in the 1 µg rESAT6 group there was 1 case of pain, 1 case of itching, and 1 case of blister. No other local or systemic adverse reactions or events were reported.

CONCLUSIONS

The rESAT6 can differentiate effectively among MTB infection, BCG vaccination, and NTM infection and is safe in healthy volunteers.

Value of the tuberculin skin testing and of an interferon-gamma release assay in haemodialysis patients after exposure to M. tuberculosis

Background

Patients with end-stage renal disease (ESRD) and Mycobacterium tuberculosis infection pose a high risk of developing active TB disease. It is therefore important to detect latent TB infection (LTBI) to be able to offer treatment and prevent progression to TB disease. We assessed the value of the tuberculin skin test (TST) and of an interferon-gamma release assay (Quantiferon®-TB Gold in-Tube, QFT) for diagnosing LTBI in ESRD patients, after prolonged exposure to a highly contagious TB case in a haemodialysis unit. As a high number of patients presented erythema without induration in the TST response, this type of reaction was also analysed.

Method

The TST and QFT were simultaneously performed twelve weeks after the last possible exposure to a bacilliferous TB patient. If the first TST (TST-1) was negative, a second TST (TST-2) was performed 15 days later to detect a booster response. A comparison was made between the TST responses (including those cases with erythema without induration) and those for the QFT. The correlation with risk of infection and the concordance between tests were both analysed.

Results

A total of 52 patients fulfilled the inclusion criteria. Overall, 11 patients (21.2%) had a positive TST response: 3 for TST-1 and 8 for TST-2, and 18 patients (34.6%) showed a positive QFT response (p = 0.065). Erythema without induration was found in 3 patients at TST-1 and in a further 9 patients at TST-2. The three patients with erythema without induration in TST-1 had a positive TST-2 response. Concordance between TST and QFT was weak for TST-1 (κ = 0.21); it was moderate for overall TST (κ = 0.49); and it was strong if both induration and erythema (κ = 0.67) were considered.

Conclusions

In patients with ESRD, erythema without induration in the TST response could potentially be an indicator of M. tuberculosis infection. The QFT shows better accuracy for LTBI diagnosis than the TST.

Interferon-γ release assays for the diagnosis of tuberculosis and tuberculosis infection in HIV-infected adults: a systematic review and meta-analysis

BACKGROUND

Despite the widespread use of interferon-γ release assays (IGRAs), their role in diagnosing tuberculosis and targeting preventive therapy in HIV-infected patients remains unclear. We conducted a comprehensive systematic review to contribute to the evidence-based practice in HIV-infected people.

METHODOLOGY/PRINCIPAL FINDINGS

We searched MEDLINE, Cochrane, and Biomedicine databases to identify articles published between January 2005 and July 2011 that assessed QuantiFERON®-TB Gold In-Tube (QFT-GIT) and T-SPOT®.TB (T-SPOT.TB) in HIV-infected adults. We assessed their accuracy for the diagnosis of tuberculosis and incident active tuberculosis, and the proportion of indeterminate results. The search identified 38 evaluable studies covering a total of 6514 HIV-infected participants. The pooled sensitivity and specificity for tuberculosis were 61% and 72% for QFT-GIT, and 65% and 70% for T-SPOT.TB. The cumulative incidence of subsequent active tuberculosis was 8.3% for QFT-GIT and 10% for T-SPOT.TB in patients tested positive (one study each), and 0% for QFT-GIT (two studies) and T-SPOT.TB (one study) respectively in those tested negative. Pooled indeterminate rates were 8.2% for QFT-GIT and 5.9% for T-SPOT.TB. Rates were higher in high burden settings (12.0% for QFT-GIT and 7.7% for T-SPOT.TB) than in low-intermediate burden settings (3.9% for QFT-GIT and 4.3% for T-SPOT.TB). They were also higher in patients with CD4(+) T-cell count <200 (11.6% for QFT-GIT and 11.4% for T-SPOT.TB) than in those with CD4(+) T-cell count ≥ 200 (3.1% for QFT-GIT and 7.9% for T-SPOT.TB).

CONCLUSIONS/SIGNIFICANCE

IGRAs have suboptimal accuracy for confirming or ruling out active tuberculosis disease in HIV-infected adults. While their predictive value for incident active tuberculosis is modest, a negative QFT-GIT implies a very low short- to medium-term risk. Identifying the factors associated with indeterminate results will help to optimize the use of IGRAs in clinical practice, particularly in resource-limited countries with a high prevalence of HIV-coinfection.

Tuberculosis infection versus anti-tumor necrosis factor therapy: screening challenges in psoriatic patients

OBJECTIVES

The aim of this study was to analyze the performance of the tuberculin skin test (TST) for screening and monitoring patients treated with anti-tumor necrosis factor agents, in a high-incidence area.

METHODS

A 3-year retrospective study was carried out on 268 subjects. The study included 68 patients with moderate-to-severe psoriasis, screened for latent tuberculosis infection (LTBI) and subjects without psoriasis (100 adults and 100 children) with close contact with infected individuals.

RESULTS

Positive tuberculin skin test (TST) results (induration >5 mm) were observed in 70.5% (48/68) of patients with psoriasis, higher than those observed in subjects with suspicion of tuberculosis or with close contact with infected individuals: 51% (51/100) in the adult group and 30% (30/100) in the children group.

CONCLUSIONS

These results show that the prevalence of LTBI evaluated with the TST in the psoriatic group is higher than in subjects without psoriasis.

LIMITATION

The positive reactions were not confirmed by other verification methods.

Comparison of the 2-step tuberculin skin test and the quantiFERON-TB Gold In-Tube Test for the screening of tuberculosis infection before liver transplantation

The ability of interferon-gamma release assays (IGRAs) to detect latent tuberculosis (TB) infection before liver transplantation (LT)is not well established. The aims of this study were (1) to compare the ability of the tuberculin skin test (TST) and the QuantiFERON-TB Gold In-Tube (QFT-IT) test (a whole-blood IGRA) to diagnose latent TB infections in patients awaiting LT and (2) to correlate the results with the severity of liver disease. We conducted a prospective, cross-sectional study of patients who were evaluated for LT between July 2008 and July 2010. The 95 patients who were included underwent the 2-step TST and the QFT-IT test. The mean Model for End-Stage Liver Disease (MELD) score was 13.8. Forty-four patients (46.3%) had positive TST results, 42 (44.2%) had positive QFT-IT results, and 2 (2.1%) had indeterminate QFT-IT results. Simultaneous TST and QFT-IT testing yielded a positivity rate of 55.8% [95% confidence interval (CI) = 45.3-65.9] with either test, and the 2-step TST yielded a positivity rate of 46.3% (95% CI = 36.1-56.8); the difference was 9.5% (P = 0.004). In an adjusted analysis, the rates for positive TST results were lower in patients with MELD scores > or = 18 [odds ratio (OR) = 0.2, 95% CI = 0.04-0.7], lower in Child-Pugh-Turcotte (CPT) class C patients versus CPT class A patients (OR = 0.1, 95% CI = 0.02-0.6), and higher in males (OR = 6.4, 95% CI = 1.9-22.0). In contrast, only being male (OR = 3.5, 95% CI = 1.1-11.0) was associated with positive QFT-IT results; no association was found with the MELD score (OR = 0.8, 95% CI = 0.2-2.8) or the CPT class (OR = 0.3; 0.05-1.4). In conclusion, the QFT-IT test is better than the TST for detecting latent TB infection in patients with more advanced liver disease. Our results support the regular use of the QFT-IT test for screening patients with end-stage liver disease for latent TB infection before LT.