False-negative interferon-γ release assay results in active tuberculosis: a TBNET study

High risk of drug-resistant tuberculosis in IGRA-negative contacts: should preventive treatment be considered?

PURPOSE

Deciding whether to provide preventive treatment to contacts of individuals with multidrug-resistant (MDR) tuberculosis is complex.

METHODS

We present the diagnostic pathways, clinical course and outcome of tuberculosis treatment in eight siblings from a single family. Tuberculosis disease was diagnosed by Mycobacterium tuberculosis culture and molecular detection of M. tuberculosis-specific DNA from bronchopulmonary specimens using GeneXpert® MTB/RIF. M. tuberculosis infection was diagnosed by an interferon-gamma release assay (IGRA; QuantiFERON®-TB Gold Plus). Whole exome sequencing for genetic predisposition to mycobacterial infection was performed in one patient.

RESULTS

Six of eight siblings aged 16-20 years from a migrant family of Somali origin were diagnosed with pulmonary MDR tuberculosis over a 12-month period. The remaining male siblings, aged 11 and 14 years, were asymptomatic during contact investigation. Chest radiographs, computed tomography (CT) scans, sputum cultures and nucleic acid amplification tests were negative, and the IGRA did not detect M. tuberculosis infection. A repeat CT scan eight months later was unremarkable, and repeated sputum cultures remained negative. In the absence of sufficient evidence of M. tuberculosis infection, no preventive treatment was offered. At month seven of consistent clinical observation, both children were diagnosed with pulmonary tuberculosis; the older with advanced disease and subsequent post-tuberculosis lung disease. Whole exome sequencing revealed no Mendelian variant associated with susceptibility to mycobacterial infection.

CONCLUSION

When significant risk of tuberculosis transmission exists, close contacts of MDR tuberculosis patients should be offered preventive treatment with levofloxacin despite a negative IGRA test result.

Disseminated tuberculosis after anti-TNF alpha treatment: Do not blindly trust the IGRA test

INTRODUCTION

Interferon gamma release assay (IGRA) is used to detect latent tuberculosis prior to biological treatments in the context of suspected inflammatory rheumatism.

METHODS

We report the case of a 50-year-old woman with negative IGRA test before adalimumab introduction for presumed axial spondyloarthritis.

RESULTS

The worsening of symptoms under treatment led to further investigations and the diagnostic of disseminated tuberculosis (TB) was later established with miliary and multiple bone locations such as spondylitis and sacroilitis. The patient's history revealed past exposure to tuberculosis. This observation illustrates the limitations of IGRA in such situation due to its variable performance for active TB diagnosis.

CONCLUSION

Misdiagnosis is frequent in bone tuberculosis due to non-specific signs. We draw the attention to the importance of a global risk assessment prior to the introduction of biological treatment for suspected chronic inflammatory rheumatism and recall the risk factors for false-negative IGRA. An extended treatment course may be necessary after exposure to anti-TNF-alpha.

Vaccines and Dementia: Part II. Efficacy of BCG and Other Vaccines Against Dementia

There is growing awareness that infections may contribute to the development of senile dementia including Alzheimer's disease (AD), and that immunopotentiation is therefore a legitimate target in the management of diseases of the elderly including AD. In Part I of this work, we provided a historical and molecular background to how vaccines, adjuvants, and their component molecules can elicit broad-spectrum protective effects against diverse agents, culminating in the development of the tuberculosis vaccine strain Bacille Calmette-Guérin (BCG) as a treatment for some types of cancer as well as a prophylactic against infections of the elderly such as pneumonia. In Part II, we critically review studies that BCG and other vaccines may offer a measure of protection against dementia development. Five studies to date have determined that intravesicular BCG administration, the standard of care for bladder cancer, is followed by a mean ∼45% reduction in subsequent AD development in these patients. Although this could potentially be ascribed to confounding factors, the finding that other routine vaccines such as against shingles (herpes zoster virus) and influenza (influenza A virus), among others, also offer a degree of protection against AD (mean 29% over multiple studies) underlines the plausibility that the protective effects are real. We highlight clinical trials that are planned or underway and discuss whether BCG could be replaced by key components of the mycobacterial cell wall such as muramyl dipeptide. We conclude that BCG and similar agents merit far wider consideration as prophylactic agents against dementia.

Host factors associated with false negative results in an interferon-γ release assay in adults with active tuberculosis

OBJECTIVE

To identify host factors associated with false-negative results of interferon-γ release tests in adults with active tuberculosis.

METHODS

The clinical data of 943 patients with active tuberculosis diagnosed by acid-fast smear staining, Mycobacterium tuberculosis culture, Mycobacterium tuberculosis PCR and pathological examination at West China Hospital of Sichuan University were retrospectively analysed. According to the results of the interferon γ release test (IGRA), the patients were divided into the IGRA- group and IGRA+ group. Logistic regression was used to analyze the sociodemographic data and clinical characteristics of participants in the IGRA- group and IGRA+ group.

RESULTS

Among 943 patients with active tuberculosis, 174 (18.5 %) were IGRA negative (false negative), and 769 (81.5 %) were IGRA positive. Multivariate logistic regression analysis identified the following characteristics independently associated with IGRA negativity: age (OR: 1.02; 95 % CI: 1.01 1.03; p = 0.006), anti-tuberculosis treatment >1 month (OR: 1.68; 95 % CI: 1.12 2.52; p = 0.013), HIV infection (OR: 9.48; 95 % CI: 3.23 27.85; p = 0.000), combined with connective tissue diseases (OR: 2.78; 95 % CI: 1.30 5.94; p = 0.008) and low hemoglobin (OR: 0.99; 95 % CI: 0.98 1.00; p = 0.044) was associated with an increased false-negative probability of IGRA.

CONCLUSION

Age, anti-tuberculosis therapy >1 month, coinfection with HIV, coassociated connective tissue disease and decreased hemoglobin were identified as risk factors for false-negative results of IGRA. Our results suggest a careful interpretation of IGRA in adults with these characteristics.

Phage Interactions with the Nervous System in Health and Disease

The central nervous system manages all of our activities (e.g., direct thinking and decision-making processes). It receives information from the environment and responds to environmental stimuli. Bacterial viruses (bacteriophages, phages) are the most numerous structures occurring in the biosphere and are also found in the human organism. Therefore, understanding how phages may influence this system is of great importance and is the purpose of this review. We have focused on the effect of natural bacteriophages in the central nervous system, linking them to those present in the gut microbiota, creating the gut-brain axis network, as well as their interdependence. Importantly, based on the current knowledge in the field of phage application (e.g., intranasal) in the treatment of bacterial diseases associated with the brain and nervous system, bacteriophages may have significant therapeutic potential. Moreover, it was indicated that bacteriophages may influence cognitive processing. In addition, phages (via phage display technology) appear promising as a targeted therapeutic tool in the treatment of, among other things, brain cancers. The information collected and reviewed in this work indicates that phages and their impact on the nervous system is a fascinating and, so far, underexplored field. Therefore, the aim of this review is not only to summarize currently available information on the association of phages with the nervous system, but also to stimulate future studies that could pave the way for novel therapeutic approaches potentially useful in treating bacterial and non-bacterial neural diseases.

Performance of T-Track® TB, a Novel Dual Marker RT-qPCR-Based Whole-Blood Test for Improved Detection of Active Tuberculosis

Tuberculosis (TB) is one of the leading causes of death by an infectious disease. It remains a major health burden worldwide, in part due to misdiagnosis. Therefore, improved diagnostic tests allowing the faster and more reliable diagnosis of patients with active TB are urgently needed. This prospective study examined the performance of the new molecular whole-blood test T-Track^® TB, which relies on the combined evaluation of IFNG and CXCL10 mRNA levels, and compared it to that of the QuantiFERON^®-TB Gold Plus (QFT-Plus) enzyme-linked immunosorbent assay (ELISA). Diagnostic accuracy and agreement analyses were conducted on the whole blood of 181 active TB patients and 163 non-TB controls. T-Track^® TB presented sensitivity of 94.9% and specificity of 93.8% for the detection of active TB vs. non-TB controls. In comparison, the QFT-Plus ELISA showed sensitivity of 84.3%. The sensitivity of T-Track^® TB was significantly higher (p < 0.001) than that of QFT-Plus. The overall agreement of T-Track^® TB with QFT-Plus to diagnose active TB was 87.9%. Out of 21 samples with discordant results, 19 were correctly classified by T-Track^® TB while misclassified by QFT-Plus (T-Track^® TB-positive/QFT-Plus-negative), and two samples were misclassified by T-Track^® TB while correctly classified by QFT-Plus (T-Track^® TB-negative/QFT-Plus-positive). Our results demonstrate the excellent performance of the T-Track^® TB molecular assay and its suitability to accurately detect TB infection and discriminate active TB patients from non-infected controls.

Significant difference in Th1/Th2 paradigm induced by tuberculosis-specific antigens between IGRA-positive and IGRA-negative patients

False negative interferon-γ release assay (IGRA) results constitute the major dilemma for the diagnosis of tuberculosis (TB) infections. Herein, we conducted a cohort study to compare the host immunological response to TB-specific antigens between active TB patients with positive and negative IGRA results and control groups. A total of 274 laboratory-confirmed TB patients were included in our analysis, consisting of 221 were IGRA positive and 53 were IGRA negative. Patients with the elderly were identified as an independent risk factor for negative IGRA results. In addition, the elevated level of IL-4 and the decreased levels of IFN-γ, IL-2, IL-6, IL-1β, and IL-12 in IGRA negative TB relative to IGRA positive TB group, demonstrating a significant difference in Th1/Th2 paradigm between two groups. The IFN-γ&IL-2 based assay could correctly identify 247 out of 307 MTB-infected individuals [271 TB patients and 36 individuals with latent TB infection (LTBI)], demonstrating a sensitivity of 80.5%. Then the IFN-γ and IL-4 were applied to distinguish healthy control and IGRA-negative group. When using the stepwise algorithm, the sensitivity for detecting Mycobacterium tuberculosis (MTB) infections was significantly increased from 80.5% to 89.6%. Additionally, patients with negative IGRA results had a conversion to culture-negative status longer than those with positive IGRA results. In conclusion, a stepwise algorithm outperforms IGRA assays to accurately identify MTB infections by the combination IFN-γ, IL-2, and IL-4. Further study is needed to evaluate the accuracy of our diagnostic algorithm in the LTBI population.

Immuno-Diagnosis of Active Tuberculosis by a Combination of Cytokines/Chemokines Induced by Two Stage-Specific Mycobacterial Antigens: A Pilot Study in a Low TB Incidence Country

Active tuberculosis (aTB) remains a major killer from infectious disease, partially due to delayed diagnosis and hence treatment. Classical microbiological methods are slow and lack sensitivity, molecular techniques are costly and often unavailable. Moreover, available immuno-diagnostic tests lack sensitivity and do not differentiate between aTB and latent TB infection (LTBI). Here, we evaluated the performance of the combined measurement of different chemokines/cytokines induced by two different stage-specific mycobacterial antigens, Early-secreted-antigenic target-6 (ESAT-6) and Heparin-binding-haemagglutinin (HBHA), after a short in vitro incubation of either peripheral blood mononuclear cells (PBMC) or whole blood (WB). Blood samples were collected from a training cohort comprising 22 aTB patients, 22 LTBI subjects and 17 non-infected controls. The concentrations of 13 cytokines were measured in the supernatants. Random forest analysis identified the best markers to differentiate M. tuberculosis-infected from non-infected subjects, and the most appropriate markers to differentiate aTB from LTBI. Logistic regression defined predictive abilities of selected combinations of cytokines, first on the training and then on a validation cohort (17 aTB, 27 LTBI, 25 controls). Combining HBHA- and ESAT-6-induced IFN-γ concentrations produced by PBMC was optimal to differentiate infected from non-infected individuals in the training cohort (100% correct classification), but 2/16 (13%) patients with aTB were misclassified in the validation cohort. ESAT-6-induced-IP-10 combined with HBHA-induced-IFN-γ concentrations was selected to differentiate aTB from LTBI, and correctly classified 82%/77% of infected subjects as aTB or LTBI in the training/validation cohorts, respectively. Results obtained on WB also selected ESAT-6- and HBHA-induced IFN-γ concentrations to provided discrimination between infected and non-infected subjects (89%/90% correct classification in the training/validation cohorts). Further identification of aTB patients among infected subjects was best achieved by combining ESAT-6-induced IP-10 with HBHA-induced IL-2 and GM-CSF. Among infected subjects, 90%/93% of the aTB patients were correctly identified in the training/validation cohorts. We therefore propose a two steps strategy performed on 1 mL WB for a rapid identification of patients with aTB. After elimination of most non-infected subjects by combining ESAT-6 and HBHA-induced IFN-γ, the combination of IP-10, IL-2 and GM-CSF released by either ESAT-6 or HBHA correctly identifies most patients with aTB.

Clinical evaluation of QuantiFERON®-TB Gold Plus directly compared with QuantiFERON®-TB Gold In-Tube and T-Spot®.TB for active pulmonary tuberculosis in the elderly

BACKGROUND

Reduced sensitivity of tuberculosis (TB) interferon-γ release assays (IGRAs) among the elderly has been reported, which is presumably due to diminished immune function. We evaluated the clinical performance of QuantiFERON®-TB Gold plus (QFT-Plus) compared with QuantiFERON®-TB Gold In-Tube (QFT-GIT) and T-Spot®.TB (T-SPOT) in the elderly.

METHODS

Blood samples for all three IGRAs were drawn at the same time from all the participants. Both CD4 and CD8 T-cell counts in patients' peripheral blood were also measured.

RESULTS

A total of 142 active pulmonary TB patients (median age: 84, interquartile range; 76-89 years) were recruited. The sensitivities of the tested IGRAs (excluding invalid/indeterminate cases) were as follows: QFT-Plus, 93.6%; QFT-GIT, 91.4%; and T-SPOT 68.1%. QFT-Plus displayed significantly higher sensitivity than T-SPOT (p < 0.00001). All three IGRAs exhibited the same specificity (100%), as assessed using blood samples from healthy, low TB-risk individuals (n = 118; median age: 39, IQR; 32-47 years). Positivity in 43 active TB patients with CD4 T-cell counts <200/μL, 39 of whom were ≥80 years of age, was as follows: QFT-Plus, 83.7%; QFT-GIT, 74.4%; and T-SPOT, 58.1%. The difference between TB2-TB1 of the QFT-Plus assay was statistically correlated with CD8 but not CD4 T-cell counts in blood (r = 0.193, p = 0.0298).

CONCLUSIONS

QFT-Plus showed high performance in the detection of TB infection in patients irrespective of their advanced age (≥80 years) or lower CD4 counts. QFT-Plus can be useful for the diagnosis of TB infection in all patients, including those who are elderly and/or immunocompromised.

Diagnostic accuracy of the interferon-gamma release assay (IGRA) for cases of feline mycobacteriosis

The aim of this study was to evaluate the sensitivity and specificity of the interferon-gamma release assay (IGRA) for diagnosing infections with members of the Mycobacterium (M.) tuberculosis-complex (MTBC) and non-tuberculous mycobacteria (NTM) in domestic cats, and to generate defined feline-specific cut-off values using receiver operating characteristic (ROC) curve analysis to improve test performance. Records of 594 cats that had been tested by IGRA were explored to identify individuals that had a culture and/or polymerase chain reaction (PCR)-confirmed case of mycobacterial disease, and those that had a final diagnosis of non-mycobacterial disease. A total of 117 cats - 80 with mycobacterial disease and 37 diagnosed with a condition other than mycobacteriosis - were identified for further detailed analysis. This population was used to estimate test sensitivity and specificity, as well as likelihood ratios for the IGRA to correctly identify a cat with or without mycobacterial disease. Agreement between IGRA results and culture/PCR using current and proposed new cut-off values was also determined. ROC analysis of defined confirmed infected and non-mycobacterial disease control cats allowed an adjustment of current test cut-offs that increased the overall test sensitivity for MTBC infections from 83.1 % (95 % confidence interval [CI]: 71.5-90.5 %) to 90.2 % (95 % CI: 80.2-95.4%), and M. bovis infection from 43 % (95 % CI: 28.2-60.7%) to 68 % (95 % CI: 51.4-82.1%) while maintaining high test specificity (100 % in both cases). Overall agreement between IGRA results and culture/PCR, while recognising that neither culture nor PCR tests have perfect sensitivity, improved from weak (κ = 0.57) to moderate (κ = 0.71) using new proposed IGRA test cut-off values. Application of these results, based upon the statistical analysis of accumulated test data, can improve the diagnostic performance of the feline IGRA, particularly for identifying infections with M. bovis, without compromising specificity.

Combined IFN-γ and IL-2 release assay for detect active pulmonary tuberculosis: a prospective multicentre diagnostic study in China

BACKGROUND

We performed a prospective multicentre diagnostic study to evaluate the combined interferon-γ (IFN-γ) and interleukin-2 (IL-2) release assay for detect active pulmonary tuberculosis (TB) in China.

METHODS

Adult patients presenting symptoms suggestive of pulmonary TB were consecutively enrolled in three TB-specialized hospitals. Sputum specimens and blood sample and were collected from each participant at enrolment. The levels of Mycobacterium tuberculosis (MTB)-specific antigen-stimulated IFN-γ and IL-2 were determined using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Between July 2017 and December 2018, a total of 3245 patients with symptoms suggestive of pulmonary TB were included in final analysis. Of 3245 patients, 2536 were diagnosed as active TB, consisting of 1092 definite TB and 1444 clinically diagnosed TB. The overall sensitivity and specificity of IFN-γ were 83.8% and 81.5%, respectively. In addition, compared with IFN-γ, the specificity of IL-2 increased to 94.3%, while the sensitivity decreased to 72.6%. In addition, the highest sensitivity was achieved with parallel combination of IFN-γ/IL-2, with a sensitivity of 87.9%, and its overall specificity was 79.8%. The sensitivity of series combination test was 68.5%. Notably, the sensitivity of series combination test in definite TB (72.1%) was significantly higher than that in clinically diagnosed TB (65.8%).

CONCLUSION

In conclusion, we develop a new immunological method that can differentiate between active TB and other pulmonary diseases. Our data demonstrates that the various IFN-γ/IL-2 combinations provides promising alternatives for diagnosing active TB cases in different settings. Additionally, the diagnostic accuracy of series combination correlates with severity of disease in our cohort.

Case of Crohn's Disease Initially Misdiagnosed as Intestinal Tuberculosis Due to Active Pulmonary Tuberculosis

Differentiating Crohn's disease (CD) from intestinal tuberculosis (TB) is a challenge. In patients suspected of having CD or intestinal TB compounded with active pulmonary TB in its early stages, clinicians often lean towards a diagnosis of intestinal TB. A 14-year-old female patient was admitted with symptoms of abdominal pain and diarrhea with hematochezia. Colonoscopy revealed a stricture of the ileocecal valve and scattered longitudinal ulcers. Initial chest radiography showed consolidation in the left lower lobe of the lung. Chest CT revealed branching nodular opacities and consolidation. The TB PCR of the bronchial washing fluid was positive. The patient was diagnosed with pulmonary and intestinal TB. The colonoscopy findings favored CD. Despite this, anti-tubercular therapy was initiated based on the radiology findings and PCR test. After treatment with anti-tubercular therapy, the patient's diarrhea and abdominal pain worsened despite the improvement observed on her chest radiography. Follow-up colonoscopy revealed aggravation of her ulcers. The patient was diagnosed with CD and treated with prednisolone and mesalazine. Her clinical condition improved, and follow-up colonoscopy showed significant improvement of the ulcers. This case highlights the need for caution in diagnosis and suggests that clinicians consider reevaluation in similar cases.

Screening of latent TB infection in patients with recently diagnosed bronchogenic carcinoma

BACKGROUND

Cancer and pulmonary tuberculosis are major global health concerns and are associated with substantial morbidity and mortality. The association between active tuberculosis and subsequent cancer development has been investigated for many years. This study was planned to determine the prevalence of latent tuberculosis infection in patients with recently diagnosed bronchogenic carcinoma.

METHODS

Sixty-four newly diagnosed primary lung cancer patients were enrolled. Diagnosis of latent tuberculosis infection was performed with QuantiFERON-TB Gold In-Tube tests, with exclusion of active tuberculosis.

RESULTS

Latent tuberculosis infection was detected in 16 (25%) patients, and 8 (12.5%) had indeterminate results of the QuantiFERON-TB Gold In-Tube test. Being a current smoker was associated with a higher prevalence of latent tuberculosis (p = 0.001). Comorbidities, tumor site, and histopathology were not associated with latent tuberculosis infection.

CONCLUSIONS

There is a considerable risk of concurrent latent tuberculosis in newly diagnosed primary bronchogenic carcinoma. The need for treatment of latent tuberculosis in these patients and its influence on the outcome and prognosis are issues for further investigations.

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

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

Disseminated Tuberculosis Involving Lung, Peritoneum, and Endometrium in an Immunocompetent 17-Year-Old Patient

A 17-year-old Guatemalan female with a recent history of spontaneous abortion requiring dilation and curettage at 16 weeks' gestation presented two weeks post-procedure to a pediatric hospital for three days of worsening generalized abdominal pain, diarrhea, fevers, and cough. The patient's vital signs showed hypoxia, tachypnea, tachycardia, and hypotension; she was alert and oriented with a thin body habitus and suprapubic abdominal tenderness without rebound, guarding, or hepatosplenomegaly. She had no crackles, rales, or wheezing on lung examination. Labs revealed neutrophilic leukocytosis, acute kidney injury, transaminitis, and coagulopathy. Pelvic ultrasound demonstrated a septated pelvic fluid collection with an endometrial thickening. CT abdomen and pelvis showed significant nodular omental thickening and ascites. CT angiogram of the chest demonstrated an apical lung cavity and bilateral micro-nodularity without lymphadenopathy. Due to concern for septic shock secondary to endometritis, the patient was started on broad-spectrum antibiotics and intubated for acute hypoxic respiratory failure. Repeat dilation and evacuation revealed degenerative first trimester products of conception and necrotizing granulomatous endometritis with Mycobacterium tuberculosis (M. tuberculosis) bacteria. Paracentesis indicated tuberculosis (TB) in ascites fluid, and bronchoalveolar lavage (BAL) showed pulmonary TB. Human immunodeficiency virus (HIV) screen and serum QuantiFERON®-TB Gold testing were negative. Rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE) therapy was initiated alongside piperacillin-tazobactam for the treatment of both disseminated TB and septic abortion. She was extubated with hemodynamic stability, but fevers persisted. Repeat fallopian tube fluid sampling after five weeks of RIPE indicated numerous acid-fast bacilli. The patient's septic clinical picture clouded her TB diagnosis as it appeared unusual that a healthy 17-year-old would concurrently have a septic abortion and disseminated TB; the lack of lymphadenopathy on CT scan also contributed to diagnostic uncertainty. Among patients from endemic regions, TB is a cause of spontaneous abortion. Conversely, during pregnancy, progesterone suppresses the T-helper 1 (Th1) proinflammatory response and increases susceptibility to TB. Peripartum women are at higher risk for disseminated TB, and postpartum women are twice as likely to experience reactivation of latent TB than nonpregnant women. Disseminated TB must be considered in pregnant adolescents presenting with appropriate clinical characteristics and imaging findings.

A blood RNA transcript signature for TB exposure in household contacts

Background

Current tools for diagnosing latent TB infection (LTBI) detect immunological memory of past exposure but are unable to determine whether exposure is recent. We sought to identify a whole-blood transcriptome signature of recent TB exposure.

Methods

We studied household contacts of TB patients; healthy volunteers without recent history of TB exposure; and patients with active TB. We performed whole-blood RNA sequencing (in all), an interferon gamma release assay (IGRA; in contacts and healthy controls) and PET/MRI lung scans (in contacts only). We evaluated differentially-expressed genes in household contacts (log2 fold change ≥1 versus healthy controls; false-discovery rate < 0.05); compared these to differentially-expressed genes seen in the active TB group; and assessed the association of a composite gene expression score to independent exposure/treatment/immunological variables.

Results

There were 186 differentially-expressed genes in household contacts (n = 26, age 22–66, 46% male) compared with healthy controls (n = 5, age 29–38, 100% male). Of these genes, 141 (76%) were also differentially expressed in active TB (n = 14, age 27–69, 71% male). The exposure signature included genes from inflammatory response, type I interferon signalling and neutrophil-mediated immunity pathways; and genes such as BATF2 and SCARF1 known to be associated with incipient TB. The composite gene-expression score was higher in IGRA-positive contacts (P = 0.04) but not related to time from exposure, isoniazid prophylaxis, or abnormalities on PET/MRI (all P > 0.19).

Conclusions

Transcriptomics can detect TB exposure and, with further development, may be an approach of value for epidemiological research and targeting public health interventions.

Factors associated with false negative interferon-γ release assay results in patients with tuberculosis: A systematic review with meta-analysis

Which factors are related to false negative results of the interferon-γ release assay (IGRA) is unclear. This systematic review described the risk factors associated with false negative IGRA results. Two authors independently identified studies designed to evaluate risk factors for false negative IGRA results from PubMed, the Cochrane Register of Control Trial database, and EMBASE, accessed on October 22, 2018. Meta-analyses were conducted with random-effect models, and heterogeneity was calculated with the I² method. Of 1,377 titles and abstracts screened, 47 full texts were selected for review, and we finally included 17 studies in this systematic review. The most commonly studied risk factor (14 studies) was advanced age, followed by low peripheral lymphocyte counts (7 studies), and these factors were associated with false negative results even with different tuberculosis incidences (pooled odds ratio 2.06; 95% CI, 1.68–2.52 in advanced age and 2.68; 95% CI, 2.00–3.61 in low peripheral lymphocyte counts). Advanced age and low peripheral lymphocyte counts may be common risk factors for false negative IGRA results, suggesting that people with these factors need to be carefully followed, even if they have negative IGRA results.

Quantitative investigation of factors relevant to the T cell spot test for tuberculosis infection in active tuberculosis

Background

Previous qualitative studies suggested that the false negative rate of the T cell spot test for tuberculosis infection (T-SPOT.TB) is associated with many risk factors in tuberculosis patients. However, more precise quantitative studies are lacking. The purpose of this study was to investigate the factors affecting quantified spot-forming cells (SFCs) to early secreted antigenic target 6 kDa (ESAT-6) or culture filtrate protein 10 kDa (CFP-10) in patients with active tuberculosis.

Methods

We retrospectively analyzed the data of 360 patients who met the inclusion criteria. Using the SFCs to ESAT-6 or CFP-10 levels as dependent variables, variables with statistical significance in the univariate analysis were subjected to optimal scaling regression analysis. The combination of ESAT-6 and CFP-10 (i.e., T-SPOT.TB) was analyzed by the exact logistic regression model.

Results

The results showed that the SFCs to ESAT-6 regression model had statistical significance (P < 0.001) and that previous treatment and CD4+ and platelet counts were its independent risk factors (all P < 0.05). Their importance levels were 0.095, 0.596 and 0.100, respectively, with a total of 0.791. The SFCs to CFP-10 regression model also had statistical significance (P < 0.001); platelet distribution width and alpha-2 globulin were its independent risk factors (all P < 0.05). Their importance levels were 0.287 and 0.247, respectively, with a total of 0.534. The quantification graph showed that quantified SFCs to ESAT-6 or CFP-10 grading had a linear correlation with risk factors. Albumin-globulin ratio, CD4+ and CD8+ were independent risk factors for false negative T-SPOT.TB (all P < 0.05).

Conclusions

In T-SPOT.TB-assisted diagnosis of patients with active tuberculosis, previous treatment, decreased CD4+ and platelet count might lead to the decreased SFCs to ESAT-6, decreased alpha-2 globulin and high platelet distribution width might lead to the decreased SFCs to CFP-10, decreased albumin-globulin ratio, CD4+ and CD8+ might lead to an increase in the false negative rate of the T-SPOT.TB.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4310-y) contains supplementary material, which is available to authorized users.

Severe disseminated tuberculosis in HIV-negative refugees

In high-income countries, the presentation of tuberculosis is changing, primarily because of migration, and understanding the specific health needs of susceptible populations is becoming increasingly important. Although disseminated tuberculosis is well documented in HIV-positive patients, the disease is poorly described and less expected in HIV-negative individuals. In this Grand Round, we report eight HIV-negative refugees, who presented with extensively disseminated tuberculosis. We discuss the multifactorial causes, such as deprivations during long journeys, precarious living conditions, and the experience of violence, which might add to nutritional factors and chronic disorders, eventually resulting in a state of predisposition to immune deficiency. We also show that disseminated tuberculosis is often difficult to diagnose when pulmonary symptoms are absent. Communication difficulties between refugees and health-care workers are another major hurdle, and every effort should be made to get a valid patient history. This medical history is crucial to guide imaging and other diagnostic procedures to establish a definite diagnosis, which should be confirmed by a positive tuberculosis culture. Because many of these patients are at risk for multidrug-resistant tuberculosis, drug susceptibility testing is imperative to guide therapy. In the absence of treatment guidelines for this entity, clinicians can determine treatment duration according to recommendations provided for extrapulmonary tuberculosis and affected organs. Paradoxical expansion of tuberculous lesions during therapy should be treated with corticosteroids. In many cases, treatment duration must be individualised and might even exceed 12 months.

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.

Characteristics Associated with Negative Interferon-γ Release Assay Results in Culture-Confirmed Tuberculosis Patients, Texas, USA, 2013-2015

Interferon-γ release assays (IGRAs) are the preferred diagnostic test for tuberculosis (TB) infection in at-risk populations in developed countries. However, IGRAs have high false-negative rates in patients with TB disease. Population-based studies assessing the factors associated with negative IGRA results in TB patients have not been performed. Using statewide TB surveillance data of culture-confirmed TB patients in Texas, USA, during 2013–2015, we describe the patient characteristics and treatment outcomes associated with false-negative IGRA results. Among 2,854 TB patients, 1,527 (53.5%) had an IGRA result; 97.4% (1,487/1,527) of those had a positive (87.7%) or negative (12.3%) result. Older age, HIV co-infection, non-Hispanic white race/ethnicity, and being tested with T-SPOT.TB were associated with negative IGRA results. TB patients with negative IGRA results had a higher mortality, potentially due to delayed treatment. Healthcare providers should consider these risk factors when making decisions for patients with suspected TB and negative IGRA results and potentially provide treatment.

A case report: Addison disease caused by adrenal tuberculosis

We report middle age man with skin hyperpigmentation oral and lip mucous membranes, general malaise and depression. Further examinations lead to adrenal insufficiency, Addison's disease. Imaging studies show bilateral adrenal hyperplasia, show negative result for tuberculosis. We perform laparoscopic adrenalectomy. Multiple caseosa necrosis in gross specimen and Langhan's giant cells microscopic appearance ensure patient suffered Addison's disease cause by adrenal gland tuberculosis.

Submillisievert Computed Tomography of the Chest in Contact Investigation for Drug-Resistant Tuberculosis

Close contacts with infectious tuberculosis (TB) are persons at high risk for developing active disease. We preliminarily introduced submillisievert chest computed tomography (CT) scan (effective dose, 0.19-0.25 millisievert) in a contact investigation of multi-drug resistant (MDR)-TB. Baseline CT scan showed minimal nodules or branching opacities in two of six contacts. A two-month follow-up examination revealed a radiologic progression in contact 1, subsequently having the microbiologic diagnosis of MDR-TB at an asymptomatic early stage, whereas nodules transiently increased after 3 months in contact 2, followed by a decrease after one year. Contact 1 was cured after 1.5-year of anti-MDR-TB treatment. In conclusion, early identification of secondary MDR-TB is feasible with submillisievert chest CT scans in contact investigations of MDR-TB, minimizing of MDR-TB transmission and offering a favorable treatment outcome. This was a clinical trial study and was registered at www.ClinicalTrials.gov (Identifier: NCT02454738).

Close contact interferon-gamma response to the new PstS1(285-374):CPF10: a preliminary 1-year follow-up study

Background

The available diagnostic tools for latent tuberculosis (TB) infection (LTBI) via interferon-gamma (IFN-g) release assays (IGRA) are based on ESAT6:CFP10 stimulation. However, the mycobacterial antigen PstS1 is also highly immunogenic and some of its fragments, such as PstS1_(285–374), have shown higher immunoreactivity in LTBI than in active TB. PstS1_(285–374), therefore, could increase the accuracy of the existing IGRA to detect LTBI. Thus, a new chimeric protein has recently been developed (PstS1_(285–374):CFP10) showing potential for LTBI screening of recent close contacts (rCt) exposed to Mycobacterium tuberculosis. The aim of this study was to analyze the PstS1_(285–374):CFP10 longitudinal IFN-g profile in comparison to ESAT6:CFP10 and full PstS1/CFP10 stimulation in a rCt cohort and correlate the responses to these in-house IGRA with any clinical changes/interventions that might occur.

Methods

A free-of-cost, one-year follow up was offered to 120 rCt recruited in Rio de Janeiro, RJ, Brazil. Whole blood short-term (WBA), long-term stimulation (LSA) assays, and the tuberculin skin test (TST) were performed during follow up.

Results

Among the enrolled rCt, 44.2% (53/120) returned for re-evaluation and the control group (TST negative, n = 17) showed low IFN-g reactivity to all antigen stimulations during the entire follow up, except for one participant who had shown radiological evidence of past TB/LTBI. Both incident cases were detected by IGRA-PstS1_(285–374):CFP10 during LTBI and after disease progression. Moreover, subsequent to the prophylactic treatment for LTBI (tLTBI), a significant regression in the LSA response was predominantly observed through stimulation of the new chimeric protein (8/10, 80%) followed by ESAT6:CFP10 (5/10, 50%) and PstS1/CFP10 (4/10, 40%). No clinical or epidemiological characteristics were exclusively shared among IGRA convertors.

Conclusion

It was demonstrated that the TST negative rCt without radiological evidence of LTBI/TB did not develop an IGRA-PstS1_(285–374):CFP10 response during the one-year follow up. Moreover, all incident cases were detected by our new IGRA; and a significant decrement of LSA-PstS1_(285–374):CFP10 reactivity post-prophylactic tLTBI was found. To our knowledge, this is the first study to monitor changes in the immune response profile of IGRA-PstS1_(285–374):CFP10 among rCt during a consecutive one-year period, thus providing additional evidence of its potential in the detection of LTBI.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-016-2360-4) contains supplementary material, which is available to authorized users.

Clinical Application of Interferon-γ Release Assays for the Prevention of Tuberculosis in Countries with Low Incidence

Despite global efforts to control tuberculosis (TB) the estimated number of people who developed TB worldwide increased to an all-time record of more than 10 million in 2015. The goal of the World Health Organization (WHO) to reduce the global incidence of TB to less than 100 cases per million by 2035, cannot be reached unless TB prevention is markedly improved. There is a need for an improved vaccine that better protects individuals who are exposed to Mycobacterium tuberculosis from infection and active disease compared to the current M. bovis Bacille Calmette Guérin (BCG) vaccine. In the absence of such a vaccine, prevention relies on infection control measures and preventive chemotherapy for people with latent infection with M. tuberculosis (LTBI), who have the highest risk of progression to active TB. During the past decade, interferon-γ release assays (IGRAs) have increasingly replaced the tuberculin skin test as screening tools for the diagnosis of LTBI in countries with a low incidence of TB. Despite recent WHO guidelines on the management of LTBI, the definition of groups at risk for TB remains controversial, and the role of IGRAs for TB prevention in low-incidence countries remains uncertain. We reviewed the scientific literature and provide recommendations for the use of IGRAs for LTBI diagnosis in low-incidence countries. These recommendations are based on the number of patients needing treatment in order to prevent one case of TB. As the positive predictive value of IGRAs for the development of TB is sub-optimal, research must focus on the identification of alternative biomarkers that offer better predictive ability in order to substantially reduce the number needing treatment while improving the prevention of TB and improving the effectiveness of targeted preventive chemotherapy.

Factors that Predict Negative Results of QuantiFERON-TB Gold In-Tube Test in Patients with Culture-Confirmed Tuberculosis: A Multicenter Retrospective Cohort Study

BACKGROUND

Interferon-γ release assays such as the QuantiFERON-TB Gold In-Tube Test (QFT-GIT) are designed to detect Mycobacterium tuberculosis infections, whether latent or manifesting as disease. However, a substantial number of persons with culture-confirmed tuberculosis (TB) have negative QFT-GITs. Information on host factors contributing to false-negative and indeterminate results are limited.

METHODS

A multicenter retrospective cohort study was performed with 1,264 culture-confirmed TB patients older than 18 years who were subjected to the QFT-GIT at one of the six hospitals between May 2007 and February 2014. Patients with human immunodeficiency virus infection were excluded. Clinical and laboratory data were collected in South Korea.

RESULTS

Of all patients, 87.6% (1,107/1,264) were diagnosed with pulmonary TB and 12.4% (157/1,264) with extrapulmonary TB. The rate of negative results was 14.4% (182/1,264). The following factors were highly correlated with false-negative results in the QFT-GIT: advanced age (age ≥ 65 years, odds ratio [OR] 1.57, 95% confidence interval [CI] 1.03-2.39), bilateral disease as determined by chest radiography (OR 1.75, 95% CI 1.13-2.72), malignancy (OR 2.42, 95% CI 1.30-4.49), and lymphocytopenia (total lymphocyte count < 1.0 × 109/L, OR 1.86, 95% CI 1.21-2.87).

CONCLUSIONS

Consequently, QFT-GIT results need to be interpreted with caution in patients with these host risk factors such as the elderly, bilateral disease on chest radiography, or malignancy, or lymphocytopenia.