Diagnosing tuberculosis infection in the 21st century: new tools to tackle an old enemy

Capturing Recent Mycobacterium tuberculosis Infection by Tuberculin Skin Test vs. Interferon-Gamma Release Assay

Reductions in tuberculosis (TB) incidence require identification of individuals at high risk of developing active disease, such as those with recent Mycobacterium tuberculosis (Mtb) infection. Using a prospective household contact (HHC) study in Kampala, Uganda, we diagnosed new Mtb infection using both the tuberculin skin test (TST) and interferon-gamma release assay (IGRA). Our study aimed to determine if the TST adds additional value to the characterization of IGRA converters. We identified 13 HHCs who only converted the IGRA (QFT-only converters), 39 HHCs who only converted their TST (TST-only converters), and 24 HHCs who converted both tests (QFT/TST converters). Univariate analysis revealed that TST-only converters were older. Additionally, increased odds of TST-only conversion were associated with older age (p = 0.02) and crowdedness (p = 0.025). QFT/TST converters had higher QFT quantitative values at conversion than QFT-only converters and a bigger change in TST quantitative values at conversion than TST-only converters. Collectively, these data indicate that TST conversion alone likely overestimates Mtb infection. Its correlation to older age suggests an "environmental" boosting response due to prolonged exposure to environmental mycobacteria. This result also suggests that QFT/TST conversion may be associated with a more robust immune response, which should be considered when planning vaccine studies.

Integrating SARS-CoV-2-specific interferon-γ release assay testing in the evaluation of patients hospitalized with COVID-19

IMPORTANCE

The cellular immune response is essential in the protection against severe disease in patients with established SARS-CoV-2 infection. The novelty of this study lies in the evaluation of the overall performance of a standardized assay to measure cellular immune response, the SARS-CoV-2-specific interferon-γ release assay (IGRA), in hospitalized patients with severe COVID-19. The SARS-CoV-2 IGRA was shown to accurately classify patients based on disease severity and prognosis, and the study revealed that test performance was not affected by the SARS-CoV-2 variant or control tube results. We identified an assay cut-off point with a high negative predictive value against mortality. The SARS-CoV-2 IGRA in patients hospitalized for COVID-19 may be a useful tool to assess cellular immunity and adopt targeted therapeutic and preventive measures.

Evaluation of the diagnostic efficacy of EC-Test for latent tuberculosis infection in ambulatory people with HIV

BACKGROUND

Latent tuberculosis infection (LTBI) co-infected with human immunodeficiency virus (HIV) is more likely to develop into active tuberculosis (ATB), recombinant Mycobacterium tuberculosis fusion protein ESAT6/CFP10 (EC-Test) is a latest developed method for LTBI. Compared with the interferon γ release test assays (IGRAs), the diagnostic performance of EC-Test to LTBI screening in HIV needs to be evaluated.

METHODS

A population-based multicenter prospective study was conducted in Guangxi Province, China. The baseline data was collected and LTBI were measured by QuantiFERON-TB Gold In-Tube (QFT-GIT), EC-Test and T-cell spot of the TB assay (T-SPOT.TB).

RESULTS

A total of 1478 patients were enrolled. when taking T-SPOT.TB as reference, the value of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and consistency that EC-Test to diagnosis LTBI in HIV was 40.42, 97.98, 85.26, 85.04 and 85.06% respectively; when taking QFT-GIT as reference, the value was 36.00, 92.57, 55.10, 85.09 and 81.13%, respectively. When the CD4 + cell count was <200 cells/μl, the accuracies of EC-Test to T-SPOT.TB and QFT-GIT were 87.12 and 88.89%, respectively; when it was 200 ≤ CD4 + ≤ 500 cells/μl, the accuracies of EC-Test was 86.20 and 83.18%, respectively; when the CD4 + cell count >500 cells/μl, the accuracies of EC-Test were 84.29 and 77.94%, respectively. The incidence of adverse reactions in EC-Test was 34.23% and the serious adverse reactions were 1.15%.

CONCLUSION

EC-Test has good consistency compared with IGRAs in detecting LTBI in HIV no matter in different immunosuppression status or different regions, and the safety of EC-Test is also well, suitable for LTBI screening in HIV in high prevalence settings.

First evaluation of the performance of portable IGRA, QIAreach® QuantiFERON®-TB in intermediate TB incidence setting

Diagnosis and treatment of tuberculosis infection (TBI) are the core elements of tuberculosis elimination. Interferon gamma release assays have advantages over the tuberculin skin test, although their implementation in low-resource settings is challenging. The performance of a novel digital lateral flow assay QIAreach® QuantiFERON®-TB (QIAreach QFT) against the QuantiFERON®-TB Gold Plus (QFT-Plus) assay was evaluated in an intermediate incidence setting (Malaysia) according to the manufacturer's instructions. Individuals aged 4-82 years, who were candidates for TB infection screening for contact investigation were prospectively recruited. On 196 samples, the QIAreach-QFT showed a positive percent agreement (sensitivity) was 96.5% (CI 87.9-99.6%), a negative percent agreement (specificity) 94.2% (CI 88.4% to 97.6%) and an overall percentage of agreement was 94.9% (95% CI 90.6-97.6%) with a Cohen's κ of 0,88. Out of 196, 5.6% (11/196) samples gave an error result on QIAreach-QFT and 4.1% (8/196) samples gave indeterminate result on QFT-plus. The TTR for QIAreach QFT positive samples varied from 210-1200 seconds (20 min) and significantly correlated with IFN-γ level of QFT-Plus. QIAreach QFT could be considered an accurate and reliable point-of-need test to diagnose TB infection helping to achieve the WHO End TB programme goals even in decentralised settings where laboratory expertise and infrastructure may be limited.

Oxidative Stress in the Anterior Ocular Diseases: Diagnostic and Treatment

The eye is a metabolically active structure, constantly exposed to solar radiations making its structure vulnerable to the high burden of reactive oxygen species (ROS), presenting many molecular interactions. The biomolecular cascade modification is caused especially in diseases of the ocular surface, cornea, conjunctiva, uvea, and lens. In fact, the injury in the anterior segment of the eye takes its origin from the perturbation of the pro-oxidant/antioxidant balance and leads to increased oxidative damage, especially when the first line of antioxidant defence weakens with age. Furthermore, oxidative stress is related to mitochondrial dysfunction, DNA damage, lipid peroxidation, protein modification, apoptosis, and inflammation, which are involved in anterior ocular disease progression such as dry eye, keratoconus, uveitis, and cataract. The different pathologies are interconnected through various mechanisms such as inflammation, oxidative stress making the diagnostics more relevant in early stages. The end point of the molecular pathway is the release of different antioxidant biomarkers offering the potential of predictive diagnostics of the pathology. In this review, we have analysed the oxidative stress and inflammatory processes in the front of the eye to provide a better understanding of the pathomechanism, the importance of biomarkers for the diagnosis of eye diseases, and the recent treatment of anterior ocular diseases.

A prospective observational study for justification, safety, and efficacy of a third dose of mRNA vaccine in patients receiving maintenance hemodialysis

The level of protection achieved by the standard two doses of COVID-19 mRNA vaccines in patients receiving maintenance hemodialysis (MHD) remains unclear. To study this we used the French Renal Epidemiology and Information Network (REIN) Registry to compare the incidence and severity of 1474 cases of COVID-19 diagnosed in patients receiving MHD after none, one or two doses of vaccine. Vaccination significantly reduce COVID-19 incidence and severity, but 11% of patients infected after two doses still died. Lack of vaccinal protection in patients naïve for SARS-CoV-2 could be due to defective Tfh response [38% of patients with negative spike-specific CD4+ T-cell interferon gamma release assay] and failure to generate viral neutralizing titers of anti-spike receptor binding domain (RBD) IgGs (63% of patients with titer at or under 997 BAU/ml, defining low/no responders) after two doses of vaccine. To improve protection, a third dose of vaccine was administered to 75 patients [57 low/no responders, 18 high responders after two doses] from the ROMANOV cohort that prospectively enrolled patients receiving MHD vaccinated with BNT162b2 (Pfizer). Tolerance to the third dose was excellent. High responders to two doses did not generate more anti-RBD IgGs after three doses but had more side effects. Importantly, 31 (54%) of low/no responders to two doses reached neutralizing titers of anti-RBD IgGs after three doses. A positive interferon gamma release assay and/or suboptimal titer of anti-RBD IgGs after two doses were the only predictive variables for response to three doses in multivariate analysis. Thus, the standard scheme of vaccination insufficiently protects patients receiving MHD. Anti-RBD IgG and specific CD4+ T-cell response after two doses can guide personalized administration of the third dose, which improves the humoral response of SARS-CoV-2-naïve patients receiving MHD.

Peritoneal tuberculosis mimicking advanced ovarian cancer case report: Laparoscopy as diagnostic modality

INTRODUCTION AND IMPORTANCE

Peritoneal Tuberculosis is one of extrapulmonary tuberculosis that occurs in 1-2% of patients, its incidence is higher in developing countries. It is very difficult to diagnosed and can mimic advanced ovarian cases. Making an accurate diagnosis is vital, laparoscopy is a great modality for this purpose.

CASE PRESENTATION

A 36 years-old woman got referred with abdominal distention and weight loss from an internist and digestive surgeon. The abdominal computed tomography said thickening of the stomach wall with ascites. Ultrasound concluded the uterus, ovary, and endometrium within normal. The CA 125 levels elevated to 1200 U/mL and the complete blood count was normal. We were making diagnosis of peritoneal tuberculosis, peritoneal carcinomatosis, and advanced ovarian cancer. We did the diagnostic laparoscopic and taking a biopsy sample, ascites with peritoneal carcinomatosis and omental cake were found, the peritoneal cavity was covered by miliary nodules. Histopathology results concluded peritoneal tuberculosis without malignancy signs. The patient was treated with tuberculosis drugs. The follow-up evaluations show significant clinical improvement.

CLINICAL DISCUSSION

When facing patients with massive ascites and elevated CA 125 without any ovary enlargement, a gynecologist should think that it may be a peritoneal TB case with peritoneal carcinomatosis and advance ovarian cancer possibility as differential diagnosis especially in developing countries. An exact diagnosis can be made using laparoscopy and histopathology examination.

CONCLUSION

Laparoscopy is the best modality to differentiate between peritoneal tuberculosis, peritoneal carcinomatosis, and advance ovarian cancer. The benefits are direct visualization and could take a biopsy for histology examination.

Serum CA-125 for the diagnosis of pulmonary tuberculosis: a systematic review and meta-analysis

Background

Pulmonary tuberculosis (PTB) remains the world’s deadliest infectious killer. Serum CA-125 test are useful in the diagnosis of PTB. Although studies on the relation between CA-125 and PTB have been reported, the specificity and sensitivity of serum CA-125 in diagnosing PTB vary widely among different studies. The present study was performed to evaluate the accuracy of CA-125 for the diagnosis of PTB via a meta-analysis of data obtained from previous studies.

Methods

English and Chinese medical electronic databases were searched for eligible studies published up to February 2020. STATA software was used to obtain a pooled estimation of the diagnostic accuracy of CA-125 and analyze the heterogeneity of the recruited studies. Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) was used to evaluate the quality of the obtained studies.

Results

A total of 16 articles were included in this study. The pooled sensitivity and specificity of CA-125 were 0.85 [95% confidence interval (CI) 0.75–0.91] and 0.87 (95% CI 0.78–0.93), respectively. Moreover, the pooled positive likelihood ratio (LR+), negative likelihood ratio (LR−), and diagnostic odds ratio (DOR) of CA-125 were 6.65 (95% CI 3.62–12.20), 0.18 (95% CI 0.10–0.31), and 37.82 (95% CI 13.17–108.60), respectively. The area under the summary receiver operating characteristic curve (AUC) was 0.93.

Conclusions

Taken together, the results indicate that serum CA-125 presents potential practical value for diagnosing PTB, but its clinical applicability must be further examined.

QIAreach™ QuantiFERON®-TB for the diagnosis of infection

Timely diagnosis and treatment to prevent tuberculosis (TB) transmission and the consequent replenishment of the TB infection reservoir are essential for the control and elimination of TB worldwide [1], ultimately contributing the World Health Organization (WHO)'s End TB goals [2].

QIAreach QFT demonstrated a good performance in diagnosing TB infection. This tool may offer technical and operational benefits over more complex IGRA ELISA-based assays, granting timely TB diagnosis in decentralised settings with limited infrastructure.https://bit.ly/3n6Dxll

Assessing usability of QIAreach QuantiFERON-TB platform in a high tuberculosis prevalence, low-resource setting

The World Health Organization (WHO) estimates that 1.8 billion people, close to a quarter of the world's population are infected with Mycobacterium tuberculosis [1]. Despite substantial declines in tuberculosis (TB) incidence over the past decade, Zambia still has the seventh highest TB incidence in sub-Saharan Africa and remains one of the 30 WHO high TB-burden priority countries [2]. In 2019, there were ∼59 000 new individuals with active TB disease in Zambia (incidence rate of 333 per 100 000 per year), which resulted in 15 400 TB-related deaths, of which 62% were among people living with HIV [2].

QIAreach QuantiFERON-TB is a portable IGRA with the potential to improve accessibility of TB infection diagnosis in low-resource settingshttps://bit.ly/3nTzolf

First clinical evaluation of the QIAreachTM QuantiFERON-TB for tuberculosis infection and active pulmonary disease

OBJECTIVE

1) to compare the QIAreach^TM QuantiFERON-TB (QIAreach QFT) vs. QuantiFERON®-TB Gold Plus assay (QFT-Plus) to detect tuberculosis (TB) infection; 2) to evaluate diagnostic sensitivity of QIAreach QFT using active TB as surrogate for TB infection; 3) to preliminarily evaluate QIAreach QFT in immunocompromised individuals.

METHODS

QIAreach QFT measures the level of interferon-γ (IFN-γ) in plasma specimens from blood stimulated by ESAT-6 and CFP-10 peptides in one blood collection tube (equivalent to the TB2 tube of the QFT-Plus). QIAreach QFT was applied to plasma samples from 41 patients with pulmonary TB and from 42 healthy or low-TB-risk individuals.

RESULTS

Sensitivity and specificity of QIAreach QFT vs. QFT-Plus were 100% (41/41) and 97.6% (41/42), respectively; overall concordance was 98.8% (82/83). All samples were measured within 20 min. The time to result of each sample was significantly correlated with IFN-γ level with a natural logarithmic scale (r = -0.913, p < 0.001). Seven cases in the active TB group were immunocompromised (CD4 <200/μL) and tested positive by QIAreach QFT.

CONCLUSIONS

QIAreach QFT provides an objective readout with a minimum blood sample volume (1 mL/subject), potentially being a useful point-of-care screening test for TB infection in high-TB-burden, low-resource countries and for immunocompromised patients.

Utility of interferon gamma/tumor necrosis factor alpha FluoroSpot assay in differentiation between active tuberculosis and latent tuberculosis infection: a pilot study

Background

The differential diagnosis of active tuberculosis (ATB) and latent tuberculosis infection (LTBI) remains challenging in clinical practice. We aimed to evaluate the diagnostic accuracy of the IFN-γ/TNF-α FluoroSpot assay for differentiating ATB from LTBI.

Methods

We conducted a pilot study of case-control design, using the FluoroSpot assay to simultaneously detect IFN-γ and TNF-α secretion at the single-cell level. The frequencies of antigen-specific single TNF-α-, total TNF-α-, single IFN-γ-, total IFN-γ- and dual IFN-γ/TNF-α-secreting T cells were detected. The optimal cutoffs value of frequencies for differentiating ATB from LTBI were determined according to receiver operating characteristic curve analysis. The sensitivity, specificity, predictive values (PV) and likelihood ratios (LR) of the FluoroSpot assay were calculated.

Results

Thirty patients diagnosed microbiologically with ATB, 36 healthcare workers with LTBI and 36 healthy controls were enrolled. After stimulated by ESAT-6 or CFP-10 peptides, the median frequencies of single TNF-α-, total TNF-α-, single IFN-γ-, total IFN-γ- and dual IFN-γ/TNF-α-secreting T cells in ATB patients were all significantly higher than those in LTBI and HC groups (P < 0.01). The frequencies of total IFN-γ-secreting T cells detected by FluoroSpot assay correlated significantly with those of T-SPOT.TB (r = 0.910 for ESAT-6, P < 0.001, r = 0.845 for CFP-10, P < 0.001). After stimulated by ESAT-6 peptides, with total TNF-α-secreting T cells frequencies at a cut off value of 21 iSFCs/250,000 PBMCs, the sensitivity, specificity, PLR, NLR, PPV, NPV of IFN-γ/TNF-α FluoroSpot assay in differentiating ATB from LTBI were 96.7% (95%CI, 82.8–99.9%), 94.3% (95%CI, 80.8–99.3%), 16.92 (95%CI, 4.40–65.08), 0.04 (95%CI, 0.01–0.24), 93.6% (95%CI,78.6–99.2%) and 97.1% (95%CI, 84.7–99.9%), respectively. With the frequencies of total TNF-α- and total IFN-γ-secreting T cells stimulated by ESAT-6 peptides combined, the specificity was increased to 97.1%, and the positive likelihood ratio to 31.5. The combination with CFP-10 might not improve the diagnostic accuracy of the ESAT-6 for differentiating ATB from LTBI.

Conclusions

IFN-γ/TNF-α FluoroSpot assay might have potential to help differentiate ATB from LTBI, but the findings need to be further verified by cross-sectional or prospective cohort studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06351-w.

Interleukin-6 and Mycobacterium tuberculosis dormancy antigens improve diagnosis of tuberculosis

OBJECTIVES

IFNγ-release assays (IGRAs) used for diagnosis of Mycobacterium (M.) tuberculosis infection have limited sensitivity. Alternative cytokines and M. tuberculosis latency-associated antigens may improve immune-based tests.

METHODS

Multiplex cytokine analyses was done in culture supernatants after 6-day in vitro restimulation with M. tuberculosis IGRA and latency-associated antigens (i.e. Rv2628, Rv1733) in tuberculosis patients (n = 22) and asymptomatic contacts (AC)s (n = 20) from Ghana.

RESULTS

Four cytokines (i.e. IFNγ, IP-10, IL-22 and IL-6) were significantly increased after IGRA-antigen specific restimulation. IFNγ, IP-10, and IL-22 correlated positively and showed no differences between the study groups whereas IGRA-antigen induced IL-6 was significantly higher in tuberculosis patients. Using adjusted IGRA criteria, IL-6 showed the highest sensitivity for detection of tuberculosis patients (91%) and ACs (85%) as compared to IFNγ, IP-10, and IL-22. Rv2628 and Rv1733 restimulation induced significantly higher IFNγ, IP-10, and IL-22 concentrations in ACs. Combined antigen/cytokine analyses identified study group specific patterns and a combination of Rv2628/Rv1733 induced IFNγ with IGRA-antigen induced IL-6 was optimal for classification of tuberculosis patients and ACs (AUC: 0.92, p<0.0001).

CONCLUSIONS

We demonstrate the potency of alternative cytokines, especially IL-6, and latency-associated antigens Rv1733/Rv2628 to improve detection of M. tuberculosis infection and to classify tuberculosis patients and healthy contacts.

Advances in the diagnosis of tuberculosis- Journey from smear microscopy to whole genome sequencing

The laboratory plays an important role in diagnosing tuberculosis (TB) and the identification and drug sensitivity testing (DST) of Mycobacterium tuberculosis. With a timely diagnosis and treatment with appropriate anti-TB drugs, most people who develop TB can be cured and onward transmission of infection curtailed. For a long time, laboratories used only microscopy and conventional culture-based diagnosis, however these procedures are slow and may require 3-4 weeks to yield results. Given the increasing rate of drug resistance, it has been necessary to look for new and rapid diagnostic methods. Various molecular based diagnostic technologies became available in the beginning of early 90s, providing rapid detection, identification and DST of M. tuberculosis. Molecular technologies offer the greatest potential for laboratories because they have the highest sensitivity and specificity. The present article will review some of the new methodology that has been introduced in the clinical laboratory.

Is Takayasu arteritis the result of a Mycobacterium tuberculosis infection? The use of TNF inhibitors may be the proof-of-concept to demonstrate that this association is epiphenomenal

Although the association between Takayasu arteritis (TA) and latent or active Mycobacterium tuberculosis infection has been suggested for a long time, studies conducted in recent years are challenging this notion. Until recently, the possibility of a pathogenic relationship between TA and tuberculosis (TB) was considered a medical curiosity, but the advent of tumor necrosis factor (TNF) inhibitors as therapy for recalcitrant TA cases, as well as the widespread use of Bacille Calmette-Guérin (BCG) for vaccination purposes, has relocated this association as a top priority issue. In an attempt to define whether both diseases are pathogenically linked or if their association is only epiphenomenal in nature, we conduct a thorough literature search on the development of TB in patients with TA receiving TNF inhibitors. From a total of 13 studies that included 214 patients, the occurrence of TB was observed only in two individuals exposed to infliximab. This frequency of 0.93% is similar to that encountered in patients with other rheumatic diseases exposed to TNF inhibitors. Finally, we propose a novel pathogenic model that could reconcile the epidemiological, clinical, and immunological evidence that links TA and TB, while providing rationality for the use of TNF inhibitors in patients with TA.

Screening for Latent Tuberculosis among Healthcare Workers in an Egyptian Hospital Using Tuberculin Skin Test and QuantiFERON-TB Gold In-Tube Test

Background:

Early detection of latent tuberculosis infection (LTBI) might prevent active TB development in healthcare workers (HCWs). The aim of the study is to assess the prevalence of LTBI among HCWs exposed to active TB, compare QFT-GIT and TST in the diagnosis of LTBI, and explore possible risk factors of LTBI.

Setting and Design:

This was a cross-sectional study for a period of 6 months among 153 HCWs in high-risk departments dealing with TB infection – Beni-Suef University Hospital, Egypt.

Materials and Methods:

HCWs were asked to fill a questionnaire for possible LTBI risk factors, and tuberculin skin test (TST) and serum QuantiFERON test were used for LTBI screening.

Statistical Analysis:

Statistical Package for Social Science (SPSS-18) was used for data analysis; qualitative data were compared using Chi-square test, while associations between risk factors for TB and positive QFT or TST were analyzed by a logistic regression model.

Results:

LTBI detected by QuantiFERON-TB Gold In-Tube Test (QFT-GIT) and by TST was 9.1% and 34.6%, respectively (kappa = 0.028). Logistic regression showed that departments, duration of work, the use of N95 masks, and training in infection control practices were significant predictors for positive QFT-GIT among participants (P < 0.05).

Conclusion:

Work duration of >10 years, nurse profession, diabetics, and smokers were at increased risk of having LTBI. Increased training programs and implementation of infection control measures TB to reduce the risk of LTBI are recommended.

Performance of the QuantiFERON®-TB Gold In-Tube assay in tuberculin skin test converters: a prospective cohort study

OBJECTIVE

To investigate diagnostic agreement of the QuantiFERON®-TB Gold In-Tube (QFT-GIT) test in adult tuberculin skin test (TST) converters in a high tuberculosis (TB) burden setting.

SETTING AND DESIGN

We performed a case-cohort study from 2014 to 2016 in Uganda among residents who were not infected with Mycobacterium tuberculosis. Participants were followed up for 1 year, when they were retested to determine TST conversion. All TST converters and a random sample of participants from baseline were offered QFT-GIT testing.

RESULTS

Of 368 enrolled participants, 61 (17%) converted their TST by 1 year. Among 61 converters, 42 were tested using QFT-GIT, 64% of whom were QFT-GIT-positive. Of 307 participants with a persistent negative TST, 48 were tested using QFT-GIT, 83% of whom were QFT-negative. Overall concordance of TST and QFT-GIT was moderate (κ = 0.48, 95%CI 0.30-0.66). Converters with a conversion of 15 mm had a higher proportion of concordant QFT-GIT results (79%) than converters with increments of 10-14.9 mm (52%).

CONCLUSION

Concordance between TST and QFT-GIT was moderate among TST converters in this urban African population. These findings call for improved tests that more accurately measure conversion to tuberculous infection.

Two-Hit in vitro T-Cell Stimulation Detects Mycobacterium tuberculosis Infection in QuantiFERON Negative Tuberculosis Patients and Healthy Contacts From Ghana

IFN-γ release assays [e.g., QuantiFERON (QFT)] are widely used for diagnosis of Mycobacterium tuberculosis (Mtb) infection. T-cell responses against QFT antigens ESAT6 and CFP10 are highly Mtb specific but previous studies indicated suboptimal assay sensitivity. Especially for potentially infected healthy contacts (HCs) of tuberculosis patients, alternative antigen usage and more sensitive tests may contribute to improved detection of latent Mtb infection. In a pilot case-control study of tuberculosis patients (n = 22) and HCs (n = 20) from Ghana, we performed multifaceted in vitro assays to identify optimal assay conditions. This included a two-hit stimulation assay, which is based on initial and second re-stimulation with the same antigen on d6 and intracellular IFN-γ analysis, to compare T-cell responses against ESAT6/CFP10 (E6/C10) and selected latency antigens (i.e. Rv2628, Rv1733, Rv2031, Rv3407) of Mtb. Considerable subgroups of tuberculosis patients (64%) and HCs (75%) had negative or indeterminate QFT results partially accompanied by moderate PHA induced responses and high IFN-γ background values. Intracellular IFN-γ analysis of E6/C10 specific CD4⁺ T-cell subpopulations and evaluation of responder frequencies had only moderate effects on assay sensitivity. However, two-hit in vitro stimulation significantly enhanced E6/C10 specific IFN-γ positive T-cell proportions especially in QFT non-responders, and in both study groups. Mtb latency antigen-specific T cells against Rv1733 and Rv2628 were especially detected in HCs after two-hit stimulation and T-cell responses against Rv2628 were highly capable to discriminate tuberculosis patients and HCs. Two-hit in vitro stimulation may improve moderate sensitivity of short term IFN-γ based assays, like QFT, to detect Mtb infection. Latency stage-specific antigens added significantly to detection of Mtb infection in HCs and tuberculosis patients with negative QFT test results.

Underascertainment, underreporting, representativeness and timeliness of the Iranian communicable disease surveillance system for tuberculosis

OBJECTIVES

A well-functioning disease surveillance system is essential for effective control of diseases. Therefore, conducting evaluation studies on the performance of disease surveillance systems is necessary. This study was conducted to evaluate the performance of the Iranian syndrome-based surveillance system for tuberculosis (TB) in rural areas of Fars, the third largest province located in southern Iran.

STUDY DESIGN

This was an evaluation study.

METHODS

Two independent sources of information (data from a population-based survey and data from the surveillance system) were used in this evaluation. A group of trained female nurses used a specially designed interview-administered questionnaire to obtain data on the health status of family members from mothers or other adult women in rural houses. Subsequently, the nurses obtained data from individuals who reported a history of TB during a specified period and defined whether the patients presented themselves to a rural or urban health centre or clinic.

RESULTS

A total of 48,771 individuals participated in this study. Of 156 cases who reported a history of TB, 137 (87.82%) presented themselves to at least one medical care provider seeking diagnosis and treatment services. Of patients who visited a health or medical centre, only 18 (13.14%) were reported to the highest level of the surveillance system. Accordingly, the rates of underascertainment and underreporting of the Iranian surveillance system for TB were 12.18% and 86.86%, respectively. Moreover, underascertainment was significantly higher for men (19.40%) than for women (6.74%). The mean time between the date at which TB was noticed and the date of diagnosis was 56.24 days, which was longer for men (79.29 days) than for women (40.10 days). The highest and lowest levels of underreporting were observed for private general practitioners (100%) and the health centres run by the government (87%), respectively.

CONCLUSION

The quality of the communicable disease surveillance system for TB in Iran is facing important challenges, including underascertainment, underreporting and timeliness, in addition to different types of bias. Informing the general population and health workforce about TB and the importance of timely diagnosis is a good approach to improve the performance of Iran's national communicable disease surveillance system.

Latent tuberculosis infection in patients with rheumatic diseases

Most people infected by Mycobacterium tuberculosis (Mtb) do not have any signs or disease symptoms, a condition known as latent tuberculosis infection (LTBI). The introduction of biological agents, mainly tumor necrosis factor (TNF) inhibitors, for the treatment of immune-mediated diseases such as Rheumatoid Arthritis (RA) and other rheumatic diseases, increased the risk of reactivation of LTBI, leading to development of active TB. Thus, this review will approach the aspects related to LTBI in patients with rheumatologic diseases, especially those using iTNF drugs. For this purpose it will be considered the definition and prevalence of LTBI, mechanisms associated with diseases and medications in use, criteria for screening, diagnosis and treatment. Considering that reactivation of LTBI accounts for a large proportion of the incidence of active TB, adequate diagnosis and treatment are crucial, especially in high-risk groups such as patients with rheumatologic diseases.

Microencapsulated Immunoassays for Detection of Cytokines in Human Blood

Cytokines are produced by leukocytes in blood and may be used as indicators of malignancies or infections. The objective of this study was to develop a strategy for immunosensing cytokines in whole, unprocessed human blood. Microfluidic droplet generation was employed to fabricate ∼400 μm diameter microcapsules with a hydrogel shell and an aqueous core containing sensing microbeads. The hydrogel shell was composed of poly(ethylene glycol) forming a thin (∼10 μm) immunoisolation layer protecting antibody-modified microbeads inside the capsule from immune cells on the outside. The microbeads were functionalized with antibodies against cytokines of interest: interferon (IFN)-γ and tumor necrosis factor (TNF)-α. While nonfouling, a hydrogel shell was permeable to cytokine molecules; these molecules were captured on microbeads and were detected with fluorescently labeled secondary antibodies. Calibration of encapsulated immunoassays with known concentrations of cytokines revealed a limit of detection of 14.8 and 14.4 pM for IFN-γ and TNF-α, respectively. We also demonstrated the concept of multi-cytokine detection by fabricating distinct populations of capsules carrying either anti-IFN-γ or anti-TNF-α microbeads and dispensing these capsules into a solution containing both cytokine types. Importantly, when placed into whole blood for 16 h, microcapsules were free of leukocytes, effectively protecting sensing beads from the blood components. To further demonstrate utility of this strategy, encapsulated microbeads were used for detection of IFN-γ in blood of patients with latent tuberculosis infection (LTBI) and unexposed healthy controls. When compared to gold standard technology (interferon gamma release assay or IGRA), our encapsulated immunoassay accurately predicted LTBI diagnosis in 11 out of 14 patients. Overall, encapsulation of immunoassays represents a promising strategy for keeping sensing elements operational in a highly fouling complex environment such as blood.

Assessing and screening for T-cell epitopes from Mycobacterium tuberculosis RD2 proteins for the diagnosis of active tuberculosis

The Region of D eletion 2 (RD2) of Mycobacterium tuberculosis encodes reserved antigens that contribute to bacterial virulence. Among these antigens, Rv1983, Rv1986, Rv1987, and Rv1989c have been shown to be immunodominant in infected cattle; however, their diagnostic utility has not been evaluated in humans.

In this study, we screened 87 overlapping synthetic peptides encoded by five RD2 proteins for diagnosing tuberculosis epitopes in 50 active tuberculosis (TB) cases, 31 non-tuberculosis patients and 36 healthy individuals. A pool of promising epitopes was then assessed for their diagnostic value in 233 suspected TB patients using a whole blood IFN-γ release assay.

Only 10 peptides were recognized by more than 10% of active tuberculosis patients. The IFN-γ release responses to Rv1986-P9, P15, P16, Rv1988-P4, P11, and Rv1987-P11 were significantly higher in the active TB group than in the control groups (p < 0.05). The whole blood IFN-γ release assay based on these epitopes yielded a sensitivity of 51% and a specificity of 85% in diagnosing active tuberculosis, and the corresponding results using the T-SPOT.TB assay were 76% and 75%, respectively.

In conclusion, these results suggest that the six epitopes from the RD2 of M. tuberculosis have potential diagnostic value in TB.

A Novel Microfluidic Point-of-Care Biosensor System on Printed Circuit Board for Cytokine Detection

Point of Care (PoC) diagnostics have been the subject of considerable research over the last few decades driven by the pressure to detect diseases quickly and effectively and reduce healthcare costs. Herein, we demonstrate a novel, fully integrated, microfluidic amperometric enzyme-linked immunosorbent assay (ELISA) prototype using a commercial interferon gamma release assay (IGRA) as a model antibody binding system. Microfluidic assay chemistry was engineered to take place on Au-plated electrodes within an assay cell on a printed circuit board (PCB)-based biosensor system. The assay cell is linked to an electrochemical reporter cell comprising microfluidic architecture, Au working and counter electrodes and a Ag/AgCl reference electrode, all manufactured exclusively via standard commercial PCB fabrication processes. Assay chemistry has been optimised for microfluidic diffusion kinetics to function under continual flow. We characterised the electrode integrity of the developed platforms with reference to biological sampling and buffer composition and subsequently we demonstrated concentration-dependent measurements of H₂O₂ depletion as resolved by existing FDA-validated ELISA kits. Finally, we validated the assay technology in both buffer and serum and demonstrate limits of detection comparable to high-end commercial systems with the addition of full microfluidic assay architecture capable of returning diagnostic analyses in approximately eight minutes.

QuantiFERON-TB Gold In-Tube test in active tuberculosis patients and healthy adults

Interferon-gamma (IFN-γ) release assays have improved latent tuberculosis (TB) detection and have been considered promising for the diagnosis of TB disease. However, diagnosis efficacy data is limited in high burden countries. The aim of this study was to determine the diagnostic potential of the QuantiFERON-TB Gold In-Tube (QFT-GIT) test for the diagnosis of active TB in an endemic setting for TB. A cross-sectional study was conducted in a group of 102 Thai patients with clinical symptoms and chest x-ray findings suggesting of active pulmonary TB and a group of 112 healthy adults. Testing was carried out using sputum microscopy, mycobacterial culture and QFT-GIT test. Of these patients, QFT-GIT was positive in 73 (71.57%), negative in 27 (26.47%), and undetermined in 2 (1.96%) cases. Among healthy controls, QFT-GIT was positive in 18 (16.07%), negative in 93 (83.04%), and undetermined in 1 (0.89%) person. Based on TB culture results, the sensitivity of QFTGIT for diagnosing active TB was 84.21% (95% confidence interval (CI); 72.13-92.52). The positive and negative predictive values were 65.75% (95% CI; 59.26-71.70) and 66.67% (95% CI; 49.94-80.04), respectively. The median IFN-γ level in culture-confirmed TB patients was 3.91 compared to 0.03 IU/mL of the healthy group. QFT-GIT appears to be a useful indirect test for TB diagnosis in Thailand and its use is recommended in association with clinical and radiological assessments for identifying active or latent TB.

Management and diagnosis of tuberculosis in solid organ transplant candidates and recipients: Expert survey and updated review. J Clin Tuberc Other Mycobact Dis 2018;11:37-46. [PMID: 31720390 PMCID: PMC6830179 DOI: 10.1016/j.jctube.2018.04.001]

Background : Optimal screening and management of latent tuberculosis infection (LTBI) and active tuberculosis (TB) in solid organ transplant (SOT) candidates and recipients is necessary to prevent morbidity and mortality. Methods : We conducted a cross-sectional survey of TB and transplant experts across the United States reviewing the clinical practice preferences on key management issues related to LTBI and TB in SOT candidates and recipients. Results : Thirty TB and 13 SOT experts were surveyed (response rate = 53.8%). Both groups agreed that tuberculin skin test (TST) and chest x-ray screening in SOT candidates was useful (78.6% and 84.6%, respectively). TST after SOT was not useful for most transplant experts and TB experts (0% vs. 32.1%, respectively), but both groups were split on usefulness of interferon gamma release assays (IGRA) in SOT recipients (42.9% TB experts vs. 46.2% SOT experts). Most experts recommend LTBI treatment prior to SOT if close monitoring is assured (82.1% TB experts vs. 76.9% transplant experts). LTBI treatment with isoniazid was preferred for patients on calcineurin inhibitors. Evaluation for suspected TB in SOT recipients varied, but most TB experts favored sputum testing (88.9%) whereas most transplant experts favored bronchoscopic testing (69.2%). Preferred TB treatment regimens in SOT recipients were similar to regimens recommended for immunocompetent patients. Conclusions : Most TB and transplant experts recommend evaluation and treatment for LTBI in SOT candidates. Liver transplant candidates, however, should only be treated if close monitoring can be assured and after consulting with a hepatologist. Practice preferences varied regarding the initial diagnostic approach for suspected TB in SOT recipients; however, most experts agreed that SOT recipients should receive similar treatments as immunocompetent patients.

Evaluation of a synthetic peptide for the detection of anti-Mycobacterium tuberculosis curli pili IgG antibodies in patients with pulmonary tuberculosis

Tuberculosis (TB) remains a serious threat in underdeveloped areas. Mycobacterium tuberculosis curli pili (MTP), a virulence factor, is a potential biomarker for a reliable point of care (POC) test and was evaluated for its ability to react with Immunoglobulin G (IgG) in TB patients. An MTP synthetic peptide in a slot blot assay was used to screen serum/plasma samples (n = 65) in 3 separate cohorts, including 40 TB positive (16 HIV co-infected), 20 TB negative/HIV negative patients and 5 healthy volunteers. Forty samples were true positives (HIV positive, n = 16), 23 true negatives (HIV negative) and 2 false positives (HIV negative). The McNemar test demonstrated a 3.08% accuracy estimate (CI: -2.1% - 3.08%). This confirms that MTP is expressed during infection, including HIV-TB co-infection, is likely to be suitable for the design of a POC test and supports the validation of MTP for TB detection in larger patient populations.

Preparation of immunochromatographic strips for rapid detection of early secreted protein ESAT-6 and culture filtrate protein CFP-10 from Mycobacterium tuberculosis

The early secreted protein early secretory antigenic target 6(ESAT-6) and the culture filtrate protein 10 (CFP-10) are 2 antigens that are specific to Mycobacterium tuberculosis. These 2 antigens are good targets for tuberculosis (TB) detection.To rapidly diagnose TB across a variety of samples, we developed colloidal gold immunochromatographic strips (ICSs) based on ESAT-6 and CFP-10.The strips were evaluated using 233 samples, including sputum, plasma, and pleural effusion samples.The positive detection rates for ICSs for ESAT-6 and CFP-10 in sputum (culture-positive for M tuberculosis) were 100% and 91.2%, respectively. The positive detection rates for ICSs for ESAT-6 and CFP-10 in plasma were 34.1% and 29.4%, respectively. The positive detection rates for ICSs for ESAT-6 and CFP-10 in pleural effusion were 64.7% and 55.9%, respectively. Experimental analysis of culture supernatant showing that the ICS developed for ESAT-6 had a sensitivity of 100% and a specificity of 91.2%. While the ICS developed for CFP-10 had a sensitivity of 91.2% and a specificity of 88.2%.The validity of the test is limited by source of sample. The technique is sensitive and specific for samples in sputum and culture media but not for plasma or pleural effusion samples. Detection of M tuberculosis using ICSs is rapid, simple, and relatively effective; thus, ICSs are a potential screening tool for TB.

Usefulness of interferon-γ release assay for the diagnosis of sputum smear-negative pulmonary and extra-pulmonary TB in Zhejiang Province, China

Background

Quick diagnosis of smear-negative pulmonary tuberculosis (TB) and extra-pulmonary TB are urgently needed in clinical diagnosis. Our research aims to investigate the usefulness of the interferon-γ release assay (IGRA) for the diagnosis of smear-negative pulmonary and extra-pulmonary TB.

Methods

We performed TB antibody and TB-IGRA tests on 389 pulmonary TB patients (including 120 smear-positive pulmonary TB patients and 269 smear-negative pulmonary TB patients), 113 extra-pulmonary TB patients, 81 patients with other pulmonary diseases and 100 healthy controls. Blood samples for the TB-Ab test and the TB-IGRA were collected, processed, and interpreted according to the manufacturer’s protocol.

Results

The detection ratio of smear-positive pulmonary TB patients and smear-negative pulmonary TB patients were 90.8% (109 of 120) and 89.6% (241 of 269), respectively. There was no statistically significant difference of its performance between these two sample sets (P > 0.05). The detection ratio of positive TB patients and extra-pulmonary TB patients were 90.0% (350 of 389) and 87.6% (99 of 113), respectively, which was not significantly different (P > 0.05).

Conclusions

In this work, the total detection ratio using TB-IGRA was 89.4%, therefore TB-IGRA has diagnostic values in smear-negative pulmonary TB and extra-pulmonary TB diagnosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-017-0331-1) contains supplementary material, which is available to authorized users.

QuantiFERON®-TB Gold In-Tube for contact screening in BCG-vaccinated adults: A longitudinal cohort study

OBJECTIVE

To assess the utility of QuantiFERON®-TB Gold In-tube (QFT-GIT) for targeting preventive therapy in BCG-vaccinated contacts of tuberculosis (TB), based on its high specificity and negative predictive value for development of TB.

METHODS

We compared two screening strategies for TB contact tracing in two consecutive periods: the tuberculin skin test (TST) period, when all contacts were screened with the TST alone; and the QFT-GIT period, when BCG-vaccinated contacts underwent TST and QFT-GIT. Diagnosis of TB infection among BCG-vaccinated contacts relied on TST ≥5 mm in the TST period, while in the QFT-GIT period either a positive QFT-GIT or a TST ≥15 mm was required.

MEASUREMENTS AND MAIN RESULTS

Six hundred and sixty-one contacts were compared. In the QFT-GIT period there was a reduction in diagnoses of TB infection (77.4% vs. 51.2%; p <0.01) and preventive therapy prescribed (62.1% vs. 48.2%; p = 0.02) among the 290 BCG-vaccinated contacts. After a median follow-up of 5 years, cumulative incidences of TB were 0.62 and 0.29 in the TST and QFT-GIT periods respectively (p = 0.59).

CONCLUSIONS

In BCG-vaccinated TB contacts, the addition of QFT-GIT safely reduced TB diagnosis and treatment rates without increasing the risk of subsequent active TB.

Assessment of the influence of direct tobacco smoke on infection and active TB management

BACKGROUND

Smoking is a risk factor for tuberculosis (TB) infection and disease progression. Tobacco smoking increases susceptibility to TB in a variety of ways, one of which is due to a reduction of the IFN-γ response. Consequently, an impaired immune response could affect performance of IFN-γ Release Assays (IGRAs).

OBJECTIVE

In the present study, we assess the impact of direct tobacco smoking on radiological manifestations, sputum conversion and immune response to Mycobacterium tuberculosis, analyzing IFN-γ secretion by IGRAs.

METHODS

A total of 525 participants were studied: (i) 175 active pulmonary TB patients and (ii) 350 individuals coming from contact tracing studies, 41 of whom were secondary TB cases. Clinical, radiological and microbiological data were collected. T-SPOT.TB and QFN-G-IT were processed according manufacturer's instructions.

RESULTS

In smoking patients with active TB, QFN-G-IT (34.4%) and T-SPOT.TB (19.5%) had high frequencies of negative results. In addition, by means of an unconditional logistic regression, smoking was a main factor associated with IGRAs' false-negative results (aOR: 3.35; 95%CI:1.47-7.61; p<0.05). Smoking patients with active TB presented a high probability of having cavitary lesions (aOR: 1.88; 95%CI:1.02-3.46;p<0.05). Mean culture negativization (months) ± standard deviation (SD) was higher in smokers than in non-smokers (2.47±1.3 versus 1.69±1.4). Latent TB infection (LTBI) was favored in smoking contacts, being a risk factor associated with infection (aOR: 11.57; 95%CI:5.97-22.41; p<0.00005). The IFN-γ response was significantly higher in non-smokers than in smokers. Smoking quantity and IFN-γ response analyzed by IGRAs were dose-dependent related.

CONCLUSIONS

Smoking had a negative effect on radiological manifestations, delaying time of sputum conversion. Our data establish a link between tobacco smoking and TB due to a weakened IFN-γ response caused by direct tobacco smoke.

Tuberculosis and biologics in rheumatology: A special situation

India has a huge patient burden of rheumatic diseases (RDs) including rheumatoid arthritis. The use of biologics has transformed the treatment paradigm for RD; however, biologic treatment-related infections (especially tuberculosis [TB]) are an area of potential concern for TB-endemic nations like India. Anti-tumor necrosis factor (TNF) therapy impairs the physiological TNF-mediated signaling and may cause reactivation and dissemination of latent TB infection (LTBI). Careful screening is, thus, crucial in RD patients who are about to commence anti-TNF treatment. To date, there is no consensus available for the screening, evaluation and treatment of LTBI as well as on the drug dosage and duration regimen (monotherapy or combination therapy) in the Indian population. An evidence-based algorithm for LTBI screening and management in RD patients undergoing biologic disease-modifying anti-rheumatic drug therapy is suggested in this review for Indian rheumatologists. The proposed algorithm guides physicians through a step-wise screening approach, including medical history, tuberculin skin test, interferon gamma release assay, chest radiograph and management of LTBI with isoniazid therapy or its combination with rifampicin. Further, the provided algorithm can aid the national bodies (such as National TB Control Program) in formulating recommendations for LTBI in this high-risk population.

Mycobacterium tuberculosis DosR Regulon Gene Rv2004c Encodes a Novel Antigen with Pro-inflammatory Functions and Potential Diagnostic Application for Detection of Latent Tuberculosis

Approximately 1.7 billion people in the world harbor latent Mycobacterium tuberculosis (Mtb) with a substantial risk of progression to clinical outcome. Containment of these seed beds of Mtb is essential to eliminate tuberculosis completely in high burden settings such as India. Hence, there is an urgent need for the identification of new serological markers for detection or vaccine candidates to prevent latent tuberculosis infection (LTBI). DosR regulon antigens of Mtb might serve as attractive targets for LTBI diagnosis or vaccine development as they are specifically expressed and are upregulated during latent phase. In this study, we investigated the role of Rv2004c, a member of DosR regulon (exclusive to Mtb complex), in host–pathogen interaction and its immunogenic potential in LTBI, active TB, and healthy control cohorts. Rv2004c elicited strong antibody response in individuals with LTBI compared to active TB patients and healthy cohorts. Recombinant Rv2004c induced pro-inflammatory cytokine response in human peripheral blood mononuclear cells and THP-1 cells via NF-κB phosphorylation. Interaction of Rv2004c with toll-like receptor (TLR)-2 was confirmed using HEK-Blue hTLR-2 and pull-down assays. Rv2004c enhanced the surface expression of TLR-2 at mRNA and protein levels in THP-1 cells. Our findings revealed that Rv2004c induces strong humoral and cell mediated immune responses. Given these observations, we propose Rv2004c to be a potential diagnostic marker or an attractive vaccine candidate that can be useful against LTBI.

The Role of QuantiFERON®-TB Gold and Tuberculin Skin Test as Diagnostic Tests for Intraocular Tuberculosis in HIV-Positive and HIV-Negative Patients in South Africa

PURPOSE

To compare QuantiFERON®-TB Gold and tuberculin skin testing as diagnostic tests for intraocular tuberculosis in HIV positive and negative patients.

METHODS

A prospective study evaluating two different tests to help diagnose intraocular tuberculosis.

RESULTS

Thirty-five of 106 patients (33.0%) were diagnosed with intraocular tuberculosis including 11 (31.4%) with HIV infection. Patients were 6.95 times more likely to have intraocular tuberculosis if TST alone was positive (p < 0.001) versus 2.19 times more likely if Quantiferon alone was positive (p = 0.04). Tuberculin skin testing showed superior specificity (60.3% vs 33.3%) (p = 0.001) but similar sensitivity (90.3% vs 85.7%), positive (54.9% vs 40.5%) and negative predictive values (92.1% vs 81.5%) compared to Quantiferon. Specificity did not increase significantly if both skin testing and Quantiferon were positive.

CONCLUSIONS

In South Africa, with its high HIV burden and limited public health resources, Quantiferon testing should not replace tuberculin skin testing as it provides little additional diagnostic information.

Utility of Th1-cell immune responses for distinguishing active tuberculosis from non-active tuberculosis: A case-control study

Currently available Interferon-γ release assay (IGRA) cannot reliably differentiate active TB (ATB) from non-active TB (non-ATB). A study was performed to evaluate the value of Mycobacterium tuberculosis (MTB) specific Th1 cell immune responses which test IFN-γ and IL-2 simultaneous for differentiating ATB from non-ATB. Forty-nine newly diagnosed inpatients with ATB (26 pulmonary TB and 23 extrapulmonary TB) were enrolled as the ATB group. Forty-five volunteers with latent tuberculosis infection (LTBI) and twenty with evidence of previous TB were enrolled during the same period as the non-ATB group. Clinical examination and MTB specific Th1 cell immune responses were performed for all participants. After being stimulated with ESAT-6 and CFP-10, the median frequencies of single IL-2-, single IFN-γ-, and dual IFN-γ/IL-2-secreting T-cells were all higher in the ATB group than in the non-ATB group (20(8–45) vs. 7(3–13), P<0.001;131(44–308) vs. 10(6–27), P<0.001;25(9–74) vs. 7(3–23), P = 0.001, respectively). Evaluation of the diagnostic performance of detecting single IFN-γ-secreting T cells for pulmonary TB employed a cutoff value of 35 iSFCs/250,000 PBMC. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) were 92.3%, 80.0%, 64.9%, 96.3%, 4.62, and 0.10, respectively. For extrapulmonary TB, using a cutoff value of 23 iSFCs/ 250,000 PBMC, the sensitivity, specificity, PPV, NPV, PLR, and NLR were 91.3%, 76.9%, 58.3%, 96.2%, 3.96, and 0.11, respectively. When combining frequencies and proportion of single IFN-γ-secreting T cells, the test sensitivity was 100% in parallel tests and the specificity was 87.7% in serial tests for pulmonary TB. MTB specific Th1 cell immune responses (FluoroSpot) had value for the differentiation of ATB and non-ATB. Further confirmatory studies are indicated.

An attenuated Mycobacterium tuberculosis clinical strain with a defect in ESX-1 secretion induces minimal host immune responses and pathology

Although Mycobacterium tuberculosis (M.tb) DK9897 is an attenuated strain, it was isolated from a patient with extrapulmonary tuberculosis and vaccination with a subunit vaccine (H56) induced poor protection against it. Both attenuation and lack of protection are because M.tb DK9897 cannot secrete the EsxA virulence factor nor induce a host response against it. Genome sequencing identified a frameshift mutation in the eccCa1 gene. Since the encoded EccCa1 protein provides energy for ESX-1 secretion, it suggested a defect in the ESX-1 type VII secretion system. Genetic complementation with a plasmid carrying the M.tb H37Rv sequence of eccCa1-eccCb1-pe35 re-established EsxA secretion, host specific EsxA T-cell responses, and increased strain virulence. The ESX-1 secretion defect prevents several virulence factors from being functional during infection and therefore attenuates M.tb. It precludes specific T-cell responses against strong antigens and we found very little in vivo cytokine production, gross pathology or granuloma formation in lungs from M.tb DK9897 infected animals. This coincides with M.tb DK9897 being unable to disrupt the phagosome membrane and make contact to the cytosol.

An Assay System for Point-of-Care Diagnosis of Tuberculosis using Commercially Manufactured PCB Technology

Rapid advances in clinical technologies, detection sensitivity and analytical throughput have delivered a significant expansion in our knowledge of prognostic and diagnostic biomarkers in many common infectious diseases, such as Tuberculosis (TB). During the last decade, a significant number of approaches to TB diagnosis have been attempted at Point-of-Care (PoC), exploiting a large variation of techniques and materials. In this work, we describe an electronics-based Enzyme-Linked ImmunoSorbent Assay (eELISA), using a Lab-on-a-Printed Circuit Board (LoPCB) approach, for TB diagnosis based on cytokine detection. The test relies upon an electrochemical (amperometric) assay, comprising a high-precision bioinstrumentation board and amperometric sensors, produced exclusively using standard PCB manufacturing processes. Electrochemical detection uses standard Au and Ag electrodes together with a bespoke, low-power, multichannel, portable data-acquisition system. We demonstrate high-performance assay chemistry performed at microfluidic volumes on Au pads directly at the PCB surface with improved limit of detection (~10 pg/mL) over standard colorimetric ELISA methods. The assay has also been implemented in plasma, showing the utility of the system for medical applications. This work is a significant step towards the development of a low-cost, portable, high-precision diagnostic and monitoring technology, which once combined with appropriate PCB-based microfluidic networks will provide complete LoPCB platforms.

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

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

Immunizations: An Evolving Paradigm for Oral Health Care Providers

Oral health care professionals are at risk for the transmission of bacterial and viral microorganisms. Providers need to be knowledgeable about the exposure/transmission of life-threatening infections and options for prevention. This article is designed to increase the oral health care provider's awareness of the latest assessment of vaccine-preventable diseases that pose a high risk in the dental health care setting. Specific dosing strategies are suggested for the prevention of infections based on available evidence and epidemiologic changes. This information will provide a clear understanding for prevention of vaccine-preventable diseases that pose a public health consequence.

Clinical and Laboratory Diagnosis of Intestinal Tuberculosis

Background:

Tuberculosis (TB) remains a worldwide problem. Intestinal TB (ITB) constitutes a major public health problem in developing countries and has been associated with significant morbidity and mortality. The aim of this study was to characterize the clinical, radiological, endoscopic, and pathological features of ITB and to define the strategy for establishing the diagnosis.

Methods:

A retrospective study (from January 2000 to June 2015) was carried out in Peking Union Medical College Hospital and all hospitalized cases were diagnosed as ITB during the study period were included. The relevant clinical information, laboratory results, microbiological, and radiological investigations were recorded.

Results:

Of the 85 cases, 61 cases (71.8%) were ranged from 20 to 50 years. The ileocecal region was involved in about 83.5% (71/85) of patients. About 41.2% (35/85) of patients had co-existing extra ITB, especially active pulmonary TB. Abdominal pain (82.4%) was the most common presenting symptom followed by weight loss (72.9%) and fever (64.7%). Both T-cell spot of TB test (T-SPOT.TB) and purified protein derivatives (PPD) tests were performed in 26 patients: 20 (76.9%) positive T-SPOT.TB and 13 (50.0%) positive PPD were detected, with a statistical significant difference (P = 0.046). Twenty cases (23.5%) were histopathology and/or pathogen confirmed TB; 27 cases (31.8%) were diagnosed by clinical manifestation consistent with ITB and evidence of active extra ITB; 38 cases (44.7%) were diagnosed by good response to diagnostic anti-TB therapy.

Conclusions:

ITB is difficult to diagnose even with modern medical techniques due to its nonspecific clinical and laboratory features. At present, combination of clinical, endoscopic, radiological, and pathological features continues to be the key to the diagnosis of ITB.

Use of the QuantiFERON-TB Gold In-Tube Test in the Diagnosis and Monitoring of Treatment Efficacy in Active Pulmonary Tuberculosis

The value of QuantiFERON in the diagnosis of tuberculosis disease and in the monitoring of the response to anti-tuberculosis treatment is unclear. The aims of this study were to evaluate the accuracy of the QuantiFERON-TB Gold In-Tube (QFT-GIT) test in the diagnosis of tuberculosis and in the monitoring of the response to anti-tuberculosis treatment in patients with active pulmonary tuberculosis (PTB). Between January 2013 and December 2015, 133 cases with active PTB and 133 controls with no mycobacterial infection, matched by age (within 3 years) and by the week that they visited Tainan Chest Hospital, were enrolled in the study. Serial testing by QFT-GIT at baseline and after 2 and 6 months of treatment was performed. At these time points, a comparison of the performance of QFT-GIT with that of sputum culture status among study subjects was conducted. Compared to baseline, 116 (87.2%) cases showed a decreased response, whereas 17 (12.8%) showed persistent or stronger interferon-gamma (IFN-γ) responses at 2 months. PTB patients IFN-γ responses declined significantly from baseline to 2 months (median, 6.32 vs. 4.12; p < 0.005). The sensitivity values of the QFT-GIT test for the detection of pulmonary tuberculosis at cut-off points of 0.35 IU/mL, 0.20 IU/mL, and 0.10 IU/mL were 74.4%, 78.2%, and 80.5%, respectively. The specificity values at cut-off points of 0.35 IU/mL, 0.20 IU/mL, and 0.10 IU/mL were 66.2%, 63.9%, and 57.1%, respectively. Our results support the QFT-GIT assay as a potential tool for diagnosing tuberculosis and for monitoring the efficacy of anti-tuberculosis treatment.

Interferon-Gamma Release Assay Performance of Cerebrospinal Fluid and Peripheral Blood in Tuberculous Meningitis in China

The aim of this study was to examine the performance of T-SPOT.TB on cerebrospinal fluid (CSF) and peripheral blood (PB) in diagnosis of tuberculous meningitis (TBM) in China. Of 100 patients with presumed TBM prospectively enrolled from Sep 2012 to Oct 2014, 53 were TBM (21 definite and 32 probable TBM cases) and 37 were non-TBM cases; the other 10 patients were excluded from analysis due to inconclusive diagnosis, no sufficient CSF samples, or incomplete follow-up. T-SPOT.TB on CSF and PB and routine laboratory tests of CSF were performed simultaneously. The receiver operating characteristic (ROC) curve and cut-off value of CSF T-SPOT.TB and routine CSF parameters were established between TBM and non-TBM group. The area under ROC curve (AUC) of the T-SPOT.TB on CSF and PB was 0.81 and 0.89, which was higher than that of the routine CSF parameters (AUC 0.67–0.77). Although the sensitivity of CSF T-SPOT.TB was lower than that of PB T-SPOT.TB (60.8% versus 90.6%, P < 0.001), the specificity of CSF T-SPOT.TB was significantly higher than that of PB T-SPOT.TB (97.2% versus 75.7%, P = 0.007). These results indicated that the diagnostic accuracies of PB and CSF T-SPOT.TB are higher than routine laboratory tests. Furthermore, the higher specificity of CSF T-SPOT.TB makes it a useful rule-in test in rapid diagnosis of TBM.

Diagnosis of Tuberculous Meningitis Using a Combination of Peripheral Blood T-SPOT.TB and Cerebrospinal Fluid Interferon-γ Detection Methods

OBJECTIVE

To evaluate the effectiveness of combined peripheral blood T-SPOT.TB and cerebrospinal fluid interferon-γ (cIFN-γ) detection methods in the diagnosis of tuberculous meningitis (TBM).

METHODS

A total of 30 individuals with TBM and 39 control individuals without TBM participated in this study. IFN-γ-secreting T cells were detected by enzyme-linked immunospot (ELISPOT), and cIFN-γ was detected by enzyme-linked immunosorbent assay (ELISA). We collected cerebrospinal fluid from 10 patients in the TBM group on initial visit and at 4 weeks, to observe changes.

RESULTS

The sensitivity and specificity of peripheral-blood T-SPOT.TB testing in the diagnosis of TBM were 70% and 87%, respectively. The area under the ROC curve of cIFN-γ for TBM diagnosis was 0.819, and the corresponding sensitivity and specificity were 83% and 85%, respectively. When T-SPOT.TB and cIFN-γ results were positive, the specificity and positive predictive value of TBM diagnosis reached 100%.

CONCLUSIONS

Combined use of T-SPOT.TB and cIFN-γ could improve the diagnosis efficiency of TBM. Dynamic observation of cIFN-γ is also important in monitoring TBM because the level of this analyte significantly decreases after treatment.

Current trends and intricacies in the management of HIV-associated pulmonary tuberculosis

Human immunodeficiency virus (HIV) epidemic has undoubtedly increased the incidence of tuberculosis (TB) globally, posing a formidable global health challenge affecting 1.2 million cases. Pulmonary TB assumes utmost significance in the programmatic perspective as it is readily transmissible as well as easily diagnosable. HIV complicates every aspect of pulmonary tuberculosis from diagnosis to treatment, demanding a different approach to effectively tackle both the diseases. In order to control these converging epidemics, it is important to diagnose early, initiate appropriate therapy for both infections, prevent transmission and administer preventive therapy. Liquid culture methods and nucleic acid amplification tests for TB confirmation have replaced conventional solid media, enabling quicker and simultaneous detection of mycobacterium and its drug sensitivity profile Unique problems posed by the syndemic include Acquired rifampicin resistance, drug-drug interactions, malabsorption of drugs and immune reconstitution inflammatory syndrome or paradoxical reaction that complicate dual and concomitant therapy. While the antiretroviral therapy armamentarium is constantly reinforced by discovery of newer and safer drugs every year, only a few drugs for anti tuberculosis treatment have successfully emerged. These include bedaquiline, delamanid and pretomanid which have entered phase III B trials and are also available through conditional access national programmes. The current guidelines by WHO to start Antiretroviral therapy irrespective of CD4+ cell count based on benefits cited by recent trials could go a long way in preventing various complications caused by the deadly duo. This review provides a consolidated gist of the advancements, concepts and updates that have emerged in the management of HIV-associated pulmonary TB for maximizing efficacy, offering latest solutions for tackling drug-drug interactions and remedial measures for immune reconstitution inflammatory syndrome.

Vaccinations in children on immunosuppressive medications for renal disease

Renal diseases are often treated with immunosuppressive medications, placing patients at risk of infections, some of which are vaccine-preventable. However, in such patients vaccinations may be delayed or disregarded due to complications of the underlying disease process and challenges in its management. The decision to administer vaccines to immunosuppressed children is a risk-benefit balance as such children may have a qualitatively diminished immunological response or develop diseases caused by the vaccine pathogen. Vaccination may cause a flare-up of disease activity or provocation of graft rejection in renal transplant recipients. Moreover, it cannot be assumed that a given antibody level provides the same protection in immunosupressed children as in healthy ones. We have evaluated the safety and efficacy of licensed vaccines in children on immunosuppressive therapy and in renal transplant recipients. The limited evidence available suggests that vaccines are most effective if given early, ideally before the requirement for immunosuppressive therapy, which may require administration of accelerated vaccine courses. Once treatment with immunosuppressive drugs is started, inactivated vaccines are usually considered to be safe when the disease is quiescent, but supplemental doses may be required. In the majority of cases, live vaccines are to be avoided. All vaccines are generally contraindicated within 3-6 months of a renal transplant.

Amperometric IFN-γ immunosensors with commercially fabricated PCB sensing electrodes

Lab-on-a-Chip (LoC) technology has the potential to revolutionize medical Point-of-Care diagnostics. Currently, considerable research efforts are focused on innovative production technologies that will make commercial upscaling of lab-on-chip products financially viable. Printed circuit board (PCB) manufacturing techniques have several advantages in this field. In this paper we focus on transferring a complete IFN-γ enzyme-linked immune-sorbent assay (ELISA) onto a commercial PCB electrochemical biosensing platform, We adapted a commercially available ELISA to detect the enzyme product TMB/H2O2 using amperometry, successfully reproducing the colorimetry-obtained ELISA standard curve. The results demonstrate the potential for the integration of these components into an automated, disposable, electronic ELISA Lab-on-PCB diagnostic platform.

The T-SPOT.TB Test for Diagnosis of Breast Tuberculosis

OBJECTIVE

To assess the diagnostic value of the T-SPOT.TB test in cases of breast turberculosis (BTB) in China.

METHODS

We enrolled 13 female patients with primary BTB as the BTB test group and 10 healthy volunteers as the control group. The 2 groups underwent T-SPOT.TB tests and tuberculin skin tests (TSTs) before receiving a core-needle biopsy or excision biopsy. We then collected and analyzed T-SPOT.TB and TST data.

RESULTS

The sensitivity of the T-SPOT.TB test for detection of BTB (84.6%) was significantly greater than that of TST (53.8%) (P <.05); the specificity of each test (80.0% and 60.0%, respectively) for BTB was not significantly different (P >.05).

CONCLUSION

The T-SPOT.TB test could be a useful adjunct to current tests for diagnosis of BTB and could be used for early diagnosis of this condition.

Assessing the Prevalence of Latent Tuberculosis among Health Care Providers in Zagazig City, Egypt Using Tuberculin Skin Test and QuantiFERON-TB Gold In-Tube Test

AIM

Early detection of latent tuberculosis infection (LTBI) will prevent development of active TB among health care providers. The aim of the study was to assess the prevalence of LTBI among health care providers and compare the QuantiFERON-TB Gold In-Tube Test (QFT-GIT) and Tuberculin skin test in efforts to detect LTBI and to investigate possible associated risk factors of infection.

METHODS

A cross sectional study was carried out during the period of 6 months in the Chest Hospital in Zagazig city and the Nephrology Unit at Zagazig University Hospitals in 132 randomly selected health care providers who were examined for LTBI by QFT-GIT and Tuberculin skin test and for the associated risk factors as well.

RESULTS

The prevalence of LTBI identified by QFT-GIT and by Tuberculin skin test was 28.8% and 59.1%, respectively. Poor agreement was observed between the two tests (kappa=0.10). Working more than 10 years, being nurse, diabetic and smoker were risk factors significantly associated with LTBI (p<0.05).

CONCLUSIONS

QFT-GIT is considered a useful tool in detecting LTBI cases, especially in a country where BCG vaccination is a national policy (as in Egypt). Duration of work, profession, diabetes and smoking are the risk factors for LTBI. Active surveillance and infection control measures are recommended to reduce the risk of LTBI.

The Use of Interferon Gamma Inducible Protein 10 as a Potential Biomarker in the Diagnosis of Latent Tuberculosis Infection in Uganda

Background

In the absence of a gold standard for the diagnosis of latent tuberculosis (TB) infection (LTBI), the current tests available for the diagnosis of LTBI are limited by their inability to differentiate between LTBI and active TB disease. We investigated IP-10 as a potential biomarker for LTBI among household contacts exposed to sputum positive active TB cases.

Methods

Active TB cases and contacts were recruited into a cohort with six months’ follow-up. Contacts were tested for LTBI using QuantiFERON^®-TB Gold In-Tube (QFN) assay and the tuberculin skin test (TST). Baseline supernatants from the QFN assay of 237 contacts and 102 active TB cases were analysed for Mycobacterium tuberculosis (MTB) specific and mitogen specific IP-10 responses.

Results

Contacts with LTBI (QFN⁺TST⁺) had the highest MTB specific IP-10 responses at baseline, compared to uninfected contacts (QFN^-TST^-) p<0.0001; and active cases, p = 0.01. Using a cut-off of 8,239 pg/ml, MTB specific IP-10 was able to diagnose LTBI with a sensitivity of 87.1% (95% CI, 76.2–94.3) and specificity of 90.9% (95% CI, 81.3–96.6). MTB specific to mitogen specific IP-10 ratio was higher in HIV negative active TB cases, compared to HIV negative latently infected contacts, p = 0.0004. Concentrations of MTB specific IP-10 were higher in contacts with TST conversion (negative at baseline, positive at 6-months) than in those that were persistently TST negative, p = 0.001.

Conclusion

IP-10 performed well in differentiating contacts with either latent or active TB from those who were uninfected but was not able to differentiate LTBI from active disease except when MTB specific to mitogen specific ratios were used in HIV negative adults. In addition, IP-10 had the potential to diagnose ‘recent TB infection’ in persons classified as having LTBI using the TST. Such individuals with strong IP-10 responses would likely benefit from chemoprophylaxis.