Diagnosis of latent tuberculosis: Can we do better?

Prevalence of Latent Tuberculosis Infection (LTBI) in Mexican Patients With Rheumatoid Arthritis (RA)

INTRODUCTION

Patients with rheumatoid arthritis (RA) are at increased risk of developing tuberculosis, and even more so if they receive biological agents. In Mexico, the prevalence of latent tuberculosis infection (LTBI) in RA diagnosed by interferon-gamma release assay (IGRA) is largely unknown. The objective was to determine LTBI prevalence and the associated risk factors in rheumatoid arthritis patients.

METHODS

A cross-sectional study was performed comprising 82 patients with RA who attended the rheumatology service at a second-level hospital. Demographic characteristics, comorbidity, Bacillus Calmette-Guerin (BCG) vaccination and smoking history, type of treatment, disease activity and functional capacity were investigated. The Disease Activity Score 28 and the Health Assessment Questionnaire-Disability Index were applied for the estimate of RA activity and functional capacity. Further information was compiled from the electronic medical records and personal interviews. LTBI was determined by QuantiFERON TB Gold Plus (QIAGEN, Germantown, USA).

RESULTS

Prevalence of LTBI was 14% (95% confidence interval (CI): 8.6% to 23.9%). Factors associated with LTBI were history of smoking (odds ratio (OR) = 6.63 95% CI 1.01 to 43.3) and disability score (OR = 7.19 95%CI 1.41 to 36.6).

CONCLUSIONS

The prevalence of LTBI in Mexican patients with RA was 14%. Our results suggest prevention of smoking and functional incapacity could reduce the risk of LTBI. Further research could endorse our results.

The prevalence of tuberculosis infection in India: A systematic review and meta-analysis

Background & objectives

The National Prevalence Survey of India (2019-2021) estimated 31 per cent tuberculosis infection (TBI) burden among individuals above 15 years of age. However, so far little is known about the TBI burden among the different risk groups in India. Thus, this systematic review and meta-analysis, aimed to estimate the prevalence of TBI in India based on geographies, sociodemographic profile, and risk groups.

Methods

To identify the prevalence of TBI in India, data sources such as MEDLINE, EMBASE, CINAHL, and Scopus were searched for articles reporting data between 2013-2022, irrespective of the language and study setting. TBI data were extracted from 77 publications and pooled prevalence was estimated from the 15 community-based cohort studies. Articles were reviewed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines and were sourced using a predefined search strategy from different databases.

Results

Out of 10,521 records, 77 studies (46 cross-sectional and 31 cohort studies) were included. The pooled TBI prevalence for India based on the community-based cohort studies was estimated as 41 per cent [95% confidence interval (CI) 29.5-52.6%] irrespective of the risk of acquiring it, while the estimation was 36 per cent (95% CI 28-45%) prevalence observed among the general population excluding high-risk groups. Regions with high active TB burden were found to have a high TBI prevalence such as Delhi and Tamil Nadu. An increasing trend of TBI was observed with increasing age in India.

Interpretation & conclusions

This review demonstrated a high prevalence of TBI in India. The burden of TBI was commensurate with active TB prevalence suggesting possible conversion of TBI to active TB. A high burden was recorded among people residing in the northern and southern regions of the country. Such local epidemiologic variation need to be considered to reprioritize and implement-tailored strategies for managing TBI in India.

The prevalence and risk factors for tuberculosis among healthcare workers in Yogyakarta, Indonesia

Healthcare workers (HCWs) are at risk of contracting TB, particularly when in high tuberculosis (TB) burden settings. Routine surveillance data and evidence are limited on the burden of TB amongst HCWs in Indonesia. We aimed to measure the prevalence of TB infection (TBI) and disease among HCWs in four healthcare facilities in Yogyakarta province in Indonesia, and explore risk factors for TBI. A cross-sectional TB screening study targeted all HCWs from four pre-selected facilities (1 hospital, 3 primary care) in Yogyakarta, Indonesia. Voluntary screening included symptom assessment, Chest X-ray (CXR), Xpert MTB/RIF (if indicated) and tuberculin skin test (TST). Analyses were descriptive and included multivariable logistic regression. Of 792 HCWs, 681 consented (86%) to the screening; 59% (n = 401) were female, 62% were medical staff (n = 421), 77% worked in the one participating hospital (n = 524), and the median time working in the health sector was 13 years (IQR: 6-25 years). Nearly half had provided services for people with TB (46%, n = 316) and 9% reported ever having TB (n = 60). Among participants with presumptive TB (15%, n = 99/662), none were diagnosed microbiologically or clinically with active TB disease. TBI was detected in 25% (95% CI: 22-30; n = 112/441) of eligible HCWs with a TST result. A significant association was found between TB infection and being male (adjusted Odds Ratio (aOR) 2.02 (95%CI: 1.29-3.17)), currently working in the participating hospital compared to primary care (aOR 3.15 (95%CI: 1.75-5.66)), and older age (1.05 OR increase per year of life between 19-73 years (95%CI: 1.02-1.06)). This study supports prioritisation of HCWs as a high-risk group for TB infection and disease, and the need for comprehensive prevention and control programs in Indonesia. Further, it identifies characteristics of HCWs in Yogyakarta at higher risk of TBI, who could be prioritised in screening programs if universal coverage of prevention and control measures cannot be achieved.

Tuberculosis challenges: Resistance, co-infection, diagnosis, and treatment

Early diagnosis of tuberculosis (TB), followed by effective treatment, is the cornerstone of global TB control efforts. An estimated 3 million cases of TB remain undetected each year. Early detection and effective management of TB can prevent severe disease and reduce mortality and transmission. Intrinsic and acquired drug resistance of Mycobacterium tuberculosis (MTB) severely restricted the anti-TB therapeutic options, and public health policies are required to preserve the new medications to treat TB. In addition, TB and HIV frequently accelerate the progression of each other, and one disease can enhance the other effect. Overall, TB-HIV co-infections show an adverse bidirectional interaction. For HIV-infected patients, the risk of developing TB disease is approximately 22 times higher than for persons with a protective immune response. Analysis of the current TB challenges is critical to meet the goals of the end TB strategy and can go a long way in eradicating the disease. It provides opportunities for global TB control and demonstrates the efforts required to accelerate eliminating TB. This review will discuss the main challenges of the TB era, including resistance, co-infection, diagnosis, and treatment.

Presumed Latent Tuberculosis-related Intermediate Uveitis Manifesting as Recurrent Vitreous Hemorrhage

Purpose: We report a case of recurrent vitreous hemorrhage in a patient with presumed latent tuberculosis-related intermediate uveitis, and we review the literature.Case summary: A 58-year-old male visited our clinic complaining of ocular pain, conjunctival hyperemia, decreased vision, and uncontrolled intraocular pressure (IOP) in the left eye. The best-corrected visual acuity (BCVA) was 0.4 and the IOP of the left eye was 34 mmHg. Slit lamp examination revealed conjunctival hyperemia, corneal edema, and inflammatory cells in the anterior chamber and anterior vitreous; fundus examination revealed mild vitreous opacity attributable to vitritis. The high IOP and the intraocular inflammation were treated with antiglaucoma agents and corticosteroids under the impression of chronic anterior uveitis and uveitic glaucoma. Of the tests performed to identify the cause of the uveitis-related vitreous hemorrhage, the interferon-gamma release assay was positive. A presumptive diagnosis of latent tuberculosis-related uveitis was made after pulmonary tuberculosis was excluded by our respiratory internal medicine department. Isoniazid was administered for 9 months. The vitreous hemorrhage recurred 1 month after antituberculosis therapy commenced but, at 2 months, all of the hemorrhage was absorbed and the BCVA improved to 1.0 without further recurrence.Conclusions: Intraocular tuberculosis can present with various clinical manifestations. If tuberculosis-related uveitis is presumed, tests for latent and manifest tuberculosis should be scheduled to allow of early diagnosis and immediate antituberculosis therapy.

Immunological Characterization of Proteins Expressed by Genes Located in Mycobacterium tuberculosis-Specific Genomic Regions Encoding the ESAT6-like Proteins

The 6 kDa early secreted antigen target (ESAT6) is a low molecular weight and highly immunogenic protein of Mycobacterium tuberculosis with relevance in the diagnosis of tuberculosis and subunit vaccine development. The gene encoding the ESAT6 protein is located in the M. tuberculosis-specific genomic region known as the region of difference (RD)1. There are 11 M. tuberculosis-specific RDs absent in all of the vaccine strains of BCG, and three of them (RD1, RD7, and RD9) encode immunodominant proteins. Each of these RDs has genes for a pair of ESAT6-like proteins. The immunological characterizations of all the possible proteins encoded by genes in RD1, RD7 and RD9 have shown that, besides ESAT-6 like proteins, several other proteins are major antigens useful for the development of subunit vaccines to substitute or supplement BCG. Furthermore, some of these proteins may replace the purified protein derivative of M. tuberculosis in the specific diagnosis of tuberculosis by using interferon-gamma release assays and/or tuberculin-type skin tests. At least three subunit vaccine candidates containing ESAT6-like proteins as antigen components of multimeric proteins have shown efficacy in phase 1 and phase II clinical trials in humans.

Nano-based drug delivery optimization for tuberculosis treatment: A review

Regardless of advanced technology and innovation, infectious diseases continue to be one of the extreme health challenges in modern world. Tuberculosis (TB) is one of the top ten causes of deaths worldwide and the leading cause of death from a single infectious agent. The conventional TB drug therapy requires a long term treatment with frequent and multiple drug dosing with a stiff administration schedule, which results in low patient compliance. This eventually leads to the recurrence of the infection and the emergence of multiple drug resistance. Hence, there is an urgent need to develop more successful and effective strategies to overcome the problems of drug resistance, duration of treatment course and devotion to treatment. Nanotechnology has considerable potential for diagnosis, treatment and prevention of infectious diseases including TB. The main advantages of nanoparticles to be used as drug carriers are their small size, high stability, enhanced delivery of hydrophilic and hydrophobic drugs, intracellular delivery of macromolecules, targeted delivery of drugs to specific cells or tissues, and the feasibility of various drug administration routes. Moreover, these carriers are adapted to facilitate controlled, slow, and persistent drug release from the matrix. Above properties of nanoparticles permit the improvement of drug bioavailability and reduction of dosing frequency and may reduce the toxicity and resolve the problem of low adherence to the prescribed therapy. In this review, various types of nanocarriers have been evaluated as promising drug delivery systems for different administration routes and main research outcomes in this area have been discussed.

Comparison of Latent Tuberculosis Infections among General versus Tuberculosis Health Care Workers in Myanmar

Health care workers (HCWs) in high tuberculosis (TB) prevalence countries have to care for many cases, thus increasing their risk of infection. The objective of the study was to compare the prevalence of latent TB infection (LTBI) between general HCWs and TB HCWs, and also to explore the associated factors. A cross-sectional study was conducted in Nay Pyi Taw, Myanmar from September 2019 to January 2020. Staff working at two general hospitals were recruited. Those allocated for TB care were classified as TB HCWs, while the remaining were classified as general HCWs. Participants were interviewed using a structured questionnaire, and screened for LTBI using a tuberculin skin test (TST). Individuals who had an induration of 10 mm or more with normal chest radiograph were regarded as having LTBI. The prevalence of LTBI among general HCWs was 2.04 times higher than that of TB HCWs (31.2% vs. 15.3%, p < 0.001). The associated factors for LTBI included low education level, duration of work experience ≥ 10 years, a low knowledge of regular TB screening, and teaching cough etiquette to TB patients. The higher prevalence of LTBI in the general HCWs in this study was due to confounding by education and experience. After adjustment for these, we have no evidence to support that either group of HCWs had higher LTBI risk.

A healthy patient with positive mantoux test but negative quantiferon Gold assay and no evidence of risk factors - to treat or not to treat?

A 56-year-old woman who vaccinated as a child with the Bacillus Calmette-Guerin (BCG), now tests positive to the tuberculin skin test (TST) but test negative to the Quantiferon Gold assay. She has no history of tuberculosis contact and is asymptomatic. This dilemma now is, should be treated for tuberculosis or not, based only on the TST results? To prevent these falsepositive results with TST and avoid treatment with isoniazid (INH) it may be helpful to use interferon-gamma release assay (IGRA) instead, which unlike the TB skin test is not affected by prior BCG vaccination.

Is latent tuberculosis infection challenging in Iranian health care workers? A systematic review and meta-analysis

Background

The high chances of getting latent tuberculosis infection (LTBI) among health care workers (HCWs) will an enormous problem in low and upper-middle-income countries.

Method

Search strategies were done through both national and international databases include SID, Barakat knowledge network system, Irandoc, Magiran, Iranian national library, web of science, Scopus, PubMed/MEDLINE, OVID, EMBASE, the Cochrane library, and Google Scholar search engine. The Persian and the English languages were used as the filter in national and international databases, respectively. Medical Subject Headings (MeSH) terms was used to controlling comprehensive vocabulary. The search terms were conducted without time limitation till January 01, 2019.

Results

The prevalence of LTBI in Iranian’s HCWs, based on the PPD test was 27.13% [CI95%: 18.64–37.7]. The highest prevalence of LTBI in Iranian’s HCWs were estimated 41.4% [CI95%: 25.4–59.5] in the north, and 33.8% [CI95%: 21.1–49.3] in the west. The lowest prevalence of LTBI was evaluated 18.2% [CI95%: 3.4–58.2] in the south of Iran. The prevalence of LTBI in Iranian’s HCWs who had work-experience more than 20 years old were estimated 20.49% [CI95%: 11–34.97]. In the PPD test, the prevalence of LTBI in Iranian’s HCWs who had received the Bacille Calmette–Guérin (BCG) was estimated 15% [CI95%: 3.6–47.73]. While, in the QFT, the prevalence of LTBI in Iranian’s HCWs in non-vaccinated was estimated 25.71% [CI95%: 13.96–42.49].

Conclusions

This meta-analysis shows the highest prevalence of LTBI in Iranian’s HCWs in the north and the west probably due to neighboring countries like Azerbaijan and Iraq, respectively. It seems that Iranian’s HCWs have not received the necessary training to prevent of TB. We also found that BCG was not able to protect Iranian’s HCWs from TB infections, completely.

A novel strategy for interpreting the T-SPOT.TB test results read by an ELISPOT plate imager

Background

The T-SPOT.TB can be read by an ELISPOT plate imager as an alternative to a labor-intensive and time-consuming manual reading, but its accuracy has not been sufficiently discussed to date.

Methods

1,423 test results obtained from manual reading using a microscope and an ELISPOT plate imager were compared. The agreement of qualitative test results was assessed using Cohen's kappa coefficient. The relationship of spot counts was studied using Bland-Altman analysis.

Results

The overall percent agreement of the qualitative test results was 95.43% with a kappa coefficient of 0.91. Positive test results with the maximum net spot count of 8 and borderline test results showed relatively high discordance. The agreement of spot counts in panel A, panel B, and nil control was good, and variability did not increase with higher spot counts. On the basis of study findings, a novel strategy for interpreting the test results by an ELISPOT plate imager was proposed.

Conclusions

To increase diagnostic accuracy, positive test results with the maximum net spot count of 8 and borderline test results should be manually confirmed. Our strategy could be a practical guide for laboratories to build their own strategies for interpreting the test results by an ELISPOT plate imager.

Latent Tuberculosis Infection among Healthcare Workers in Duhok Province: From Screening to Prophylactic Treatment

Healthcare workers (HCWs) are at increased risk of infection with Mycobacterium tuberculosis (Mtb) and, hence, of developing tuberculosis (TB) disease. The aims of this study are to identify the prevalence and determinants of latent TB infection (LTBI) among HCWs in Duhok Province. This is a cross-sectional prospective study conducted during April–July 2018 in different health care facilities of Duhok province. HCWs at multiple levels were selected by a non-systematic random sampling method. Information on demographic and associated risk factors of LTBI were collected by using a standardized questionnaire. Thereafter, all HCWs underwent QuantiFERON Gold Plus (QFT-Plus) assay. HCWs with indeterminate QFT-Plus underwent a Tuberculin Skin Test. HCWs with positive results were further evaluated by smear microscopy investigation and chest X-ray examination. Three hundred ninety-five HCWs were enrolled; 49 (12%) tested positive for LTBI. The mean age of the HCWs was 33.4 ± 9.25 with a female predominance (51.1%). According to the univariate analysis, LTBI was significantly higher among HCWs with the following: age groups ≥ 30 years, alcohol intake, ≥ 11 years of employment, high risk stratification workplaces, and medical doctors. In the multivariate analysis, the age group of 30–39 years (OR = 0.288, 95% CI: 0.105–0.794, p value = 0.016) was the only risk factor associated with LTBI. Further medical investigations did not reveal active TB cases among HCWs with LTBI. With regards to prophylactic treatment, 31 (63.3%) LTBI HCWs accepted the treatment, whereas 18 (36.7%) declined the chemoprophylaxis. Of these 31 HCWs on chemoprophylaxis, 12 (38.7%) received isoniazid (INH) for six months, 17 (54.8%) received INH in combination with rifampicin (RMP) for three months, and two (6.5%) received alternative therapy because of anti-TB drug intolerance. In conclusions, although Iraq is a relatively high TB burden country, the prevalence of LTBI among Duhok HCWs is relatively low. It is important to screen HCWs in Duhok for LTBI, particularly medical doctors, young adults, alcoholics, and those whom had a long duration of employment in high-risk workplaces. The acceptance rate of HCWs with LTBI to chemoprophylaxis was low. Therefore, ensuring medical efforts to educate the healthcare staff particularly, non-professionals are a priority to encourage chemoprophylaxis acceptance.

Tuberculosis incidence among infected contacts detected through contact tracing of smear-positive patients

BACKGROUND

The contacts of people with pulmonary tuberculosis (PTB) have a high risk of becoming infected and developing tuberculosis (TB). Our aim was to determine the incidence of TB and its risk factors in a cohort of contacts with latent TB infection (LTBI) detected through contact tracing of smear-positive PTB cases.

METHODS AND FINDINGS

We performed a population-based retrospective cohort study including contacts that had LTBI, and were contacts of people with PTB who started treatment between 2008 and 2014. We followed up contacts until they developed TB or until the end date for follow-up (31st December 2016). We used Kaplan-Meier curves to compute incidence at 2 and 5 years, and Cox regression to compute hazard ratios (HR) and their 95% confidence intervals (CI). We analyzed 3097 close contacts of 565 PTB cases. After exclusion of 81 co-prevalent TB cases, 953 contacts had LTBI, of which 14 developed TB. Their risk of developing TB after two and five years was 0.7% (CI: 0.3-1.6) and 1.8% (CI: 1.1-3.1) respectively. Contacts who had not been referred for LTBI treatment had a 1.0% (CI: 0.2-4.0) risk at 5 years. Risk of developing TB at 5 years was 1.2% (CI: 0.5-3.0) among people who completed treatment, and 11.1% (CI: 5.1-23.3) for those who did not. Risk factors for TB were not completing LTBI treatment (HR 9.4, CI: 2.9-30.8) and being female (HR 3.5, CI: 1.1-11-3).

CONCLUSIONS

LTBI treatment plays a fundamental role in decreasing the risk of developing TB. It is necessary to achieve a maximum contact tracing coverage and the highest possible compliance with LTBI treatment.

Comparative sensitivity of the test with tuberculosis recombinant allergen, containing ESAT6-CFP10 protein, and Mantoux test with 2 TU PPD-L in newly diagnosed tuberculosis children and adolescents in Moscow

BACKGROUND

A group of Russian scientists has developed Diaskintest, which comprises Mycobacterium tuberculosis-specific recombinant proteins CFP10-ESAT6, for skin testing (0.2 μg/0.1 ml).

STUDY PURPOSE

To evaluate the comparative sensitivity of TST with 2 TU PPD-L and a skin test with tuberculous recombinant allergen (Diaskintest) containing the ESAT6-CFP10 protein in children and adolescents with newly diagnosed active tuberculosis during mass screening in the primary medical service in Moscow.

MATERIALS AND METHODS

The trial was a comprehensive retrospective group study of children and adolescents diagnosed in Moscow with active tuberculosis in 2013-2016, aged 0 to 17 years inclusive.

RESULTS

From 441 patients selected for analysis 408 patients had both tests (TST with 2 TU PPD-L and Diaskintest) performed, in 193 patients both tests were given simultaneously, of them 162 patients were BCG-vaccinated. Comparative results of both tests in 408 patients with tuberculosis: at cut-off ≥ 5 mm, both tests has similar sensitivity: Diaskintest 98.3% (95% CI 97.0-99.6%), TST 98.0% (95% CI 96.7-99.4%), at cut-off ≥10 mm, the sensitivity decreases for both tests: Diaskintest 90.0% (95% CI 87.0-93.0%), TST 88.7% (95% CI 85.6-91.9%), but at cut-off ≥ 15 mm, the decrease in sensitivity is statistically significant: for Diaskintest 61.5% (95% CI 56.7-66.3%), and for TST 46.3% (95% CI 41.4-51.3%), p <0.0001. The results of simultaneous setting of tests on different hands in 193 people (including 162 BCG-vaccinated), do not differ from the results for 408 people. The correlation between the results of Diaskintest and TST was significant in all groups.

CONCLUSION

In children and adolescents with active tuberculosis, Diaskintest of 0.2 μg/ml and the Mantoux test with 2 TU PPD-L have high sensitivity (98%) at a cut-off of 5 mm; however, at cut-off ≥ 15 mm sensitivity is significantly reduced, and the decrease is more pronounced in the Mantoux test. The advantage of Diaskintest is that, unlike the Mantoux test, it has high specificity under the conditions of mass BCG vaccination. The test is simple to carry out, and can be used in mass screening.

Dynamic balance of pro- and anti-inflammatory signals controls disease and limits pathology

Immune responses to pathogens are complex and not well understood in many diseases, and this is especially true for infections by persistent pathogens. One mechanism that allows for long-term control of infection while also preventing an over-zealous inflammatory response from causing extensive tissue damage is for the immune system to balance pro- and anti-inflammatory cells and signals. This balance is dynamic and the immune system responds to cues from both host and pathogen, maintaining a steady state across multiple scales through continuous feedback. Identifying the signals, cells, cytokines, and other immune response factors that mediate this balance over time has been difficult using traditional research strategies. Computational modeling studies based on data from traditional systems can identify how this balance contributes to immunity. Here we provide evidence from both experimental and mathematical/computational studies to support the concept of a dynamic balance operating during persistent and other infection scenarios. We focus mainly on tuberculosis, currently the leading cause of death due to infectious disease in the world, and also provide evidence for other infections. A better understanding of the dynamically balanced immune response can help shape treatment strategies that utilize both drugs and host-directed therapies.

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

BACKGROUND

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

OBJECTIVES

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

DATA SOURCES

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

REVIEW METHODS

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014009033.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Paradoxical response to osimertinib therapy in a patient with T790M-mutated lung adenocarcinoma

A 'paradoxical response' to cancer treatment is a term used to describe the emergence of unexpected new lesions and the progression of existing lesions, despite appropriate and effective therapy. 'Pseudo-progression' is a phenomenon in which lymphocytes activated by an immune checkpoint inhibitor accumulate in a tumor and expand its shadow, mimicking enlargement of the primary lesion or development of a new metastatic lesion. Patients receiving cancer chemotherapy may respond differently to treatment, by exhibiting a response, deterioration, or the simultaneous occurrence of both. These variations may be attributed to the heterogeneity of the cancer. However, differences in the temporary response to epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) treatment are rarely observed. If such a phenomenon is observed, it should not affect the evaluation of the therapeutic effect or be considered as an indication for the discontinuation of treatment. We herein report a rare case of a transient increase in carcinomatous pleural fluid as a paradoxical response to osimertinib treatment in a patient with T790M-mutated lung adenocarcinoma. The primary lesion and pulmonary metastases responded well to therapy. Although this paradoxical response is very rare, of non-malignant nature, and does not usually require treatment modification of, physicians must acknowledge that it is not a clinically discouraging characteristic when using EGFR-TKI to treat T790M-mutated lung adenocarcinoma.

Imaging of thoracic tuberculosis in children: current and future directions

Tuberculosis continues to be an important cause of morbidity and mortality worldwide. It is the leading cause of infection-related deaths worldwide. Children are amongst the high-risk groups for developing tuberculosis and often pose a challenge to the clinicians in making a definitive diagnosis. The newly released global tuberculosis report from World Health Organization reveals a 50% increase in fatality from tuberculosis in children. Significantly, diagnostic and treatment algorithms of tuberculosis for children differ from those of adults. Bacteriologic confirmation of the disease is often difficult in children; hence radiologists have an important role to play in early diagnosis of this disease. Despite advancing technology, the key diagnostic imaging modalities for primary care and emergency services, especially in rural and low-resource areas, are chest radiography and ultrasonography. In this article, we discuss various diagnostic imaging modalities used in diagnosis and treatment of tuberculosis and their indications. We highlight the use of US as point-of-care service along with mediastinal US and rapid MRI protocols, especially in mediastinal lymphadenopathy and thoracic complications. MRI is the ideal modality in high-resource areas when adequate infrastructure is available. Because the prevalence of tuberculosis is highest in lower-resource countries, we also discuss global initiatives in low-resource settings.

Role of apoptosis and autophagy in tuberculosis

Tuberculosis (TB) is one of the oldest known human diseases and is transmitted by the bacteria Mycobacterium tuberculosis (Mtb). TB has a rich history with evidence of TB infections dating back to 5,800 bc TB is unique in its ability to remain latent in an individual for decades, with the possibility of later reactivation, causing widespread systemic symptoms. Currently, it is estimated that more than one-third of the world's population (~2 billion people) are infected with Mtb. Prolonged periods of therapy and complexity of treatment regimens, especially in active infection, have led to poor compliance in patients being treated for TB. Therefore, it is vitally important to have a thorough knowledge of the pathophysiology of Mtb to understand the disease progression, as well as to develop novel diagnostic tests and treatments. Alveolar macrophages represent both the primary host cell and the first line of defense against the Mtb infection. Apoptosis and autophagy of macrophages play a vital role in the pathogenesis and also in the host defense against Mtb. This review will outline the role of these two cellular processes in defense against Mtb with particular emphasis on innate immunity and explore developing therapies aimed at altering host responses to the disease.

Latent Tuberculosis Infection Among Immigrant and Refugee Children Arriving in the United States: 2010

Immigrants and refugees age 2-14 years entering the United States from countries with estimated tuberculosis (TB) incidence rate ≥20 per 100,000 population are screened for TB. Children with TB disease are treated before US arrival. Children with positive tuberculin skin tests (TST), but negative TB evaluation during their pre-immigration examination, are classified with latent TB infection (LTBI) and are recommended for re-evaluation post-arrival. We examined post-immigration TB evaluation and therapy for children arriving with LTBI. We reviewed medical exam data from immigrant children with medical conditions and all refugee children arriving during 2010. Medical examination data were available for 67,334 children. Of these, 8231 (12 %) had LTBI pre-immigration; 5749 (70 %) were re-evaluated for TB post-immigration, and 64 % were retested by TST or IGRA. The pre-immigration LTBI diagnosis was changed for 38 % when retested by TST and for 71 % retested by IGRA. Estimated LTBI therapy initiation and completion rates were 68 and 12 %. In this population, testing with IGRA may limit the number of children targeted for therapy. Increased pre-immigration TB screening with post-immigration follow-up evaluation leading to completion of LTBI therapy should be encouraged to prevent TB reactivation.

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.

Methods Used in Economic Evaluations of Tuberculin Skin Tests and Interferon Gamma Release Assays for the Screening of Latent Tuberculosis Infection: A Systematic Review

BACKGROUND

Latent tuberculosis infection (LTBI) provides a constant pool of new active tuberculosis cases; a third of the earth's population is estimated to be infected with LTBI.

OBJECTIVE

The objective of this systematic review was to assess the quality and summarize the available evidence from published economic evaluations reporting on the cost-effectiveness of tuberculin skin tests (TSTs) compared with interferon gamma release assays (IGRAs) for the screening of LTBI.

METHODS

An extensive systematic review of the published literature was conducted. A two-step process was adopted to identify relevant articles: information was extracted into evidence tables and then analyzed. The quality of the publications was assessed using a 10-item checklist specific for economic evaluations.

RESULTS

Twenty-eight studies were identified for inclusion in this review. Most of the studies found IGRAs to be more cost-effective than TSTs; however, the conclusions from the studies varied significantly. Most studies scored highly on the checklist although only one fulfilled all the stipulated criteria. A wide variety of methodological approaches were documented; identified differences included the type of economic evaluation and model, time horizon, perspective, and outcomes measures.

CONCLUSIONS

The lack of consistent methods across studies makes it difficult to draw any firm conclusions about the most cost-effective option between TSTs and IGRAs. This problem can be solved by improving the quality of economic evaluation studies in the field of LTBI screening, through adherence to quality checklists.

Profile of interferon-gamma response to latency-associated and novel in vivo expressed antigens in a cohort of subjects recently exposed to Mycobacterium tuberculosis

Recently some latency-associated antigens (LAA) of Mycobacterium tuberculosis were described, as Rv2029c, Rv2031c, Rv2034, Rv2628 and Rv3353c. Of which, the Rv2034 and Rv3353c also demonstrated in vivo expression. Therefore evaluating the immune response to these antigens may help to understand their role in latent TB infection. In a 1-year longitudinal study, IFN-γ response by in vitro peripheral blood mononuclear cells stimulation with LAA was investigated in subjects recently exposed to TB, classified by IFN-γ release assay (IGRA) using RD1 antigens (ESAT-6:CFP-10) and tuberculin skin test (TST) response. Except for Rv3353c, all the LAA triggered higher mean IFN-γ response in IGRA-RD1(+) groups (p < 0.05). Combining the IFN-γ-responders to Rv2029c, Rv2031c plus Rv2034 detected 90.3% (28/31) of IGRA-RD1(+) and 66.7% (24/36) of TST(+) contacts, while 95% (19/20) and 11% (2/17) were identified by classifying them according to a TST and IGRA-RD1 double-positive or double-negative response, respectively. In the follow-up, the TST convertors (negative to positive) also demonstrated an IFN-γ conversion to Rv2029c and Rv2031c, whereas the unique TB incident case was exclusively detected via IGRA-Rv2029c and TST before developing TB. A reversion rate to LAA (60%-100%) after prophylactic treatment was observed at TST(+)/IGRA-RD1(+) group. Further studies into the performance of these antigens are thus warranted.

Hepatic abscess as a paradoxical response to antituberculous chemotherapy for tubercular lymphadenitis

Tubercular liver abscess developing as a paradoxical reaction (PR) to antitubercular therapy (ATT) is relatively uncommon in the absence of disseminated disease and immunocompromised status of the host even in countries such as India where the disease is rampant. We report a rare case of hepatic abscess that developed paradoxically during antituberculous therapy for tubercular lymphadenitis in a 30-year-old woman who tested negative for HIV. Diagnosis was performed with the help of ultrasonography (USG)-guided aspiration of the abscess followed by cytopathological examination and PCR confirmation of the disease from the USG-guided aspirate. The patient responded well to oral corticosteroid therapy without any alteration of the ongoing ATT regimen. Details of the case and other relevant literature regarding the pathogenesis of this event are discussed in detail.

Biomarker detection of global infectious diseases based on magnetic particles

Infectious diseases affect the daily lives of millions of people all around the world, and are responsible for hundreds of thousands of deaths, mostly in the developing world. Although most of these major infectious diseases are treatable, the early identification of individuals requiring treatment remains a major issue. The incidence of these diseases would be reduced if rapid diagnostic tests were widely available at the community and primary care level in low-resource settings. Strong research efforts are thus being focused on replacing standard clinical diagnostic methods, such as the invasive detection techniques (biopsy or endoscopy) or expensive diagnostic and monitoring methods, by affordable and sensitive tests based on novel biomarkers. The development of new methods that are needed includes solid-phase separation techniques. In this context, the integration of magnetic particles within bioassays and biosensing devices is very promising since they greatly improve the performance of a biological reaction. The diagnosis of clinical samples with magnetic particles can be easily achieved without pre-enrichment, purification or pretreatment steps often required for standard methods, simplifying the analytical procedures. The biomarkers can be specifically isolated and preconcentrated from complex biological matrixes by magnetic actuation, increasing specificity and the sensitivity of the assay. This review addresses these promising features of the magnetic particles for the detection of biomarkers in emerging technologies related with infectious diseases affecting global health, such as malaria, influenza, dengue, tuberculosis or HIV.

Mycobacterial dormancy regulon protein Rv2623 as a novel biomarker for the diagnosis of latent and active tuberculous meningitis

The present study was designed to investigate Rv2623 antigen, a major dormancy regulon protein of Mycobacterium tuberculosis (MTB) in CSF of suspected latent and active tuberculous meningitis (TBM) patients. A total of 100 CSF samples from TBM (n = 31), suspected latent TBM (n = 22), and suitable noninfectious control subjects (n = 47) were collected and evaluated for Rv2623 antigen level using ELISA protocol. A significantly high (P < 0.05) mean absorbance was observed in samples of suspected latent TBM and active TBM patients as compared to non-TBM control patients. However, no significant difference in Rv2623 level was observed between suspected latent TBM and TBM patients. Our preliminary findings suggest that Rv2623 may be useful as a potential biomarker for the diagnosis of the latent as well as active TBM infection. Futher evaluation of this biomarker in large number of samples is therefore needed to confirm the result.

Splenic abscess as a paradoxical response to chemotherapy in tuberculous pleural effusion

We report a rare case of tuberculous pleural effusion that developed multiple splenic abscesses after antituberculosis chemotherapy. She responded to addition of oral corticosteroid to antituberculosis regimen. The relevant literature, regarding pathogenesis and clinical importance of recognizing a paradoxical response, is discussed.

Non-compliance with health surveillance is a matter of Biosafety: a survey of latent tuberculosis infection in a highly endemic setting

Objective This study aimed at identifying demographic, socio-economic and tuberculosis (TB) exposure factors associated with non-compliance with the tuberculin skin test, the management and prevention of non-compliance to the test. It was carried out in the context of a survey of latent TB infection among undergraduate students taking healthcare courses in two universities in Salvador, Brazil, a city highly endemic for TB. Methods This is a cross-sectional study of 1164 volunteers carried out between October 2004 and June 2008. Bivariate analysis followed by logistic regression was used to measure the association between non-compliance and potential risk factors through non-biased estimates of the adjusted OR for confounding variables. A parallel evaluation of occupational risk perception and of knowledge of Biosafety measures was also conducted. Results The non-compliance rate was above 40% even among individuals potentially at higher risk of disease, which included those who had not been vaccinated (OR 3.33; 95% CI 1.50 to 7.93; p=0.0018), those reporting having had contact with TB patients among close relatives or household contacts (p=0.3673), or those whose tuberculin skin test status was shown within the survey to have recently converted (17.3% of those completing the study). In spite of the observed homogeneity in the degree of Biosafety knowledge, and the awareness campaigns developed within the study focussing on TB prevention, the analysis has shown that different groups have different behaviours in relation to the test. Family income was found to have opposite effects in groups studying different courses as well as attending public versus private universities. Conclusions Although the data presented may not be directly generalisable to other situations and cultural settings, this study highlights the need to evaluate factors associated with non-compliance with routine testing, as they may affect the efficacy of Biosafety programs.

Nanotechnology diagnostics for infectious diseases prevalent in developing countries

Infectious diseases are prevalent in the developing world and are one of the developing world's major sources of morbidity and mortality. While infectious diseases can initiate in a localized region, they can spread rapidly at any moment due to the ease of traveling from one part of the world to the next. This could lead to a global pandemic. One key to preventing this spread is the development of diagnostics that can quickly identify the infectious agent so that one can properly treat or in some severe cases, quarantine a patient. There have been major advances in diagnostic technologies but infectious disease diagnostics are still based on 50-year technologies that are limited by speed of analysis, need for skilled workers, poor detection threshold and inability to detect multiple strains of infectious agents. Here, we describe advances in nanotechnology and microtechnology diagnostics for infectious diseases. In these diagnostic schemes, the nanomaterials are used as labels or barcodes while microfluidic systems are used to automate the sample preparation and the assays. We describe the current state of the field and the challenges.