Tuberculosis elimination in the post Millennium Development Goals era

Global treatment outcomes of extensively drug-resistant tuberculosis in adults: A systematic review and meta-analysis

INTRODUCTION

Historically, extensively drug-resistant tuberculosis has been notoriously difficult to treat with devasting outcomes. As we are coming to the end of an era where the 2006 extensively drug-resistant tuberculosis definitions and old treatment regimens are being replaced, we aimed to estimate the proportion of extensively drug-resistant tuberculosis patients globally who achieved successful treatment outcomes.

METHODS

We conducted a systematic review of PubMed/MEDLINE, Scopus, Web of Science, and Embase from January 1, 2005, through April 3, 2023. Included studies reported WHO treatment outcomes, or adaptions hereof, for pre-extensively and/or extensively drug-resistant tuberculosis patients according to the 2006 WHO definition. Eligible studies included cohorts of at least 10 adults (aged>18 years) that were not pregnant. Using a random-effects model, we calculated pooled proportions of treatment outcomes and performed sensitivity and subgroup analyses. PROSPERO registration number: CRD42022340961.

RESULTS

Among 5056 studies reviewed, we identified 94 studies from 26 countries, involving 10,223 extensively drug-resistant tuberculosis patients. The pooled proportion of successful treatment outcomes was 44.2% (95%CI: 38.3-50.3). Sensitivity analyses consistently produced similar estimates. A slight improvement in treatment outcomes was observed after 2013. Furthermore, 25 studies reported outcomes for 3564 individuals with pre-extensively drug-resistant tuberculosis, of which 63.3% achieved successful treatment (95%CI: 43.1-72.5).

CONCLUSION

Globally, the success rate of extensively drug-resistant tuberculosis treatment is 44.2%, far below the WHO's target rate of 75%. These results may serve as a reference for future studies assessing extensively drug-resistant tuberculosis treatment outcomes under the 2021 definition treated with better treatment regimens available. Comprehensive surveillance data of extensively drug-resistant tuberculosis outcomes from the whole world are desirable to monitor treatment progress.

Prevalence of Latent Tuberculous Infection in Patients with Nontuberculous Mycobacterial Lung Disease and Colonization: A Prospective Study in An Intermediate Tuberculosis Burden Country

Background

Controlling latent tuberculosis infection (LTBI) is important in eliminating tuberculosis (TB); however, the prevalence of LTBI has rarely been studied in patients with nontuberculous mycobacterial (NTM) lung disease (LD) and colonization (LC).

Methods

We prospectively recruited subjects with NTM isolated from sputum mycobacterial cultures from December 2011 to June 2019. NTM-LD and NTM-LC were defined according to the American Thoracic Society guidelines. Patients with negative cultures were recruited as controls. Patients with a history of active TB or positive TB cultures were excluded. LTBI was confirmed using a QuantiFERON-TB Gold In-tube test. The prevalence and factors associated with LTBI were analyzed.

Results

A total of 406 participants were enrolled, including 171 in the NTM-LD group, 153 in the NTM-LC group, and 82 in the control group. The prevalence of LTBI was higher in the NTM-LD and NTM-LC groups than in the controls (21.6%, 20.9%, and 6.1%; P = .006). Multivariable analysis showed that old age (adjusted odds ratio [aOR], 1.021, per year increment; P = .042), NTM-LD (aOR, 4.030; P = .005), NTM-LC (aOR, 3.610; P = .011, compared with the controls), and pulmonary cavitary lesions (aOR, 3.393; P = .034) were independently associated with LTBI.

Conclusions

The prevalence of LTBI was higher in the patients with NTM-LD and NTM-LC than in the controls. Old age, pulmonary cavitation, and NTM isolated from sputum were associated with a higher risk of LTBI.

Completion and Adverse Drug Events of Latent Tuberculosis Infection Treatment in Patients Receiving Dialysis: Predictors and Impacts of Different Regimens in a Prospective Cohort Study

Although patients with end-stage renal disease receiving maintenance hemodialysis are at high risk for tuberculosis, the optimal treatment regimen for latent tuberculosis infection (LTBI) in this group has scarcely been studied for predictors of completion rate and adverse drug events (ADE). We prospectively enrolled dialysis patients for LTBI intervention from three medical centers in Taiwan. LTBI treatments were 3 months of weekly rifapentine plus isoniazid (3HP) and 9 months of daily isoniazid (9H). Completion rate, ADE, and reasons for treatment termination were recorded. Factors associated with treatment termination and ADE were analyzed using multivariate logistic regression. In all, 91 treatment courses (41 9H and 50 3HP) were surveyed. The completion rates were 61% for 9H and 82% for 3HP (P = 0.046). Use of 9H and development of ADE with a grade of ≥2 (≥grade 2 ADE) were associated with treatment termination. Hypersensitivity occurred in 29.2% of subjects in the 3HP group and 10.8% in the 9H group (P = 0.035) and independently correlated with 3HP regimen, diabetes mellitus (DM), and peritoneal dialysis (PD). Similarly, the independent predictors of ≥grade 2 ADE were use of 3HP regimen, presence of DM, and use of PD, whereas ≥grade 3 ADE were associated with eosinophil counts of >700/mm³ after 2 weeks of LTBI treatment even after adjustment for age and gender. In conclusion, for patients on dialysis, 3HP showed a higher rate of completion but also a higher rate of ≥grade 2 ADE than 9H. In addition, DM and PD were risk factors for ≥grade 2 ADE. Eosinophilia after 2-week treatment might be an alert for severe ADE.

Latent Tuberculosis Infection Increases in Kidney Transplantation Recipients Compared With Transplantation Candidates: A Neglected Perspective in Tuberculosis Control

Background

The prevalence and incidence of latent tuberculosis infection (LTBI) in patients with kidney transplantation remain unclear.

Methods

In this prospective study, we enrolled kidney transplantation candidates (KTCs) and recipients (KTRs) from 2014 to 2018. We defined LTBI as a positive result of QuantiFERON-TB Gold In-tube (QFT). We analyzed the predictors for LTBI acquisition and followed up on QFT assay test for 2 years among those initially without LTBI.

Results

Of 425 patients enrolled, 305 (71.8%) patients belonged to the KTC group and 120 (28.2%) to the KTR group. The initial QFT showed positive results in 32 (10.5%) and 24 (20.0%) patients in the KTC and KTR groups, respectively (P = .009). The QFT response value in patients with LTBI was higher in the KTR group than in the KTC group (1.85 vs 1.06 IU/mL, P = .046). Multivariate logistic regression showed that old age, absence of bacillus Calmette–Guérin (BCG) scar, presence of donor-specific antibody, and KTR group were independent factors for positive LTBI. For participants with initial negative QFT, positive QFT conversion within a 2-year follow-up was higher after kidney transplantation (20%) than in KTCs (5.5%) (P = .034).

Conclusions

This study is the first cohort to follow up LTBI status in patients with kidney transplantation and shows its higher prevalence and incidence in KTRs. It indicates that surveillance of LTBI after renal transplantation is important. In addition to status of kidney transplantation, old age, no BCG vaccination, and positive donor-specific antibody are also positive predictors for LTBI.

Historical review of studies on the effect of treating latent tuberculosis

Tuberculosis Preventive Therapy (TPT) is widely used in particular among high-risk populations such as close contacts and immunosuppressed people mostly in high-income settings. TPT is widely recommended for high-risk populations including HIV-infected and household contacts globally, but is not widely used. Historical trials on risk groups as well as the general population have documented a marked effect on reductions in incidence of active disease among those treated, as well as on prevalence of latent TB infection (LTBI) in populations where massive roll-out of TPT has previously taken place. This review summarizes the results of large historical trials conducted more than 50 years ago among Inuit and African populations as well as risk groups in the USA and Europe exhibiting similarities with current high-burden populations with current limited use of TPT. The trials demonstrated a 27-95% reduction in incidence of active TB among those receiving preventive treatment compared with placebo, with efficacy depending somewhat on length of treatment but mostly on adherence rates. It was possible to achieve satisfactory adherence rates in most of the trial populations and liver toxicity rates were generally low. The historical trials on preventive treatment for LTBI have documented that large-scale TPT is possible and effective even in high-burden populations in high-incidence areas and is therefore a relevant tool to consider in striving to eliminate the TB epidemic.

The impact on incident tuberculosis by kidney function impairment status: analysis of severity relationship

Background

The risk of tuberculosis (TB) in patients with impaired kidney function remains unclear by different stages of renal function impairment.

Methods

We retrospectively recruited all patients with kidney function in a tertiary-care referral center from January 2008 to December 2013 and followed them till December 2016. We defined the primary outcome as active TB development and analyzed the impact of kidney function impairment.

Results

During the study period, a total of 289,579 patients were enrolled for analysis, and of them, 1012 patients had active TB events in an average of 4.13 years of follow-up. According to kidney function impairment, the incidence rate of TB was similar in patients with no chronic kidney disease (CKD) or stage 1 and stage 2, and it increased apparently at stage 3a (167.68 per 100,000 person-years) to stage 3b, stage 4 and stage 5 (229.25, 304.95 and 349.29 per 100,000 person-years, respectively). In a Cox proportional hazard regression model, the dose response of TB risk among different stages of kidney function impairment increased significantly from CKD stage 3a to stage 5. Patients with long-term dialysis had a hazard ratio of 2.041 (1.092–3.815, p = 0.0254), which is similar to that of stage 4 CKD but lower than that of stage 5.

Conclusion

In patients with impaired kidney function, the risk of TB increases from CKD stage 3, and in stage 5, the risk is even higher than that of those receiving dialysis. Further strategies of TB control need to consider this high-risk group.

The global prevalence of latent tuberculosis: a systematic review and meta-analysis

In 1999, the World Health Organization (WHO) estimated that one-third of the world's population had latent tuberculosis infection (LTBI), which was recently updated to one-fourth. However, this is still based on controversial assumptions in combination with tuberculin skin test (TST) surveys. Interferon-γ release assays (IGRAs) with a higher specificity than TST have since been widely implemented, but never used to estimate the global LTBI prevalence.We conducted a systematic review and meta-analysis of LTBI estimates based on both IGRA and TST results published between 2005 and 2018. Regional and global estimates of LTBI prevalence were calculated. Stratification was performed for low, intermediate and high TB incidence countries and a pooled estimate for each area was calculated using a random effects model.Among 3280 studies screened, we included 88 studies from 36 countries with 41 IGRA (n=67 167) and 67 TST estimates (n=284 644). The global prevalence of LTBI was 24.8% (95% CI 19.7-30.0%) and 21.2% (95% CI 17.9-24.4%), based on IGRA and a 10-mm TST cut-off, respectively. The prevalence estimates correlated well to WHO incidence rates (Rs=0.70, p<0.001).In the first study of the global prevalence of LTBI derived from both IGRA and TST surveys, we found that one-fourth of the world's population is infected. This is of relevance, as both tests, although imperfect, are used to identify individuals eligible for preventive therapy. Enhanced efforts are needed targeting the large pool of latently infected individuals, as this constitutes an enormous source of potential active tuberculosis.

Utility of a clinical scoring system in prioritizing TB investigations - a systematic review

Introduction: Tuberculosis (TB) is among the 10 most common causes of death worldwide and it is the leading cause of mortality in people with human immunodeficiency virus (HIV). Clinical scoring systems have the potential to improve case finding and to prioritize patients for TB testing. Areas covered: This systematic review investigated the utility of prediction models to improve pulmonary tuberculosis (pTB) case finding. Studies were searched through PubMed until 15th of August 2018 and 20 studies were eligible according to the inclusion criteria. Data on study population, outcome measurements, predictors, and performance were extracted. Many studies showed promising results but lacked external validation. Furthermore, head-to-head studies are needed to compare the different prediction models. Sensitivities of the prediction models ranged from 26% to 96% and specificities from 18% to 92%, negative likelihood ratios (LR-) from 0.22 to 0.8 and positive likelihood ratios(LR+) 1.07 to 7.32. Composite scores including paraclinical measures added to sensitivity. Expert opinion: TB case finding is of utmost importance to advance the quest for global TB elimination, and simple measures to identify high-risk populations or persons to undergo further diagnostic evaluation are highly needed. A number of clinical scores are available and could be implemented in practice to improve case finding.

A new DNA sensor system for specific and quantitative detection of mycobacteria

In the current study, we describe a novel DNA sensor system for specific and quantitative detection of mycobacteria, which is the causative agent of tuberculosis. Detection is achieved by using the enzymatic activity of the mycobacterial encoded enzyme topoisomerase IA (TOP1A) as a biomarker. The presented work is the first to describe how the catalytic activities of a member of the type IA family of topoisomerases can be exploited for specific detection of bacteria. The principle for detection relies on a solid support anchored DNA substrate with dual functions namely: (1) the ability to isolate mycobacterial TOP1A from crude samples and (2) the ability to be converted into a closed DNA circle upon reaction with the isolated enzyme. The DNA circle can act as a template for rolling circle amplification generating a tandem repeat product that can be visualized at the single molecule level by fluorescent labelling. This reaction scheme ensures specific, sensitive, and quantitative detection of the mycobacteria TOP1A biomarker as demonstrated by the use of purified mycobacterial TOP1A and extracts from an array of non-mycobacteria and mycobacteria species. When combined with mycobacteriophage induced lysis as a novel way of effective yet gentle extraction of the cellular content from the model Mycobacterium smegmatis, the DNA sensor system allowed detection of mycobacteria in small volumes of cell suspensions. Moreover, it was possible to detect M. smegmatis added to human saliva. Depending on the composition of the sample, we were able to detect 0.6 or 0.9 million colony forming units (CFU) per mL of mycobacteria, which is within the range of clinically relevant infection numbers. We, therefore, believe that the presented assay, which relies on techniques that can be adapted to limited resource settings, may be the first step towards the development of a new point-of-care diagnostic test for tuberculosis.

New active leads for tuberculosis booster drugs by structure-based drug discovery

The transcriptional repressor EthR from Mycobacterium tuberculosis, a member of the TetR family of prokaryotic homo-dimeric transcription factors, controls the expression of the mycobacterial mono-oxygenase EthA. EthA is responsible for the bio-activation of the second-line tuberculosis pro-drug ethionamide, and consequently EthR inhibitors boost drug efficacy. Here, we present a comprehensive in silico structure-based screening protocol that led to the identification of a number of novel scaffolds of EthR inhibitors in subsequent biophysical screening by thermal shift assay. Growth inhibition assays demonstrated that five of the twenty biophysical hits were capable of boosting ethionamide activity in vitro, with the best novel scaffold displaying an EC₅₀ of 34 μM. In addition, the co-crystal structures of EthR with four new ligands at resolution ranging from 2.1 to 1.4 Å confirm the binding and inactivation mode, and will enable future lead development.

A highly transmissible tuberculosis outbreak: the importance of bars

The transmission of tuberculosis (TB) in bars is difficult to study. The objective was to describe a large TB outbreak in a company's bar and other leisure settings. A descriptive study of a TB outbreak was carried out. Contacts were studied in the index case's workplace bar (five circles of contacts) and other recreational areas (social network of three bars in the index case's neighbourhood). Chest X-rays were recommended to contacts with positive tuberculin skin tests (TST) (⩾5 mm). The risk of latent tuberculosis infection (LTBI) was determined using an adjusted odds ratio. The dose-response relationship was determined using the chi-square test for linear trend. We studied 316 contacts at the index case's workplace and detected five new cases of TB. The prevalence of LTBI was 57·9% (183/316) and was higher in the first circle, 96·0% (24/25), and lower in the fifth, 46·5% (20/43) (P < 0·0001). Among 58 contacts in the three neighbourhood bars, two TB cases were detected and the LTBI prevalence was 51·7% (30/58). Two children of one secondary TB company patient became ill. Bars may be transmission locations for TB and, as they are popular venues for social events, should be considered as potential areas of exposure.

Diagnosis of Tuberculosis in HIV Co-infected Individuals: Current Status, Challenges and Opportunities for the Future

Tuberculosis (TB) remains one of the most important causes of death among people co-infected with human immunodeficiency virus (HIV). The diagnosis of TB remains challenging in HIV co-infected individuals, due to a high frequency of smear-negative disease and high rates of extrapulmonary TB. Accurate, ease of use and rapid diagnosis of active TB are critical to the World Health Organization (WHO) End TB Strategy by 2050. Traditional laboratory techniques do not provide rapid and accurate results to effectively manage HIV co-infected patients. Over the last decade, molecular methods have provided significant steps in the fight against TB. However, many HIV co-infected patients do not have access to these molecular diagnostic tests. Given the costs closely related with confirming a TB diagnosis in HIV patients, an overtreatment for TB is used in this patient population. Nowadays, an estimated US $8 billion a year is required to provide TB treatment, which is very high compared with making an important strategy to improve the current diagnostic tests. This review focuses on current advances in diagnosing active TB with an emphasis on the diagnosis of HIV-associated TB. Also discussed are the main challenges that need to be overcome for improving an adequate initial diagnosis of active TB in HIV-positive patients.

Mycobacteria-specific cytokine responses as correlates of treatment response in active and latent tuberculosis

OBJECTIVES

A biomarker indicating successful tuberculosis (TB) therapy would assist in determining appropriate length of treatment. This study aimed to determine changes in mycobacteria-specific antigen-induced cytokine biomarkers in patients receiving therapy for latent or active TB, to identify biomarkers potentially correlating with treatment success.

METHODS

A total of 33 adults with active TB and 36 with latent TB were followed longitudinally over therapy. Whole blood stimulation assays using mycobacteria-specific antigens (CFP-10, ESAT-6, PPD) were done on samples obtained at 0, 1, 3, 6 and 9 months. Cytokine responses (IFN-γ, IL-1ra, IL-2, IL-10, IL-13, IP-10, MIP-1β, and TNF-α) in supernatants were measured by Luminex xMAP immunoassay.

RESULTS

In active TB cases, median IL-1ra (with CFP-10 and with PPD stimulation), IP-10 (CFP-10, ESAT-6), MIP-1β (ESAT-6, PPD), and TNF-α (ESAT-6) responses declined significantly over the course of therapy. In latent TB cases, median IL-1ra (CFP-10, ESAT-6, PPD), IL-2 (CFP-10, ESAT-6), and IP-10 (CFP-10, ESAT-6) responses declined significantly.

CONCLUSIONS

Mycobacteria-specific cytokine responses change significantly over the course of therapy, and their kinetics in active TB differ from those observed in latent TB. In particular, mycobacteria-specific IL-1ra responses are potential correlates of successful therapy in both active and latent TB.

[Medication adherence and monitoring of antihypertensive treatment]

Lack of adherence to medication may be the explanation for unsatisfactory drug efficacy and is often misinterpreted as resistance to treatment. When encountering patients with persistent high blood pressure despite antihypertensive treatment, it is therefore important to discover whether they are actually taking their medication. This article aims to provide an updated overview of methods of revealing and monitoring medication adherence. The article is based on non-systematic literature searches in PubMed and on the senior authors' own clinical experience.

[Drug-resistant tuberculosis. Epidemiology, diagnostics and therapy]

Drug-resistant tuberculosis (DR-TB) is one of the serious problems in the fight against tuberculosis on a global scale. This review article describes in brief the global epidemiology, diagnostics and treatment of DR-TB. The situation in Germany, Switzerland and Austria is addressed in detail. The article concludes with a presentation of current research topics in the field of resistant TB.

Adherence to medication and drug monitoring in apparent treatment-resistant hypertension

Poor drug adherence is one of the main reasons for the failure to achieve treatment targets in hypertensive patients. In patients who receive pharmacological treatment, assessment of drug adherence is of the utmost importance. The aim of this review is to present an update of the methods available to reveal and monitor non-adherence in patients with apparent treatment-resistant hypertension. Methods for monitoring adherence are divided into indirect and direct methods. The indirect methods are mainly based on self-reported adherence and can easily be manipulated by the patient. Directly observed therapy and therapeutic drug monitoring are examples of direct methods. There are limitations and advantages to all of the methods, and because of the patient's ability to manipulate the outcome of indirect methods, direct methods should be preferred. Therapeutic drug monitoring and directly observed therapy with subsequent ambulatory blood pressure measurement are considered to be reliable methods and should be used more in the routine assessment of patients with apparent treatment-resistant hypertension.