Tuberculosis

Clinical Features and Outcomes of Patients With Tubercular Uveitis Treated With Antitubercular Therapy in the Collaborative Ocular Tuberculosis Study (COTS)-1

Importance

Eradication of systemic tuberculosis (TB) has been limited by neglected populations and the HIV pandemic. Whereas ocular TB often presents as uveitis without any prior evidence of systemic TB, the existing uncertainty in the diagnosis of TB uveitis may perpetuate missed opportunities to address systemic TB.

Objective

To examine the clinical features of TB uveitis and the associations with response to antitubercular therapy (ATT).

Design, Setting, and Participants

This retrospective multinational cohort study included patients from 25 ophthalmology referral centers diagnosed with TB uveitis and treated with ATT from January 1, 2004, through December 31, 2014, with a minimum follow-up of 1 year.

Main Outcomes and Measures

Treatment failure, defined as a persistence or recurrence of inflammation within 6 months of completing ATT, inability to taper oral corticosteroids to less than 10 mg/d or topical corticosteroid drops to less than 2 drops daily, and/or recalcitrant inflammation necessitating corticosteroid-sparing immunosuppressive therapy.

Results

A total of 801 patients (1272 eyes) were studied (mean [SD] age, 40.5 [14.8] years; 413 [51.6%] male and 388 [48.4%] female; 577 [73.6%] Asian). Most patients had no known history (498 of 661 [75.3%]) of systemic TB. Most patients had bilateral involvement (471 of 801 [58.8%]). Common clinical signs reported include vitreous haze (523 of 1153 [45.4%]), retinal vasculitis (374 of 874 [42.8%]), and choroidal involvement (419 of 651 [64.4%]). Treatment failure developed in 102 of the 801 patients (12.7%). On univariate regression analysis, the hazard ratios (HRs) associated with intermediate uveitis (HR, 2.21; 95% CI, 1.07-4.55; P = .03), anterior uveitis (HR, 2.68; 95% CI, 1.32-2.35; P = .006), and panuveitis (HR, 3.28; 95% CI, 1.89-5.67; P < .001) were significantly higher compared with posterior distribution. The presence of vitreous haze had a statistically significant association (HR, 1.95; 95% CI, 1.26-3.02; P = .003) compared with absence of vitreous haze. Bilaterality had an associated HR of 1.50 (95% CI, 0.96-2.35) compared with unilaterality (HR, 1 [reference]), although this finding was not statistically significant (P = .07). On multivariate Cox proportional hazards regression analysis, the presence of vitreous haze had an adjusted HR of 2.98 (95% CI, 1.50-5.94; P = .002), presence of snow banking had an adjusted HR of 3.71 (95% CI, 1.18-11.62; P = .02), and presence of choroidal involvement had an adjusted HR of 2.88 (95% CI, 1.22-6.78; P = .02).

Conclusions and Relevance

A low treatment failure rate occurred in patients with TB uveitis treated with ATT. Phenotypes and test results are studied whereby patients with panuveitis having vitreous and choroidal involvement had a higher risk of treatment failure. These findings are limited by retrospective methods. A prospectively derived composite clinical risk score might address this diagnostic uncertainty through holistic and standardized assessment of the combinations of clinical features and investigation results that may warrant diagnosis of TB uveitis and treatment with ATT.

Designing and Evaluating Interventions to Halt the Transmission of Tuberculosis

To reduce the incidence of tuberculosis, it is insufficient to simply understand the dynamics of tuberculosis transmission. Rather, we must design and rigorously evaluate interventions to halt transmission, prioritizing those interventions most likely to achieve population-level impact. Synergy in reducing tuberculosis transmission may be attainable by combining interventions that shrink the reservoir of latent Mycobacterium tuberculosis infection (preventive therapy), shorten the time between disease onset and treatment initiation (case finding and diagnosis), and prevent transmission in key settings, such as the built environment (infection control). In evaluating efficacy and estimating population-level impact, cluster-randomized trials and mechanistic models play particularly prominent roles. Historical and contemporary evidence suggests that effective public health interventions can halt tuberculosis transmission, but an evidence-based approach based on knowledge of local epidemiology is necessary for success. We provide a roadmap for designing, evaluating, and modeling interventions to interrupt the process of transmission that fuels a diverse array of tuberculosis epidemics worldwide.

Host Antimicrobial Peptides: The Promise of New Treatment Strategies against Tuberculosis

Tuberculosis (TB) continues to be a devastating infectious disease and remerges as a global health emergency due to an alarming rise of antimicrobial resistance to its treatment. Despite of the serious effort that has been applied to develop effective antitubercular chemotherapies, the potential of antimicrobial peptides (AMPs) remains underexploited. A large amount of literature is now accessible on the AMP mechanisms of action against a diversity of pathogens; nevertheless, research on their activity on mycobacteria is still scarce. In particular, there is an urgent need to integrate all available interdisciplinary strategies to eradicate extensively drug-resistant Mycobacterium tuberculosis strains. In this context, we should not underestimate our endogenous antimicrobial proteins and peptides as ancient players of the human host defense system. We are confident that novel antibiotics based on human AMPs displaying a rapid and multifaceted mechanism, with reduced toxicity, should significantly contribute to reverse the tide of antimycobacterial drug resistance. In this review, we have provided an up to date perspective of the current research on AMPs to be applied in the fight against TB. A better understanding on the mechanisms of action of human endogenous peptides should ensure the basis for the best guided design of novel antitubercular chemotherapeutics.

Plasma cell-free DNA level and its integrity as biomarkers to distinguish non-small cell lung cancer from tuberculosis

AIMS

The aim of this study was to evaluate the potential clinical value of the plasma cell-free DNA (cfDNA) concentrations and strand integrity as an auxiliary tool for Non-small cell lung cancer (NSCLC) differential diagnosis from tuberculosis in patients with solitary pulmonary nodules detected by computed tomography (CT).

METHODS

This research was divided into 3 groups: NSCLC (n=106), tuberculosis (n=105) and healthy controls (n=107). The quantization of plasma DNA fragments was performed by quantitative real-time PCR. Amplifying and quantifying shorter (115bp) and longer (247bp) fragments from abundant genomic ALU repeats.

RESULTS

The level of cfDNA (ALU115) in patients with NSCLC [95.67 (51.28, 238.85) ng/μl] was significantly higher than that in patients with tuberculosis [59.60 (34.25, 102.53) ng/μl, P=0.001] and that in healthy controls [44.66 (24.56, 66.54) ng/μl, P=0.001]. The integrity of cfDNA in patients with NSCLC [5.91(4.14, 7.45)] was also significantly higher than that in patients with tuberculosis [3.85 (2.91, 5.06), P=0.000] and that in healthy controls [2.78(2.18, 4.82), P=0.000]. Receiver-operating characteristic (ROC) curve analysis showed that cfDNA(ALU115) and its integrity could be used as biomarkers to distinguish NSCLC from tuberculosis (AUC=0.628, P=0.001, cut-off values=91.48, sensitivity=57.50%, specificity=64.80%; AUC=0.722, P=0.000, cut-off values=5.54, sensitivity=55.70%, specificity=82.90%, respectively). In addition, the effect of integrity of cfDNA(AUC=0.722) to distinguish NSCLC from tuberculosis was higher than traditional tumor marker Carbohydrate antigen 125(CA125) (AUC=0.626), Neuron-specific enolase(NSE) (AUC=0.716) and Carcino-embryonic antigen(CEA) (AUC=0.589).

CONCLUSIONS

cfDNA and its integrity could be used as indicators for identification of NSCLC from tuberculosis. Moreover, the effect of integrity of cfDNA to distinguish NSCLC from tuberculosis was higher than traditional tumor marker CA125, NSE and CEA.

Substantially Higher and Earlier Occurrence of Anti-Tuberculosis Drug-Related Adverse Reactions in HIV Coinfected Tuberculosis Patients: A Matched-Cohort Study

Little information exists on the frequency, severity, and timing of first-line anti-tuberculosis drug-related adverse events (TB-AEs) in HIV-tuberculosis coinfected (HIV-TB) patients in the antiretroviral therapy (ART) era. This matched-cohort study included HIV-TB patients as cases and HIV-uninfected tuberculosis (non-HIV-TB) patients as controls. Tuberculosis was culture-confirmed in both groups. Cases were matched to controls in a 1:4 ratio on age, sex, and year of diagnosis. TB-AEs were defined as Grade 2 or higher requiring drug discontinuation/regimen change. From 2003 to 2015, 94 cases and 376 controls were analyzed (95% men, 98% Asians). Standard four-drug combination therapy was initiated in 91% of cases and 89% of controls (p = 0.45). Cases had a higher frequency of TB-AE [51% (48/94) vs. 10% (39/376), p < 0.001]. Their major TB-AEs were fever (19%), rash (11%), and neutropenia (11%). TB-AEs were more severe in cases [Grade 3 or higher: cases (71%, 34/48) vs. controls (49%, 19/39), p < 0.001]. The time from treatment initiation to TB-AE was shorter in cases [median 18 (interquartile range 12-28) vs. 27 (15-57) days, p = 0.027], and 73% of TB-AEs in cases occurred within 4 weeks of starting anti-tuberculosis treatment. HIV infection was an independent risk factor for TB-AEs in the multivariate Cox analysis [adjusted HR (aHR): 6.96; 95% confidence interval: 3.93-12.3]. TB-AEs occurred more frequently in HIV-TB than in non-HIV-TB patients, and were more severe. The majority of TB-AEs occurred within 4 weeks of initiating anti-tuberculosis treatment. Because TB-AEs may delay ART initiation, careful monitoring during this period is warranted in coinfected patients.

Identification of differentially expressed circular RNAs in human monocyte derived macrophages response to Mycobacterium tuberculosis infection

Macrophages act as the first line of host immune defense against Mycobacterium tuberculosis (Mtb). Recent studies have demonstrated circular RNAs (circRNAs) are implicated in a variety of physiological and pathological processes; however, the role of circRNAs in macrophages response to Mtb infection remain unknown. To address this issue, here we characterized circRNAs expression profiles in human monocyte derived macrophages (MDMs) response to Mtb infection using microarray assay. Our results revealed that many circRNAs were differentially expressed in human MDMs after Mtb infection; of these, 32 circRNAs were up-regulated and 110 were down-regulated. Real time PCR results were generally consistent with the microarray data. Furthermore, we found that hsa_circ_0043497 and hsa_circ_0001204 may be effective diagnostic biomarkers for TB. This study provides the first evidence that circRNAs alterations are involved in human MDMs response to TB infection and reveal potential targets for diagnostics and the treatment of TB.

Isolated hepatic tuberculosis in the caudate lobe mimicking intrahepatic carcinoma

Although tuberculosis (TB) remains a worldwide epidemic, isolated hepatic TB is an extremely rare entity and poorly described in the literature. Isolated hepatic TB may pose a diagnostic dilemma due to the non-specific clinical symptoms and imaging features. We present a case of a 54-year-old female with an isolated caseating granulomatous lesion at the caudate lobe of liver involving the pancreatic head.

Asymptomatic pulmonary tuberculosis mimicking lung cancer on imaging: A retrospective study

Asymptomatic pulmonary tuberculosis (PTB) mimicking lung cancer is rare and has been documented in few studies. Accurately diagnosing this atypical disease remains an enormous challenge for clinicians. The aim of the present study was to characterize asymptomatic patients with PTB who were initially diagnosed with lung cancer according to their chest computer tomography (CT) or whole-body 18F-fludeoxyglucose-positron emission tomography-computer tomography (PET-CT) presentations. The clinical characteristics and radiographic features of patients with PTB were analyzed and compared to those of patients with lung cancer. In patients with PTB, all lesions exhibited suspected malignant signs on chest CT and the maximum standard uptake value (SUVmax) of PET-CT imaging was between 2.65 and 10.9. Compared with lung cancer, the factors associated with PTB included an age <60 years (82% vs. 46%, P=0.03), being male (77% vs. 51%, P=0.025), the presence of diabetes (55% vs. 16%, P<0.01), spiculated margins (82% vs. 44%, P=0.002) and a lower SUVmax (P=0.036). The optimal cut-off level was SUVmax 8.45 for discriminating between PTB and lung cancer. At this point, the sensitivity and specificity were 63.0 and 88.9%, respectively. The results of the current study revealed methods of distinguishing between the two similar diseases. Furthermore, the results of the current study may increase awareness that although imaging of lesions may resemble lung cancer, a diagnosis of PTB should be considered. Accurate diagnosis of PTB would mean that patients would be able to avoid undergoing unnecessary operations that induce a high financial burden.

Recent controversies about MDR and XDR-TB: Global implementation of the WHO shorter MDR-TB regimen and bedaquiline for all with MDR-TB?

Tuberculosis (TB) is now the biggest infectious disease killer worldwide. Although the estimated incidence of TB has marginally declined over several years, it is out of control in some regions including in Africa. The advent of multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) threatens to further destabilize control in several regions of the world. Drug-resistant TB constitutes a significant threat because it underpins almost 25% of global TB mortality, is associated with high morbidity, is a threat to healthcare workers and is unsustainably costly to treat. The advent of highly resistant TB with emerging bacillary resistance to newer drugs has raised further concern. Encouragingly, in addition to preventative strategies, several interventions have recently been introduced to curb the drug-resistant TB epidemic, including newer molecular diagnostic tools, new (bedaquiline and delamanid) and repurposed (linezolid and clofazimine) drugs and shorter and individualized treatment regimens. However, there are several controversies that surround the use of new drugs and regimens, including whether, how and to what extent they should be used, and who specifically should be treated so that outcomes are optimally improved without amplifying the burden of drug resistance, and other potential drawbacks, thus sustaining effectiveness of the new drugs. The equipoise surrounding these controversies is discussed and some recommendations are provided.

Substituted N-Phenyl-5-(2-(phenylamino)thiazol-4-yl)isoxazole-3-carboxamides Are Valuable Antitubercular Candidates that Evade Innate Efflux Machinery

Tuberculosis remains one of the deadliest infectious diseases in the world, and the increased number of multidrug-resistant and extremely drug-resistant strains is a significant reason for concern. This makes the discovery of novel antitubercular agents a cogent priority. We have previously addressed this need by reporting a series of substituted 2-aminothiazoles capable to inhibit the growth of actively replicating, nonreplicating persistent, and resistant Mycobacterium tuberculosis strains. Clues from the structure-activity relationships lining up the antitubercular activity were exploited for the rational design of improved analogues. Two compounds, namely N-phenyl-5-(2-(p-tolylamino)thiazol-4-yl)isoxazole-3-carboxamide 7a and N-(pyridin-2-yl)-5-(2-(p-tolylamino)thiazol-4-yl)isoxazole-3-carboxamide 8a, were found to show high inhibitory activity toward susceptible M. tuberculosis strains, with an MIC₉₀ of 0.125-0.25 μg/mL (0.33-0.66 μM) and 0.06-0.125 μg/mL (0.16-0.32 μM), respectively. Moreover, they maintained good activity also toward resistant strains, and they were selective over other bacterial species and eukaryotic cells, metabolically stable, and apparently not susceptible to the action of efflux pumps.

Modular programming for tuberculosis control, the "AuTuMN" platform

BACKGROUND

Tuberculosis (TB) is now the world's leading infectious killer and major programmatic advances will be needed if we are to meet the ambitious new End TB Targets. Although mathematical models are powerful tools for TB control, such models must be flexible enough to capture the complexity and heterogeneity of the global TB epidemic. This includes simulating a disease that affects age groups and other risk groups differently, has varying levels of infectiousness depending upon the organ involved and varying outcomes from treatment depending on the drug resistance pattern of the infecting strain.

RESULTS

We adopted sound basic principles of software engineering to develop a modular software platform for simulation of TB control interventions ("AuTuMN"). These included object-oriented programming, logical linkage between modules and consistency of code syntax and variable naming. The underlying transmission dynamic model incorporates optional stratification by age, risk group, strain and organ involvement, while our approach to simulating time-variant programmatic parameters better captures the historical progression of the epidemic. An economic model is overlaid upon this epidemiological model which facilitates comparison between new and existing technologies. A "Model runner" module allows for predictions of future disease burden trajectories under alternative scenario situations, as well as uncertainty, automatic calibration, cost-effectiveness and optimisation. The model has now been used to guide TB control strategies across a range of settings and countries, with our modular approach enabling repeated application of the tool without the need for extensive modification for each application.

CONCLUSIONS

The modular construction of the platform minimises errors, enhances readability and collaboration between multiple programmers and enables rapid adaptation to answer questions in a broad range of contexts without the need for extensive re-programming. Such features are particularly important in simulating an epidemic as complex and diverse as TB.

Mixed Th1 and Th2 Mycobacterium tuberculosis-specific CD4 T cell responses in patients with active pulmonary tuberculosis from Tanzania

Mycobacterium tuberculosis (Mtb) and helminth infections elicit antagonistic immune effector functions and are co-endemic in several regions of the world. We therefore hypothesized that helminth infection may influence Mtb-specific T-cell immune responses. We evaluated the cytokine profile of Mtb-specific T cells in 72 individuals with pulmonary TB disease recruited from two Sub-Saharan regions with high and moderate helminth burden i.e. 55 from Tanzania (TZ) and 17 from South Africa (SA), respectively. We showed that Mtb-specific CD4 T-cell functional profile of TB patients from Tanzania are primarily composed of polyfunctional Th1 and Th2 cells, associated with increased expression of Gata-3 and reduced expression of T-bet in memory CD4 T cells. In contrast, the cytokine profile of Mtb-specific CD4 T cells of TB patients from SA was dominated by single IFN-γ and dual IFN-γ/TNF-α and associated with TB-induced systemic inflammation and elevated serum levels of type I IFNs. Of note, the proportion of patients with Mtb-specific CD8 T cells was significantly reduced in Mtb/helminth co-infected patients from TZ. It is likely that the underlying helminth infection and possibly genetic and other unknown environmental factors may have caused the induction of mixed Th1/Th2 Mtb-specific CD4 T cell responses in patients from TZ. Taken together, these results indicate that the generation of Mtb-specific CD4 and CD8 T cell responses may be substantially influenced by environmental factors in vivo. These observations may have major impact in the identification of immune biomarkers of disease status and correlates of protection.

Mycobacterium tuberculosis (Mtb) and helminth infections are co-endemic in several regions of the world and their immune responses may be mutually antagonistic. We therefore hypothesized that helminth infection would impact and potentially shape Mtb-specific T-cell responses and systemic inflammation in patients suffering from active pulmonary tuberculosis (TB) enrolled from two helminth endemic regions i.e. Tanzania (TZ) and South Africa (SA). In this study, we demonstrate for the first time that TB patients from SA and TZ harbor distinct immune responses to Mtb antigens. Indeed, we showed that Mtb-specific CD4 T-cell responses of TB patients from TZ were composed by a mixed T helper type 1 (Th1) and Th2 responses. In contrast, the cytokine profile of Mtb-specific CD4 T cells of TB patients from SA was dominated by Th1 cells and associated with TB-induced systemic inflammation and elevated serum levels of type I IFN. Taken together, these data indicate that Mtb-specific T-cell responses are diverse in human populations and can be strongly influenced by host and pathogen genetic background, co-infections and yet unknown environmental factors. Identification of correlates of risk and protection from TB disease will help in the rational development of protective T-cell based vaccines against TB, early monitoring TB treatment outcomes and focused follow up of high risk populations.

The role of human host genetics in tuberculosis resistance

INTRODUCTION

Tuberculosis (TB) remains a public health problem: the latest estimate of new incident cases per year is a staggering 10.4 million. Despite this overwhelming number, the majority of the immunocompetent population can control infection with Mycobacterium tuberculosis. The human genome underlies the immune response and contributes to the outcome of TB infection. Areas covered: Investigations of TB resistance in the general population have closely mirrored those of other infectious diseases and initially involved epidemiological observations. Linkage and association studies, including studies of VDR, SLC11A1 and HLA-DRB1 followed. Genome-wide association studies of common variants, not necessarily sufficient for disease, became possible after technological advancements. Other approaches involved the identification of those individuals with rare disease-causing mutations that strongly predispose to TB, epistasis and the role of ethnicity in disease. Despite these efforts, infection outcome, on an individual basis, cannot yet be predicted. Expert commentary: The early identification of future disease progressors is necessary to stem the TB epidemic. Human genetics may contribute to this endeavour and could in future suggest pathways to target for disease prevention. This will however require concerted efforts to establish large, well-phenotyped cohorts from different ethnicities, improved genomic resources and a better understanding of the human genome architecture.

Detection and Quantification of Differentially Culturable Tubercle Bacteria in Sputum from Patients with Tuberculosis

RATIONALE

Recent studies suggest that baseline tuberculous sputum comprises a mixture of routinely culturable and differentially culturable tubercle bacteria (DCTB). The latter seems to be drug tolerant and dependent on resuscitation-promoting factors (Rpfs).

OBJECTIVES

To further explore this, we assessed sputum from patients with tuberculosis for DCTB and studied the impact of exogenous culture filtrate (CF) supplementation ex vivo.

METHODS

Sputum samples from adults with tuberculosis and HIV-1 and adults with no HIV-1 were used for most probable number (MPN) assays supplemented with CF and Rpf-deficient CF, to detect CF-dependent and Rpf-independent DCTB, respectively.

MEASUREMENTS AND MAIN RESULTS

In 110 individuals, 19.1% harbored CF-dependent DCTB and no Rpf-independent DCTB. Furthermore, 11.8% yielded Rpf-independent DCTB with no CF-dependent DCTB. In addition, 53.6% displayed both CF-dependent and Rpf-independent DCTB, 1.8% carried CF-independent DCTB, and 13.6% had no DCTB. Sputum from individuals without HIV-1 yielded higher CF-supplemented MPN counts compared with counterparts with HIV-1. Furthermore, individuals with HIV-1 with CD4 counts greater than 200 cells/mm³ displayed higher CF-supplemented MPN counts compared with participants with HIV-1 with CD4 counts less than 200 cells/mm³. CF supplementation allowed for detection of mycobacteria in 34 patients with no culturable bacteria on solid media. Additionally, the use of CF enhanced detection of sputum smear-negative individuals.

CONCLUSIONS

These observations demonstrate a novel Rpf-independent DCTB population in sputum and reveal that reduced host immunity is associated with lower prevalence of CF-responsive bacteria. Quantification of DCTB in standard TB diagnosis would be beneficial because these organisms provide a putative biomarker to monitor treatment response and risk of disease recurrence.

Mycobacterium tuberculosis Rv3615c is a highly immunodominant antigen and specifically induces potent Th1-type immune responses in tuberculosis pleurisy

T-cell responses have been demonstrated to be essential for preventing Mycobacterium tuberculosis infection. The Th1-cytokines produced by T cells, such as INF-γ, IL-2, and TNF-α, not only limit the invasion of M. tuberculosis but also eliminate the pathogen at the site of infection. Bacillus Calmette-Guérin (BCG) is known to induce Th1-type responses but the protection is inadequate. Identification of immunogenic components, in addition to those expressed in BCG, and induction of a broad spectrum of Th1-type responses provide options for generating sufficient adaptive immunity. Here, we studied human pulmonary T-cell responses induced by the M. tuberculosis-specific antigen Rv3615c, a protein with a similar size and sequence homology to ESAT-6 and CFP-10, which induced dominant CD4⁺ T-cell responses in human tuberculosis (TB) models. We characterized T-cell responses including cytokine profiling, kinetics of activation, expansion, differentiation, TCR usage, and signaling of activation induced by Rv3615c compared with other M. tuberculosis-specific antigens. The expanded CD4⁺ T cells induced by Rv3615c predominately produced Th1, but less Th2 and Th17, cytokines and displayed effector/memory phenotypes (CD45RO⁺CD27^-CD127^-CCR7^-). The magnitude of expansion and cytokine production was comparable to those induced by well-characterized the 6 kDa early secreted antigenic target (ESAT-6), the 10 kDa culture filtrate protein (CFP-10) and BCG. Rv3615c contained multiple epitopes Rv3615c_1-15, Rv3615c_6-20, Rv3615c_66-80, Rv3615c_71-85 and Rv3615c_76-90 that activated CD4⁺ T cells. The Rv3615c-specific CD4⁺ T cells shared biased of T-cell receptor variable region of β chain (TCR Vβ) 1, 2, 4, 5.1, 7.1, 7.2 and/or 22 chains to promote their differentiation and proliferation respectively, by triggering a signaling cascade. Our data suggest that Rv3615c is a major target of Th1-type responses and can be a highly immunodominant antigen specific for M. tuberculosis infection.

Development of a One-Step Multiplex PCR Assay for Differential Detection of Major Mycobacterium Species

The prevalence of tuberculosis continues to be high, and nontuberculous mycobacterial (NTM) infection has also emerged worldwide. Moreover, differential and accurate identification of mycobacteria to the species or subspecies level is an unmet clinical need. Here, we developed a one-step multiplex PCR assay using whole-genome analysis and bioinformatics to identify novel molecular targets. The aims of this assay were to (i) discriminate between the Mycobacterium tuberculosis complex (MTBC) and NTM using rv0577 or RD750, (ii) differentiate M. tuberculosis (M. tuberculosis) from MTBC using RD9, (iii) selectively identify the widespread M. tuberculosis Beijing genotype by targeting mtbk_20680, and (iv) simultaneously detect five clinically important NTM (M. avium, M. intracellulare, M. abscessus, M. massiliense, and M. kansasii) by targeting IS1311, DT1, mass_3210, and mkan_rs12360 An initial evaluation of the multiplex PCR assay using reference strains demonstrated 100% specificity for the targeted Mycobacterium species. Analytical sensitivity ranged from 1 to 10 pg for extracted DNA and was 10³ and 10⁴ CFU for pure cultures and nonhomogenized artificial sputum cultures, respectively, of the targeted species. The accuracy of the multiplex PCR assay was further evaluated using 55 reference strains and 94 mycobacterial clinical isolates. Spoligotyping, multilocus sequence analysis, and a commercial real-time PCR assay were employed as standard assays to evaluate the multiplex PCR assay with clinical M. tuberculosis and NTM isolates. The PCR assay displayed 100% identification agreement with the standard assays. Our multiplex PCR assay is a simple, convenient, and reliable technique for differential identification of MTBC, M. tuberculosis, M. tuberculosis Beijing genotype, and major NTM species.

The antibacterial prodrug activator Rv2466c is a mycothiol-dependent reductase in the oxidative stress response of Mycobacterium tuberculosis

The Mycobacterium tuberculosis rv2466c gene encodes an oxidoreductase enzyme annotated as DsbA. It has a CPWC active-site motif embedded within its thioredoxin fold domain and mediates the activation of the prodrug TP053, a thienopyrimidine derivative that kills both replicating and nonreplicating bacilli. However, its mode of action and actual enzymatic function in M. tuberculosis have remained enigmatic. In this study, we report that Rv2466c is essential for bacterial survival under H₂O₂ stress. Further, we discovered that Rv2466c lacks oxidase activity; rather, it receives electrons through the mycothiol/mycothione reductase/NADPH pathway to activate TP053, preferentially via a dithiol-disulfide mechanism. We also found that Rv2466c uses a monothiol-disulfide exchange mechanism to reduce S-mycothiolated mixed disulfides and intramolecular disulfides. Genetic, phylogenetic, bioinformatics, structural, and biochemical analyses revealed that Rv2466c is a novel mycothiol-dependent reductase, which represents a mycoredoxin cluster of enzymes within the DsbA family different from the glutaredoxin cluster to which mycoredoxin-1 (Mrx1 or Rv3198A) belongs. To validate this DsbA-mycoredoxin cluster, we also characterized a homologous enzyme of Corynebacterium glutamicum (NCgl2339) and observed that it demycothiolates and reduces a mycothiol arsenate adduct with kinetic properties different from those of Mrx1. In conclusion, our work has uncovered a DsbA-like mycoredoxin that promotes mycobacterial resistance to oxidative stress and reacts with free mycothiol and mycothiolated targets. The characterization of the DsbA-like mycoredoxin cluster reported here now paves the way for correctly classifying similar enzymes from other organisms.

Collaborative public-private initiatives targeting multidrug-resistant tuberculosis (MDR-TB) supported by the Lilly MDR-TB Partnership: experiences in 2012-2016

Since 2003, the Lilly Foundation has supported the noncommercial Lilly MDR-TB Partnership, which involves more than 45 local, national, global, and nongovernmental organizations and governments. The aim of the Lilly MDR-TB Partnership is to achieve significant global impact on multidrug-resistant tuberculosis (MDR-TB) by addressing a series of important local health care needs in highly affected countries: China, India, Russia, and South Africa. The main focus of activities during 2012–2016 was on community needs in primary care. Supported projects seek to make meaningful and measurable progress toward global and national TB objectives. The partnership programs share an overall conceptual approach known as “research, report, advocate”, based on the piloting of novel approaches on a small scale, with outcomes assessed at early stages. The results are analyzed and communicated to governments, health-policy experts, and local and national stakeholders, including those in other countries facing similar MDR-TB challenges. For successful, cost-effective initiatives, the analysis is used as support when advocating for the scaling up of initiatives to regional or national levels. This article discusses representative examples of projects supported by the Lilly MDR-TB Partnership in the time period 2012–2016. The examples illustrate the potential for globally informed, locally designed primary-care collaborations to strengthen health care systems and support TB policies and offer observations to inform future health care public–private partnerships.

The paradigm shift to end tuberculosis. Are we ready to assume the changes?

INTRODUCTION

Tuberculosis (TB) is the number one infectious disease killer and exemplifies the most neglected of them. Drug-susceptible TB presents with high mortality especially in atypical forms, disproportionally affecting immunosuppressed and vulnerable populations. The drug-resistant TB (DR-TB) epidemic, a world crisis, is sustained and increased through person-to-person transmission in households and the community. TB diagnostics and treatment in recent years are highly evolving fields. New rapid molecular tests are changing the perspectives in diagnosis and resistance screening. Also, new drugs and shorter regimens for DR-TB are appearing. For the first time in recent history, a large number of randomized control trials are incoming. Areas covered: This article reviews most TB advances including new diagnostic tests, drugs, and regimens and outlines upcoming drug trials while disclosing the potential gaps the in development of patient-centered systems and current organizational challenges leading to a delay in the uptake of these innovations. Expert commentary: Innovations are occurring, but not many are implemented on a wide scale in developing countries. TB health systems and staff are not getting updated in parallel. More efforts and funds are needed not only to implement current novelties but also to research for future solutions to eliminate TB.

A review of computational and mathematical modeling contributions to our understanding of Mycobacterium tuberculosis within-host infection and treatment

Tuberculosis (TB) is an ancient and deadly disease characterized by complex host-pathogen dynamics playing out over multiple time and length scales and physiological compartments. Computational modeling can be used to integrate various types of experimental data and suggest new hypotheses, mechanisms, and therapeutic approaches to TB. Here, we offer a first-time comprehensive review of work on within-host TB models that describe the immune response of the host to infection, including the formation of lung granulomas. The models include systems of ordinary and partial differential equations and agent-based models as well as hybrid and multi-scale models that are combinations of these. Many aspects of M. tuberculosis infection, including host dynamics in the lung (typical site of infection for TB), granuloma formation, roles of cytokine and chemokine dynamics, and bacterial nutrient availability have been explored. Finally, we survey applications of these within-host models to TB therapy and prevention and suggest future directions to impact this global disease.

The Goldilocks model of immune symbiosis with Mycobacteria and Candida colonizers

Mycobacteria and Candida species include significant human pathogens that can cause localized or disseminated infections. Although these organisms may appear to have little in common, several shared pathways of immune recognition and response are important for both control and infection-related pathology. In this article, we compare and contrast the innate and adaptive components of the immune system that pertain to these infections in humans and animal models. We also explore a relatively new concept in the mycobacterial field: biological commensalism. Similar to the well-established model of Candida infection, Mycobacteria species colonize their human hosts in equilibrium with the immune response. Perturbations in the immune response permit the progression to pathologic disease at the expense of the host. Understanding the immune factors required to maintain commensalism may aid with the development of diagnostic and treatment strategies for both categories of pathogens.

Lipids in infectious diseases - The case of AIDS and tuberculosis

Lipids play a central role in many infectious diseases. AIDS (Acquired Immune Deficiency Syndrome) and tuberculosis are two of the deadliest infectious diseases to have struck mankind. The pathogens responsible for these diseases, Human Immunodeficiency Virus-1 and Mycobacterium tuberculosis, rely on lipids and on lipid membrane properties to gain access to their host cells, to persist in them and ultimately to egress from their hosts. In this Review, we discuss the life cycles of these pathogens and the roles played by lipids and membranes. We then give an overview of therapies that target lipid metabolism, modulate host membrane properties or implement lipid-based drug delivery systems. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Mycobacterium tuberculosis Lipoprotein MPT83 Induces Apoptosis of Infected Macrophages by Activating the TLR2/p38/COX-2 Signaling Pathway

Tuberculosis caused by Mycobacterium tuberculosis continues to pose a serious global health threat. The attenuated Mycobacterium bovis bacillus Calmette-Guérin, as the only licensed vaccine, has limited protective efficacy against TB. The development of more effective antituberculosis vaccines is urgent and demands for further identification and understanding of M. tuberculosis Ags. MPT83 (Rv2873), a secreted mycobacterial lipoprotein, has been applied into subunit vaccine development and shown protective effects against M. tuberculosis infection in animals; however, the understanding of the underlying mechanism is limited. In present study, we systematically studied the effect of MPT83 on macrophage apoptosis by constructing Mycobacterium smegmatis strain overexpressing MPT83 (MS_MPT83) and purifying rMPT83 protein. We found that MPT83 induced apoptosis in both human and mouse macrophages. MPT83 induced cyclooxygenase-2 (COX-2) expression at both the transcriptional and protein levels in macrophages, whereas silencing or inhibiting COX-2 blocked rMPT83-induced apoptosis or the enhanced apoptotic response to MS_MPT83 in comparison with M. smegmatis transfected with pMV261 vector (MS_Vec), indicating that COX-2 is required for MPT83-induced apoptosis. Additionally, tlr2 deficiency led to significant reduction of COX-2 expression, accompanied by less apoptosis in macrophages stimulated with rMPT83 or infected with MS_MPT83. Moreover, the activation of p38 accounted for MPT83-induced COX-2 expression. Finally, lower bacteria burdens in the lungs and spleens and enhanced survival were observed in mice i.v. infected with MS_MPT83 compared with MS_Vec. Taken together, our results established a proapoptotic effect of MPT83 and identified the TLR2/p38/COX-2 axis in MPT83-induced macrophage apoptosis.

What We Have Learned and What We Have Missed in Tuberculosis Pathophysiology for a New Vaccine Design: Searching for the "Pink Swan"

This is a call to encourage the search for a new vaccine to stop the progression of Mycobacterium tuberculosis infection to tuberculosis (TB) disease. TB is a highly discreet and stigmatized disease, with a massive impact on human health. It has killed 1.2 billion people in the last 200 years and still kills 1.5 million people per year. Over the last 20 years, the TB vaccine field has experienced spectacular developments, and we have learned about (1) the importance of the Th1 response in controlling infection, mainly against RD1 and Ag85 antigens; (2) the stability of the antigenic repertoire; (3) the dynamics of M. tuberculosis granulomas; or (4) the link between typical and atypical pulmonary TB and the immune status of the host. However, we still do not (1) know how to avoid M. tuberculosis infection and reinfection; (2) understand the major role of the increase in lesion size in progression from infection to disease; (3) the role of interlobular septa in encapsulating pulmonary lesions; or (4) the role of neutrophilic infiltration and an exaggerated inflammatory response in the development of TB disease. These are strong reasons to pursue new, imaginative proposals involving both the antibody response and a balanced, tolerant immune response that averts progression toward TB. So far, the scientific mindset has been quite monolithic and has mainly focused on the stimulation of conventional T cells. But this approach has failed. For that reason, we are seeking unconventional perspectives to find a “pink swan,” a more efficacious and safer vaccine candidate.

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.

Regional solar radiation is inversely correlated with incidence and severity of tuberculosis in Chile

Vitamin D (VD) deficiency has been linked to increased incidence and morbidity of tuberculosis (TB). Chile has large variations in solar radiation (SR; a proxy of VD status) and high prevalence of VD deficiency in its southernmost regions with low SR. We investigated the correlation between regional SR and rates of TB incidence, admissions and deaths in Chile by reviewing national records on prospectively collected mandatory disease notifications, admissions and mortality between 2001 and 2011. Over the study period, 26 691 new TB notifications were registered. The TB incidence rate was 14·77 (95% confidence intervals (CIs) 14·60-14·95), admission rate was 12·12 (95% CI 11·96-12·28) and mortality rate was 1·61 (95% CI 1·55-1·67) per 100 000 population per year. Multivariable linear regressions adjusting for significant demographic TB risk factors in Chile (regional prevalence of HIV infection, rates of migration from TB-endemic countries and rates of imprisonment) revealed an independent and highly statistically significant inverse association between SR and TB incidence rate (β -1·05, 95% CI -1·73 to -0·36, P = 0·007), admission rate (β -1·58, 95% CI -2·23 to -0·93, P < 0·001), and mortality rate (β -0·15, 95% CI -0·23 to -0·07, P = 0·002). These findings support a potential pathogenic role of VD deficiency in TB incidence and severity.

Treatment Outcomes of Patients Treated for Pulmonary Tuberculosis after Undergoing Gastrectomy

Gastrectomy is a proxy of malnutrition, which may lead to increased risk for developing pulmonary tuberculosis (TB). Malabsorption in gastrectomy patients could lead to low serum levels of rifampicin, which may be related to higher treatment failure. However, there is limited information on treatment outcomes of TB in patients who have undergone gastrectomy. This study aims to determine treatment outcomes and adverse effects in patients treated for TB after undergoing gastrectomy for gastric cancer. During the study period, 112 patients were treated for active TB that developed after gastrectomy for gastric cancer. Among them, we selected 15 patients who were culture positive at initial diagnosis and had evidence of active TB on imaging studies; namely, the remaining 97 patients without initial culture or imaging studies were excluded. We thus performed a case-control study of gastric cancer patients treated for TB after undergoing gastrectomy (n = 15). The control group was defined as age- and sex-matched TB patients who had not received gastrectomy (n = 45). Treatment failure in clinical, microbiological aspects, and adverse events were analyzed. Patients who had undergone gastrectomy exhibited higher 4-month clinical failure rates, compared to non-gastrectomy patient: 4 (26.7%) vs. 1 (2.2%), P = 0.012. Gastrointestinal adverse effects were more frequent in patients with gastrectomy, compared to non-gastrectomy patients: 9 (60%) vs. 5 (11.1%), P < 0.001. In conclusion, patients treated for TB after undergoing gastrectomy are associated with higher rates of gastrointestinal adverse events and treatment failure.

The epidemiology, pathogenesis, transmission, diagnosis, and management of multidrug-resistant, extensively drug-resistant, and incurable tuberculosis

Global tuberculosis incidence has declined marginally over the past decade, and tuberculosis remains out of control in several parts of the world including Africa and Asia. Although tuberculosis control has been effective in some regions of the world, these gains are threatened by the increasing burden of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. XDR tuberculosis has evolved in several tuberculosis-endemic countries to drug-incurable or programmatically incurable tuberculosis (totally drug-resistant tuberculosis). This poses several challenges similar to those encountered in the pre-chemotherapy era, including the inability to cure tuberculosis, high mortality, and the need for alternative methods to prevent disease transmission. This phenomenon mirrors the worldwide increase in antimicrobial resistance and the emergence of other MDR pathogens, such as malaria, HIV, and Gram-negative bacteria. MDR and XDR tuberculosis are associated with high morbidity and substantial mortality, are a threat to health-care workers, prohibitively expensive to treat, and are therefore a serious public health problem. In this Commission, we examine several aspects of drug-resistant tuberculosis. The traditional view that acquired resistance to antituberculous drugs is driven by poor compliance and programmatic failure is now being questioned, and several lines of evidence suggest that alternative mechanisms-including pharmacokinetic variability, induction of efflux pumps that transport the drug out of cells, and suboptimal drug penetration into tuberculosis lesions-are likely crucial to the pathogenesis of drug-resistant tuberculosis. These factors have implications for the design of new interventions, drug delivery and dosing mechanisms, and public health policy. We discuss epidemiology and transmission dynamics, including new insights into the fundamental biology of transmission, and we review the utility of newer diagnostic tools, including molecular tests and next-generation whole-genome sequencing, and their potential for clinical effectiveness. Relevant research priorities are highlighted, including optimal medical and surgical management, the role of newer and repurposed drugs (including bedaquiline, delamanid, and linezolid), pharmacokinetic and pharmacodynamic considerations, preventive strategies (such as prophylaxis in MDR and XDR contacts), palliative and patient-orientated care aspects, and medicolegal and ethical issues.

Design and use of mouse control DNA for DNA biomarker extraction and PCR detection from urine: Application for transrenal Mycobacterium tuberculosis DNA detection

Urine samples are increasingly used for diagnosing infections including Escherichia coli, Ebola virus, and Zika virus. However, extraction and concentration of nucleic acid biomarkers from urine is necessary for many molecular detection strategies such as polymerase chain reaction (PCR). Since urine samples typically have large volumes with dilute biomarker concentrations making them prone to false negatives, another impediment for urine-based diagnostics is the establishment of appropriate controls particularly to rule out false negatives. In this study, a mouse glyceraldehyde 3-phosphate dehydrogenase (GAPDH) DNA target was added to retrospectively collected urine samples from tuberculosis (TB)-infected and TB-uninfected patients to indicate extraction of intact DNA and removal of PCR inhibitors from urine samples. We tested this design on surrogate urine samples, retrospective 1milliliter (mL) urine samples from patients in Lima, Peru and retrospective 5mL urine samples from patients in Cape Town, South Africa. Extraction/PCR control DNA was detectable in 97% of clinical samples with no statistically significant differences among groups. Despite the inclusion of this control, there was no difference in the amount of TB IS6110 Tr-DNA detected between TB-infected and TB-uninfected groups except for samples from known HIV-infected patients. We found an increase in TB IS6110 Tr-DNA between TB/HIV co-infected patients compared to TB-uninfected/HIV-infected patients (N=18, p=0.037). The inclusion of an extraction/PCR control DNA to indicate successful DNA extraction and removal of PCR inhibitors should be easily adaptable as a sample preparation control for other acellular sample types.

Tuberculosis and the Heart

Owing to the high prevalence of tuberculosis (TB) and human immunodeficiency virus/AIDS, tuberculous heart disease remains an important problem in TB endemic areas. In this review, we reiterate salient aspects of the traditional understanding and approach to its management, and provide important updates on the pathophysiology, diagnosis, and treatment garnered over the past decade of focused clinical and basic science research. We emphasize that, if implemented widely, these improved evidence-based approaches to the disease can build on the early progress made in treating tuberculous heart disease and help further the goal of significantly reducing its historically high morbidity and mortality.

The top-cited systematic reviews/meta-analyses in tuberculosis research: A PRISMA-compliant systematic literature review and bibliometric analysis

BACKGROUND

The top-cited systematic reviews/meta-analyses in tuberculosis research have not been identified. The objective of this study was to identify the 100 top-cited systematic reviews/meta-analyses in tuberculosis research, and to understand factors resulting in highly cited works, and establish trends in systematic reviews/meta-analyses in tuberculosis research.

METHODS

The Web of Science Core Collection was searched for systematic reviews/meta-analyses on tuberculosis up to January 31, 2016. Articles were ranked by citation count and screened by 2 authors. The following information was collected and analyzed from each included study: citation of Web of Science Core Collection, author, country, year, journal, institution, page number, and reference number.

RESULTS

The 100 top-cited studies were cited from 54 to 662 times and were published between 1997 and 2014. Ten authors have more than 1 study as the first author and 10 authors have more than 1 study as corresponding author. The country with the most top-cited studies was USA (n = 26). The institutions with the largest number of the studies were McGill University in Canada (n = 18). The studies were published in 32 journals, whereas 12 were published in PloS Medicine, followed by Lancet Infectious Diseases (n = 11).

CONCLUSIONS

Developed countries and high-impact journals may publish more top-cited systematic review/meta-analysis in tuberculosis research.

Miliary tuberculosis: Epidemiologicaland clinical analysis of large-case series from moderate to low tuberculosis endemic Country

The aim of this study was to determine the clinical features, and outcome of the patients with miliary tuberculosis (TB).We retrospectively evaluated 263 patients (142 male, 121 female, mean age: 44 years, range: 16-89 years) with miliary TB. Criteria for the diagnosis of miliary TB were at least one of the followings in the presence of clinical presentation suggestive of miliary TB such as prolonged fever, night sweats, anorexia, weight loss: radiologic criterion and pathological criterion and/or microbiological criterion; pathological criterion and/or microbiological criterion.The miliary pattern was seen in 88% of the patients. Predisposing factors were found in 41% of the patients. Most frequent clinical features and laboratory findings were fever (100%), fatigue (91%), anorexia (85%), weight loss (66%), hepatomegaly (20%), splenomegaly (19%), choroid tubercules (8%), anemia (86%), pancytopenia (12%), and accelerated erythrocyte sedimentation rate (89%). Tuberculin skin test was positive in 29% of cases. Fifty percent of the patients met the criteria for fever of unknown origin. Acid-fast bacilli were demonstrated in 41% of patients (81/195), and cultures for Mycobacterium tuberculosis were positive in 51% (148/292) of tested specimens (predominantly sputum, CSF, and bronchial lavage). Blood cultures were positive in 20% (19/97). Granulomas in tissue samples of liver, lung, and bone marrow were present in 100% (21/21), 95% (18/19), and 82% (23/28), respectively. A total of 223 patients (85%) were given a quadruple anti-TB treatment. Forty-four (17%) patients died within 1 year after diagnosis established. Age, serum albumin, presence of military pattern, presence of mental changes, and hemoglobin concentration were found as independent predictors of mortality. Fever resolved within first 21 days in the majority (90%) of the cases.Miliary infiltrates on chest X-ray should raise the possibility of miliary TB especially in countries where TB is endemic. Although biopsy of the lungs and liver may have higher yield rate of organ involvement histopathologicaly, less invasive procedures including a bone marrow biopsy and blood cultures should be preferred owing to low complication rates.

Hybrid methodology for tuberculosis incidence time-series forecasting based on ARIMA and a NAR neural network

Tuberculosis (TB) affects people globally and is being reconsidered as a serious public health problem in China. Reliable forecasting is useful for the prevention and control of TB. This study proposes a hybrid model combining autoregressive integrated moving average (ARIMA) with a nonlinear autoregressive (NAR) neural network for forecasting the incidence of TB from January 2007 to March 2016. Prediction performance was compared between the hybrid model and the ARIMA model. The best-fit hybrid model was combined with an ARIMA (3,1,0) × (0,1,1)12 and NAR neural network with four delays and 12 neurons in the hidden layer. The ARIMA-NAR hybrid model, which exhibited lower mean square error, mean absolute error, and mean absolute percentage error of 0·2209, 0·1373, and 0·0406, respectively, in the modelling performance, could produce more accurate forecasting of TB incidence compared to the ARIMA model. This study shows that developing and applying the ARIMA-NAR hybrid model is an effective method to fit the linear and nonlinear patterns of time-series data, and this model could be helpful in the prevention and control of TB.

Essential but Not Vulnerable: Indazole Sulfonamides Targeting Inosine Monophosphate Dehydrogenase as Potential Leads against Mycobacterium tuberculosis

A potent, noncytotoxic indazole sulfonamide was identified by high-throughput screening of >100,000 synthetic compounds for activity against Mycobacterium tuberculosis (Mtb). This noncytotoxic compound did not directly inhibit cell wall biogenesis but triggered a slow lysis of Mtb cells as measured by release of intracellular green fluorescent protein (GFP). Isolation of resistant mutants followed by whole-genome sequencing showed an unusual gene amplification of a 40 gene region spanning from Rv3371 to Rv3411c and in one case a potential promoter mutation upstream of guaB2 (Rv3411c) encoding inosine monophosphate dehydrogenase (IMPDH). Subsequent biochemical validation confirmed direct inhibition of IMPDH by an uncompetitive mode of inhibition, and growth inhibition could be rescued by supplementation with guanine, a bypass mechanism for the IMPDH pathway. Beads containing immobilized indazole sulfonamides specifically interacted with IMPDH in cell lysates. X-ray crystallography of the IMPDH-IMP-inhibitor complex revealed that the primary interactions of these compounds with IMPDH were direct pi-pi interactions with the IMP substrate. Advanced lead compounds in this series with acceptable pharmacokinetic properties failed to show efficacy in acute or chronic murine models of tuberculosis (TB). Time-kill experiments in vitro suggest that sustained exposure to drug concentrations above the minimum inhibitory concentration (MIC) for 24 h were required for a cidal effect, levels that have been difficult to achieve in vivo. Direct measurement of guanine levels in resected lung tissue from tuberculosis-infected animals and patients revealed 0.5-2 mM concentrations in caseum and normal lung tissue. The high lesional levels of guanine and the slow lytic, growth-rate-dependent effect of IMPDH inhibition pose challenges to developing drugs against this target for use in treating TB.

Association between diabetes mellitus and active tuberculosis in Africa and the effect of HIV

OBJECTIVE

To determine current evidence for the association between diabetes and active tuberculosis in Africa, and how HIV modifies, or not, any association between diabetes and active tuberculosis.

METHODS

We conducted a systematic review by searching the EMBASE, Global Health and MEDLINE databases. Studies were eligible for inclusion if they explored the association between diabetes mellitus prevalence and active tuberculosis incidence or prevalence, used a comparison group, were conducted in an African population and adjusted the analysis for at least age. Study characteristics were compared, and risk of bias was assessed. The range of effect estimates was determined for the primary association and for effect modification by HIV.

RESULTS

Three eligible studies were identified: two investigated the primary association and two investigated HIV as a potential effect modifier. All studies were case-control studies, including a combined total of 1958 tuberculosis cases and 2111 non-tuberculosis controls. Diabetes diagnostic methods and analysis strategies varied between studies. Individual study adjusted odds ratios of active tuberculosis for the effect of diabetes mellitus (unstratified) ranged from 0.88 (95% CI 0.17-4.58) to 10.7 (95% CI 4.5-26.0). Individual study P-values for HIV interaction ranged from 0.01 to 0.83. Quantitative synthesis of individual study data was not performed due to heterogeneity between studies.

CONCLUSIONS

Few data currently exist on the association between diabetes and active tuberculosis in Africa, and on the effect of HIV on this association. Existing data are disparate. More regional research is needed to guide policy and practice on the care and control of tuberculosis and diabetes in Africa.

Antituberculosis compounds from a deep-sea-derived fungus Aspergillus sp. SCSIO Ind09F01

Eleven diketopiperazine and fumiquinazoline alkaloids (1-11) together with a tetracyclic triterpenoid helvolic acid (12) were obtained from the cultures of a deep-sea derived fungus Aspergillus sp. SCSIO Ind09F01. The structures of these compounds (1-12) were determined mainly by the extensive NMR, ESIMS spectra data and by comparison with previously described compounds. Besides, anti-tuberculosis, cytotoxic, antibacterial, COX-2 inhibitory and antiviral activities of these compounds were evaluated. Gliotoxin (3), 12,13-dihydroxy-fumitremorgin C (11) and helvolic acid (12) exhibited very strong anti-tuberculosis activity towards Mycobacterium tuberculosis with the prominent MIC₅₀ values of <0.03, 2.41 and 0.894 μM, respectively, which was here reported for the first time. Meanwhile gliotoxin also displayed significant selective cytotoxicities against K562, A549 and Huh-7 cell lines with the IC₅₀ values of 0.191, 0.015 and 95.4 μM, respectively.

Effect of new tuberculosis diagnostic technologies on community-based intensified case finding: a multicentre randomised controlled trial

BACKGROUND

Inadequate case detection results in high levels of undiagnosed tuberculosis in sub-Saharan Africa. Data for the effect of new diagnostic tools when used for community-based intensified case finding are not available, so we investigated whether the use of sputum Xpert-MTB/RIF and the Determine TB LAM urine test in two African communities could be effective.

METHODS

In a pragmatic, randomised, parallel-group trial with individual randomisation stratified by country, we compared sputum Xpert-MTB/RIF, and if HIV-infected, the Determine TB LAM urine test (novel diagnostic group), with laboratory-based sputum smear microscopy (routine diagnostic group) for intensified case finding in communities with high tuberculosis and HIV prevalence in Cape Town, South Africa, and Harare, Zimbabwe. Participants were randomly assigned (1:1) to these groups with computer-generated allocation lists, using culture as the reference standard. In Cape Town, participants were randomised and tested at an Xpert-equipped mobile van, while in Harare, participants were driven to a local clinic where the same diagnostic tests were done. The primary endpoint was the proportion of culture-positive tuberculosis cases initiating tuberculosis treatment in each study group at 60 days. This trial is registered at ClinicalTrials.gov, number NCT01990274.

FINDINGS

Between Oct 18, 2013, and March 31, 2015, 2261 individuals were screened and 875 (39%) of these met the criteria for diagnostic testing. 439 participants were randomly assigned to the novel group and 436 to the routine group. 74 (9%) of 875 participants had confirmed tuberculosis. If late culture-based treatment initiation was excluded, more patients with culture-positive tuberculosis were initiated on treatment in the novel group at 60 days (36 [86%] of 42 in the novel group vs 18 [56%] of 32 in the routine group). Thus the difference in the proportion initiating treatment between groups was 29% (95% CI 9-50, p=0·0047) and 53% more patients initiated therapy in the novel diagnostic group than in the routine diagnostic group. One culture-positive patient was treated based only on a positive LAM test.

INTERPRETATION

Compared with traditional tools, Xpert-MTB/RIF for community-based intensified case finding in HIV and tuberculosis-endemic settings increased the proportion of patients initiating treatment. By contrast, urine LAM testing was not found to be useful for intensive case finding in this setting.

FUNDING

European and Developing Countries Clinical Trials Partnership and South African Medical Research Council.

[A case-series analysis of tuberculosis in pediatric patients treated in a tertiary level hospital]

BACKGROUND

Tuberculosis (TB) remains a challenge because severe forms occur most frequently in children under 5 years of age and the diagnosis is complex. The objective of this paper was to describe the clinical presentation, frequency, diagnostic methods used and response to treatment in children with TB treated at a tertiary level hospital.

METHODS

The study was retrospective and descriptive of a cohort of consecutive cases treated from January 2010 to December 2013. Ninety-three medical records of children diagnosed with TB according to the definition of the NOM-006-SSA2-2013 were reviewed. Descriptive statistics were used for the analysis.

RESULTS

From 93 children, 58% were male (mean age of 7 years), 97% with a history of BCG vaccination, and 6% had contact with a TB case. The most frequent clinical forms were pulmonary (30.1%), lymph node (24.7%), miliary/disseminated (16.1%), meningeal (13%), and osteal TB (7.5%). The most common symptoms were fever and weight loss (50% and 40%, respectively). BAAR and culture were positive in 26% and 7% of all cases, respectively. The histopathological study was conclusive in 90% of the cases. The treatment was successful in 94.6%, with not associated mortality.

CONCLUSIONS

The association of clinical symptoms with alterations in chest radiography and positive PPD are useful in establishing the presumptive diagnosis and an early and appropriate treatment.

Impact of the GeneXpert MTB/RIF Technology on Tuberculosis Control

Molecular technology revolutionized the diagnosis of tuberculosis (TB) with a paradigm shift to faster, more sensitive, clinically relevant patient care. The most recent molecular leader is the GeneXpert MTB/RIF assay (Xpert) (Cepheid, Sunnyvale, CA), which was endorsed by the World Health Organization with unprecedented speed in December 2010 as the initial diagnostic for detection of HIV-associated TB and for where high rates of drug resistance are suspected. South Africa elected to take an aggressive smear replacement approach to facilitate earlier diagnosis and treatment through the decision to implement the Xpert assay nationally in March 2011, against the backdrop of approximately 6.3 million HIV-infected individuals, one of highest global TB and HIV coinfection rates, no available implementation models, uncertainties around field performance and program costs, and lack of guidance on how to operationalize the assay into existing complex clinical algorithms. South Africa's national implementation was conducted as a phased, forecasted, and managed approach (March 2011 to September 2013), through political will and both treasury-funded and donor-funded support. Today there are 314 GeneXperts across 207 microscopy centers; over 8 million assays have been conducted, and South Africa accounts for over half the global test cartridge usage. As with any implementation of new technology, challenges were encountered, both predicted and unexpected. This chapter discusses the challenges and consequences of such large-scale implementation efforts, the opportunities for new innovations, and the need to strengthen health systems, as well as the impact of the Xpert assay on rifampin-sensitive and multidrug-resistant TB patient care that translated into global TB control as we move toward the sustainable development goals.

Towards new TB vaccines: What are the challenges?

New and effective tuberculosis (TB) vaccines are urgently needed to control pulmonary TB, and in particular to prevent the spread of drug-resistant strains of Mycobacterium tuberculosis. These drug-resistant strains can range from those resistant to first-line drugs to those that are almost impossible to treat. To develop new and effective vaccines for HIV and malaria has been difficult and it is proving to be just as challenging for TB. TB is a complicated disease with a spectrum from apparently controlled latent infection to active clinical disease and so different types of preventive or post-exposure vaccine may be needed. Identifying the most promising vaccine candidates to move into clinical trials is difficult, as we lack biomarker signatures that can predict protective efficacy. There is a risk that the failure of the MVA-85A vaccine to show efficacy when given to previously BCG-vaccinated South African infants will impact on the resources available for the development and trials of other candidate TB vaccines. Continued support for the development of new TB vaccines should remain a priority as an effective vaccine would bring huge public health benefits.