Moving toward Tuberculosis Elimination. Critical Issues for Research in Diagnostics and Therapeutics for Tuberculosis Infection

Efficacy of macozinone in mice with genetically diverse susceptibility to Mycobacterium tuberculosis infection

Host heterogeneity in pulmonary tuberculosis leads to varied responses to infection and drug treatment. The present portfolio of anti-TB drugs needs to be boosted with new drugs and drug regimens. Macozinone, a clinical-stage molecule targeting the essential enzyme, DprE1, represents an attractive option. Mice (I/St, B6, (AKRxI/St)F1, B6.I-100 and B6.I-139) genetically diverse susceptibility to Mycobacterium tuberculosis (Mtb) H37Rv infection were subjected to aerosol- or intravenous infection to determine the efficacy of macozinone (MCZ). They were treated with macozinone or reference drugs (isoniazid, rifampicin). Lung and spleen bacterial burdens were measured at four and eight weeks post-infection. Lung histology was evaluated at four weeks of treatment. Treatment with macozinone resulted in a statistically significant reduction in the bacterial load in the lungs and spleen as early as four weeks after treatment initiation in mice susceptible or resistant to Mtb infection. In the TB hypoxic granuloma model, macozinone was more potent than rifampicin in reducing the CFU counts. However, histopathological analysis revealed significant lung changes in I/St mice after eight weeks of treatment initiation. Macozinone demonstrated efficacy to varying degrees across all mouse models of Mtb infection used. These results should facilitate its further development and potential introduction into clinical practice.

Predictors for False-Negative Interferon-Gamma Release Assay Results in Hemodialysis Patients with Latent Tuberculosis Infection

The present study aimed to clinically evaluate the effect of T-cell dysfunction in hemodialysis (HD) patients with latent tuberculosis (TB) infection (LTBI) who were false-negatives in the QuantiFERON-TB Gold In-Tube (QFT-GIT) test. Whole blood samples from a total of 20 active TB patients, 83 HD patients, and 52 healthy individuals were collected, and the QFT-GIT test was used for measuring Mycobacterium tuberculosis (MTB)-specific interferon gamma (IFN-γ) level. The positive rate of the IFN-γ release assays (IGRAs) in HD patients was lower than the negative rate. The mean value of MTB-specific IFN-γ level, which determines the positive rate of the IGRA test, was highest in active TB, followed by HD patients and healthy individuals. Among HD patients, phytohemagglutinin A (PHA)-stimulated IFN-γ levels of approximately 40% were 10.00 IU/mL or less. However, there was no low level of PHA-stimulated IFN-γ in the healthy individuals. This reveals that T-cell function in HD patients was reduced compared to healthy individuals, which leads to the possibility that QFT-GIT results in HD patients are false-negative. The clinical manifestations of TB in patients on HD are quite non-specific, making timely diagnosis difficult and delaying the initiation of curative treatment, delay being a major determinant of outcome.

Uncovering the Mast Cell Response to Mycobacterium tuberculosis

The immunologic mechanisms that contribute to the response to Mycobacterium tuberculosis infection still represent a challenge in the clinical management and scientific understanding of tuberculosis disease. In this scenario, the role of the different cells involved in the host response, either in terms of innate or adaptive immunity, remains key for defeating this disease. Among this coordinated cell response, mast cells remain key for defeating tuberculosis infection and disease. Together with its effector’s molecules, membrane receptors as well as its anatomical locations, mast cells play a crucial role in the establishment and perpetuation of the inflammatory response that leads to the generation of the granuloma during tuberculosis. This review highlights the current evidences that support the notion of mast cells as key link to reinforce the advancements in tuberculosis diagnosis, disease progression, and novel therapeutic strategies. Special focus on mast cells capacity for the modulation of the inflammatory response among patients suffering multidrug resistant tuberculosis or in co-infections such as current COVID-19 pandemic.

Cascade Immune Mechanisms of Protection against Mycobacterium tuberculosis (IMPAc-TB): study protocol for the Household Contact Study in the Western Cape, South Africa

Background

Natural immunity against Mycobacterium tuberculosis exists, and > 90% of those infected remain disease-free. Innate and adaptive immune responses required to mediate such protection against tuberculosis (TB) are, however, poorly understood.

Methods

This is an analytical study exploring protective and non-protective pathways of immunity against Mycobacterium tuberculosis. Adults without HIV infection are recruited at community healthcare clinics in high TB incidence areas of the Western Cape Province, South Africa. Data regarding participants’ medical, social and medication usage will be collected, and clinical examinations and point-of-care tests documented. Reference tests for TB (chest radiographs and sputum tests for GeneXpert MTB/RIF Ultra®, Auramine smear and liquid cultures) and investigations to classify infection states [interferon-gamma release assay (IGRA) and SARS-CoV-2 polymerase chain reaction (PCR) nasopharyngeal swab and IgG], are done on all participants who meet the inclusion criteria. 18F-Fluorodeoxyglucose positron emission tomography combined with computerized tomography will be done on all close contacts (contacts) and healthy control (controls) participants. Participants are divided into 12 study groups representing a spectrum of TB clinical phenotypes and prior SARS-CoV-2 infection based on their TB status, exposure history, results of IGRA test at baseline and 3 months, SARS-CoV-2 serology, and PCR results, and for contacts and controls, PET-CT imaging findings indicative of sub-clinical TB lesions. Samples for experimental assays include whole blood for isolation of peripheral blood mononuclear cells and blood in PAXgene® tubes for RNA isolation. All SARS-CoV-2 PCR negative study participants undergo bronchoscopy for collecting bronchoalveolar lavage samples.

Discussion

The paired blood and BAL samples will be used for comprehensive analyses of the tissue-specific and systemic immunity that will include e.g., cytometry by time-of-flight analyses, RNA-sequencing, multiplex immunoassays, epigenetic analysis, and mechanistic studies of control of infection by Mycobacterium tuberculosis. Results will be integrated with those from mice and non-human primate studies to provide a comprehensive analysis of protective pathways in natural and vaccine-induced immunity against Mycobacterium tuberculosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07349-8.

The pharmacotherapeutic management of pulmonary tuberculosis: an update of the state-of-the-art

INTRODUCTION

Pulmonary tuberculosis (TB) remains an important global health challenge of the 21st century, and the emerging resistance against anti-TB drugs is still a growing concern. And while there was a significant cumulative reduction in the incidence of TB between 2015 and 2019, 2.8% of all TB cases in 2019 were reported to be drug resistant.

AREA COVERED

This review provides the reader with an update on pharmacotherapy for patients with TB susceptible or resistant to drug therapy. The authors also include promising investigational drugs herein. Finally, the authors share with the reader their expert opinions on the current state of the art and their future perspectives.

EXPERT OPINION

The current pharmacotherapeutic management aims to enhance favorable treatment outcomes and reduce treatment-related adverse events. One approach is to use shorter and all-oral regimens for eligible patients. Traditional longer regimens for most patients are also optimized to lower incidence of treatment failure and serious adverse events.

Lymphocyte-Related Immunological Indicators for Stratifying Mycobacterium tuberculosis Infection

Background

Easily accessible tools that reliably stratify Mycobacterium tuberculosis (MTB) infection are needed to facilitate the improvement of clinical management. The current study attempts to reveal lymphocyte-related immune characteristics of active tuberculosis (ATB) patients and establish immunodiagnostic model for discriminating ATB from latent tuberculosis infection (LTBI) and healthy controls (HC).

Methods

A total of 171 subjects consisted of 54 ATB, 57 LTBI, and 60 HC were consecutively recruited at Tongji hospital from January 2019 to January 2021. All participants were tested for lymphocyte subsets, phenotype, and function. Other examination including T-SPOT and microbiological detection for MTB were performed simultaneously.

Results

Compared with LTBI and HC, ATB patients exhibited significantly lower number and function of lymphocytes including CD4⁺ T cells, CD8⁺ T cells and NK cells, and significantly higher T cell activation represented by HLA-DR and proportion of immunosuppressive cells represented by Treg. An immunodiagnostic model based on the combination of NK cell number, HLA-DR⁺CD3⁺ T cells, Treg, CD4⁺ T cell function, and NK cell function was built using logistic regression. Based on receiver operating characteristic curve analysis, the area under the curve (AUC) of the diagnostic model was 0.920 (95% CI, 0.867-0.973) in distinguishing ATB from LTBI, while the cut-off value of 0.676 produced a sensitivity of 81.48% (95% CI, 69.16%-89.62%) and specificity of 91.23% (95% CI, 81.06%-96.20%). Meanwhile, AUC analysis between ATB and HC according to the diagnostic model was 0.911 (95% CI, 0.855-0.967), with a sensitivity of 81.48% (95% CI, 69.16%-89.62%) and a specificity of 90.00% (95% CI, 79.85%-95.34%).

Conclusions

Our study demonstrated that the immunodiagnostic model established by the combination of lymphocyte-related indicators could facilitate the status differentiation of MTB infection.

Lymphocyte Non-Specific Function Detection Facilitating the Stratification of Mycobacterium tuberculosis Infection

Background

Inadequate tuberculosis (TB) diagnostics, especially for discrimination between active TB (ATB) and latent TB infection (LTBI), are major hurdle in the reduction of the disease burden. The present study aims to investigate the role of lymphocyte non-specific function detection for TB diagnosis in clinical practice.

Methods

A total of 208 participants including 49 ATB patients, 64 LTBI individuals, and 95 healthy controls were recruited at Tongji hospital from January 2019 to October 2020. All subjects were tested with lymphocyte non-specific function detection and T-SPOT assay.

Results

Significantly positive correlation existed between lymphocyte non-specific function and phytohemagglutinin (PHA) spot number. CD4⁺ T cell non-specific function showed the potential for differentiating patients with negative T-SPOT results from those with positive T-SPOT results with an area under the curve (AUC) of 0.732 (95% CI, 0.572-0.893). The non-specific function of CD4⁺ T cells, CD8⁺ T cells, and NK cells was found significantly lower in ATB patients than in LTBI individuals. The AUCs presented by CD4⁺ T cell non-specific function, CD8⁺ T cell non-specific function, and NK cell non-specific function for discriminating ATB patients from LTBI individuals were 0.845 (95% CI, 0.767-0.925), 0.770 (95% CI, 0.683-0.857), and 0.691 (95% CI, 0.593-0.789), respectively. Application of multivariable logistic regression resulted in the combination of CD4⁺ T cell non-specific function, NK cell non-specific function, and culture filtrate protein-10 (CFP-10) spot number as the optimally diagnostic model for differentiating ATB from LTBI. The AUC of the model in distinguishing between ATB and LTBI was 0.939 (95% CI, 0.898-0.981). The sensitivity and specificity were 83.67% (95% CI, 70.96%-91.49%) and 90.63% (95% CI, 81.02%-95.63%) with the threshold as 0.57. Our established model showed superior performance to TB-specific antigen (TBAg)/PHA ratio in stratifying TB infection status.

Conclusions

Lymphocyte non-specific function detection offers an attractive alternative to facilitate TB diagnosis. The three-index diagnostic model was proved to be a potent tool for the identification of different events involved in TB infection, which is helpful for the treatment and management of patients.

Combination of prealbumin and tuberculosis-specific antigen/phytohemagglutinin ratio for discriminating active tuberculosis from latent tuberculosis infection

BACKGROUND

Given that there is no rapid and effective method for distinguishing active tuberculosis (ATB) from latent tuberculosis infection (LTBI), the discrimination between these two statuses remains challenging. This study sought to investigate the value of nutritional indexes and tuberculosis-specific antigen/phytohemagglutinin ratio (TBAg/PHA ratio) for distinguishing ATB from LTBI.

METHODS

Participants were consecutively recruited based on positive T-SPOT.TB results between January 2018 and January 2020. ATB was diagnosed by positive mycobacterial culture and/or positive GeneXpert MTB/RIF, with clinical symptoms and radiological characteristics suggestive of ATB. Individuals with positive T-SPOT.TB but without the evidence of ATB were defined as LTBI. Patients younger than 17 years and undergoing anti-TB treatment were excluded.

RESULTS

A total of 709 (312 ATB and 397 LTBI) and another 309 (120 ATB and 189 LTBI) subjects were respectively recruited from Tongji Hospital (Qiaokou cohort) and Sino-French New City Hospital (Caidian cohort). The level of prealbumin was significantly lower in ATB than in LTBI. With a cut-off value of 139 mg/L, the sensitivity and specificity of prealbumin in distinguishing ATB from LTBI were 50.96% (45.41%-56.51%) and 91.69% (88.97%-94.40%). Meanwhile, TBAg/PHA ratio was found statistically higher in ATB compared with LTBI. If using the threshold of 0.29, the sensitivity and specificity of TBAg/PHA ratio were 65.71% (60.44%-70.97%) and 90.93% (88.11%-93.76%), respectively. Moreover, the combination of prealbumin and TBAg/PHA ratio (obtaining by diagnostic model) yielded better specificity (90.18%, [87.25%-93.10%]) and sensitivity (87.18%, [83.47%-90.89%]), while the clinical utility index (CUI) positive and CUI negative were respectively 0.76 and 0.81. After anti-TB treatment, TBAg/PHA ratio was declined while the level of prealbumin was restored (Wilcoxon test, P < 0.001). Furthermore, the performance of diagnostic model obtained in Qiaokou cohort was confirmed in Caidian cohort.

CONCLUSIONS

The diagnostic model based on combination of prealbumin and TBAg/PHA ratio is a rapid and accurate tool for discriminating ATB from LTBI.

Validation of Differentially Expressed Immune Biomarkers in Latent and Active Tuberculosis by Real-Time PCR

Tuberculosis (TB) remains a major global threat and diagnosis of active TB ((ATB) both extra-pulmonary (EPTB), pulmonary (PTB)) and latent TB (LTBI) infection remains challenging, particularly in high-burden countries which still rely heavily on conventional methods. Although molecular diagnostic methods are available, e.g., Cepheid GeneXpert, they are not universally available in all high TB burden countries. There is intense focus on immune biomarkers for use in TB diagnosis, which could provide alternative low-cost, rapid diagnostic solutions. In our previous gene expression studies, we identified peripheral blood leukocyte (PBL) mRNA biomarkers in a non-human primate TB aerosol-challenge model. Here, we describe a study to further validate select mRNA biomarkers from this prior study in new cohorts of patients and controls, as a prerequisite for further development. Whole blood mRNA was purified from ATB patients recruited in the UK and India, LTBI and two groups of controls from the UK (i) a low TB incidence region (CNTRLA) and (ii) individuals variably-domiciled in the UK and Asia ((CNTRLB), the latter TB high incidence regions). Seventy-two mRNA biomarker gene targets were analyzed by qPCR using the Roche Lightcycler 480 qPCR platform and data analyzed using GeneSpring™ 14.9 bioinformatics software. Differential expression of fifty-three biomarkers was confirmed between MTB infected, LTBI groups and controls, seventeen of which were significant using analysis of variance (ANOVA): CALCOCO2, CD52, GBP1, GBP2, GBP5, HLA-B, IFIT3, IFITM3, IRF1, LOC400759 (GBP1P1), NCF1C, PF4V1, SAMD9L, S100A11, TAF10, TAPBP, and TRIM25. These were analyzed using receiver operating characteristic (ROC) curve analysis. Single biomarkers and biomarker combinations were further assessed using simple arithmetic algorithms. Minimal combination biomarker panels were delineated for primary diagnosis of ATB (both PTB and EPTB), LTBI and identifying LTBI individuals at high risk of progression which showed good performance characteristics. These were assessed for suitability for progression against the standards for new TB diagnostic tests delineated in the published World Health Organization (WHO) technology product profiles (TPPs).

Serum Procalcitonin Levels Predict Mortality Risk in Patients With Pulmonary Tuberculosis: A Single-Center Prospective Observational Study

Globally, tuberculosis is the leading infectious cause of death; discovering biomarkers that predict a high mortality risk may improve treatment outcomes. We prospectively enrolled 252 pulmonary tuberculosis patients who were not coinfected with human immunodeficiency virus and initiated antituberculosis treatment, measured serum procalcitonin levels (PCT), and assessed mortality risk. PCT serum levels higher than 0.13 (day 0), 0.05 (day 7), 0.12 (day 14), or 0.06 (day 28) ng/mL predicted nonsurvivors with odds ratios of 7.9, 14.3, 20.0, and 7.3, respectively (P ≤ .005 for all), respectively. Therefore, serum PCT levels are a promising mortality risk indicator for patients with pulmonary tuberculosis. Main Point. For patients with pulmonary tuberculosis, a promising mortality risk indicator is the level of serum procalcitonin, which is weakly associated with sputum bacterial load and independent of radiographic findings.

Toward patient-centered tuberculosis preventive treatment: preferences for regimens and formulations in Lima, Peru

BACKGROUND

To ensure patient-centered tuberculosis preventive treatment, it is important to consider factors that make it easier for patients to complete treatment. However, there is little published literature about patient preferences for different preventive treatment regimen options, particularly from countries with high tuberculosis burdens.

METHODS

We conducted a qualitative research study using a framework analysis approach to understand tuberculosis preventive treatment preferences among household contacts. We conducted three focus group discussions with 16 members of families affected by tuberculosis in Lima, Peru. Participants were asked to vote for preferred preventive treatment regimens and discuss the reasons behind their choices. Coding followed a deductive approach based on prior research, with data-driven codes added.

RESULTS

In total, 7 (44%) participants voted for 3 months isoniazid and rifapentine, 4 (25%) chose 3 months isoniazid and rifampicin, 3 (19%) chose 4 months rifampicin, and 2 (13%) chose 6 months isoniazid. Preferences for shorter regimens over 6 months of isoniazid were driven by concerns over "getting tired" or "getting bored" of taking medications, the difficulty of remembering to take medications, side effects, and interference with daily life. For some, weekly dosing was perceived as being easier to remember and less disruptive, leading to a preference for 3 months isoniazid and rifapentine, which is dosed weekly. However, among caregivers, having a child-friendly formulation was more important than regimen duration. Caregivers reported difficulty in administering pills to children, and preferred treatments available as syrup or dispersible formulations.

CONCLUSIONS

There is demand for shorter regimens and child-friendly formulations for tuberculosis preventive treatment in high-burden settings. Individual preferences differ, suggesting that patient-centered care would best be supported by having multiple shorter regimens available.

A sensitive EZMTT method provides microscale, quantitative and high-throughput evaluation of drug efficacy in the treatment of Mycobacterium tuberculosis infectious diseases

Drug resistance has become a serious public health problem in mycobacterial infectious diseases. Here, we investigated a water soluble tetrazolium salt (EZMTT)-based detection method to provide an easy, safe and quantitative antimycobacterial susceptibility test (AMST) method, especially for targeting early detection of loss of drug susceptibility in mycobacteria. After a single addition of the EZMTT detection reagent at the inoculation of mycobacteria culture, the AMST was continuously analyzed in a sealed 96-well plate (100 μl), or a sealed tube to ensure biosafety. Using Mycobacterium tuberculosis H37Ra as the model strain, the EZMTT assay was developed with high reproducibility (Z factor of 0.64) for facile measurements of growth and drug susceptibility. In the comparative AMST study, the 7-day EZMTT method identified not only the same set of drug resistance as the other two methods (the 30-day traditional Löwenstein Jensen solid medium assay and the 10-14 day 8 ml Mycobacteria Growth Indicator Tube liquid method), but also additional strains with loss of drug susceptibility. In conclusion, we demonstrated that the EZMTT-based AMST assay in a sealed microtiter plate has great potential for routine use in medical diagnosis and drug screening to battle the unmet medical need in the treatment of multi- and extensive-drug resistant mycobacteria.

Blood RNA signatures predict recent tuberculosis exposure in mice, macaques and humans

Tuberculosis (TB) is the leading cause of death due to a single infectious disease. Knowing when a person was infected with Mycobacterium tuberculosis (M.tb) is critical as recent infection is the strongest clinical risk factor for progression to TB disease in immunocompetent individuals. However, time since M.tb infection is challenging to determine in routine clinical practice. To define a biomarker for recent TB exposure, we determined whether gene expression patterns in blood RNA correlated with time since M.tb infection or exposure. First, we found RNA signatures that accurately discriminated early and late time periods after experimental infection in mice and cynomolgus macaques. Next, we found a 6-gene blood RNA signature that identified recently exposed individuals in two independent human cohorts, including adult household contacts of TB cases and adolescents who recently acquired M.tb infection. Our work supports the need for future longitudinal studies of recent TB contacts to determine whether biomarkers of recent infection can provide prognostic information of TB disease risk in individuals and help map recent transmission in communities.

Diagnostic Accuracy of T-SPOT.TB Assay for Tuberculous Meningitis: An Updated Meta-Analysis

Background: The role of T-SPOT.TB (T-SPOT) assay for tuberculous meningitis (TBM) diagnosis has not been fully assessed. Here, we conducted an updated meta-analysis to evaluate the diagnostic accuracy of peripheral blood (PB) T-SPOT and cerebrospinal fluid (CSF) T-SPOT for diagnosing TBM. Methods: Relevant studies in the PubMed database, EmBase database, Cochrane database, Scopus database, Google Scholar, China National Knowledge Internet, and Wan-Fang database were retrieved from August 1, 2005, to June 22, 2020. Statistical analysis was performed using Stata, Revman, and Meta-Disc software. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), summary receiver operating characteristic curves, and the area under the curve were determined and analyzed. Results: A total of 27 studies were eligible for inclusion within the meta-analysis. The pooled sensitivity and specificity of PB T-SPOT for TBM diagnosis were 0.78 (95% CI, 0.76-0.81) and 0.68 (95% CI, 0.66-0.71), respectively, whereas the pooled PLR, NLR, and DOR were 2.80 (95% CI, 2.29-3.42), 0.32 (95% CI, 0.27-0.38), and 10.08 (95% CI, 7.21-14.08), respectively. On the other hand, the pooled sensitivity and specificity of CSF T-SPOT on diagnosing TBM were 0.76 (95% CI, 0.72-0.80) and 0.88 (95% CI, 0.85-0.90), respectively, whereas the pooled PLR, NLR, and DOR were 5.92 (95% CI, 4.25-8.25), 0.28 (95% CI, 0.21-0.39), and 29.05 (95% CI, 16.40-51.45), respectively. The area under the summary receiver operating characteristic curve values of PB T-SPOT and CSF T-SPOT for TBM diagnosis were 0.83 (95% CI, 0.80-0.86) and 0.92 (95% CI, 0.89-0.94), respectively. Conclusions: CSF T-SPOT showed a higher specificity compared with PB T-SPOT for diagnosing TBM. Both two T-SPOT assays have considerable potential in improving the diagnosis of TBM. Furthermore, the standardization of the operating procedure is further needed when performing CSF T-SPOT.

Latent Tuberculosis and HIV Infection

Purpose of Review

Tuberculosis is the number one infectious killer of people with HIV worldwide, but it can be both prevented and treated. Prevention of tuberculosis by screening for and treating latent tuberculosis infection (LTBI), along with the initiation of antiretroviral therapy (ART), is the key component of HIV care.

Recent Findings

While access to ART has increased worldwide, uptake and completion of LTBI treatment regimens among people living with HIV (PWH) are very poor. Concomitant TB-preventive therapy and ART are complex because of drug–drug interactions, but these can be managed. Recent clinical trials of shorter preventive regimens have demonstrated safety and efficacy in PWH with higher completion rates. More research is needed to guide TB-preventive therapy in children and in pregnant women, and for drug-resistant TB (DR-TB).

Summary

Antiretroviral therapy and tuberculosis-preventive treatment regimens can be optimized to avoid drug–drug interactions, decrease pill burden and duration, and minimize side effects in order to increase adherence and treatment completion rates among PWH and LTBI.

Risk-benefit analysis of tuberculosis infection testing for household contact management in high-burden countries: a mathematical modelling study

BACKGROUND

Preventive therapy for tuberculosis reduces the risk of disease in people who have been infected but who are not sick. Countries with a high burden of tuberculosis that are expanding preventive therapy use must decide how tuberculosis infection testing should be used for risk stratification among household contacts of patients with tuberculosis.

METHODS

We modelled the risks of tuberculosis disease and severe adverse events, comparing the following two preventive therapy strategies: preventive therapy for all household contacts, or preventive therapy for only household contacts with a positive tuberculin skin test (TST) result. We used data from clinical trials and literature on tuberculosis natural history to model outcomes, assuming different preventive therapy regimens, ages, and TST positivity prevalence.

FINDINGS

Assuming 25% prevalence of TST positivity among 1000 household contacts aged 0-17 years, a treat-all approach with isoniazid and rifapentine compared with a treat-TST-only approach led to 13 fewer incident tuberculosis cases (IQR -5 to -18) and four additional severe adverse events (2 to 6). With rifampicin, the difference was 11 fewer incident tuberculosis cases (-3 to -17) and two additional severe adverse events (1 to 3). For adults, a treat-all approach led to fewer incident tuberculosis cases, and additional adverse events increased with age. Assuming 25% prevalence of TST positivity among adult contacts, a treat-all approach would lead to around two fewer tuberculosis cases per 1000 contacts for all regimens; the number of additional severe adverse events ranged from seven (IQR 5 to 8) for 18 to 34-year-olds treated with rifampicin to 63 (50 to 74) for people older than 64 years treated with isoniazid and rifapentine. A rifampicin-only regimen was associated with the fewest additional severe adverse events (seven [IQR 5 to 8] per 1000 adults aged 18-34 years and 35-64 years, and 17 [9 to 23] per 1000 adults older than 64 years).

INTERPRETATION

Based on the available data, giving preventive therapy to all household contacts would probably reduce the incidence of tuberculosis cases in high-burden settings. Adverse events could be minimised by using non-isoniazid regimens and, in adults older than 18 years, focusing treatment on individuals with a positive infection test.

FUNDING

Bill & Melinda Gates Foundation, UK Medical Research Council, and UK Department for International Development.

Phenazine Antibiotic-Inspired Discovery of Bacterial Biofilm-Eradicating Agents

Bacterial biofilms are surface-attached communities of slow-growing and non-replicating persister cells that demonstrate high levels of antibiotic tolerance. Biofilms occur in nearly 80 % of infections and present unique challenges to our current arsenal of antibiotic therapies, all of which were initially discovered for their abilities to target rapidly dividing, free-floating planktonic bacteria. Bacterial biofilms are credited as the underlying cause of chronic and recurring bacterial infections. Innovative approaches are required to identify new small molecules that operate through bacterial growth-independent mechanisms to effectively eradicate biofilms. One source of inspiration comes from within the lungs of young cystic fibrosis (CF) patients, who often endure persistent Staphylococcus aureus infections. As these CF patients age, Pseudomonas aeruginosa co-infects the lungs and utilizes phenazine antibiotics to eradicate the established S. aureus infection. Our group has taken a special interest in this microbial competition strategy and we are investigating the potential of phenazine antibiotic-inspired compounds and synthetic analogues thereof to eradicate persistent bacterial biofilms. To discover new biofilm-eradicating agents, we have established an interdisciplinary research program involving synthetic medicinal chemistry, microbiology and molecular biology. From these efforts, we have identified a series of halogenated phenazines (HPs) that potently eradicate bacterial biofilms, and future work aims to translate these preliminary findings into ground-breaking clinical advances for the treatment of persistent biofilm infections.