A randomised double blind placebo controlled phase 2 trial of adjunctive aspirin for tuberculous meningitis in HIV-uninfected adults

Pre-treatment untargeted cerebrospinal fluid metabolomic profiling in tuberculous meningitis uncovers pathways associated with mortality

BACKGROUND

Dysregulation of cerebrospinal fluid (CSF) tryptophan metabolism contributes to the high mortality of tuberculous meningitis (TBM). We aimed to identify novel metabolic pathways associated with TBM mortality through untargeted metabolome-wide analysis.

METHODS

We measured 619 metabolites using untargeted liquid chromatography-mass spectrometry in pre-treatment CSF from adults with TBM from Indonesia (n = 388, 34 HIV positive) and Vietnam (n = 679, 250 HIV positive). Sixty-day mortality was modeled using Cox regression, adjusting for age and HIV status. Metabolites were ranked in a screening subset (n = 194, Indonesia) and validated in the same cohort (n = 194) and externally (n = 679, Vietnam). Secondary analysis included variable selection, clustering to classify associated metabolites into subgroups, comparison with non-infectious controls, and correlation with patient characteristics, CSF cytokines, CSF protein, and serum metabolite concentrations.

FINDINGS

Sixty-day mortality was 21.6% and was associated with the concentration of 10 CSF metabolites, including tryptophan. The strongest association was with 3-hydroxyoctanoate (FA 8:0;3OH), part of a cluster of hydroxylated fatty acids also including hydroxy-isocaproate (FA 6:0;OH), hydroxyisobutyrate (FA 4:0;OH), and C4-OH-carnitine. These fatty acids correlated weakly with CSF tumor necrosis factor alpha, interleukin-6 (IL-6), leukocyte counts, bacterial load, and CSF protein. Mediation analysis showed that the variation in fatty acids was linked directly to mortality rather than through disease severity.

CONCLUSION

We identified and validated nine new metabolites associated with TBM mortality, independent of HIV status, disease severity, and tryptophan. These metabolites suggest that altered fatty acid β-oxidation is linked to TBM-associated mortality. Interventions targeting cerebral fatty acid metabolism may improve survival of TBM.

FUNDING

National Institute of Health; Wellcome Trust, UK.

Host-Directed Therapies Based on Protease Inhibitors to Control Mycobacterium tuberculosis and HIV Coinfection

Despite continuous and extensive global efforts in the fight against tuberculosis (TB), this infectious disease continues to exert a tremendous burden on public health concerns and deaths worldwide. TB, caused by the bacterial species Mycobacterium tuberculosis, is highly frequent in people living with HIV. The continuing epidemics of both chronic infections and the emergence of antimicrobial resistance, as well as the lack of effective diagnostic tools and drug-drug interactions, pose major challenges in the fight against these pathogens. Developing a wide range of host-directed therapies may improve treatment outcomes, helping alleviate the morbidity and mortality associated with both infections. In this review, we discuss the identification and development of new host-directed strategies based on protease inhibitors and their clinical relevance as adjunctive treatment. In the context of therapeutic agents with novel mechanisms, selective protease inhibitors, including saquinavir (SQV) and cystatins (CstC and CstF), are valuable targets that may provide effective therapeutic solutions for controlling Mtb and HIV coinfection.

Host-directed therapy for tuberculosis

Current TB treatment regimens are hindered by drug resistance, numerous adverse effects, and long treatment durations, highlighting the need for 'me-better' treatment regimens. Host-directed therapy (HDT) has gained recognition as a promising approach in TB treatment. It allows the repurposing of existing drugs approved for other conditions and aims to enhance the effectiveness of existing anti-TB therapies, minimize drug resistance, decrease treatment duration, and adverse effects. By modulating the host immune response, HDT ameliorates immunopathological damage and improves overall outcomes by promoting autophagy, antimicrobial peptide production, and other mechanisms. It holds promise for addressing the challenges posed by multiple and extensively drug-resistant Mycobacterium tuberculosis strains, which are increasingly difficult to treat using conventional therapies. This article reviews various HDT candidates, including repurposed drugs, explores their underlying mechanisms such as autophagy promotion and inflammation reduction, while emphasizing their potential to improve TB treatment outcomes and outlining future research directions.

Effectiveness and safety of shortened intensive treatment for children with tuberculous meningitis (SURE): a protocol for a phase 3 randomised controlled trial evaluating 6 months of antituberculosis therapy and 8 weeks of aspirin in Asian and African children with tuberculous meningitis

INTRODUCTION

Childhood tuberculous meningitis (TBM) is a devastating disease. The long-standing WHO recommendation for treatment is 2 months of intensive phase with isoniazid (H), rifampicin (R), pyrazinamide (Z) and ethambutol (E), followed by 10 months of isoniazid and rifampicin. In 2022, WHO released a conditional recommendation that 6 months of intensified antituberculosis therapy (ATT) could be used as an alternative for drug-susceptible TBM. However, this has never been evaluated in a randomised clinical trial. Trials evaluating ATT shortening regimens using high-dose rifampicin and drugs with better central nervous system penetration alongside adjuvant anti-inflammatory therapy are needed to improve outcomes.

METHODS AND ANALYSIS

The Shortened Intensive Therapy for Children with Tuberculous Meningitis (SURE) trial is a phase 3, randomised, partially blinded, factorial trial being conducted in Asia (India and Vietnam) and Africa (Uganda, Zambia and Zimbabwe). It is coordinated by the Medical Research Council Clinical Trial Unit at University College London (MRCCTU at UCL). 400 children (aged 29 days to <18 years) with clinically diagnosed TBM will be randomised, using a factorial design, to either a 24-week intensified regimen (isoniazid (20 mg/kg), rifampicin (30 mg/kg), pyrazinamide (40 mg/kg) and levofloxacin (20 mg/kg)) or the standard 48-week ATT regimen and 8 weeks of high-dose aspirin or placebo. The primary outcome for the first randomisation is all-cause mortality, and for the second randomisation is the paediatric modified Rankin Scale (mRS), both at 48 weeks. Nested substudies include pharmacokinetics, pharmacogenetics, pathophysiology, diagnostics and prognostic biomarkers, in-depth neurodevelopmental outcomes, MRI and health economics.

ETHICS AND DISSEMINATION

Local ethics committees at all participating study sites and respective regulators approved the SURE protocol. Ethics approval was also obtained from UCL, UK (14935/001). Informed consent from parents/carers and assent from age-appropriate children are required for all participants. Results will be published in international peer-reviewed journals, and appropriate media will be used to summarise results for patients and their families and policymakers.

TRIAL REGISTRATION

ISRCTN40829906 (registered 13 November 2018).

Tuberculous meningitis-related ischemic stroke: A retrospective study from a tertiary care hospital

Background

Patients with tuberculous meningitis (TBM) are at high risk of ischemic stroke, and stroke is a poor prognosticator of TBM. However, reports regarding the predictors of stroke in TBM patients are scanty. The aim of this study was to investigate the clinical characteristics and predictors of tuberculous meningitis-related ischemic stroke (TBMRIS).

Methods

This retrospective study was conducted among TBM patients without traditional vascular risk factors from a tertiary care hospital between January 2017 and November 2022. Patients were divided into TBMRIS group and TBM-only group according to presence of stroke. Clinical, laboratory and radiological variables were compared between the two groups. Predictors of stroke were identified using binary logistic regression analysis.

Results

A total of 176 TBM patients were included in the study. Forty-nine patients with stroke were classified as TBMRIS group and 127 patients without stroke were classified as TBM-only group. In TBMRIS group, 41 (83.7 %) patients experienced stroke within 3 months after the onset of meningitis symptoms and 10 (20.4 %) patients presented silent stroke. Stroke occurred in basal ganglia in 57.1 % of patients. About 73.5 % of patients showed multiple stroke lesions and 38.8 % of patients had stroke involving multiple vascular territories. There were significant differences in focal neurological deficit, stage of meningitis, short-term outcome, serum sodium, cerebrospinal fluid (CSF) white cell count, CSF adenosine deaminase (ADA), CSF protein, leptomeningeal enhancement, tuberculoma between TBMRIS group and TBM-only group. Binary logistic regression analysis revealed that focal neurological deficit, CSF white cell count and leptomeningeal enhancement were the independent risk factors for stroke, and tuberculoma was negatively correlated with stroke.

Conclusion

Most of TBMRIS develop within 3 months after the onset of meningitis symptoms and basal ganglia is the most frequent site. Multiple stroke lesions and involvement of multiple vascular territories are commonly observed. Focal neurological deficit, CSF white cell count and leptomeningeal enhancement are the predictors of stroke in patients with TBM.

Tuberculous meningitis diagnosis and treatment: classic approaches and high-throughput pathways

Tuberculous meningitis (TBM), a severe form of non-purulent meningitis caused by Mycobacterium tuberculosis (Mtb), is the most critical extrapulmonary tuberculosis (TB) manifestation, with a 30-40% mortality rate despite available treatment. The absence of distinctive clinical symptoms and effective diagnostic tools complicates early detection. Recent advancements in nucleic acid detection, genomics, metabolomics, and proteomics have led to novel diagnostic approaches, improving sensitivity and specificity. This review focuses on nucleic acid-based methods, including Xpert Ultra, metagenomic next-generation sequencing (mNGS), and single-cell sequencing of whole brain Tissue, alongside the diagnostic potential of metabolomic and proteomic biomarkers. By evaluating the technical features, diagnostic accuracy, and clinical applicability, this review aims to inform the optimization of TBM diagnostic strategies and explores the integration and clinical translation of multi-omics technologies.

Advancing the chemotherapy of tuberculous meningitis: a consensus view

Tuberculous meningitis causes death or disability in approximately 50% of affected individuals and kills approximately 78 200 adults every year. Antimicrobial treatment is based on regimens used for pulmonary tuberculosis, which overlooks important differences between lung and brain drug distributions. Tuberculous meningitis has a profound inflammatory component, yet only adjunctive corticosteroids have shown clear benefit. There is an active pipeline of new antitubercular drugs, and the advent of biological agents targeted at specific inflammatory pathways promises a new era of improved tuberculous meningitis treatment and outcomes. Yet, to date, tuberculous meningitis trials have been small, underpowered, heterogeneous, poorly generalisable, and have had little effect on policy and practice. Progress is slow, and a new approach is required. In this Personal View, a global consortium of tuberculous meningitis researchers articulate a coordinated, definitive way ahead via globally conducted clinical trials of novel drugs and regimens to advance treatment and improve outcomes for this life-threatening infection.

Repurposed Drugs and Plant-Derived Natural Products as Potential Host-Directed Therapeutic Candidates for Tuberculosis

Tuberculosis (TB) is one of the leading causes of death due to infectious disease. It is a treatable disease; however, conventional treatment requires a lengthy treatment regimen with severe side effects, resulting in poor compliance among TB patients. Intermittent drug use, the non-compliance of patients, and prescription errors, among other factors, have led to the emergence of multidrug-resistant TB, while the mismanagement of multidrug-resistant TB (MDR-TB) has eventually led to the development of extensively drug-resistant tuberculosis (XDR-TB). Thus, there is an urgent need for new drug development, but due to the enormous expenses and time required (up to 20 years) for new drug research and development, new therapeutic approaches to TB are required. Host-directed therapies (HDT) could be a most attractive strategy, as they target the host defense processes instead of the microbe and thereby may prevent the alarming rise of MDR- and XDR-TB. This paper reviews the progress in HDT for the treatment of TB using repurposed drugs which have been investigated in clinical trials (completed or ongoing) and plant-derived natural products that are in clinical or preclinical trial stages. Additionally, this review describes the existing challenges to the development and future research directions in the implementation of HDT.

Spatially heterogeneous lipid dysregulation in tuberculous meningitis

Tuberculous (TB) meningitis is the deadliest form of extrapulmonary TB which disproportionately affects children and immunocompromised individuals. Studies in pulmonary TB have shown that Mycobacterium tuberculosis can alter host lipid metabolism to evade the immune system. Cholesterol lowering drugs (i.e., statins) reduce the risk of infection, making them a promising host-directed therapy in pulmonary TB. However, the effect of M. tuberculosis infection on the young or adult brain lipidome has not been studied. The brain is the second-most lipid-rich organ, after adipose tissue, with a temporally and spatially heterogeneous lipidome that changes from infancy to adulthood. The young, developing brain in children may be uniquely vulnerable to alterations in lipid composition and homeostasis, as perturbations in cholesterol metabolism can cause developmental disorders leading to intellectual disabilities. To begin to understand the alterations to the brain lipidome in pediatric TB meningitis, we utilized our previously published young rabbit model of TB meningitis and applied mass spectrometry (MS) techniques to elucidate spatial differences. We used matrix assisted laser desorption/ionization-MS imaging (MALDI-MSI) and complemented it with region-specific liquid chromatography (LC)-MS/MS developed to identify and quantify sterols and oxysterols difficult to identify by MALDI-MSI. MALDI-MSI revealed several sphingolipids, glycerolipids and glycerophospholipids that were downregulated in brain lesions. LC-MS/MS revealed the downregulation of cholesterol, several sterol intermediates along the cholesterol biosynthesis pathway and enzymatically produced oxysterols as a direct result of M. tuberculosis infection. However, oxysterols produced by oxidative stress were increased in brain lesions. Together, these results demonstrate significant spatially regulated brain lipidome dysregulation in pediatric TB meningitis.

Critical illness due to infection in people living with HIV

People living with HIV comprise a substantial number of the patients admitted to intensive care. This number varies according to geography, but all areas of the world are affected. In lower-income and middle-income countries, the majority of intensive care unit (ICU) admissions relate to infections, whereas in high-income countries, they often involve HIV-associated non-communicable diseases diagnoses. Management of infections potentially resulting in admission to the ICU in people living with HIV include sepsis, respiratory infections, COVID-19, cytomegalovirus infection, and CNS infections, both opportunistic and non-opportunistic. It is crucial to know which antiretroviral therapy (ART) is appropriate, when is the correct time to administer it, and to be aware of any safety concerns and potential drug interactions with ART. Although ART is necessary for controlling HIV infections, it can also cause difficulties relevant to the ICU such as immune reconstitution inflammatory syndrome, and issues associated with ART administration in patients with gastrointestinal dysfunction on mechanical ventilation. Managing infection in people with HIV in the ICU is complex, requiring collaboration from a multidisciplinary team knowledgeable in both the management of the specific infection and the use of ART. This team should include intensivists, infectious disease specialists, pharmacists, and microbiologists to ensure optimal outcomes for patients.

Potential of Neuroinflammation-Modulating Strategies in Tuberculous Meningitis: Targeting Microglia

Tuberculous meningitis (TBM) is the most severe complication of tuberculosis (TB) and is associated with high rates of disability and mortality. Mycobacterium tuberculosis (M. tb), the infectious agent of TB, disseminates from the respiratory epithelium, breaks through the blood-brain barrier, and establishes a primary infection in the meninges. Microglia are the core of the immune network in the central nervous system (CNS) and interact with glial cells and neurons to fight against harmful pathogens and maintain homeostasis in the brain through pleiotropic functions. However, M. tb directly infects microglia and resides in them as the primary host for bacillus infections. Largely, microglial activation slows disease progression. The non-productive inflammatory response that initiates the secretion of pro-inflammatory cytokines and chemokines may be neurotoxic and aggravate tissue injuries based on damages caused by M. tb. Host-directed therapy (HDT) is an emerging strategy for modulating host immune responses against diverse diseases. Recent studies have shown that HDT can control neuroinflammation in TBM and act as an adjunct therapy to antibiotic treatment. In this review, we discuss the diverse roles of microglia in TBM and potential host-directed TB therapies that target microglia to treat TBM. We also discuss the limitations of applying each HDT and suggest a course of action for the near future.

Recent advances in understanding the human host immune response in tuberculous meningitis

Tuberculous meningitis (TBM), the most severe form of tuberculosis, causes death in approximately 25% cases despite antibiotic therapy, and half of survivors are left with neurological disability. Mortality and morbidity are contributed to by a dysregulated immune response, and adjunctive host-directed therapies are required to modulate this response and improve outcomes. Developing such therapies relies on improved understanding of the host immune response to TBM. The historical challenges in TBM research of limited in vivo and in vitro models have been partially overcome by recent developments in proteomics, transcriptomics, and metabolomics, and the use of these technologies in nested substudies of large clinical trials. We review the current understanding of the human immune response in TBM. We begin with M. tuberculosis entry into the central nervous system (CNS), microglial infection and blood-brain and other CNS barrier dysfunction. We then outline the innate response, including the early cytokine response, role of canonical and non-canonical inflammasomes, eicosanoids and specialised pro-resolving mediators. Next, we review the adaptive response including T cells, microRNAs and B cells, followed by the role of the glutamate-GABA neurotransmitter cycle and the tryptophan pathway. We discuss host genetic immune factors, differences between adults and children, paradoxical reaction, and the impact of HIV-1 co-infection including immune reconstitution inflammatory syndrome. Promising immunomodulatory therapies, research gaps, ongoing challenges and future paths are discussed.

Advancing Diagnosis and Treatment in People Living with HIV and Tuberculosis Meningitis

PURPOSE OF REVIEW

Tuberculous meningitis (TBM) is the most severe form of tuberculosis. Inadequate diagnostic testing and treatment regimens adapted from pulmonary tuberculosis without consideration of the unique nature of TBM are among the potential drivers. This review focuses on the progress being made in relation to both diagnosis and treatment of TBM, emphasizing promising future directions.

RECENT FINDINGS

The molecular assay GeneXpert MTB/Rif Ultra has improved sensitivity but has inadequate negative predictive value to "rule-out" TBM. Evaluations of tests focused on the host response and bacterial components are ongoing. Clinical trials are in progress to explore the roles of rifampin, fluoroquinolones, linezolid, and adjunctive aspirin. Though diagnosis has improved, novel modalities are being explored to improve the rapid diagnosis of TBM. Multiple ongoing clinical trials may change current therapies for TBM in the near future.

Tweaking host immune responses for novel therapeutic approaches against Mycobacterium tuberculosis

In TB, combat between the human host and Mycobacterium tuberculosis involves intricate interactions with immune cells. M. tuberculosis has evolved a complex evasion system to circumvent immune cells, leading to persistence and limiting its clearance by the host. Host-directed therapies are emerging approaches to modulate host responses, including inflammatory responses, cytokine responses, and autophagy, by using small molecules to curb mycobacterial infections. Targeting host immune pathways reduces the chances of antibiotic resistance to M. tuberculosis because, unlike antibiotics, this approach acts directly on the cells of the host. In this review, we discuss the role of immune cells during M. tuberculosis proliferation, provide a updated understanding of immunopathogenesis, and explore the range of host-modulating options for the clearance of this pathogen.

SMA-TB: study protocol for the phase 2b randomized double-blind, placebo-controlled trial to estimate the potential efficacy and safety of two repurposed drugs, acetylsalicylic acid and ibuprofen, for use as adjunct therapy added to, and compared with, the standard WHO recommended TB regimen

BACKGROUND

The duration and regimen of tuberculosis (TB) treatment is currently based predominantly on whether the M. tuberculosis (Mtb) strain is drug-sensitive (DS) or multidrug-resistant (MDR) with doses adjusted by patients' weight only. The systematic stratification of patients for personalized treatment does not exist for TB. As each TB case is different, individualized treatment regimens should be applied to obtain better outcomes. In this scenario, novel therapeutic approaches are urgently needed to (1) improve outcomes and (2) shorten treatment duration, and host-directed therapies (HDT) might be the best solution. Within HDT, repurposed drugs represent a shortcut in drug development and can be implemented at the short term. As hyperinflammation is associated with worse outcomes, HDT with an anti-inflammatory effect might improve outcomes by reducing tissue damage and thus the risk of permanent sequelae.

METHODS

SMA-TB is a multicentre randomized, phase IIB, placebo-controlled, three-arm, double-blinded clinical trial (CT) that has been designed in the context of the EC-funded SMA-TB Project ( www.smatb.eu ) in which we propose to use 2 common non-steroidal anti-inflammatory drugs (NSAID), acetylsalicylic acid (ASA) and ibuprofen (Ibu), as an HDT for use as adjunct therapy added to, and compared with, the standard of care (SoC) World Health Organization (WHO)-recommended TB regimen in TB patients. A total of 354 South African and Georgian adults diagnosed with confirmed pulmonary TB will be randomized into SoC TB treatment + placebo, SoC + acetylsalicylic acid or SoC + ibuprofen.

DISCUSSION

SMA-TB will provide proof of concept of the HDT as a co-adjuvant treatment and identify the suitability of the intervention for different population groups (different epidemiological settings and drug susceptibility) in the reduction of tissue damage and risk of bad outcomes for TB patients. This regimen potentially will be more effective and targeted: organ saving, reducing tissue damage and thereby decreasing the length of treatment and sequelae, increasing cure rates and pathogen clearance and decreasing transmission rates. It will result in better clinical practice, care management and increased well-being of TB patients.

TRIAL REGISTRATION

Clinicaltrials.gov NCT04575519. Registered on October 5, 2020.

The effect of antithrombotic treatment on mortality in patients with acute infection: A meta-analysis of randomized clinical trials

BACKGROUND AND AIMS

Acute infections cause relevant activation of innate immunity and inflammatory cascade. An excessive response against pathogens has been proved to trigger the pathophysiological process of thrombo-inflammation. Nevertheless, an association between the use of antithrombotic agents and the outcome of critically ill patients with infectious diseases is lacking. The aim of this meta-analysis is to determine the impact of antithrombotic treatment on survival of patients with acute infective disease.

METHODS

MEDLINE, Embase, Cinahl, Web of Science and Cochrane Central Register of Controlled Trials (CENTRAL) databases were systematically searched from inception to March 2021. We included randomized controlled trials (RCTs) that evaluated any antithrombotic agent in patients with infectious diseases other than COVID-19. Two authors independently performed study selection, data extraction and risk of bias evaluation. The primary outcome was all-cause mortality. Summary estimates for mortality were calculated using the inverse-variance random-effects method.

RESULTS

A total of 16,588 patients participating in 18 RCTs were included, of whom 2141 died. Four trials evaluated therapeutic-dose anticoagulation, 1 trial prophylactic-dose anticoagulation, 4 trials aspirin, and 9 trials other antithrombotic agents. Overall, the use of antithrombotic agents was not associated with all-cause mortality (relative risk 0.96; 95% confidence interval, 0.90-1.03).

CONCLUSIONS

The use of antithrombotics is not associated with all-cause mortality in patients with infectious disease other than COVID-19. Complex pathophysiological interplays between inflammatory and thrombotic pathways may explain these results and need further investigation.

REGISTRATION

PROSPERO, CRD42021241182.

Pro-inflammatory and pro-resolving lipid mediators of inflammation in HIV: effect of aspirin intervention

BACKGROUND

Persons with HIV (PWH) have an increased risk of cardiovascular disease (CVD) compared to HIV-seronegative individuals (SN). Inflammation contributes to this risk but the role of lipid mediators, with central roles in inflammation, in HIV infection remain to be established; further aspirin reduces CVD risk in the general population through production of some of these anti-inflammatory lipid mediators, but they have not been studied in PWH.

METHODS

We evaluated the relationship between plasma lipid mediators (i.e. 50 lipid mediators including classic eicosanoids and specialized pro-resolving mediators (SPMs)) and HIV status; and the impact of aspirin in PWH on regulating these autacoids. Plasma samples were obtained from 110 PWH receiving antiretroviral therapy (ART) from a randomized trial of aspirin (ACTG-A5331) and 107 matched SN samples (MACS-WIHS Combined Cohort).

FINDINGS

PWH had lower levels of arachidonic acid-derived pro-inflammatory prostaglandins (PGs: PGE2 and PGD2) and thromboxanes (Tx: TxB2), and higher levels of select pro-resolving lipid mediators (e.g. RvD4 and MaR2n-3 DPA) compared to SN. At the interval tested, aspirin intervention was observed to reduced PGs and Tx, and while we did not observe an increase in aspirin triggered mediators, we observed the upregulation of other SPM in aspirin treated PWH, namely MaR2n-3 DPA.

INTERPRETATION

Together these observations demonstrate that plasma lipid mediators profiles, some with links to systemic inflammation and CVD risk, become altered in PWH. Furthermore, aspirin intervention did not increase levels of aspirin-triggered pro-resolving lipid mediators, consistent with other reports of an impaired aspirin response in PWH.

FUNDING

NIH.

Bacterial meningitis in Africa

Bacterial meningitis differs globally, and the incidence and case fatality rates vary by region, country, pathogen, and age group; being a life-threatening disease with a high case fatality rate and long-term complications in low-income countries. Africa has the most significant prevalence of bacterial meningitis illness, and the outbreaks typically vary with the season and the geographic location, with a high incidence in the meningitis belt of the sub-Saharan area from Senegal to Ethiopia. Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) are the main etiological agents of bacterial meningitis in adults and children above the age of one. Streptococcus agalactiae (group B Streptococcus), Escherichia coli, and Staphylococcus aureus are neonatal meningitis's most common causal agents. Despite efforts to vaccinate against the most common causes of bacterial neuro-infections, bacterial meningitis remains a significant cause of mortality and morbidity in Africa, with children below 5 years bearing the heaviest disease burden. The factors attributed to this continued high disease burden include poor infrastructure, continued war, instability, and difficulty in diagnosis of bacterial neuro-infections leading to delay in treatment and hence high morbidity. Despite having the highest disease burden, there is a paucity of African data on bacterial meningitis. In this article, we discuss the common etiologies of bacterial neuroinfectious diseases, diagnosis and the interplay between microorganisms and the immune system, and the value of neuroimmune changes in diagnostics and therapeutics.

Host-directed immunotherapy of viral and bacterial infections: past, present and future

The advent of COVID-19 and the persistent threat of infectious diseases such as tuberculosis, malaria, influenza and HIV/AIDS remind us of the marked impact that infections continue to have on public health. Some of the most effective protective measures are vaccines but these have been difficult to develop for some of these infectious diseases even after decades of research. The development of drugs and immunotherapies acting directly against the pathogen can be equally challenging, and such pathogen-directed therapeutics have the potential disadvantage of selecting for resistance. An alternative approach is provided by host-directed therapies, which interfere with host cellular processes required for pathogen survival or replication, or target the host immune response to infection (immunotherapies) to either augment immunity or ameliorate immunopathology. Here, we provide a historical perspective of host-directed immunotherapeutic interventions for viral and bacterial infections and then focus on SARS-CoV-2 and Mycobacterium tuberculosis, two major human pathogens of the current era, to indicate the key lessons learned and discuss candidate immunotherapeutic approaches, with a focus on drugs currently in clinical trials.

Risk factors of poor developmental outcome in children with tuberculous meningitis

BACKGROUND

Neurodevelopmental delay is a significant long-term complication of childhood tuberculous meningitis (TBM). The objective of this study was to assess risk factors for neurodevelopmental delay in children with TBM.

METHODS

We conducted a retrospective cohort study of children diagnosed with TBM at Tygerberg Hospital, Cape Town, South Africa, over a 30-year period between 1985 and 2015. We assessed the relationship between demographic, clinical, laboratory and neuro-imaging characteristics, and cognitive impairment at the conclusion of anti-tuberculous treatment. Poor outcome was defined as moderate-to severe cognitive impairment.

RESULTS

A total of 327 TBM patients were included, 71 (21.7%) suffered a poor outcome. Multivariate analysis revealed that decreased level of consciousness (adjusted OR (aOR): 4.68; 95%CI: 2.43-13.88; p = 0.005), brainstem dysfunction (aOR: 3.20; 95%CI: 1.70-6.00; p < 0.001), and radiological infarction (aOR: 3.47; 95%CI: 1.87-6.45; p < 0.001) were associated with a poor developmental outcome. Left hemispherical (single and multiple) stroke and bilateral stroke were associated with poor developmental outcomes.

CONCLUSION

Certain neurological signs as well as radiological infarct characteristics are important predictors of poor developmental outcome. Anticipation of the likely level of cognitive impairment at diagnosis allows more accurate prognostication and prompt institution of supportive and rehabilitative measures, after the acute illness.

A phase 2A trial of the safety and tolerability of increased dose rifampicin and adjunctive linezolid, with or without aspirin, for HIV-associated tuberculous meningitis (The LASER-TBM Trial)

BACKGROUND

Drug regimens which include intensified antibiotics alongside effective anti-inflammatory therapies may improve outcomes in Tuberculous Meningitis (TBM). Safety data on their use in combination and in the context of HIV is needed to inform clinical trial design.

METHODS

We conducted a phase 2 open-label parallel-design RCT to assess safety of high-dose rifampicin, linezolid and high-dose aspirin in HIV-associated TBM. Participants were randomised (1.4:1:1) to three treatment arms (arm 1, standard of care (SOC); arm 2 SOC + additional rifampicin (up to 35mg/kg/day)) + linezolid 1200mg/day reducing after 28/7 to 600mg/day; arm 3, as per arm 2 + aspirin 1000mg/day) for 56 days, when the primary outcome of adverse events of special interest (AESI) or death was assessed.

RESULTS

52 participants with HIV-associated TBM were randomised. 59% had mild disease (MRC Grade 1) vs 39% (Grade 2) vs 2% (Grade 3). 33% had microbiologically-confirmed TBM; 41% 'possible', 25% 'probable'. AESI or death occurred in 10/16 (63%) (arm 3) vs 4/14 (29%) (arm 2) vs 6/20 (30%) (arm 1) (p = 0.083). The cumulative proportion of AESI or death (Kaplan-Meier) demonstrated worse outcomes in arm 3 vs arm 1 (p = 0.04), however only one event in arm 3 was attributable to aspirin and was mild. There was no difference in efficacy (modified Rankin scale) at day 56 between arms.

CONCLUSIONS

High-dose rifampicin and adjunctive linezolid can safely be added to SOC in HIV-associated TBM. Larger studies are required to evaluate whether potential toxicity associated with these interventions, particularly high-dose aspirin, is outweighed by mortality or morbidity benefit.

Intensified tuberculosis treatment to reduce the mortality of HIV-infected and uninfected patients with tuberculosis meningitis (INTENSE-TBM): study protocol for a phase III randomized controlled trial

BACKGROUND

Tuberculous meningitis (TBM) is the most lethal and disabling form of tuberculosis (TB), particularly in sub-Saharan Africa. Current anti-TB treatment is poorly effective since TBM mortality reaches 40% in HIV-negative patients and up to 70% in HIV-co-infected patients. To reduce TBM-induced morbidity and mortality, the INTENSE-TBM trial evaluates two interventions in both HIV-infected and uninfected patients: an anti-TB treatment intensification using oral high-dose rifampicin (35 mg/kg daily) and linezolid (1200 mg daily and then 600 mg daily) during the first 8 weeks of the anti-TB treatment and the use of adjunctive aspirin (200 mg daily).

METHODS

This is a randomized controlled, phase III, multicenter, 2 × 2 factorial plan superiority trial. The trial has four arms, combining the two experimental treatments (intensified TBM regimen and aspirin) with the two reference treatments (WHO standard TB treatment and placebo), and is open-label for anti-TB treatment and double-blind placebo-controlled for aspirin treatment. This trial is conducted in adults or adolescents of age ≥15 years with TBM defined as "definite," "probable," or "possible" using Tuberculosis Meningitis International Research Consortium criteria, in four African countries: Ivory Coast, Madagascar, Uganda, and South Africa. The primary outcome is all-cause death between inclusion and week 40.

DISCUSSION

The INTENSE-TBM trial represents a key opportunity to enhance TBM treatment with widely available existing drugs notably in high-incidence settings of both TB and HIV. The trial design is pragmatic and the results will permit early and effective applications in TBM patient care, in both HIV and TB high-incidence countries.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04145258. Registered on October 30, 2019.

Host-directed therapies in pulmonary tuberculosis: Updates on anti-inflammatory drugs

Tuberculosis (TB) is a lethal disease and remains one of the top ten causes of mortality by an infectious disease worldwide. It can also result in significant morbidity related to persistent inflammation and tissue damage. Pulmonary TB treatment depends on the prolonged use of multiple drugs ranging from 6 months for drug-susceptible TB to 6-20 months in cases of multi-drug resistant disease, with limited patient tolerance resulting from side effects. Treatment success rates remain low and thus represent a barrier to TB control. Adjunct host-directed therapy (HDT) is an emerging strategy in TB treatment that aims to target the host immune response to Mycobacterium tuberculosis in addition to antimycobacterial drugs. Combined multi-drug treatment with HDT could potentially result in more effective therapies by shortening treatment duration, improving cure success rates and reducing residual tissue damage. This review explores the rationale and challenges to the development and implementation of HDTs through a succinct report of the medications that have completed or are currently being evaluated in ongoing clinical trials.

Global Frequency and Clinical Features of Stroke in Patients With Tuberculous Meningitis: A Systematic Review

IMPORTANCE

Stroke in tuberculous meningitis (TBM) is associated with significant morbidity and mortality.

OBJECTIVE

To determine the country-specific, regional, and overall prevalence of stroke among patients with TBM, including their clinical manifestations, stroke locations, and outcomes.

EVIDENCE REVIEW

This systematic review searched records in MEDLINE by PubMed, Scopus, and EMBASE until July 2020 for relevant articles on the occurrence and characteristics of stroke in TBM. Randomized clinical trials and cohort studies that included a population of patients with TBM were analyzed for clinical manifestations, type of stroke, area of stroke, vascular territory, and outcomes. Studies that did not report the occurrence of stroke, reported as abstract only with no full-texts available, and articles not in English were excluded. The country-specific, regional, and overall frequencies of stroke among patients with TBM were determined; secondary analysis enumerated the summary estimates of the clinical presentations, common locations of stroke, and outcomes. The Murad tool was used to assess methodological quality.

FINDINGS

From 852 articles identified, 71 studies involving 2194 patients with stroke in TBM were included. The sample size for each study ranged from 17 to 806 patients. The frequency of stroke in TBM showed an estimate of 0.30 (95% CI, 0.26-0.33). The most common clinical manifestations were fever and headache. The lateral striate, middle cerebral, and medial striate arteries were typically affected. The basal ganglia, cortex and lobar, and internal capsule were the frequently involved areas of the brain. The pooled proportions of mortality and poor outcomes were 0.22 (95% CI, 0.16-0.29) and 0.51 (95% CI, 0.37-0.66), respectively.

CONCLUSIONS AND RELEVANCE

The results of this systematic review suggest that stroke is considerably frequent among patients with TBM. The reported frequencies of stroke in TBM and its clinical features vary across the studies and populations.

Recent Advances in Host-Directed Therapies for Tuberculosis and Malaria

Tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis, and malaria, caused by parasites from the Plasmodium genus, are two of the major causes of death due to infectious diseases in the world. Both diseases are treatable with drugs that have microbicidal properties against each of the etiologic agents. However, problems related to treatment compliance by patients and emergence of drug resistant microorganisms have been a major problem for combating TB and malaria. This factor is further complicated by the absence of highly effective vaccines that can prevent the infection with either M. tuberculosis or Plasmodium. However, certain host biological processes have been found to play a role in the promotion of infection or in the pathogenesis of each disease. These processes can be targeted by host-directed therapies (HDTs), which can be administered in conjunction with the standard drug treatments for each pathogen, aiming to accelerate their elimination or to minimize detrimental side effects resulting from exacerbated inflammation. In this review we discuss potential new targets for the development of HDTs revealed by recent advances in the knowledge of host-pathogen interaction biology, and present an overview of strategies that have been tested in vivo, either in experimental models or in patients.

Cerebral Infarction and Evan's Ratio on MRI Affect the Severity and Prognosis of Tuberculosis Meningitis Patients

Background: Magnetic resonance imaging (MRI) is widely used in the diagnosis of tuberculous meningitis (TBM) and its complications. We aimed to explore the relationship between MRI features and neurological deficits and TBM patients’ prognosis. Methods: patients diagnosed with TBM were subjected to a neurological evaluation on admission and divided into groups based on the Medical Research Council (MRC) scale. After several years of follow-up, the patients were further divided into groups according to the Modified Rankin Score (MRS). Their MR images were analyzed for meningeal enhancement, tuberculomas, infarction, hydrocephalus, and abscess, including the location and size of the lesion. Any changes in MRI features during the follow-up were recorded. MRI features between groups were compared, and the relationship between dynamic changes in images and Rankin grading was explored. Results: We found significant differences in acute cerebral infarction (ACI) and old cerebral infarctions (OCI) between the MRC groups, and the ORs of ACI and OCI were 21.818 (95% CI: 2.440−195.075) and 6.788 (95% CI: 1.516−30.392), respectively. There were significant differences in ACI, OCI, and Evan’s ratio between the MRS groups (p < 0.05), and the ORs of ACI, OCI, and hydrocephalus were 6.375 (95% CI: 1.501−27.080), 5.556 (95% CI: 1.332−23.177), and 9.139 (95% CI: 2.052−40.700), respectively. The changes of Evan’s ratio were related to the MRS grading (r = 0.335, p = 0.040). Conclusions: For patients with TBM, the presence of ACI or OCI is associated with neurological deficits, and ACI, OCI, and hydrocephalus can be regarded as poor prognostic predictors. Changes in Evan’s ratio will affect the outcome.

Tuberculous meningitis: progress and remaining questions

Tuberculous meningitis is a devastating brain infection that is caused by Mycobacterium tuberculosis and is notoriously difficult to diagnose and treat. New technologies characterising the transcriptome, proteome, and metabolome have identified new molecules and pathways associated with tuberculous meningitis severity and poor outcomes that could offer novel diagnostic and therapeutic targets. The next-generation GeneXpert MTB/RIF Ultra assay, when used on CSF, offers diagnostic sensitivity for tuberculous meningitis of approximately 70%, although it is not widely available and a negative result cannot rule out tuberculous meningitis. Small trials indicate that clinical outcomes might be improved with increased doses of rifampicin, the addition of linezolid or fluoroquinolones to standard antituberculosis therapy, or treatment with adjunctive aspirin combined with corticosteroids. Large phase 3 clinical trials are underway worldwide to address these and other questions concerning the optimal management of tuberculous meningitis; these studies also form a platform for studying pathogenesis and identifying novel diagnostic and treatment strategies, by allowing the implementation of new genomic, transcriptomic, proteomic, and metabolomic technologies in nested substudies.

Immunomodulatory effects of pharmaceutical opioids and antipyretic analgesics: Mechanisms and relevance to infection

Understanding how pharmaceutical opioids and antipyretic analgesics interact with the immune system potentially has major clinical implications for management of patients with infectious diseases and surgical and critical care patients. An electronic search was carried out on MEDLINE, EMBASE, PsycINFO, CENTRAL and the Cochrane library to identify reports describing the immunomodulatory effects of opioid analgesics and antipyretic analgesics, and their effects in infectious diseases. In adaptive immunity, nonsteroidal anti-inflammatory drugs have divergent effects: augmenting cell-mediated immunity but inhibiting humoral immunity. Nonsteroidal anti-inflammatory drugs have demonstrated a beneficial role in Mycobacterium tuberculosis infection and histoplasmosis in animals, and may be plausible adjuvants to antimicrobial agents in these diseases. There is a need to evaluate these findings rigorously in human clinical trials. There is preliminary evidence demonstrating antiviral effects of indomethacin in SARS CoV-2 in vitro; however, uncertainty regarding its clinical benefit in humans needs to be resolved in large clinical trials. Certain opioid analgesics are associated with immunosuppressive effects, with a developing understanding that fentanyl, morphine, methadone and buprenorphine suppress innate immunity, whilst having diverse effects on adaptive immunity. Morphine suppresses key cells of the innate immunity and is associated with greater risk of infection in the postsurgical setting. Efforts are needed to achieve adequate analgesia whilst avoiding suppression of the innate immunity in the immediate postoperative period caused by certain opioids, particularly in cancer surgery.

Neutrophil-Mediated Immunopathology and Matrix Metalloproteinases in Central Nervous System - Tuberculosis

Tuberculosis (TB) remains one of the leading infectious killers in the world, infecting approximately a quarter of the world’s population with the causative organism Mycobacterium tuberculosis (M. tb). Central nervous system tuberculosis (CNS-TB) is the most severe form of TB, with high mortality and residual neurological sequelae even with effective TB treatment. In CNS-TB, recruited neutrophils infiltrate into the brain to carry out its antimicrobial functions of degranulation, phagocytosis and NETosis. However, neutrophils also mediate inflammation, tissue destruction and immunopathology in the CNS. Neutrophils release key mediators including matrix metalloproteinase (MMPs) which degrade brain extracellular matrix (ECM), tumor necrosis factor (TNF)-α which may drive inflammation, reactive oxygen species (ROS) that drive cellular necrosis and neutrophil extracellular traps (NETs), interacting with platelets to form thrombi that may lead to ischemic stroke. Host-directed therapies (HDTs) targeting these key mediators are potentially exciting, but currently remain of unproven effectiveness. This article reviews the key role of neutrophils and neutrophil-derived mediators in driving CNS-TB immunopathology.

Addressing TB-related mortality in adults living with HIV: a review of the challenges and potential solutions

Tuberculosis (TB) is the leading cause of death in people living with HIV (PLHIV) globally, causing 208,000 deaths in PLHIV in 2019. PLHIV have an 18-fold higher risk of TB, and HIV/TB mortality is highest in inpatient facilities, compared with primary care and community settings. Here we discuss challenges and potential mitigating solutions to address TB-related mortality in adults with HIV. Key factors that affect healthcare engagement are stigma, knowledge, and socioeconomic constraints, which are compounded in people with HIV/TB co-infection. Innovative approaches to improve healthcare engagement include optimizing HIV/TB care integration and interventions to reduce stigma. While early diagnosis of both HIV and TB can reduce mortality, barriers to early diagnosis of TB in PLHIV include difficulty producing sputum specimens, lower sensitivity of TB diagnostic tests in PLHIV, and higher rates of extra pulmonary TB. There is an urgent need to develop higher sensitivity biomarker-based tests that can be used for point-of-care diagnosis. Nonetheless, the implementation and scale-up of existing tests including molecular World Health Organization (WHO)-recommended diagnostic tests and urine lipoarabinomannan (LAM) should be optimized along with expanded TB screening with tools such as C-reactive protein and digital chest radiography. Decreased survival of PLHIV with TB disease is more likely with late HIV diagnosis and delayed start of antiretroviral (ART) treatment. The WHO now recommends starting ART within 2 weeks of initiating TB treatment in the majority of PLHIV, aside from those with TB meningitis. Dedicated TB treatment trials focused on PLHIV are needed, including interventions to improve TB meningitis outcomes given its high mortality, such as the use of intensified regimens using high-dose rifampin, new and repurposed drugs such as linezolid, and immunomodulatory therapy. Ultimately holistic, high-quality, person-centered care is needed for PLHIV with TB throughout the cascade of care, which should address biomedical, socioeconomic, and psychological barriers.

Targeting Molecular Inflammatory Pathways in Granuloma as Host-Directed Therapies for Tuberculosis

Globally, more than 10 million people developed active tuberculosis (TB), with 1.4 million deaths in 2020. In addition, the emergence of drug-resistant strains in many regions of the world threatens national TB control programs. This requires an understanding of host-pathogen interactions and finding novel treatments including host-directed therapies (HDTs) is of utter importance to tackle the TB epidemic. Mycobacterium tuberculosis (Mtb), the causative agent for TB, mainly infects the lungs causing inflammatory processes leading to immune activation and the development and formation of granulomas. During TB disease progression, the mononuclear inflammatory cell infiltrates which form the central structure of granulomas undergo cellular changes to form epithelioid cells, multinucleated giant cells and foamy macrophages. Granulomas further contain neutrophils, NK cells, dendritic cells and an outer layer composed of T and B lymphocytes and fibroblasts. This complex granulomatous host response can be modulated by Mtb to induce pathological changes damaging host lung tissues ultimately benefiting the persistence and survival of Mtb within host macrophages. The development of cavities is likely to enhance inter-host transmission and caseum could facilitate the dissemination of Mtb to other organs inducing disease progression. This review explores host targets and molecular pathways in the inflammatory granuloma host immune response that may be beneficial as target candidates for HDTs against TB.

A case of Clival Tuberculosis and associated meningitis

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Mycobacterium tuberculosis is infamous for its ability to mimic other pathology and manifest in unusual locations.

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The clivus is an extremely rare site for manifestation of MTB.

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A high index of suspicion and empirical approach is vital for successful management, as obtaining a definitive diagnosis of intracranial MTB may take weeks or months.

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Intracranial MTB can cause potentially lethal complications including meningitis, hydrocephalus and infectious vasculitis, however appropriate and timely management may lead to good outcomes.

Herein we report a 30-year-old man presenting with fevers, headaches and weight loss. On admission he was disorientated and demonstrated no focal signs of neurological deficit. Magnetic resonance imaging revealed a large area of abnormal bone marrow signal centred within the clivus with extension into the sphenoid sinus and signs of associated basal meningitis. A sphenoid sinus biopsy was performed and proved non diagnostic. The patient was treated empirically with antitubercular therapy (ATT). Lumbar puncture provided cerebrospinal fluid from which Mycobacterium tuberculosis (MTB) was isolated 35 days later. His clinical course was complicated by development of communicating hydrocephalus requiring placement of a ventriculoperitoneal shunt and addition of thalidomide. The patient was discharged following a ten-week admission with complete resolution of symptoms and remains well two years later.

The use of thalidomide to treat children with tuberculosis meningitis: A review

Much of the morbidity and mortality caused by tuberculous meningitis (TBM) is mediated by a dysregulated immune response. Effective host-directed therapy is therefore critical to improve survival and clinical outcomes. Currently only one host-directed therapy (HDT), corticosteroids, is proven to improve mortality. However, there is no evidence that corticosteroids reduce morbidity and the mechanism of action for mortality reduction is uncertain. Further, it has no proven benefit in HIV co-infected individuals. One promising host-directed therapy approach is to restrict the immunopathology arising from tumour necrosis factor (TNF)-α excess is via TNF-α inhibitors. There are accumulating data on the role of thalidomide, anti-TNF-α monoclonal antibodies (infliximab, adalimumab) and the soluble TNF-α receptor (etanercept) in TBM treatment. Thalidomide was developed nearly seventy years ago and has been a highly controversial drug. Birth defects and toxic adverse effects have limited its use but an improved understanding of its immunological mechanism of action suggest that it may have a crucial role in regulating the destructive host response seen in inflammatory conditions such as TBM. Observational studies at our institution found low dosage adjunctive thalidomide safe in treating tuberculous mass lesions and blindness related to optochiasmatic arachnoiditis, with good clinical and radiological response. In this review, we discuss possible mechanisms of action for thalidomide, based on our clinico-radiologic experience and post-mortem histopathological work. We also propose a rationale for its use in the treatment of certain TBM-related complications.

Risk factors for ischemic stroke in children with tuberculous meningitis

PURPOSE

Cerebrovascular complications are commonly observed in children with tuberculous meningitis. We aimed to determine which clinical factors were associated with stroke at admission in children with tuberculous meningitis and, in children stroke-free at admission, which factors were associated with development of stroke on treatment.

METHODS

We analysed a cohort of 474 children diagnosed with 'definite' and 'probable' tuberculous meningitis, with prospectively collected data, at Tygerberg Hospital, Cape Town, South Africa from 1985 to 2005. We considered either hemiparesis or radiological arterial ischemic infarction as evidence of stroke.

RESULTS

At admission, 339 (71.5%) children presented with stroke. Features associated with stroke at admission included age <3 years (odds ratio (OR) 3.70; 95% confidence interval (CI): 2.44-5.63; p < 0.01), convulsions (OR: 2.25; 95% CI: 1.46-3.45; p < 0.01) and hydrocephalus (OR: 1.63; 95% CI: 1.05-2.53; p = 0.03). In the group of children without stroke at admission (n = 135), 33 (24.4%) developed stroke by 1 month. Similar factors predicted stroke and included age <3 years (OR: 2.60; 95% CI: 1.17-5.80; p = 0.02), convulsions (OR: 2.25; 95% CI: 1.46-3.45; p < 0.01), CSF cell count <10 or >500/L (OR: 3.12; 95% CI: 1.03-9.43; p = 0.04) and hydrocephalus (OR: 2.99; 95% CI: 1.30-6.89; p = 0.01).

CONCLUSION

A large proportion of children with tuberculous meningitis present with stroke at admission. Of those with no evidence of stroke at admission, a quarter develop stroke by 1 month, suggesting that there could be a brief window in which to give preventive therapy.

Host Directed Therapies for Tuberculous Meningitis

A dysregulated host immune response significantly contributes to morbidity and mortality in tuberculous meningitis (TBM). Effective host directed therapies (HDTs) are critical to improve survival and clinical outcomes. Currently only one HDT, dexamethasone, is proven to improve mortality. However, there is no evidence dexamethasone reduces morbidity, how it reduces mortality is uncertain, and it has no proven benefit in HIV co-infected individuals. Further research on these aspects of its use, as well as alternative HDTs such as aspirin, thalidomide and other immunomodulatory drugs is needed. Based on new knowledge from pathogenesis studies, repurposed therapeutics which act upon small molecule drug targets may also have a role in TBM. Here we review existing literature investigating HDTs in TBM, and propose new rationale for the use of novel and repurposed drugs. We also discuss host variable responses and evidence to support a personalised approach to HDTs in TBM.

Study protocol for a phase 2A trial of the safety and tolerability of increased dose rifampicin and adjunctive linezolid, with or without aspirin, for HIV-associated tuberculous meningitis [LASER-TBM]

Background: Tuberculous meningitis (TBM) is the most lethal form of tuberculosis with a mortality of ~50% in those co-infected with HIV-1. Current antibiotic regimens are based on those known to be effective in pulmonary TB and do not account for the differing ability of the drugs to penetrate the central nervous system (CNS). The host immune response drives pathology in TBM, yet effective host-directed therapies are scarce. There is sufficient data to suggest that higher doses of rifampicin (RIF), additional linezolid (LZD) and adjunctive aspirin (ASA) will be beneficial in TBM yet rigorous investigation of the safety of these interventions in the context of HIV associated TBM is required. We hypothesise that increased dose RIF, LZD and ASA used in combination and in addition to standard of care for the first 56 days of treatment with be safe and tolerated in HIV-1 infected people with TBM.

Methods: In an open-label randomised parallel study, up to 100 participants will receive either; i) standard of care (n=40, control arm), ii) standard of care plus increased dose RIF (35mg/kg) and LZD (1200mg OD for 28 days, 600mg OD for 28 days) (n=30, experimental arm 1), or iii) as per experimental arm 1 plus additional ASA 1000mg OD (n=30, experimental arm 2). After 56 days participants will continue standard treatment as per national guidelines. The primary endpoint is death and the occurrence of solicited treatment-related adverse events at 56 days. In a planned pharmacokinetic (PK) sub-study we aim to assess PK/pharmacodynamic (PD) of oral vs IV rifampicin, describe LZD and RIF PK and cerebrospinal fluid concentrations, explore PK/PD relationships, and investigate drug-drug interactions between LZD and RIF. Safety and pharmacokinetic data from this study will inform a planned phase III study of intensified therapy in TBM.

Clinicaltrials.gov registration: NCT03927313 (25/04/2019)

Central nervous system tuberculosis

PURPOSE OF REVIEW

Central nervous system (CNS) tuberculosis is the most devastating form of tuberculosis (TB), with mortality and or neurological sequelae in over half of individuals. We reviewed original research and systematic reviews published since 1 January 2019 for new developments in CNS TB pathophysiology, diagnosis, management and prognosis.

RECENT FINDINGS

Insight in the pathophysiology is increasing steadily since the landmark studies in 1933, focussing on granuloma type classification, the relevance of the M. tuberculosis bacterial burden and the wide range of immunological responses. Although Xpert/RIF has been recommended by the WHO for extrapulmonary TB diagnosis, culture is still needed to increase the sensitivity of TB meningitis diagnosis. Sequential MRIs can improve understanding of neurological deficits at baseline and during treatment. Pharmacokinetic/pharmacodynamic modelling suggests that higher doses of rifampicin and isoniazid in TB meningitis could improve survival.

SUMMARY

Recent studies in the field of CNS-TB have largely focussed on TB meningitis. The outcome may improve by optimizing treatment dosing. This needs to be confirmed in clinical trials. Due to the important role of inflammation, these trials should be used as the platform to study the inflammatory and metabolomic responses. This could improve understanding of the biology of this disease and improve patient outlook by enabling individualised host-directed therapy.

Platelet Activation and the Immune Response to Tuberculosis

In 2019 10 million people developed symptomatic tuberculosis (TB) disease and 1.2 million died. In active TB the inflammatory response causes tissue destruction, which leads to both acute morbidity and mortality. Tissue destruction in TB is driven by host innate immunity and mediated via enzymes, chiefly matrix metalloproteinases (MMPs) which are secreted by leukocytes and stromal cells and degrade the extracellular matrix. Here we review the growing evidence implicating platelets in TB immunopathology. TB patients typically have high platelet counts, which correlate with disease severity, and a hypercoagulable profile. Platelets are present in human TB granulomas and platelet-associated gene transcripts are increased in TB patients versus healthy controls. Platelets most likely drive TB immunopathology through their effect on other immune cells, particularly monocytes, to lead to upregulation of activation markers, increased MMP secretion, and enhanced phagocytosis. Finally, we consider current evidence supporting use of targeted anti-platelet agents in the treatment of TB due to growing interest in developing host-directed therapies to limit tissue damage and improve treatment outcomes. In summary, platelets are implicated in TB disease and contribute to MMP-mediated tissue damage via their cellular interactions with other leukocytes, and are potential targets for novel host-directed therapies.

Improving host-directed therapy for tuberculous meningitis by linking clinical and multi-omics data

There is a clear need to improve host-directed therapy for tuberculous meningitis (TBM), the most severe and deadly manifestation of tuberculosis. Corticosteroids represent the only host-directed therapy of proven benefit in TBM, yet their effect is modest, the mechanism by which they reduce mortality is unknown, and there is evidence for heterogeneity in their effect. Novel therapeutic approaches are therefore urgently needed. Cellular metabolism is critical for the function of immune cells; through unbiased metabolomics we recently found that high concentrations of cerebrospinal fluid (CSF) tryptophan are associated with increased mortality in Indonesian TBM patients, and that CSF tryptophan concentrations are under strong genetic regulation. Many questions remain. How exactly is tryptophan metabolism altered during TBM? How does it correlate with inflammation, immunopathology, and response to corticosteroids? How is tryptophan metabolism genetically regulated? What is the effect of HIV co-infection on tryptophan metabolism before and during TBM treatment? The ULTIMATE project addresses these questions by integrating data and specimens from large patient studies and clinical trials evaluating the effects of corticosteroids in Vietnam and Indonesia. Through its powerful and unbiased approach, ULTIMATE aims to identify which TBM patients benefit from corticosteroids and if novel therapeutic targets, such as the tryptophan pathway, could be targeted.

Serum and cerebrospinal fluid host proteins indicate stroke in children with tuberculous meningitis

Introduction

Stroke is a common complication in children with tuberculous meningitis (TBM). Host proteins may give us insight into the mechanisms of stroke in TBM and serve as biomarkers for detection of stroke, however, they have not been widely explored. In this study, we compared the concentrations of cerebrospinal fluid (CSF) and serum proteins between children who had TBM-related stroke and children with TBM without stroke.

Methods

We collected CSF and serum from 47 children consecutively admitted to the Tygerberg Academic Hospital in Cape Town, South Africa between November 2016, and November 2017, on suspicion of having TBM. A multiplex platform was used to measure the concentrations of 69 host proteins in CSF and serum from all study participants.

Results

After classification of study participants, 23 (48.9%) out of the 47 study participants were diagnosed with TBM, of which 14 (60.9%) demonstrated radiological arterial ischemic infarction. The levels of lipocalin-2, sRAGE, IP-10/ CXCL10, sVCAM-1, MMP-1, and PDGF-AA in CSF samples and the levels of D-dimer, ADAMTS13, SAA, ferritin, MCP-1/ CCL2, GDF-15 and IL-13 in serum samples were statistically different between children who had TBM-related stroke and children with TBM without stroke. After correcting for multiple testing, only the levels of sVCAM-1, MMP-1, sRAGE, and IP-10/ CXCL10 in CSF were statistically different between the two groups. CSF and serum protein biosignatures indicated stroke in children diagnosed with TBM with up to 100% sensitivity and 88.9% specificity.

Conclusion

Serum and CSF proteins may serve as biomarkers for identifying individuals with stroke amongst children diagnosed with TBM at admission and may guide us to understand the biology of stroke in TBM. This was a pilot study, and thus further investigations in larger studies are needed.

Investigator-initiated Randomized Controlled Trials in Infectious Diseases: Better Value for Money for Registration Trials of New Antimicrobials

Randomized controlled trials (RCTs) conducted by the industry are expensive, especially trials conducted for registration of new drugs for multidrug-resistant (MDR) bacteria. Lower-cost investigator-initiated trials have recently been successful in recruiting patients with severe infections caused by MDR bacteria. In this viewpoint, we contrast the aims, methods, and resulting costs of industry-led and investigator-initiated trials and ask whether contemporary registration trial costs are justified. Contract research organizations, delivering and monitoring industry-sponsored trials at a significant cost, have little incentive to make trials more efficient or less expensive. The value of universal monitoring of all trial data is questionable. We propose that clinical trial networks play a more influential role in RCT design and planning, lead adaptive risk-based trial monitoring, and work with the industry to maximize efficient recruitment and lower costs in registration trials for the approval of new antimicrobials.

Evaluation of the molecular bacterial load assay for detecting viable Mycobacterium tuberculosis in cerebrospinal fluid before and during tuberculous meningitis treatment

New tools to monitor treatment response and predict outcome from tuberculous meningitis (TBM) are urgently required. We retrospectively evaluated the 16S rRNA-based molecular bacterial load assay (MBLA) to quantify viable Mycobacterium tuberculosis in serial cerebrospinal fluid (CSF) from adults with TBM. 187 CSF samples were collected before and during the first two months of treatment from 99 adults TBM, comprising 56 definite, 43 probable or possible TBM, and 18 non-TBM and preserved at −80°C prior to MBLA. We compared MBLA against MGIT culture, GeneXpert MTB/RIF (Xpert) and Ziehl-Neelsen (ZN) smear. Before treatment, MBLA was positive in 34/99 (34.3%), significantly lower than MGIT 47/99 (47.5%), Xpert 51/99 (51.5%) and ZN smear 55/99 (55.5%). After one month of treatment, MBLA and MGIT were positive in 3/38 (7.9%) and 4/38 (10.5%), respectively, whereas Xpert and ZN smear remained positive in 19/38 (50.0%) and 18/38 (47.4%). In summary, MBLA was less likely to detect CSF bacteria before the start of treatment compared with MGIT culture, Xpert and ZN smear. MBLA and MGIT positivity fell during treatment because of detecting only viable bacteria, whereas Xpert and ZN smear remained positive for longer because of detecting both live and dead bacteria. Sample storage and processing may have reduced MBLA-detectable viable bacteria; and sampling earlier in treatment may yield more useful results. Prospective studies with CSF sampling after 1–2 weeks are warranted.

Defeating Paediatric Tuberculous Meningitis: Applying the WHO "Defeating Meningitis by 2030: Global Roadmap"

Children affected by tuberculous meningitis (TBM), as well as their families, have needs that lie at the intersections between the tuberculosis and meningitis clinical, research, and policy spheres. There is therefore a substantial risk that these needs are not fully met by either programme. In this narrative review article, we use the World Health Organization (WHO) “Defeating Meningitis by 2030: global roadmap” as a starting point to consider key goals and activities to specifically defeat TBM in children. We apply the five pillars outlined in the roadmap to describe how this approach can be adapted to serve children affected by TBM. The pillars are (i) prevention; (ii) diagnosis and treatment; (iii) surveillance; (iv) support and care for people affected by meningitis; and (v) advocacy and engagement. We conclude by calling for greater integration between meningitis and TB programmes at WHO and at national levels.

Repurposing Immunomodulatory Drugs to Combat Tuberculosis

Tuberculosis (TB) is an infectious disease caused by an obligate intracellular pathogen, Mycobacterium tuberculosis (M.tb) and is responsible for the maximum number of deaths due to a single infectious agent. Current therapy for TB, Directly Observed Treatment Short-course (DOTS) comprises multiple antibiotics administered in combination for 6 months, which eliminates the bacteria and prevents the emergence of drug-resistance in patients if followed as prescribed. However, due to various limitations viz., severe toxicity, low efficacy and long duration; patients struggle to comply with the prescribed therapy, which leads to the development of drug resistance (DR). The emergence of resistance to various front-line anti-TB drugs urgently require the introduction of new TB drugs, to cure DR patients and to shorten the treatment course for both drug-susceptible and resistant populations of bacteria. However, the development of a novel drug regimen involving 2-3 new and effective drugs will require approximately 20-30 years and huge expenditure, as seen during the discovery of bedaquiline and delamanid. These limitations make the field of drug-repurposing indispensable and repurposing of pre-existing drugs licensed for other diseases has tremendous scope in anti-DR-TB therapy. These repurposed drugs target multiple pathways, thus reducing the risk of development of drug resistance. In this review, we have discussed some of the repurposed drugs that have shown very promising results against TB. The list includes sulfonamides, sulfanilamide, sulfadiazine, clofazimine, linezolid, amoxicillin/clavulanic acid, carbapenems, metformin, verapamil, fluoroquinolones, statins and NSAIDs and their mechanism of action with special emphasis on their immunomodulatory effects on the host to attain both host-directed and pathogen-targeted therapy. We have also focused on the studies involving the synergistic effect of these drugs with existing TB drugs in order to translate their potential as adjunct therapies against TB.

Efficacy and safety of aspirin as an adjunctive therapy in tubercular meningitis: A systematic review and meta-analysis

BACKGROUND

Tubercular meningitis (TBM) is associated with high mortality and stroke with chronic neurological sequelae even with best of care and antitubercular therapy. Studies have shown that aspirin as an adjunctive therapy might play some role in management of TBM. This systematic review and meta-analysis has been planned to evaluate the efficacy and safety of aspirin as an adjunctive therapy in TBM patients.

METHODS

We conducted a systematic search of randomized controlled trials in patients with tubercular meningitis published till October 2019 in all major clinical journals. Study was registered with PROSPERO with registration number: CRD42019136689. Articles were tested for eligibility and assessed for quality and various bias. Data synthesis and analysis was done using Review manager 5.3. The primary end point for assessment of efficacy was mortality at three months. The secondary end point was stroke or composite outcome of stroke and mortality at three months. Adverse effects were also assessed as secondary safety end point.

FINDINGS

Overall, three eligible randomized controlled trials with 365 participants were included that provided quantitative data for this meta-analysis. The analysis of primary and secondary end points was done using fixed effect model. There was not significant reduction in mortality [hazard ratio 0.78 (95% CI 0.45-1.35, p = 0.37)] and composite outcome of mortality and new onset stroke [hazard ratio 0.86 (95% CI 0.60-1.24, p = 0.43)] in aspirin group as compared to placebo. However, aspirin as compared to placebo significantly reduced new onset stroke [hazard ratio of 0.51 (95% CI 0.29-0.87, p = 0.01)].

INTERPRETATION

We did not find significant reduction in mortality and composite outcome (mortality and new onset stroke) with aspirin as compared to placebo but there was significant reduction in new onset stroke in aspirin group as compared to placebo with Number Needed to Treat (NNT) = 10, which might be of clinical importance since stroke is responsible for high mortality and morbidity in these subset of patients. However, a large well conducted randomized controlled trial is required to put more light on the available evidence.

Acute bacterial meningitis

Purpose of review

Community-acquired bacterial meningitis is a continually changing disease. This review summarises both dynamic epidemiology and emerging data on pathogenesis. Updated clinical guidelines are discussed, new agents undergoing clinical trials intended to reduce secondary brain damage are presented.

Recent findings

Conjugate vaccines are effective against serotype/serogroup-specific meningitis but vaccine escape variants are rising in prevalence. Meningitis occurs when bacteria evade mucosal and circulating immune responses and invade the brain: directly, or across the blood–brain barrier. Tissue damage is caused when host genetic susceptibility is exploited by bacterial virulence. The classical clinical triad of fever, neck stiffness and headache has poor diagnostic sensitivity, all guidelines reflect the necessity for a low index of suspicion and early Lumbar puncture. Unnecessary cranial imaging causes diagnostic delays. cerebrospinal fluid (CSF) culture and PCR are diagnostic, direct next-generation sequencing of CSF may revolutionise diagnostics. Administration of early antibiotics is essential to improve survival. Dexamethasone partially mitigates central nervous system inflammation in high-income settings. New agents in clinical trials include C5 inhibitors and daptomycin, data are expected in 2025.

Summary

Clinicians must remain vigilant for bacterial meningitis. Constantly changing epidemiology and emerging pathogenesis data are increasing the understanding of meningitis. Prospects for better treatments are forthcoming.

The Manipulation of the Lipid Mediator Metabolism as Adjunct Host-Directed Therapy in Tuberculosis

Host-directed therapies (HDTs) enhance the host response to tuberculosis (TB) infection to reduce disease severity. For instance, the manipulation of lipid mediator production diminishes the hyperactive immune response which is a known pathological feature of TB that generates lung tissue damage. Non-steroidal anti-inflammatory drugs (NSAIDs) and omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) are examples of such HDTs. In this mini-review, we recapitulate the literature available on the effects of NSAIDs and n-3 LCPUFA in TB as well as the immunological pathways underpinning these effects. Many NSAIDs have a great deal of data describing their effects and safety and in many jurisdictions are inexpensive, and sold over the counter in neighborhood convenience stores and supermarkets. The potential benefits of NSAIDs in TB are well-documented in pre-clinical studies. The reduction of pro-inflammatory lipid mediator production by inhibiting cyclooxygenase (COX) pathways with NSAIDs has been found to improve lung histopathology, bacterial control, and survival. Additionally, n-3 LCPUFA and its novel bioactive metabolites produced by COX and lipoxygenase (LOX) have been identified as safe and effective pro-resolving and antibacterial pharmaconutrients. Nevertheless, heterogeneous results have been reported in pre-clinical TB studies. Recently, the importance of the correct timing of NSAIDs and n-3 LCPUFA administration in TB has also been highlighted. This mini-review will provide a better understanding of the potential contribution of these therapies toward reducing inflammatory lung damage and improving bactericidal activity, especially during later stages of TB infection. It further highlights that clinical trials are required to confirm benefit and safety in TB patients.