Intensified treatment with high dose rifampicin and levofloxacin compared to standard treatment for adult patients with tuberculous meningitis (TBM-IT): protocol for a randomized controlled trial

The diagnosis of tuberculous meningitis: advancements in new technologies and machine learning algorithms

Tuberculous meningitis (TBM) poses a diagnostic challenge, particularly impacting vulnerable populations such as infants and those with untreated HIV. Given the diagnostic intricacies of TBM, there's a pressing need for rapid and reliable diagnostic tools. This review scrutinizes the efficacy of up-and-coming technologies like machine learning in transforming TBM diagnostics and management. Advanced diagnostic technologies like targeted gene sequencing, real-time polymerase chain reaction (RT-PCR), miRNA assays, and metagenomic next-generation sequencing (mNGS) offer promising avenues for early TBM detection. The capabilities of these technologies are further augmented when paired with mass spectrometry, metabolomics, and proteomics, enriching the pool of disease-specific biomarkers. Machine learning algorithms, adept at sifting through voluminous datasets like medical imaging, genomic profiles, and patient histories, are increasingly revealing nuanced disease pathways, thereby elevating diagnostic accuracy and guiding treatment strategies. While these burgeoning technologies offer hope for more precise TBM diagnosis, hurdles remain in terms of their clinical implementation. Future endeavors should zero in on the validation of these tools through prospective studies, critically evaluating their limitations, and outlining protocols for seamless incorporation into established healthcare frameworks. Through this review, we aim to present an exhaustive snapshot of emerging diagnostic modalities in TBM, the current standing of machine learning in meningitis diagnostics, and the challenges and future prospects of converging these domains.

Mathematical Model for Growth and Rifampicin-Dependent Killing Kinetics of Escherichia coli Cells

Antibiotic resistance is a global health threat. We urgently need better strategies to improve antibiotic use to combat antibiotic resistance. Currently, there are a limited number of antibiotics in the treatment repertoire of existing bacterial infections. Among them, rifampicin is a broad-spectrum antibiotic against various bacterial pathogens. However, during rifampicin exposure, the appearance of persisters or resisters decreases its efficacy. Hence, to benefit more from rifampicin, its current standard dosage might be reconsidered and explored using both computational tools and experimental or clinical studies. In this study, we present the mathematical relationship between the concentration of rifampicin and the growth and killing kinetics of Escherichia coli cells. We generated time-killing curves of E. coli cells in the presence of 4, 16, and 32 μg/mL rifampicin exposures. We specifically focused on the oscillations with decreasing amplitude over time in the growth and killing kinetics of rifampicin-exposed E. coli cells. We propose the solution form of a second-order linear differential equation for a damped oscillator to represent the mathematical relationship. We applied a nonlinear curve fitting solver to time-killing curve data to obtain the model parameters. The results show a high fitting accuracy.

High-dose rifampicin for the treatment of tuberculous meningitis: a meta-analysis of randomized controlled trials

WHAT IS KNOWN AND OBJECTIVE

Tuberculous meningitis (TBM) is one of the most serious types of extrapulmonary tuberculosis and has caused distress to human. Effective treatment is particularly important. The aim of this meta-analysis is to compare the efficacy of high-dose and standard-dose rifampicin.

METHODS

Databases including PubMed, Web of Science, Embase, Scopus and the Cochrane Library databases were electronically searched to identify randomized controlled trials that reported high-dose rifampicin in treatment of patients with TBM. The retrieval time is limited from inception to June 2021. Two reviewers independently screened literature, extracted data and assessed risk bias of included studies. Meta-analysis was performed by using STATA 12.0 software.

RESULTS AND DISCUSSION

A total of 12 studies involving 1596 patients were included. The meta-analysis results showed no significant differences in 6-month mortality, 9-month mortality, Grade I-II AE, Grade III-V AE, hepatotoxicity, hepatotoxicity Grade I-II and cardiologic events between high-dose rifampicin (or high-dose rifampicin plus moxifloxacin or levofloxacin) and standard-dose groups. The log(C_max ) (WMD 0.69, 95%CI 0.59-0.79, p 0.001) and log(AUC_0-24h ) (WMD 0.79, 95%CI 0.71-0.88, p 0.001) were higher with high-dose rifampicin. Subgroup analysis revealed the rise of log(C_max ) in high-dose rifampicin orally was consistent with intravenous administration compared with the control (WMD 0.69, 95%CI 0.66-0.73, p 0.001).

WHAT IS NEW AND CONCLUSION

High-dose rifampicin was not a protective factor for 6-month mortality, despite increased plasma C_max and AUC_0-24h . However, the above conclusions are still required to be verified through more RCTs due to the limited quantity of included studies.

A Bayesian analysis of the association between Leukotriene A4 Hydrolase genotype and survival in tuberculous meningitis

Tuberculous meningitis has high mortality, linked to excessive inflammation. However, adjunctive anti-inflammatory corticosteroids reduce mortality by only 30%, suggesting that inflammatory pathophysiology causes only a subset of deaths. In Vietnam, the survival benefit of anti-inflammatory corticosteroids was most pronounced in patients with a C/T promoter variant in the leukotriene A₄ hydrolase (LTA4H) gene encoding an enzyme that regulates inflammatory eicosanoids. LTA4H TT patients with increased expression had increased survival, consistent with corticosteroids benefiting individuals with hyper-inflammatory responses. However, an Indonesia study did not find an LTA4H TT genotype survival benefit. Here using Bayesian methods to analyse both studies, we find that LTA4H TT genotype confers survival benefit that begins early and continues long-term in both populations. This benefit is nullified in the most severe cases with high early mortality. LTA4H genotyping together with disease severity assessment may target glucocorticoid therapy to patients most likely to benefit from it.

Tuberculous meningitis is a serious infection of the lining of the brain, which affects over 100,000 people a year. Without treatment, it is always fatal: even with proper antibiotics, about a quarter of patients do not survive and many will have permanent brain damage. Overactive inflammation is thought to contribute to this process. Corticosteroid drugs, which dampen the inflammatory process, are therefore often used during treatment. However, they merely reduce mortality by 30%, suggesting that only some people benefit from them.

Two recent studies have linked the genetic makeup of individuals who have tuberculous meningitis to how they respond to corticosteroids. There were, in particular, differences in the LTA4H gene that codes for an inflammation-causing protein. According to these results, only individuals carrying high-inflammation versions of the LTA4H gene would benefit from the treatment. Yet a third study did not find any effect of the genetic background of patients.

All three papers used frequentist statistics to draw their conclusions, only examining the percentage of people who survived in each group. Yet, this type of analysis can miss important details. It also does not work well when the number of patients is small, or when the effectiveness of a drug varies during the course of an illness.

Another method, called Bayesian statistics, can perform better under these limitations. In particular, it takes into account the probability of an event based on prior knowledge – for instance, that the risk of dying varies smoothly with time.

Here, Whitworth et al. used Bayesian statistics to reanalyse the data from these studies, demonstrating that death rates were correlated with the type of LTA4H gene carried by patients. In particular, corticosteroid treatment worked best for people with the high inflammation versions of the gene. However, regardless of genetic background, corticosteroids were not effective if patients were extremely sick before being treated.

The work by Whitworth et al. demonstrates the importance of using Bayesian statistics to examine the effectiveness of medical treatments. It could help to design better protocols for tuberculous meningitis treatment, tailored to the genetic makeup of patients.

Cerebrospinal fluid bacillary load by Xpert MTB/RIF Ultra PCR Cycle Threshold value predicts two-week mortality in HIV-associated tuberculous meningitis

Background

The World Health Organization recommends GeneXpert MTB/RIF Ultra (Xpert Ultra), a fully automated polymerase chain reaction (PCR) assay, as the initial tuberculous meningitis (TBM) diagnostic test. The assay’s PCR cycle threshold (Ct) values represent the number of PCR cycles required for probe signal to be detected (low Ct value = high bacillary load) and may approximate tuberculosis (TB) bacillary load. We measured the relationship between cerebrospinal fluid (CSF) TB bacillary load with mortality.

Methods

We prospectively enrolled 102 human immunodeficiency virus (HIV)–positive Ugandans with probable or definite TBM from April 2015 to August 2019. Xpert Ultra Ct tertiles and semi-quantitative categories were separately analyzed as predictors of 2-week mortality. We investigated associations between Ct and baseline clinical and CSF parameters.

Results

Subjects with Ct values in the low tertile (ie, high bacillary load) had 57% 2-week mortality—worse than the intermediate (17%) and high (25%) Ct tertiles and Xpert Ultra–negative (30%) probable TBM cases (P = .01). In contrast, the reported semi-quantitative Xpert Ultra categorization was less precise; with the medium to low category trending toward worse 2-week survival (42%) compared with very low (28%), trace (26%), and negative (30%) categories (P = .48). Ct tertile was significantly associated with baseline CSF lactate (P = .03).

Conclusions

High CSF TB bacillary load, as measured by Xpert Ultra Ct tertile, is associated with an almost 2-fold higher 2-week mortality in HIV-associated TBM and is a better predictor than the reported Xpert Ultra semi-quantitative category. Xpert Ultra Ct values could identify TBM patients at increased risk of death who may benefit from enhanced supportive care.

High dose oral rifampicin to improve survival from adult tuberculous meningitis: A randomised placebo-controlled double-blinded phase III trial (the HARVEST study)

Background: Tuberculous meningitis (TBM), the most severe form of tuberculosis (TB), results in death or neurological disability in >50%, despite World Health Organisation recommended therapy. Current TBM regimen dosages are based on data from pulmonary TB alone. Evidence from recent phase II pharmacokinetic studies suggests that high dose rifampicin (R) administered intravenously or orally enhances central nervous system penetration and may reduce TBM associated mortality. We hypothesize that, among persons with TBM, high dose oral rifampicin (35 mg/kg) for 8 weeks will improve survival compared to standard of care (10 mg/kg), without excess adverse events.

Protocol: We will perform a parallel group, randomised, placebo-controlled, double blind, phase III multicentre clinical trial comparing high dose oral rifampicin to standard of care. The trial will be conducted across five clinical sites in Uganda, South Africa and Indonesia. Participants are HIV-positive or negative adults with clinically suspected TBM, who will be randomised (1:1) to one of two arms: 35 mg/kg oral rifampicin daily for 8 weeks (in combination with standard dose isoniazid [H], pyrazinamide [Z] and ethambutol [E]) or standard of care (oral HRZE, containing 10 mg/kg/day rifampicin). The primary end-point is 6-month survival. Secondary end points are: i) 12-month survival ii) functional and neurocognitive outcomes and iii) safety and tolerability. Tertiary outcomes are: i) pharmacokinetic outcomes and ii) cost-effectiveness of the intervention. We will enrol 500 participants over 2.5 years, with follow-up continuing until 12 months post-enrolment.

Discussion: Our best TBM treatment still results in unacceptably high mortality and morbidity. Strong evidence supports the increased cerebrospinal fluid penetration of high dose rifampicin, however conclusive evidence regarding survival benefit is lacking. This study will answer the important question of whether high dose oral rifampicin conveys a survival benefit in TBM in HIV-positive and -negative individuals from Africa and Asia.

Trial registration: ISRCTN15668391 (17/06/2019)

High dose oral rifampicin to improve survival from adult tuberculous meningitis: A randomised placebo-controlled double-blinded phase III trial (the HARVEST study)

Background: Tuberculous meningitis (TBM), the most severe form of tuberculosis (TB), results in death or neurological disability in >50%, despite World Health Organisation recommended therapy. Current TBM regimen dosages are based on data from pulmonary TB alone. Evidence from recent phase II pharmacokinetic studies suggests that high dose rifampicin (R) administered intravenously or orally enhances central nervous system penetration and may reduce TBM associated mortality. We hypothesize that, among persons with TBM, high dose oral rifampicin (35 mg/kg) for 8 weeks will improve survival compared to standard of care (10 mg/kg), without excess adverse events. Protocol: We will perform a parallel group, randomised, placebo-controlled, double blind, phase III multicentre clinical trial comparing high dose oral rifampicin to standard of care. The trial will be conducted across five clinical sites in Uganda, South Africa and Indonesia. Participants are HIV-positive or negative adults with clinically suspected TBM, who will be randomised (1:1) to one of two arms: 35 mg/kg oral rifampicin daily for 8 weeks (in combination with standard dose isoniazid [H], pyrazinamide [Z] and ethambutol [E]) or standard of care (oral HRZE, containing 10 mg/kg/day rifampicin). The primary end-point is 6-month survival. Secondary end points are: i) 12-month survival ii) functional and neurocognitive outcomes and iii) safety and tolerability. Tertiary outcomes are: i) pharmacokinetic outcomes and ii) cost-effectiveness of the intervention. We will enrol 500 participants over 2.5 years, with follow-up continuing until 12 months post-enrolment. Discussion: Our best TBM treatment still results in unacceptably high mortality and morbidity. Strong evidence supports the increased cerebrospinal fluid penetration of high dose rifampicin, however conclusive evidence regarding survival benefit is lacking. This study will answer the important question of whether high dose oral rifampicin conveys a survival benefit in TBM in HIV-positive and -negative individuals from Africa and Asia. Trial registration: ISRCTN15668391 (17/06/2019).

Advances in the Diagnosis and Management of Tubercular Meningitis in Children

Tubercular meningitis (TBM) continues to be a common cause of neuromorbidity in children. There is no single diagnostic method that can rapidly detect Mycobacterium tuberculosis (M.tb) in TBM patients with high sensitivity and specificity. Newer diagnostic modalities like Xpert/RIF assay and Loop mediated isothermal amplification assay (LAMP) have gained an essential stand in molecular diagnostics due to their high specificity, modest sensitivity in cerebrospinal fluid (CSF) and quick availability of results. Intensified drug regimens using high dose rifampicin, fluoroquinolone and aspirin appear to be useful adjunct therapy but more pediatric clinical trials on large scale are needed to determine their appropriate place in pediatric TBM. The emergence of multi and extreme drug resistant M.tb strains further challenges the standard therapy. In this review authors summarize challenges of the currently used diagnostic methods and treatment for TBM and discuss the recent advances.

The current global situation for tuberculous meningitis: epidemiology, diagnostics, treatment and outcomes

Tuberculous meningitis (TBM) results from dissemination of M. tuberculosis to the cerebrospinal fluid (CSF) and meninges. Ischaemia, hydrocephalus and raised intracranial pressure frequently result, leading to extensive brain injury and neurodisability. The global burden of TBM is unclear and it is likely that many cases are undiagnosed, with many treated cases unreported. Untreated, TBM is uniformly fatal, and even if treated, mortality and morbidity are high. Young age and human immunodeficiency virus (HIV) infection are potent risk factors for TBM, while Bacillus Calmette-Guérin (BCG) vaccination is protective, particularly in young children. Diagnosis of TBM usually relies on characteristic clinical symptoms and signs, together with consistent neuroimaging and CSF parameters. The ability to confirm the TBM diagnosis via CSF isolation of M. tuberculosis depends on the type of diagnostic tests available. In most cases, the diagnosis remains unconfirmed. GeneXpert MTB/RIF and the next generation Xpert Ultra offer improved sensitivity and rapid turnaround times, and while roll-out has scaled up, availability remains limited. Many locations rely only on acid fast bacilli smear, which is insensitive. Treatment regimens for TBM are based on evidence for pulmonary tuberculosis treatment, with little consideration to CSF penetration or mode of drug action required. The World Health Organization recommends a 12-month treatment course, although data on which to base this duration is lacking. New treatment regimens and drug dosages are under evaluation, with much higher dosages of rifampicin and the inclusion of fluoroquinolones and linezolid identified as promising innovations. The inclusion of corticosteroids at the start of treatment has been demonstrated to reduce mortality in HIV-negative individuals but whether they are universally beneficial is unclear. Other host-directed therapies show promise but evidence for widespread use is lacking. Finally, the management of TBM within health systems is sub-optimal, with drop-offs at every stage in the care cascade.

High dose oral and intravenous rifampicin for improved survival from adult tuberculous meningitis: a phase II open-label randomised controlled trial (the RifT study)

Background: Tuberculous meningitis (TBM) has 44% (95%CI 35-52%) in-hospital mortality with standard therapy in Uganda. Rifampicin, the cornerstone of TB therapy, has 70% oral bioavailability and ~10-20% cerebrospinal fluid (CSF) penetration.  With current WHO-recommended TB treatment containing 8-12mg/kg rifampicin, CSF rifampicin exposures frequently fall below the minimal inhibitory concentration for M. tuberculosis. Two Indonesian phase II studies, the first investigating intravenous rifampicin 600mg and the second oral rifampicin ~30mg/kg, found the interventions were safe and resulted in significantly increased CSF rifampicin exposures and a reduction in 6-month mortality in the investigational arms. Whether such improvements can be replicated in an HIV-positive population remains to be determined. Protocol: We will perform a phase II, open-label randomised controlled trial, comparing higher-dose oral and intravenous rifampicin with current standard of care in a predominantly HIV-positive population. Participants will be allocated to one of three parallel arms (I:I:I): (i) intravenous rifampicin 20mg/kg for 2-weeks followed by oral rifampicin 35mg/kg for 6-weeks; (ii) oral rifampicin 35mg/kg for 8-weeks; (iii) standard of care, oral rifampicin 10mg/kg/day for 8-weeks. Primary endpoints will be: (i) pharmacokinetic parameters in plasma and CSF; (ii) safety. We will also examine the effect of higher-dose rifampicin on survival time, neurological outcomes and incidence of immune reconstitution inflammatory syndrome. We will enrol 60 adults with suspected TBM, from two hospitals in Uganda, with follow-up to 6 months post-enrolment. Discussion: HIV co-infection affects the bioavailability of rifampicin in the initial days of therapy, risk of drug toxicity and drug interactions, and ultimately mortality from TBM. Our study aims to demonstrate, in a predominantly HIV-positive population, the safety and pharmacokinetic superiority of one or both investigational arms compared to current standard of care. The most favourable dose may ultimately be taken forward into an adequately powered phase III trial. Trial registration: ISRCTN42218549 (24 ^th April 2018).

Clinical Outcomes of Patients With Drug-Resistant Tuberculous Meningitis Treated With an Intensified Antituberculosis Regimen

Background

Drug-resistant tuberculous meningitis (TBM) is difficult to diagnose and treat. Mortality is high and optimal treatment is unknown. We compared clinical outcomes of drug-resistant and -susceptible TBM treated with either standard or intensified antituberculosis treatment.

Methods

We analyzed the influence of Mycobacterium tuberculosis drug resistance on the outcomes of patients with TBM enrolled into a randomized controlled trial comparing a standard, 9-month antituberculosis regimen (containing rifampicin 10 mg/kg/day) with an intensified regimen with higher-dose rifampicin (15 mg/kg/day) and levofloxacin (20 mg/kg/day) for the first 8 weeks. The primary endpoint of the trial was 9-month survival. In this subgroup analysis, resistance categories were predefined as multidrug resistant (MDR), isoniazid resistant, rifampicin susceptible (INH-R), and susceptible to rifampicin and isoniazid (INH-S + RIF-S). Outcome by resistance categories and response to intensified treatment were compared and estimated by Cox regression.

Results

Of 817 randomized patients, 322 had a known drug resistance profile. INH-R was found in 86 (26.7%) patients, MDR in 15 (4.7%) patients, rifampicin monoresistance in 1 patient (0.3%), and INH-S + RIF-S in 220 (68.3%) patients. Multivariable regression showed that MDR (hazard ratio [HR], 5.91 [95% confidence interval {CI}, 3.00–11.6]), P < .001), was an independent predictor of death. INH-R had a significant association with the combined outcome of new neurological events or death (HR, 1.58 [95% CI, 1.11–2.23]). Adjusted Cox regression, corrected for treatment adjustments, showed that intensified treatment was significantly associated with improved survival (HR, 0.34 [95% CI, .15–.76], P = .01) in INH-R TBM.

Conclusions

Early intensified treatment improved survival in patients with INH-R TBM. Targeted regimens for drug-resistant TBM should be further explored.

Clinical Trials Registration

ISRCTN61649292.

New Approaches and Therapeutic Options for Mycobacterium tuberculosis in a Dormant State

We are far away from the days when tuberculosis (TB) accounted for 1 in 4 deaths during the 19th century. However, Mycobacterium tuberculosis complex (MTBC) strains are still the leading cause of morbidity and mortality by a single infectious disease, with 9.6 million cases and 1.5 million deaths reported. One-third of the world's population is estimated by the WHO to be infected with latent TB. During the last decade, several studies have aimed to define the characteristics of dormant bacteria in these latent infections. General features of the shift to a dormant state encompass several phenotypic changes that reduce metabolic activity. This low metabolic state is thought to increase the resistance of MTBC strains to host/environmental stresses, including antibiotic action. Once the stress ceases (e.g., interruption of treatment), dormant cells can reactivate and cause symptomatic disease again. Therefore, a proper understanding of dormancy could guide the rational development of new treatment regimens that target dormant cells, reducing later relapse. Here, we briefly summarize the latest data on the genetics involved in the regulation of dormancy and discuss new approaches to TB treatment.

High-performance liquid chromatography with time-programmed fluorescence detection for the quantification of Levofloxacin in human plasma and cerebrospinal fluid in adults with tuberculous meningitis

An accurate and reliable high-performance liquid chromatography with time-programmed fluorescence detection was developed and validated to measure levofloxacin in human plasma and cerebrospinal fluid (CSF). After solid phase extraction process using Evolute^® ABN 96 fixed well plate; levofloxacin and internal standard-enoxacin were separated using a mobile phase consisting of phosphate buffer 10mM with 0.025% triethylamine pH 3.0 - acetonitrile (88:12, v/v) on a Purosphere RP-8e column (5μm, 125×4.0mm) at a flow rate of 1.2mL/min at 35°C. The excitation/emission wavelengths were set to 269/400nm and 294/500nm, for enoxacin and levofloxacin, respectively. The method was linear over the concentration range of 0.02 to 20.0μg/mL with a limit of detection of 0.01μg/mL. The relative standard deviation of intra-assay and inter-assay precision for levofloxacin at four quality controls concentrations (0.02, 0.06, 3.0 and 15.0μg/mL) were less than 7% and the accuracies ranged from 96.75% to 101.9% in plasma, and from 93.00% to 98.67% in CSF. The validated method was successfully applied to quantify levofloxacin in a considerable quantity of plasma (826) and CSF (477) samples collected from 232 tuberculous meningitis patients, and the preliminary intensive pharmacokinetics analysis from 14 tuberculous meningitis patients in Vietnam is described in this paper.

Comparison of DNA Extraction Protocols and Molecular Targets to Diagnose Tuberculous Meningitis

Tuberculous meningitis (TBM) is a severe form of extrapulmonary tuberculosis. The aims of this study were to evaluate in-house molecular diagnostic protocols of DNA extraction directly from CSF samples and the targets amplified by qPCR as an accurate and fast diagnosis of TBM. One hundred CSF samples from 68 patients suspected of TBM were studied. Four DNA extraction techniques (phenol-chloroform-thiocyanate guanidine, silica thiocyanate guanidine, resin, and resin with ethanol) were compared and CSF samples were used to determine the best target (IS6110, MPB64, and hsp65 KDa) by qPCR. The extraction protocol using the phenol-chloroform-thiocyanate guanidine showed the best results in terms of quantification and sensitivity of PCR amplification, presenting up to 10 times more DNA than the second best protocol, the silica guanidine thiocyanate. The target that showed the best result for TBM diagnosis was the IS6110. This target showed 91% sensitivity and 97% specificity when we analyzed the results by sample and showed 100% sensitivity and 98% specificity when we analyzed the results by patient. The DNA extraction with phenol-chloroform-thiocyanate guanidine followed by IS6110 target amplification has been shown to be suitable for diagnosis of TBM in our clinical setting.

Leukotriene A4 Hydrolase Genotype and HIV Infection Influence Intracerebral Inflammation and Survival From Tuberculous Meningitis

Background

Tuberculous meningitis (TBM) is the most devastating form of tuberculosis, yet very little is known about the pathophysiology. We hypothesized that the genotype of leukotriene A4 hydrolase (encoded by LTA4H), which determines inflammatory eicosanoid expression, influences intracerebral inflammation, and predicts survival from TBM.

Methods

We characterized the pretreatment clinical and intracerebral inflammatory phenotype and 9-month survival of 764 adults with TBM. All were genotyped for single-nucleotide polymorphism rs17525495, and inflammatory phenotype was defined by cerebrospinal fluid (CSF) leukocyte and cytokine concentrations.

Results

LTA4H genotype predicted survival of human immunodeficiency virus (HIV)-uninfected patients, with TT-genotype patients significantly more likely to survive TBM than CC-genotype patients, according to Cox regression analysis (univariate P = .040 and multivariable P = .037). HIV-uninfected, TT-genotype patients had high CSF proinflammatory cytokine concentrations, with intermediate and lower concentrations in those with CT and CC genotypes. Increased CSF cytokine concentrations correlated with more-severe disease, but patients with low CSF leukocytes and cytokine concentrations were more likely to die from TBM. HIV infection independently predicted death due to TBM (hazard ratio, 3.94; 95% confidence interval, 2.79-5.56) and was associated with globally increased CSF cytokine concentrations, independent of LTA4H genotype.

Conclusions

LTA4H genotype and HIV infection influence pretreatment inflammatory phenotype and survival from TBM. LTA4H genotype may predict adjunctive corticosteroid responsiveness in HIV-uninfected individuals.

Management of adult infectious encephalitis in metropolitan France

Infectious encephalitis is a severe disease leading to a high mortality and morbidity. The most frequent causes include Herpes simplex virus, Varicella Zoster virus, Listeria monocytogenes, and Mycobacterium tuberculosis. Urgent treatment is required (anti-infective therapy and nonspecific supportive care). The aim of this study was to define treatment strategy, empirical and after microbiological documentation at 48hours, through a systematic literature review.

Clinical presentations, diagnosis, mortality and prognostic markers of tuberculous meningitis in Vietnamese children: a prospective descriptive study

BACKGROUND

Tuberculous meningitis in adults is well characterized in Vietnam, but there are no data on the disease in children. We present a prospective descriptive study of Vietnamese children with TBM to define the presentation, course and characteristics associated with poor outcome.

METHODS

A prospective descriptive study of 100 consecutively admitted children with TBM at Pham Ngoc Thach Hospital, Ho Chi Minh City. Cox and logistic regression were used to identify factors associated with risk of death and a combined endpoint of death or disability at treatment completion.

RESULTS

The study enrolled from October 2009 to March 2011. Median age was 32.5 months; sex distribution was equal. Median duration of symptoms was 18.5 days and time from admission to treatment initiation was 11 days. Fifteen of 100 children died, 4 were lost to follow-up, and 27/81 (33 %) of survivors had intermediate or severe disability upon treatment completion. Microbiological confirmation of disease was made in 6 %. Baseline characteristics associated with death included convulsions (HR 3.46, 95CI 1.19-10.13, p = 0.02), decreased consciousness (HR 22.9, 95CI 3.01-174.3, p < 0.001), focal neurological deficits (HR 15.7, 95CI 1.67-2075, p = 0.01), Blantyre Coma Score (HR 3.75, 95CI 0.99-14.2, p < 0.001) and CSF protein, lactate and glucose levels. Neck stiffness, MRC grade (children aged >5 years) and hydrocephalus were also associated with the combined endpoint of death or disability.

CONCLUSIONS

Tuberculous meningitis in Vietnamese children has significant mortality and morbidity. There is significant delay in diagnosis; interventions that increase the speed of diagnosis and treatment initiation are likely to improve outcomes.

Official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America Clinical Practice Guidelines: Treatment of Drug-Susceptible Tuberculosis

The American Thoracic Society, Centers for Disease Control and Prevention, and Infectious Diseases Society of America jointly sponsored the development of this guideline for the treatment of drug-susceptible tuberculosis, which is also endorsed by the European Respiratory Society and the US National Tuberculosis Controllers Association. Representatives from the American Academy of Pediatrics, the Canadian Thoracic Society, the International Union Against Tuberculosis and Lung Disease, and the World Health Organization also participated in the development of the guideline. This guideline provides recommendations on the clinical and public health management of tuberculosis in children and adults in settings in which mycobacterial cultures, molecular and phenotypic drug susceptibility tests, and radiographic studies, among other diagnostic tools, are available on a routine basis. For all recommendations, literature reviews were performed, followed by discussion by an expert committee according to the Grading of Recommendations, Assessment, Development and Evaluation methodology. Given the public health implications of prompt diagnosis and effective management of tuberculosis, empiric multidrug treatment is initiated in almost all situations in which active tuberculosis is suspected. Additional characteristics such as presence of comorbidities, severity of disease, and response to treatment influence management decisions. Specific recommendations on the use of case management strategies (including directly observed therapy), regimen and dosing selection in adults and children (daily vs intermittent), treatment of tuberculosis in the presence of HIV infection (duration of tuberculosis treatment and timing of initiation of antiretroviral therapy), as well as treatment of extrapulmonary disease (central nervous system, pericardial among other sites) are provided. The development of more potent and better-tolerated drug regimens, optimization of drug exposure for the component drugs, optimal management of tuberculosis in special populations, identification of accurate biomarkers of treatment effect, and the assessment of new strategies for implementing regimens in the field remain key priority areas for research. See the full-text online version of the document for detailed discussion of the management of tuberculosis and recommendations for practice.

Six months therapy for tuberculous meningitis

BACKGROUND

Tuberculous meningitis (TBM) is the main form of tuberculosis that affects the central nervous system and is associated with high rates of death and disability. Most international guidelines recommend longer antituberculous treatment (ATT) regimens for TBM than for pulmonary tuberculosis disease to prevent relapse. However, longer regimens are associated with poor adherence, which could contribute to increased relapse, development of drug resistance, and increased costs to patients and healthcare systems.

OBJECTIVES

To compare the effects of short-course (six months) regimens versus prolonged-course regimens for people with tuberculous meningitis (TBM).

SEARCH METHODS

We searched the following databases up to 31 March 2016: the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE; EMBASE; LILACS; INDMED; and the South Asian Database of Controlled Clinical Trials. We searched the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) and ClinicalTrials.gov for ongoing trials. We also checked article reference lists and contacted researchers in the field.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and prospective cohort studies of adults and children with TBM treated with antituberculous regimens that included rifampicin for six months or longer than six months. The primary outcome was relapse, and included studies required a minimum of six months follow-up after completion of treatment.

DATA COLLECTION AND ANALYSIS

Two review authors (SJ and HR) independently assessed the literature search results for eligibility, and performed data extraction and 'Risk of bias' assessments of the included studies. We contacted study authors for additional information when necessary. Most data came from single arm cohort studies without a direct comparison so we pooled the findings for each group of cohorts and presented them separately using a complete-case analysis. We assessed the quality of the evidence narratively, as using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was inappropriate with no direct comparisons between short- and prolonged-course regimens.

MAIN RESULTS

Four RCTs and 12 prospective cohort studies met our inclusion criteria, and included a total of 1881 participants with TBM. None of the included RCTs directly compared six months versus longer regimens, so we analysed all data as individual cohorts to obtain relapse rates in each set of cohorts.We included seven cohorts of participants treated for six months, with a total of 458 participants. Three studies were conducted in Thailand, two in South Africa, and one each in Ecuador and Papua New Guinea between the 1980s and 2009. We included 12 cohorts of participants treated for longer than six months (ranging from eight to 16 months), with a total of 1423 participants. Four studies were conducted in India, three in Thailand and one each in China, South Africa, Romania, Turkey and Vietnam, between the late 1970s and 2011.The proportion of participants classified as having stage III disease (severe) was higher in the cohorts treated for six months (33.2% versus 16.9%), but the proportion with known concurrent HIV was higher in the cohorts treated for longer (0/458 versus 122/1423). Although there were variations in the treatment regimens, most cohorts received isoniazid, rifampicin, and pyrazinamide during the intensive phase.Investigators achieved follow-up beyond 18 months after completing treatment in three out of the seven cohorts treated for six months, and five out of the 12 cohorts treated for eight to 16 months. All studies had potential sources of bias in their estimation of the relapse rate, and comparisons between the cohorts could be confounded.Relapse was an uncommon event across both groups of cohorts (3/369 (0.8%) with six months treatment versus 7/915 (0.8%) with longer), with only one death attributed to relapse in each group.Overall, the proportion of participants who died was higher in the cohorts treated for longer than six months (447/1423 (31.4%) versus 58/458 (12.7%)). However, most deaths occurred during the first six months in both treatment cohorts, which suggested that the difference in death rate was not directly related to duration of ATT but was due to confounding. Clinical cure was higher in the group of cohorts treated for six months (408/458 (89.1%) versus longer than six months (984/1336 (73.7%)), consistent with the observations for deaths.Few participants defaulted from treatment with six months treatment (4/370 (1.1%)) versus longer treatment (8/355 (2.3%)), and adherence was not well reported.

AUTHORS' CONCLUSIONS

In all cohorts most deaths occurred in the first six months; and relapse was uncommon in all participants irrespective of the regimen. Further inferences are probably inappropriate given this is observational data and confounding is likely. These data are almost all from participants who are HIV-negative, and thus the inferences will not apply to the efficacy and safety of the six months regimens in HIV-positive people. Well-designed RCTs, or large prospective cohort studies, comparing six months with longer treatment regimens with long follow-up periods established at initiation of ATT are needed to resolve the uncertainty regarding the safety and efficacy of six months regimens for TBM.

Recent Developments and Future Opportunities in the Treatment of Tuberculosis in Children

Tuberculosis in children accounts for a significant proportion of the overall burden of disease, and yet for many years research into pediatric treatment has been neglected. Recently, there have been major developments in our understanding of pediatric tuberculosis, and a large number of studies are under way or planned. New drugs and regimens are being evaluated, and older drugs are being repurposed. Shorter regimens with potentially fewer side effects are being assessed for the treatment and prevention of both drug-susceptible and drug-resistant tuberculosis. It may be possible to tailor treatment so that children with less severe disease are given shorter regimens, and weekly dosing is under investigation for preventive therapy and for the continuation phase of treatment. The interaction with human immunodeficiency virus and the management of tuberculosis meningitis are also likely to be better understood. Exciting times lie ahead for pediatric tuberculosis, but much work remains to be done.

Naïve-pooled pharmacokinetic analysis of pyrazinamide, isoniazid and rifampicin in plasma and cerebrospinal fluid of Vietnamese children with tuberculous meningitis

BACKGROUND

Among the various forms of TB, tuberculous meningitis (TBM) is the most severe, with about 30% mortality and 50% of survivors left with neurological sequelae. Children suffer more frequently from TBM than adults and outcomes are often poor due to difficulties in making the diagnosis and uncertainty regarding the best anti-tuberculosis drug regimen. The aim of this prospective study was to describe the pharmacokinetics of pyrazinamide, isoniazid and rifampicin in plasma and cerebrospinal fluid of children with tuberculous meningitis treated with the standard TBM regimen.

METHODS

We performed a prospective observational study of 100 consecutively treated children (≤ 15 years of age) with tuberculous meningitis in Ho Chi Minh City, Vietnam. Children were treated according to the 2006 WHO recommended pediatric treatment regimen consisting of isoniazid (5 mg/kg), rifampicin (10 mg/kg) and ethambutol (15 mg/kg) for 8 months, with the addition of pyrazinamide (25 mg/kg) for the first 3 months and streptomycin (15 mg/kg) for the first 2 months. Pyrazinamide, isoniazid and rifampicin concentrations were measured in plasma at day 14 and in cerebrospinal fluid (CSF) at 1 month by HPLC-UV. A naïve-pooled non-compartmental data analysis was used to describe the pharmacokinetic properties of drugs in the two-age groups of children ≤ 4 years or > 4 years of age.

RESULTS

Younger children, when compared to older children, presented a higher body weight-normalized clearance and volume of distribution, and lower median total plasma exposures for the three studied drugs with -14%, -22% and -16% for Pyrazinamide, Isoniazid and Rifampicin, respectively. In CSF, individual concentrations of isoniazid and pyrazinamide were comparable to that in plasma in both age groups; but rifampicin concentrations were lower than the minimum inhibitory concentration of susceptible bacteria in all but two children.

CONCLUSIONS

There is an age-dependent variation in the plasma and cerebrospinal fluid pharmacokinetics of rifampicin, isoniazid and pyrazinamide. The safety and efficacy of higher doses of rifampicin should be investigated for the treatment of childhood tuberculous meningitis.

Adjunctive Dexamethasone in HIV-Associated Cryptococcal Meningitis

BACKGROUND

Cryptococcal meningitis associated with human immunodeficiency virus (HIV) infection causes more than 600,000 deaths each year worldwide. Treatment has changed little in 20 years, and there are no imminent new anticryptococcal agents. The use of adjuvant glucocorticoids reduces mortality among patients with other forms of meningitis in some populations, but their use is untested in patients with cryptococcal meningitis.

METHODS

In this double-blind, randomized, placebo-controlled trial, we recruited adult patients with HIV-associated cryptococcal meningitis in Vietnam, Thailand, Indonesia, Laos, Uganda, and Malawi. All the patients received either dexamethasone or placebo for 6 weeks, along with combination antifungal therapy with amphotericin B and fluconazole.

RESULTS

The trial was stopped for safety reasons after the enrollment of 451 patients. Mortality was 47% in the dexamethasone group and 41% in the placebo group by 10 weeks (hazard ratio in the dexamethasone group, 1.11; 95% confidence interval [CI], 0.84 to 1.47; P=0.45) and 57% and 49%, respectively, by 6 months (hazard ratio, 1.18; 95% CI, 0.91 to 1.53; P=0.20). The percentage of patients with disability at 10 weeks was higher in the dexamethasone group than in the placebo group, with 13% versus 25% having a prespecified good outcome (odds ratio, 0.42; 95% CI, 0.25 to 0.69; P<0.001). Clinical adverse events were more common in the dexamethasone group than in the placebo group (667 vs. 494 events, P=0.01), with more patients in the dexamethasone group having grade 3 or 4 infection (48 vs. 25 patients, P=0.003), renal events (22 vs. 7, P=0.004), and cardiac events (8 vs. 0, P=0.004). Fungal clearance in cerebrospinal fluid was slower in the dexamethasone group. Results were consistent across Asian and African sites.

CONCLUSIONS

Dexamethasone did not reduce mortality among patients with HIV-associated cryptococcal meningitis and was associated with more adverse events and disability than was placebo. (Funded by the United Kingdom Department for International Development and others through the Joint Global Health Trials program; Current Controlled Trials number, ISRCTN59144167.).

Intensified Antituberculosis Therapy in Adults with Tuberculous Meningitis

BACKGROUND

Tuberculous meningitis is often lethal. Early antituberculosis treatment and adjunctive treatment with glucocorticoids improve survival, but nearly one third of patients with the condition still die. We hypothesized that intensified antituberculosis treatment would enhance the killing of intracerebral Mycobacterium tuberculosis organisms and decrease the rate of death among patients.

METHODS

We performed a randomized, double-blind, placebo-controlled trial involving human immunodeficiency virus (HIV)-infected adults and HIV-uninfected adults with a clinical diagnosis of tuberculous meningitis who were admitted to one of two Vietnamese hospitals. We compared a standard, 9-month antituberculosis regimen (which included 10 mg of rifampin per kilogram of body weight per day) with an intensified regimen that included higher-dose rifampin (15 mg per kilogram per day) and levofloxacin (20 mg per kilogram per day) for the first 8 weeks of treatment. The primary outcome was death by 9 months after randomization.

RESULTS

A total of 817 patients (349 of whom were HIV-infected) were enrolled; 409 were randomly assigned to receive the standard regimen, and 408 were assigned to receive intensified treatment. During the 9 months of follow-up, 113 patients in the intensified-treatment group and 114 patients in the standard-treatment group died (hazard ratio, 0.94; 95% confidence interval, 0.73 to 1.22; P=0.66). There was no evidence of a significant differential effect of intensified treatment in the overall population or in any of the subgroups, with the possible exception of patients infected with isoniazid-resistant M. tuberculosis. There were also no significant differences in secondary outcomes between the treatment groups. The overall number of adverse events leading to treatment interruption did not differ significantly between the treatment groups (64 events in the standard-treatment group and 95 events in the intensified-treatment group, P=0.08).

CONCLUSIONS

Intensified antituberculosis treatment was not associated with a higher rate of survival among patients with tuberculous meningitis than standard treatment. (Funded by the Wellcome Trust and the Li Ka Shing Foundation; Current Controlled Trials number, ISRCTN61649292.).

Adding Streptomycin to an Intensified Regimen for Tuberculous Meningitis Improves Survival in HIV-Infected Patients

In low- and middle-income countries, the mortality of HIV-associated tuberculous meningitis (TM) continues to be unacceptably high. In this observational study of 228 HIV-infected patients with TM, we compared the mortality during the first nine months of patients treated with standard antituberculosis therapy (sATT), intensified ATT (iATT), and iATT with streptomycin (iATT + STM). The iATT included levofloxacin, ethionamide, pyrazinamide, and double dosing of rifampicin and isoniazid and was given only during the hospital admission (median 7 days, interquartile range 6–9). No mortality differences were seen in patients receiving the sATT and the iATT. However, patients receiving the iATT + STM had significant lower mortality than those in the sATT group (hazard ratio [HR] 0.47, 95% confidence interval [CI] 0.24 to 0.93). After adjusting for other covariates, the mortality hazard of the iATT + STM versus the sATT remained statistically significant (adjusted HR 0.2, 95% CI 0.09 to 0.46). Other factors associated with mortality were previous ATT and low albumin concentrations. The mortality risk increased exponentially only with CD4+ lymphocyte concentrations below 100 cells/μL. In conclusion, the use of iATT resulted in a clinically important reduction in mortality compared with the standard of care only if associated with STM. The results of this study deserve further research.

Tuberculous meningitis: advances in diagnosis and treatment

INTRODUCTION

Tuberculous meningitis (TBM) is the most severe form of infection caused by Mycobacterium tuberculosis, causing death or disability in more than half of those affected. The aim of this review is to examine recent advances in our understanding of TBM, focussing on the diagnosis and treatment of this devastating condition.

SOURCES OF DATA

Papers on TBM published between 1891 and 2014 and indexed in the NCBI Pubmed. The following search terms were used: TBM, diagnosis, treatment and outcome.

AREAS OF AGREEMENT

The diagnosis of TBM remains difficult as its presentation is non-specific and may mimic other causes of chronic meningoencephalitis. Rapid recognition of TBM is crucial, however, as delays in initiating treatment are associated with poor outcome. The laboratory diagnosis of TBM is hampered by the low sensitivity of cerebrospinal fluid microscopy and the slow growth of M. tuberculosis in conventional culture systems. The current therapy of TBM is based on the treatment of pulmonary tuberculosis, which may not be ideal. The combination of TBM and HIV infection poses additional management challenges because of the need to treat both infections and the complications associated with them.

AREAS OF CONTROVERSY

The pathogenesis of TBM remains incompletely understood limiting the development of interventions to improve outcome. The optimal therapy of TBM has not been established in clinical trials, and increasing antimicrobial resistance threatens successful treatment of this condition. The use of adjunctive anti-inflammatory agents remains controversial, and their mechanism of action remains incompletely understood. The role of surgical intervention is uncertain and may not be available in areas where TBM is common.

GROWING POINTS

Laboratory methods to improve the rapid diagnosis of TBM are urgently required. Clinical trials of examining the use of high-dose rifampicin and/or fluoroquinolones are likely to report in the near future.

AREAS TIMELY FOR DEVELOPING RESEARCH

The use of biomarkers to improve the rapid diagnosis of TBM warrants further investigation. The role of novel antituberculosis drugs, such as bedaquiline and PA-824, in the treatment of TBM remains to be explored. Human genetic polymorphisms may explain the heterogeneity of response to anti-inflammatory therapies and could potentially be used to tailor therapy.

Pharmacokinetic/pharmacodynamic analysis of an intensified regimen containing rifampicin and moxifloxacin for tuberculous meningitis

Recent data suggest that intensified antimicrobial treatment may improve the outcome of tuberculous meningitis (TBM). Considering that drug exposure is the intermediate link between dose and effect, we examined the concentration-response relationship for rifampicin and moxifloxacin in TBM patients. In an open-label, phase 2 clinical trial performed in Indonesia (ClinicalTrials.gov NCT01158755), 60 TBM patients were randomised to receive standard-dose (450mg oral) or high-dose rifampicin (600mg intravenous) plus either oral moxifloxacin (400mg or 800mg) or ethambutol (750mg). After 14 days, all patients continued with standard tuberculosis treatment. Pharmacokinetic sampling was performed once in every patient during the first three critical days. Differences in exposure between patients who died or survived were tested with independent samples t-tests. The relationship between drug exposure and mortality was examined using Cox regression. Compared with patients who died during the 2 weeks of intensified treatment, surviving patients had significantly higher rifampicin plasma AUC0-6h, plasma Cmax and CSF Chighest. Additionally, patients had a 32-43% lower relative likelihood of dying with an interquartile range increase in rifampicin exposure. Moxifloxacin exposure did not show a clear relationship with survival. From exposure-response curves, a rifampicin plasma AUC0-6h of ∼70mg·h/L (AUC0-24h of ∼116mgh/L) and a Cmax of ∼22mg/L were deduced as minimum target values for treatment. A strong concentration-effect relationship was found, with higher rifampicin exposure leading to better TBM survival. The current treatment dose of rifampicin is suboptimal; higher doses of rifampicin should be evaluated.

Meningitis in HIV-positive patients in sub-Saharan Africa: a review

INTRODUCTION

Meningitis is one of the leading causes of death among patients living with HIV in sub-Saharan Africa. There is no widespread tracking of the incidence rates of causative agents among patients living with HIV, yet the aetiologies of meningitis are different than those of the general population.

METHODS

We reviewed the scientific literature published in PubMed to determine the incidence rates of meningitis among hospitalized people living with HIV in sub-Saharan Africa and report our findings from seven studies across sub-Saharan Africa.

RESULTS

We found high rates of cryptococcal meningitis (19-68%). Tuberculous meningitis was lower (1-36%), although some centres included possible cases as "other" meningitis; therefore, this may not be a true representation of the total cases. Pyogenic meningitis ranged from 6 to 30% and "other" meningitis ranged from 7 to 28% of all reported cases of meningitis. Mortality rates ranged from 25 to 68%. This review describes the most common aetiologies and provides practical diagnostic, treatment and prevention considerations as they apply to the individual living with HIV in sub-Saharan Africa.

CONCLUSIONS

Diagnosis is often limited, and wider availability of accurate and low-cost laboratory diagnostics is desperately needed for prompt diagnosis and initiation of appropriate treatment. Wider acceptance and adoption of available preventative modalities can decrease the incidence of potentially fatal central nervous system infections in African patients living with HIV.

Neutrophil-associated central nervous system inflammation in tuberculous meningitis immune reconstitution inflammatory syndrome

BACKGROUND

The immunopathogenesis of tuberculosis-associated immune reconstitution inflammatory syndrome (IRIS) remains incompletely understood, and we know of only 1 disease site-specific study of the underlying immunology; we recently showed that Mycobacterium tuberculosis culture positivity and increased neutrophils in the cerebrospinal fluid (CSF) of patients with tuberculous meningitis (TBM) are associated with TBM-IRIS. In this study we investigated inflammatory mediators at the disease site in patients with TBM-IRIS.

METHODS

We performed lumbar puncture at 3-5 time points in human immunodeficiency virus (HIV)-infected patients with TBM (n = 34), including at TBM diagnosis, at initiation of antiretroviral therapy (ART) (day 14), 14 days after ART initiation, at presentation of TBM-IRIS, and 14 days thereafter. We determined the concentrations of 40 mediators in CSF (33 paired with blood) with Luminex or enzyme-linked immunosorbent assays. Findings were compared between patients who developed TBM-IRIS (n = 16) and those who did not (TBM-non-IRIS; n = 18).

RESULTS

At TBM diagnosis and 2 weeks after ART initiation, TBM-IRIS was associated with severe, compartmentalized inflammation in the CSF, with elevated concentrations of cytokines, chemokines, neutrophil-associated mediators, and matrix metalloproteinases, compared with TBM-non-IRIS. Patients with TBM-non-IRIS whose CSF cultures were positive for M. tuberculosis at TBM diagnosis (n = 6) showed inflammatory responses similar to those seen in patients with TBM-IRIS at both time points. However, at 2 weeks after ART initiation, S100A8/A9 was significantly increased in patients with TBM-IRIS, compared with patients with TBM-non-IRIS whose cultures were positive at baseline.

CONCLUSIONS

A high baseline M. tuberculosis antigen load drives an inflammatory response that manifests clinically as TBM-IRIS in most, but not all, patients with TBM. Neutrophils and their mediators, especially S100A8/A9, are closely associated with the central nervous system inflammation that characterizes TBM-IRIS.

Tuberculous meningitis: Diagnostic and therapeutic challenges

Neurologists are often the first medical providers to evaluate patients with possible infectious meningitis. Knowledge of the clinical presentations and cerebrospinal fluid, microbiologic, and neuroimaging findings for different etiologies is essential to make a prompt diagnosis and initiate appropriate treatment. Tuberculosis is a common cause of meningitis in developing countries with a high prevalence of pulmonary tuberculosis. However, tuberculosis affects populations in every country and all neurologists need to be vigilant for possible cases of tuberculous meningitis presenting to their medical facilities. This article discusses the challenges of diagnosing and treating tuberculous meningitis and highlights recent advances in diagnostic technology.

Evaluation of GeneXpert MTB/RIF for diagnosis of tuberculous meningitis

Tuberculous meningitis (TBM) is the most severe form of tuberculosis. Microbiological confirmation is rare, and treatment is often delayed, increasing mortality and morbidity. The GeneXpert MTB/RIF test was evaluated in a large cohort of patients with suspected tuberculous meningitis. Three hundred seventy-nine patients presenting with suspected tuberculous meningitis to the Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam, between 17 April 2011 and 31 December 2012 were included in the study. Cerebrospinal fluid samples were tested by Ziehl-Neelsen smear, mycobacterial growth indicator tube (MGIT) culture, and Xpert MTB/RIF. Rifampin (RIF) resistance results by Xpert were confirmed by an MTBDR-Plus line probe assay and all positive cultures were tested by phenotypic MGIT drug susceptibility testing. Overall, 182/379 included patients (48.0%) were diagnosed with tuberculous meningitis. Sensitivities of Xpert, smear, and MGIT culture among patients diagnosed with TBM were 59.3% (108/182 [95% confidence interval {CI}, 51.8 to 66.5%]), 78.6% (143/182 [95% CI, 71.9 to 84.3%]) and 66.5% (121/182 [95% CI, 59.1 to 73.3%]), respectively. There was one false-positive Xpert MTB/RIF test (99.5% specificity). Four cases of RIF resistance (4/109; 3.7%) were identified by Xpert, of which 3 were confirmed to be multidrug-resistant (MDR) TBM and one was culture negative. Xpert MTB/RIF is a rapid and specific test for the diagnosis of tuberculous meningitis. The addition of a vortexing step to sample processing increased sensitivity for confirmed TBM by 20% (P = 0.04). Meticulous examination of a smear from a large volume of cerebrospinal fluid (CSF) remains the most sensitive technique but is not practical in most laboratories. The Xpert MTB/RIF represents a significant advance in the early diagnosis of this devastating condition.

Advances in the diagnosis and treatment of tuberculous meningitis

PURPOSE OF REVIEW

Early diagnosis and treatment of tuberculous meningitis (TBM) saves lives, but current laboratory diagnostic tests lack sensitivity and the best treatment regimens are uncertain. This article reviews the advances towards better TBM diagnosis and treatments made over the last 2 years.

RECENT FINDINGS

A modified Ziehl-Neelsen stain, interferon-gamma release assays and Mycobacterium tuberculosis antigen detection assays have all shown promise as new TBM diagnostic tests. HIV-associated TBM carries an especially grave prognosis and there are new data describing the optimal timing of antiretroviral treatment initiation and the clinical predictors of TBM immune reconstitution inflammatory syndrome. The pharmacokinetic and pharmacodynamic properties of different fluoroquinolones for TBM treatment have been compared, and there are intriguing new data to suggest higher doses of rifampicin given intravenously may improve the survival. Finally, there are preliminary data to suggest that the beneficial effect of adjunctive corticosteroids on TBM survival may be augmented by aspirin and predicted by a polymorphism in a gene responsible for eicosanoid synthesis.

SUMMARY

Much remains to be done to improve the outcome from TBM. There have been important advances in the treatment, which may influence treatment guidelines in the near future, but there remains an urgent need for better diagnostic tests.

Cost-effective diagnostic checklists for meningitis in resource-limited settings

BACKGROUND

Checklists can standardize patient care, reduce errors, and improve health outcomes. For meningitis in resource-limited settings, with high patient loads and limited financial resources, central nervous system diagnostic algorithms may be useful to guide diagnosis and treatment. However, the cost effectiveness of such algorithms is unknown.

METHODS

We used decision analysis methodology to evaluate the costs, diagnostic yield, and cost effectiveness of diagnostic strategies for adults with suspected meningitis in resource-limited settings with moderate/high HIV prevalence. We considered 3 strategies: (1) comprehensive "shotgun" approach of utilizing all routine tests; (2) "stepwise" strategy with tests performed in a specific order with additional tuberculosis (TB) diagnostics; (3) "minimalist" strategy of sequential ordering of high-yield tests only. Each strategy resulted in 1 of 4 meningitis diagnoses: bacterial (4%), cryptococcal (59%), TB (8%), or other (aseptic) meningitis (29%). In model development, we utilized prevalence data from 2 Ugandan sites and published data on test performance. We validated the strategies with data from Malawi, South Africa, and Zimbabwe.

RESULTS

The current comprehensive testing strategy resulted in 93.3% correct meningitis diagnoses costing $32.00 per patient. A stepwise strategy had 93.8% correct diagnoses costing an average of $9.72 per patient, and a minimalist strategy had 91.1% correct diagnoses costing an average of $6.17 per patient. The incremental cost-effectiveness ratio was $133 per additional correct diagnosis for the stepwise over minimalist strategy.

CONCLUSIONS

Through strategically choosing the order and type of testing coupled with disease prevalence rates, algorithms can deliver more care more efficiently. The algorithms presented herein are generalizable to East Africa and Southern Africa.

Tuberculous meningitis: more questions, still too few answers

Tuberculous meningitis is especially common in young children and people with untreated HIV infection, and it kills or disables roughly half of everyone affected. Childhood disease can be prevented by vaccination and by giving prophylactic isoniazid to children exposed to infectious adults, although improvements in worldwide tuberculosis control would lead to more effective prevention. Diagnosis is difficult because clinical features are non-specific and laboratory tests are insensitive, and treatment delay is the strongest risk factor for death. Large doses of rifampicin and fluoroquinolones might improve outcome, and the beneficial effect of adjunctive corticosteroids on survival might be augmented by aspirin and could be predicted by screening for a polymorphism in LTA4H, which encodes an enzyme involved in eicosanoid synthesis. However, these advances are insufficient in the face of drug-resistant tuberculosis and HIV co-infection. Many questions remain about the best approaches to prevent, diagnose, and treat tuberculous meningitis, and there are still too few answers.

Initial Antituberculous Regimen with Better Drug Penetration into Cerebrospinal Fluid Reduces Mortality in HIV Infected Patients with Tuberculous Meningitis: Data from an HIV Observational Cohort Study

Tuberculous meningitis (TM) is the deadliest form of tuberculosis. Nearly two-thirds of HIV infected patients with TM die, and most deaths occur within one month. Current treatment of TM involves the use of drugs with poor penetration into the cerebro-spinal fluid (CSF). In this study, we present the mortality before and after implementing a new antituberculous regimen (ATR) with a higher drug penetration in CSF than the standard ATR during the initial treatment of TM in an HIV cohort study. The new ATR included levofloxacin, ethionamide, pyrazinamide, and a double dose of rifampicin and isoniazid and was given for a median of 7 days (interquartile range 6-9). The new ATR was associated with an absolute 21.5% (95% confidence interval (CI), 7.3-35.7) reduction in mortality at 12 months. In multivariable analysis, independent factors associated with mortality were the use of the standard ATR versus the new ATR (hazard ratio 2.05; 95% CI, 1.2-3.5), not being on antiretroviral therapy, low CD4 lymphocyte counts, and low serum albumin levels. Our findings suggest that an intensified initial ATR, which likely results in higher concentrations of active drugs in CSF, has a beneficial effect on the survival of HIV-related TM.

Fluoroquinolones for treating tuberculosis (presumed drug-sensitive)

BACKGROUND

Currently the World Health Organization only recommend fluoroquinolones for people with presumed drug-sensitive tuberculosis (TB) who cannot take standard first-line drugs. However, use of fluoroquinolones could shorten the length of treatment and improve other outcomes in these people. This review summarises the effects of fluoroquinolones in first-line regimens in people with presumed drug-sensitive TB.

OBJECTIVES

To assess fluoroquinolones as substitute or additional components in antituberculous drug regimens for drug-sensitive TB.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register; CENTRAL (The Cochrane Library 2013, Issue 1); MEDLINE; EMBASE; LILACS; Science Citation Index; Databases of Russian Publications; and metaRegister of Controlled Trials up to 6 March 2013.

SELECTION CRITERIA

Randomized controlled trials (RCTs) of antituberculous regimens based on rifampicin and pyrazinamide and containing fluoroquinolones in people with presumed drug-sensitive pulmonary TB.

DATA COLLECTION AND ANALYSIS

Two authors independently applied inclusion criteria, assessed the risk of bias in the trials, and extracted data. We used the risk ratio (RR) for dichotomous data and the fixed-effect model when it was appropriate to combine data and no heterogeneity was present. We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

We identified five RCTs (1330 participants) that met the inclusion criteria. None of the included trials examined regimens of less than six months duration. Fluoroquinolones added to standard regimensA single trial (174 participants) added levofloxacin to the standard first-line regimen. Relapse and treatment failure were not reported. For death, sputum conversion, and adverse events we are uncertain if there is an effect (one trial, 174 participants, very low quality evidence for all three outcomes). Fluoroquinolones substituted for ethambutol in standard regimens Three trials (723 participants) substituted ethambutol with moxifloxacin, gatifloxacin, and ofloxacin into the standard first-line regimen. For relapse, we are uncertain if there is an effect (one trial, 170 participants, very low quality evidence). No trials reported on treatment failure. For death, sputum culture conversion at eight weeks, or serious adverse events we do not know if there was an effect (three trials, 723 participants, very low quality evidence for all three outcomes). Fluoroquinolones substituted for isoniazid in standard regimens A single trial (433 participants) substituted moxifloxacin for isoniazid. Treatment failure and relapse were not reported. For death, sputum culture conversion, or serious adverse events the substitution may have little or no difference (one trial, 433 participants, low quality evidence for all three outcomes). Fluoroquinolines in four month regimensSix trials are currently in progress testing shorter regimens with fluoroquinolones.

AUTHORS' CONCLUSIONS

Ofloxacin, levofloxacin, moxifloxacin, and gatifloxacin have been tested in RCTs of standard first-line regimens based on rifampicin and pyrazinamide for treating drug-sensitive TB. There is insufficient evidence to be clear whether addition or substitution of fluoroquinolones for ethambutol or isoniazid in the first-line regimen reduces death or relapse, or increases culture conversion at eight weeks. Much larger trials with fluoroquinolones in short course regimens of four months are currently in progress.

Detection of Mycobacterium tuberculosis GlcB or HspX Antigens or devR DNA impacts the rapid diagnosis of tuberculous meningitis in children

Background

Tuberculous meningitis (TBM) is the most common form of neurotuberculosis and the fifth most common form of extrapulmonary TB. Early diagnosis and prompt treatment are the cornerstones of effective disease management. The accurate diagnosis of TBM poses a challenge due to an extensive differential diagnosis, low bacterial load and paucity of cerebrospinal fluid (CSF) especially in children.

Methodology/Principal Findings

We describe the utility of ELISA and qPCR for the detection of Mycobacterium tuberculosis (M. tb) proteins (GlcB, HspX, MPT51, Ag85B and PstS1) and DNA for the rapid diagnosis of TBM. CSF filtrates (n = 532) derived from children were classified as ‘Definite’ TBM (M. tb culture positive, n = 29), ‘Probable and Possible’ TBM (n = 165) and ‘Not-TBM’ including other cases of meningitis or neurological disorders (n = 338). ROC curves were generated from ELISA and qPCR data of ‘Definite’ TBM and Non-Tuberculous infectious meningitis (NTIM) samples and cut-off values were derived to provide ≥95% specificity. devR qPCR, GlcB, HspX and PstS1 ELISAs showed 100% (88;100) sensitivity and 96–97% specificity in ‘Definite’ TBM samples. The application of these cut-offs to ‘Probable and Possible’ TBM groups yielded excellent sensitivity (98%, 94;99) and specificity (98%, 96;99) for qPCR and for GlcB, HspX and MPT51 antigen ELISAs (sensitivity 92–95% and specificity 93–96%). A test combination of qPCR with GlcB and HspX ELISAs accurately detected all TBM samples at a specificity of ∼90%. Logistic regression analysis indicated that these tests significantly added value to the currently used algorithms for TBM diagnosis.

Conclusions

The detection of M. tb GlcB/HspX antigens/devR DNA in CSF is likely to improve the utility of existing algorithms for TBM diagnosis and also hasten the speed of diagnosis.

Tuberculous meningitis in adults: a review of a decade of developments focusing on prognostic factors for outcome

Tuberculous meningitis (TBM) is the most severe form of TB. Despite treatment, mortality and long-term disability remain unacceptably high. Prevention, early recognition, diagnosis and treatment are fundamental to improving outcomes. However, an effective vaccine remains elusive, initial symptoms are nonspecific, and sensitive diagnostic tests are not available. There has been progress in our understanding of the immunopathology of TBM, and several factors have been found to be associated with susceptibility to infection, disease progression and clinical outcome. However, these have not yet impacted on treatment. Early treatment initiation and uninterrupted continuation, severity on presentation, seizures, stroke, cranial nerve involvement, cerebrospinal fluid cell count and lactate levels, hyponatreamia and coinfection with HIV are all found to be important prognostic factors for outcome. Pathogen lineage (Beijing genotype) and host genetics (polymorphisms in TLR2, TIRAP and LTA4H genes) can influence susceptibility to TBM. However, these findings have not yet impacted on treatment. Progress in vaccine development, opportunities for better diagnostic tests, novel insights into pathogenesis and an increasing evidence base for improving treatment should impact the current high mortality and morbidity, if translated to global and local guidelines.

Influence of antituberculosis drug resistance and Mycobacterium tuberculosis lineage on outcome in HIV-associated tuberculous meningitis

HIV-associated tuberculous meningitis (TBM) has high mortality. Aside from the devastating impact of multidrug resistance (MDR) on survival, little is understood about the influence of other bacterial factors on outcome. This study examined the influence of Mycobacterium tuberculosis drug resistance, bacterial lineage, and host vaccination status on outcome in patients with HIV-associated TBM. Mycobacterium tuberculosis isolates from the cerebrospinal fluid of 186 patients enrolled in two studies of HIV-associated TBM in Ho Chi Minh City, Vietnam, were tested for resistance to first-line antituberculosis drugs. Lineage genotyping was available for 122 patients. The influence of antituberculosis drug resistance and M. tuberculosis lineage on 9-month mortality was analyzed using Kaplan-Meier survival analysis and Cox multiple regression models. Isoniazid (INH) resistance without rifampin resistance was associated with increased mortality (adjusted hazard ratio [HR], 1.78, 95% confidence interval [CI], 1.18 to 2.66; P = 0.005), and multidrug resistance was uniformly fatal (n = 8/8; adjusted HR, 5.21, 95% CI, 2.38 to 11.42; P < 0.0001). The hazard ratio for INH-resistant cases was greatest during the continuation phase of treatment (after 3 months; HR, 5.05 [95% CI, 2.23 to 11.44]; P = 0.0001). Among drug-susceptible cases, patients infected with the "modern" Beijing lineage strains had lower mortality than patients infected with the "ancient" Indo-Oceanic lineage (HR, 0.29 [95% CI, 0.14 to 0.61]; P = 0.001). Isoniazid resistance, multidrug resistance, and M. tuberculosis lineage are important determinants of mortality in patients with HIV-associated TBM. Interventions which target these factors may help reduce the unacceptably high mortality in patients with TBM.

Tuberculous meningitis: diagnosis and treatment overview

Tuberculous meningitis (TBM) is the most common form of central nervous system tuberculosis (TB) and has very high morbidity and mortality. TBM is typically a subacute disease with symptoms that may persist for weeks before diagnosis. Characteristic cerebrospinal fluid (CSF) findings of TBM include a lymphocytic-predominant pleiocytosis, elevated protein, and low glucose. CSF acid-fast smear and culture have relatively low sensitivity but yield is increased with multiple, large volume samples. Nucleic acid amplification of the CSF by PCR is highly specific but suboptimal sensitivity precludes ruling out TBM with a negative test. Treatment for TBM should be initiated as soon as clinical suspicion is supported by initial CSF studies. Empiric treatment should include at least four first-line drugs, preferably isoniazid, rifampin, pyrazinamide, and streptomycin or ethambutol; the role of fluoroquinolones remains to be determined. Adjunctive treatment with corticosteroids has been shown to improve mortality with TBM. In HIV-positive individuals with TBM, important treatment considerations include drug interactions, development of immune reconstitution inflammatory syndrome, unclear benefit of adjunctive corticosteroids, and higher rates of drug-resistant TB. Testing the efficacy of second-line and new anti-TB drugs in animal models of experimental TBM is needed to help determine the optimal regimen for drug-resistant TB.

Sample size requirements for separating out the effects of combination treatments: randomised controlled trials of combination therapy vs. standard treatment compared to factorial designs for patients with tuberculous meningitis

BACKGROUND

In certain diseases clinical experts may judge that the intervention with the best prospects is the addition of two treatments to the standard of care. This can either be tested with a simple randomized trial of combination versus standard treatment or with a 2 x 2 factorial design.

METHODS

We compared the two approaches using the design of a new trial in tuberculous meningitis as an example. In that trial the combination of 2 drugs added to standard treatment is assumed to reduce the hazard of death by 30% and the sample size of the combination trial to achieve 80% power is 750 patients. We calculated the power of corresponding factorial designs with one- to sixteen-fold the sample size of the combination trial depending on the contribution of each individual drug to the combination treatment effect and the strength of an interaction between the two.

RESULTS

In the absence of an interaction, an eight-fold increase in sample size for the factorial design as compared to the combination trial is required to get 80% power to jointly detect effects of both drugs if the contribution of the less potent treatment to the total effect is at least 35%. An eight-fold sample size increase also provides a power of 76% to detect a qualitative interaction at the one-sided 10% significance level if the individual effects of both drugs are equal. Factorial designs with a lower sample size have a high chance to be underpowered, to show significance of only one drug even if both are equally effective, and to miss important interactions.

CONCLUSIONS

Pragmatic combination trials of multiple interventions versus standard therapy are valuable in diseases with a limited patient pool if all interventions test the same treatment concept, it is considered likely that either both or none of the individual interventions are effective, and only moderate drug interactions are suspected. An adequately powered 2 x 2 factorial design to detect effects of individual drugs would require at least 8-fold the sample size of the combination trial.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN61649292.