Lipoarabinomannan enzyme-linked immunosorbent assay for early diagnosis of childhood tuberculous meningitis

Value of urine-based lipoarabinomannan (LAM) antigen tests for diagnosing tuberculosis in children: systematic review and meta-analysis

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Urine-based lateral flow lipoarabinomannan assays, particularly the Fujifilm SILVAMP TB lipoarabinomannan (Fuji LAM) test, show promise for the diagnosis of tuberculosis in children.

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Urine-based lateral flow lipoarabinomannan assays have more value in human immunodeficiency virus (HIV)-positive children than HIV-negative children.

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The Mycobacterium tuberculosis enzyme-linked immunosorbent assay showed higher specificity than the other tests.

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Sensitivity of the Fuji LAM test did not vary much between HIV-negative and HIV-positive children.

Background

Tuberculosis (TB) is a global burden, and this is likely to remain the case due to a lack of adequate and accurate point-of-care diagnostic tests. Obtaining good-quality sputum from the bottom of the respiratory tract of children is challenging. Lipoarabinomannan (LAM) is a specific component of the mycobacterial cell envelope that is excreted in the urine of people with active TB. This study aimed to assess the performance of different types of urine-based LAM antigen tests for the diagnosis of TB in children.

Methods

Relevant databases were searched for studies that used urine-based LAM tests to diagnose TB in children. Study quality was assessed using the Joanna Briggs Institute Critical Appraisal Tool. Pooled sensitivity and specificity were calculated using the random-effect model in STATA Version 16.0. Moreover, subgroup analysis was undertaken to hinder the heterogeneity of the studies.

Results

Eleven articles were included in the final systematic review and meta-analysis. The pooled sensitivity and specificity of the Mycobacterium tuberculosis enzyme-linked immunosorbent assay (MTB-LAM-ELISA), Alere Determine TB LAM Ag (Alere LAM) test and the Fujifilm SILVAMP TB LAM (Fuji LAM) test in children aged <15 years with TB were 16.0% [95% confidence interval (CI) 10.25–42.25] and 95.61% (95% CI 93.74–97.74); 45.90% (95% CI 40.40–51.40) and 80.42% (95% CI 69.39–91.46); and 52.32% (95% CI 35.03–69.62) and 89.37% (95% CI 82.88–95.86), respectively. Subgroup analysis revealed that the pooled sensitivity and specificity of MTB-LAM-ELISA, Alere LAM test and Fuji LAM test were 33.5% (95% CI 34.86–100) and 95.83% (95% CI 91.50–100); 46.59% (95% CI 32.98–60.19) and 76.45% (95% CI 57.07–95.82); and 57.89% (95% CI 48.44–67.35%) and 87.66% (95% CI 75.29–100), respectively, in human immunodeficiency virus (HIV)-positive children; and 3.35% (95% CI 1.61–8.31) and 96.0% (95% CI 93.88–98.11); 32.33% (95% CI 7.63–57.03) and 79.07% (95% CI 62.62–95.51); and 50.95% (95% CI 27.45–74.45) and 89.47% (95% CI 84.72–94.22), respectively, in HIV-negative children.

Conclusion

The Fuji LAM and Alere LAM tests may be useful for the diagnosis of TB in children in conjunction with other more sensitive and specific tests, although a prospective study in relevant clinical settings is needed to evaluate this. There is a need for more evidence-based data on the use of these rapid diagnostic tools to diagnose TB in children independent of HIV status.

Overview of Brain-to-Gut Axis Exposed to Chronic CNS Bacterial Infection(s) and a Predictive Urinary Metabolic Profile of a Brain Infected by Mycobacterium tuberculosis

A new paradigm in neuroscience has recently emerged - the brain-gut axis (BGA). The contemporary focus in this paradigm has been gut → brain ("bottom-up"), in which the gut-microbiome, and its perturbations, affects one's psychological state-of-mind and behavior, and is pivotal in neurodegenerative disorders. The emerging brain → gut ("top-down") concept, the subject of this review, proposes that dysfunctional brain health can alter the gut-microbiome. Feedback of this alternative bidirectional highway subsequently aggravates the neurological pathology. This paradigm shift, however, focuses upon non-communicable neurological diseases (progressive neuroinflammation). What of infectious diseases, in which pathogenic bacteria penetrate the blood-brain barrier and interact with the brain, and what is this effect on the BGA in bacterial infection(s) that cause chronic neuroinflammation? Persistent immune activity in the CNS due to chronic neuroinflammation can lead to irreversible neurodegeneration and neuronal death. The properties of cerebrospinal fluid (CSF), such as immunological markers, are used to diagnose brain disorders. But what of metabolic markers for such purposes? If a BGA exists, then chronic CNS bacterial infection(s) should theoretically be reflected in the urine. The premise here is that chronic CNS bacterial infection(s) will affect the gut-microbiome and that perturbed metabolism in both the CNS and gut will release metabolites into the blood that are filtered (kidneys) and excreted in the urine. Here we assess the literature on the effects of chronic neuroinflammatory diseases on the gut-microbiome caused by bacterial infection(s) of the CNS, in the context of information attained via metabolomics-based studies of urine. Furthermore, we take a severe chronic neuroinflammatory infectious disease - tuberculous meningitis (TBM), caused by Mycobacterium tuberculosis, and examine three previously validated CSF immunological biomarkers - vascular endothelial growth factor, interferon-gamma and myeloperoxidase - in terms of the expected changes in normal brain metabolism. We then model the downstream metabolic effects expected, predicting pivotal altered metabolic pathways that would be reflected in the urinary profiles of TBM subjects. Our cascading metabolic model should be adjustable to account for other types of CNS bacterial infection(s) associated with chronic neuroinflammation, typically prevalent, and difficult to distinguish from TBM, in the resource-constrained settings of poor communities.

Microbiological diagnosis of tuberculous meningitis: Phenotype to genotype

Tuberculous meningitis (TBM) is a commonly encountered central nervous system infection. Characteristic clinical, imaging and cerebrospinal fluid parameters help clinicians to make a prompt presumptive diagnosis that enables them to start empirical anti-tuberculosis treatment. There are several close mimic to TBM, such as partially treated pyogenic meningitis, fungal meningitis, sarcoidosis, meningeal metastases and meningeal lymphomatosis. Microbiological confirmation instils a sense of confidence amongst treating physicians. With conventional phenotypic methods (cerebrospinal fluid microscopy and culture), in more than 50 per cent patients, microbiological confirmation is not achieved. Moreover, these methods take a long time before providing conclusive results. Negative result does not rule out Mycobacterium tuberculosis infection of the brain. Genotypic methods, such as IS 6110 polymerase chain reaction and automated Xpert M. tuberculosis/rifampicin (MTB/RIF) assay system improved the TBM diagnostics, as results are rapidly available. Xpert MTB/RIF assay, in addition, detects rifampicin resistance. Xpert MTB/RIF Ultra is advanced technology which has higher (60-70%) sensitivity and is being considered a game-changer in the diagnostics of TBM. A large number of TBM cases remain unconfirmed. The situation of TBM diagnostics will remain grim, if low-cost technologies are not widely available. Till then, physicians continue to rely on their clinical acumen to start empirical anti-tuberculosis treatment.

Biomarkers for tuberculosis: the case for lipoarabinomannan

Tuberculosis (TB) is considered the most onerous of infectious diseases according to recent reports from the World Health Organization. Available tests for TB diagnosis present severe limitations, and a reliable point-of-care (POC) diagnostic test does not exist. Neither is there a test to discern between the different stages of TB, and in particular to predict which patients with Mycobacterium tuberculosis infection and no clinical signs are more at risk of advancing to overt disease. We here review the usefulness of mycobacterial lipoarabinomannan (LAM) as a diagnostic marker for active and latent TB and, also, aspects of the immune response to LAM relevant to such tests. There is a high potential for urinary LAM-based POC tests for the diagnosis of active TB. Some technical challenges to optimised sensitivity of the test will be detailed. A method to quantify LAM in urine or serum should be further explored as a test of treatment effect. Recent data on the immune response to LAM suggest that markers for host response to LAM should be investigated for a prognostic test to recognise individuals at the greatest risk of disease activation.

There is a high potential for a urinary LAM-based point-of-care test to diagnose TB. Markers for host response to LAM should be explored to identify those at highest risk of developing active TB.http://ow.ly/FyCs30n4uFE

Tuberculosis in Children

Mycobacterium tuberculosis is the leading cause of death worldwide from a single bacterial pathogen. The World Health Organization estimates that annually 1 million children have tuberculosis (TB) disease and many more harbor a latent form. Accurate estimates are hindered by under-recognition and challenges in diagnosis. To date, an accurate diagnostic test to confirm TB in children does not exist. Treatment is lengthy but outcomes are generally favorable with timely initiation. With the End TB Strategy, there is an urgent need for improved diagnostics and treatment to prevent the unnecessary morbidity and mortality from TB in children.

Mycobacteria-derived biomarkers for tuberculosis diagnosis

Tuberculosis (TB) remains an escalating problem worldwide. The current diagnostic methods do not always guarantee reliable diagnosis. TB treatment is a time-consuming process that requires the use of several chemotherapeutics, to which mycobacteria are becoming increasingly resistant. This article focuses on the potential utility of biomarkers of mycobacterial origin with potential implications for TB diagnosis. Properly standardized indicators could become new diagnostic tools, improving and streamlining the identification of Mycobacterium tuberculosis infection and the implementation of appropriate therapy. These markers can also potentially provide a quick confirmation of effectiveness of new anti-mycobacterial drugs and TB vaccines, leading to a possible application in practice.

Managing latent tuberculosis infection and tuberculosis in children

Tuberculosis (TB) is a major cause of childhood morbidity and mortality worldwide. The aim of this review is to describe the management of the child with TB and latent tuberculosis infection (LTBI). To develop this article, a working group reviewed relevant epidemiological and other scientific studies and established practices in conducting LBTI and TB in children. The article describes how to manage the child with LTBI, considering transmission and infectiousness of tuberculosis, contact screening and prioritization of contacts and recommendations on treatment of children with LTBI and how to manage the child with TB considering the susceptibility of children to developing tuberculosis, epidemiology and classification of tuberculosis in children, diagnosis and treatment.

Tuberculosis in Children

Mycobacterium tuberculosis is the leading cause of death worldwide from a single bacterial pathogen. The World Health Organization estimates that annually 1 million children have tuberculosis (TB) disease and many more harbor a latent form. Accurate estimates are hindered by under-recognition and challenges in diagnosis. To date, an accurate diagnostic test to confirm TB in children does not exist. Treatment is lengthy but outcomes are generally favorable with timely initiation. With the End TB Strategy, there is an urgent need for improved diagnostics and treatment to prevent the unnecessary morbidity and mortality from TB in children.

[A visualization study of research papers on childhood tuberculous meningitis in China and abroad over the past decade]

OBJECTIVE

To introduce co-word analysis into the analysis of the current research status of childhood tuberculous meningitis, to compare the similarities and differences in research topics of the field in China and abroad over the past decade, and to discover the advantages and weak links in the study field in China.

METHODS

PubMed, CNKI, VIP, and Wanfang Data were searched for the articles which met the inclusion criteria. Ucinet 6.0 and Netdraw were used for co-occurrence analysis, and the co-article relationship between high-frequency key words was visualized.

RESULTS

A total of 226 articles abroad and 186 Chinese articles on childhood tuberculous meningitis were obtained. The figures for co-occurrence analysis of high-frequency key words in research articles on childhood tuberculous meningitis in China and abroad were successfully plotted. Compared with the studies in China, the studies abroad were more sophisticated and well-developed, with more studies on drug-resistant tuberculosis, the relationship between tuberculosis and AIDS, and the epidemiology of tuberculosis. The key words listed in the studies abroad were more standard. The studies in China on childhood tuberculous meningitis concentrated on vaccination and nursing.

CONCLUSIONS

In general, the studies on childhood tuberculous meningitis in China and abroad have the same directions. The studies abroad have a complicated network and use more standard key words. The studies on childhood tuberculous meningitis are well conducted in China. However, more studies are needed for drug-resistant tuberculosis, the relationship between tuberculosis and AIDS, and the epidemiology of tuberculosis in future.