Methods of rapid diagnosis for the etiology of meningitis in adults

A novel biosensing strategy for identification of three important bacteria causing meningitis

Bacterial meningitis is an acute infection which requires rapid diagnosis and treatment due to the high mortality and serious consequences of the disease. The purpose of this study was to design a homemade multiplex PCR and a novel fluorescence biosensor on chip (FBC) to detect three important agents of meningitis including Streptococcus pneumoniae (S. pneumoniae), Neisseria meningitidis (N. meningitidis), and Haemophilus influenzae (H. influenzae). The homemade multiplex PCR can diagnose three bacterial species simultaneously. Fabrication of FBC was carried out based on the deposition of lead nanoparticles on a quartz slide using the thermal evaporation method. Then, the SH-Cap Probe/Target ssDNA /FAM-Rep probe was loaded on lead film. The evaluation of the fluorescence reaction when the probes bind to the target ssDNA was assessed by a Cytation 5 Cell Imaging Multimode Reader Bio-Tek. The limit of detections (LOD) in homemade PCR and FBC to identify S. pneumoniae were 119 × 102 CFU/mL (0.27 ng/μL) and 380 CFU/mL (9 pg/μL), respectively. The LODs of homemade PCR and FBC for detection of N. meningitidis were 4.49 CFU/mL (1.1 pg/μL) and 13 × 103 CFU/mL (30 pg/μL), respectively. Our results confirmed the LODs of homemade PCR and FBC in detection of H. influenzae were 15.1 CFU/mL (30 fg/μL) and 41 × 102 CFU/mL (90 pg/ μL), respectively. Both techniques had appropriate sensitivity and specificity in detection of S. pneumoniae, N. meningitidis and H. influenzae.

Efficacy and safety of intrathecal dexamethasone combined with isoniazid in the treatment of tuberculous meningitis: a meta-analysis

BACKGROUND

The treatment regimen for tuberculous meningitis (TBM) remains unclear and requires optimization. There are some reports on successful adjunct intrathecal dexamethasone and isoniazid (IDI) treatment strategies for TBM, however, there is equivocal evidence on their efficacy and safety.

METHODS

A comprehensive search of English and Chinese databases was conducted from inception to February 2024. A meta-analysis was performed on randomized controlled trials (RCTs) estimating the effects of adjunct IDI on conventional anti-TB (C anti-TB) treatments or C anti-TB alone. Efficacy, adverse reaction rate, cerebrospinal fluid (CSF) leukocytes, and CSF protein were used as primary outcome indicators. CSF glucose, CSF chlorides, CSF pressure, recovery time for laboratory indicators and recovery time for clinical symptoms were used as secondary outcome indicators.

RESULTS

A total of 17 studies involving 1360 (IDI group vs. C anti-TB group: 392 vs. 372; higher-dose IDI group vs. lower-dose IDI group: 319 vs. 277) patients were included in our analysis. Efficacy was significantly higher (RR 1.3, 95% CI 1.2-1.4, P < 0.001) and adverse reaction rate was significantly lower in the IDI groups (RR 0.59, 95% CI 0.37-0.92, P = 0.021). Furthermore, CSF leukocytes (WMD - 29.33, 95% CI [- 40.64 to-18.02], P < 0.001) and CSF protein (WMD - 0.79, 95%CI [-0.96 to-0.61], P < 0.001) were significantly lower in the IDI groups. Recovery time indicators were all shorter in the IDI groups, fever (SMD - 2.45, 95% CI [-3.55 to-1.35], P < 0.001), coma (SMD-3.75, 95% CI [-4.33 to-3.17], P < 0.001), and headache (SMD  - 3.06, 95% CI [- 4.05 to-2.07], P < 0.001), respectively. Higher-dose IDI was more effective than lower-dose IDI (RR 1.23, 95% CI 1.14-1.33, P < 0.001), with no significant difference in adverse reaction rate between the two (RR 0.82, 95%CI 0.43-1.56, P = 0.544).

CONCLUSION

Adjunct IDI with C anti-TB can enhance therapeutic outcomes and reduce adverse reaction rate in adult TBM patients, with higher-dose IDI showing superior efficacy. These findings highlight the potential of IDI as an adjunctive therapy in TBM management. However, more high-quality RCTs from more regions should be conducted to support our results.

TRIAL REGISTRATION

Retrospectively registered in PROSPERO  https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023388860 .

Evaluation of cerebrospinal fluid levels for ALOX5, S100B, DEFA1, and GFAP in infectious meningitis

BACKGROUND

The aim of this study was to determine how the levels of peptide and protein-based biomarkers in cerebrospinal fluid change in bacterial, tuberculous, and aseptic meningitis, and to determine the success of these agents in distinguishing between different types of infectious meningitis.

METHODS

The levels of arachidonate-5-lipoxygenase, S100 calcium-binding protein B, defensin-α 1, and glial fibrillary acidic protein in cerebrospinal fluid samples from 20 tuberculosis, 40 bacterial, 25 aseptic meningitis patients, and 55 control groups were measured and compared using an enzyme-linked immunosorbent assay.

RESULTS

The mean age of the patients was 37.9 ± 14.4 years. The parameter that contributed the most to the differential diagnosis of the infectious meningitis groups was S100 calcium-binding protein B. The S100 calcium-binding protein B levels were significantly higher in the tuberculous meningitis group than in the other groups, and arachidonate-5-lipoxygenase levels were significantly higher in the tuberculous meningitis and bacterial meningitis groups (P < .05).

CONCLUSION

This study showed that cerebrospinal fluid arachidonate-5-lipoxygenase, and S100 calcium-binding protein B levels may differ in bacterial, aseptic, and tuberculous meningitis, and the results obtained may be quite effective as important potential biomarkers in the differential diagnosis of different types of meningitis.

Application of metabolomics in diagnostics and differentiation of meningitis: A narrative review with a critical approach to the literature

Due to its high mortality rate associated with various life-threatening sequelae, meningitis poses a vital problem in contemporary medicine. Numerous algorithms, many of which were derived with the aid of artificial intelligence, were brought up in a strive for perfection in predicting the status of sepsis-related survival or exacerbation. This review aims to provide key insights on the contextual utilization of metabolomics. The aim of this the metabolomic approach set of methods can be used to investigate both bacterial and host metabolite sets from both the host and its microbes in several types of specimens - even in one's breath, mainly with use of two methods - Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR). Metabolomics, and has been used to elucidate the mechanisms underlying disease development and metabolic identification changes in a wide range of metabolite contents, leading to improved methods of diagnosis, treatment, and prognosis of meningitis. Mass spectrometry (MS) and Nuclear Magnetic Resonance (NMR) are the main analytical platforms used in metabolomics. Its high sensitivity accounts for the usefulness of metabolomics in studies into meningitis, its sequelae, and concomitant comorbidities. Metabolomics approaches are a double-edged sword, due to not only their flexibility, but also - high complexity, as even minor changes in the multi-step methods can have a massive impact on the results. Information on the differential diagnosis of meningitis act as a background in presenting the merits and drawbacks of the use of metabolomics in context of meningeal infections.

Adult spinal cord diffuse midline glioma, H3 K27-altered mimics symptoms of central nervous system infection: a case report

Diffuse midline gliomas, H3 K27-altered are infiltrative growth gliomas with histone H3K27M mutations. This glioma is more common in the pediatric population, and the prognosis is usually poor. We report a case of diffuse midline gliomas, H3 K27-altered in an adult patient that mimicked symptoms of central nervous system infection. The patient was admitted due to double vision for 2 months and paroxysmal unconsciousness for 6 days. Initially, lumbar puncture showed persistent high intracranial pressure, high protein, and low chlorine. Magnetic resonance imaging showed diffuse thickening and enhancement of meninges and spinal meninges, and later, fever occurred. The initial diagnosis was meningitis. We suspected central nervous system infection, so we started anti-infection treatment, but the treatment was ineffective. The patient's condition gradually worsened, with lower limb weakness and even the consciousness became unclear. A repeat magnetic resonance imaging and positron emission tomography-computed tomography scan showed space-occupying lesions in the spinal cord, which was considered a tumor. Following neurosurgery, pathological tests identified the tumor as diffuse midline gliomas, H3 K27-altered. The patient was recommended for radiotherapy and temozolomide chemotherapy. The patient's condition improved after chemotherapy treatment, and he survived for an additional 6 months. Our case shows that diagnosing diffuse midline gliomas, H3 K27-altered in the central nervous system is complex and can be confused with the clinical characteristics of central nervous system infection. Therefore, clinicians should pay attention to such diseases to avoid misdiagnosis.

Diagnostic Accuracy of Cerebrospinal Fluid (CSF) Adenosine Deaminase (ADA) for Tuberculous Meningitis (TBM) in Adults: A Systematic Review and Meta-Analysis

Tuberculous meningitis is the most serious complication of tuberculosis. Early diagnosis is crucial to start relevant treatment to prevent death and disability. Electronic databases PubMed, Google Scholar, and Cochrane Library were used to find relevant articles from January 1980 to June 2022. The random-effect model in terms of pooled sensitivity, specificity, and diagnostic odds ratio (DOR) with 95% confidence interval was adopted to derive the diagnostic efficacy of cerebrospinal fluid (CSF) adenosine deaminase (ADA) for the diagnosis of tuberculous meningitis (TBM) in adult patients. A total of 22 studies (20 prospective and two retrospective data) have been included in this meta-analysis, having 1927 participants. We perceived acceptable pooled sensitivity, specificity, summary receiver operating characteristics (SROCs), and diagnostic odds ratio (DOR) of 0.85 (95% CI: 0.77-0.90), 0.90 (95% CI: 0.85-0.93), 0.94 (95% CI: 0.91-0.96) and 48 (95% CI: 26-86), respectively, for CSF-ADA for differentiating TBM from non-TBM in adult patients. To ascertain the certainty of evidence for CSF-ADA as a diagnostic marker for TBM, Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) analysis was used. CSF-ADA is an auspicious diagnostic test with a high degree of specificity and acceptable sensitivity for the diagnosis of tuberculous meningitis, however, with very low certainty of evidence.

A study of risk factors for tuberculous meningitis among patients with tuberculosis in China: An analysis of data between 2012 and 2019

Purpose

The present study aimed to explore the risk factors for tuberculous meningitis (TBM) among patients with tuberculosis (TB).

Methods

This retrospective study was conducted on patients with TB who were hospitalized in Beijing Chest Hospital between January 2012 and December 2019. Demographic and clinical data of patients with TB were extracted from electronic medical records using a standardized data collection system. Logistic regression was used to analyze the risk factors associated with TBM.

Results

Of the total number of 22,988 cases enrolled, 3.1% were cases of TBM, which included 127 definite and 581 probable TBM, respectively. Multivariate analysis showed that definite TBM was significantly associated with patients aged < 30 years [adjusted odds ratio (aOR) = 3.015, 95% confidence interval (CI): (1.451-6.266)], who were farmers [aOR = 1.490, 95%CI: (1.020-2.177)], with miliary pulmonary TB [aOR = 105.842, 95%CI: (71.704-156.235)], and with malnutrition [aOR = 2.466, 95%CI: (1.110-5.479)]. Additionally, probable TBM was significantly associated with patients aged < 30 years [aOR = 2.174, 95% CI: (1.450-3.261)], aged 30-59 years [aOR = 1.670, 95% CI: (1.222-2.282)], who were farmers [aOR = 1.482, 95%CI: (1.203-1.825)], with miliary pulmonary TB [aOR = 108.696, 95%CI: (87.122-135.613)], and with a digestive system TB [aOR = 2.906, 95%CI: (1.762-4.793)].

Conclusion

An age of < 30 years, being a farmer, and having miliary pulmonary TB were risk factors for TBM among patients with TB. Further screening of patients with TB with aforementioned characteristics could facilitate clinicians to identify patients with TBM at an early stage.

Tracing the Negative Results of Multiplex Real-Time PCR Assay for Diagnosis of Bacterial Pediatrics Meningitis

The death because of meningitis remains high in some parts of the world. It is important to know the specific cause of meningitis because the treatment differs depending on the cause. This study aimed to trace the false-negative results of multiplex RT-PCR to detect Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis serogroup by two different molecular methods. In this study, the CSF of the suspicious pediatric for acute bacterial meningitis among children aged 1 month to 14 years who are admitted to the hospitals in four cities of a certain region of Iran was collected. S. pneumoniae, H. influenzae, and N. meningitidis in CSF samples were detected by single-tube multiplex RT-PCR and specific RT-PCR with a probe on the same specimens. In this cross-sectional study, 506 CSF samples were collected during one year. The multiplex RT-PCR can detect 3.3% and 2.2% of S. pneumoniae and H. influenzae, respectively. N. meningitidis was not detected. The CSF analysis was abnormal in 53% of 506 patients. On the other hand, 11.5%, 4.8%, and 4.1% of S. pneumoniae, H. influenzae, and N. meningitidis were identified, respectively, by specific RT-PCR assay, exactly on the same specimens. Various types of PCR can be used for pathogen identification. As we change the type of PCR in our study, we could approximately increase 15% our positive results and also consequently decrease our false-negative responses.

Epidemiological characteristics and climatic variability of viral meningitis in Kazakhstan, 2014-2019

Background

The comprehensive epidemiology and impact of climate on viral meningitis (VM) in Kazakhstan are unknown. We aimed to study the incidence, in-hospital mortality and influence of climatic indicators on VM from 2014 to 2019.

Methods

Nationwide electronic healthcare records were used to explore this study. ICD-10 codes of VM, demographics, and hospital outcomes were evaluated using descriptive statistics and survival analysis.

Results

During the 2014-2019 period, 10,251 patients with VM were admitted to the hospital. 51.35% of them were children, 57.85% were males, and 85.9% were from the urban population. Enteroviral meningitis was the main cause of VM in children. The incidence rate was 13 and 18 cases per 100,000 population in 2014 and 2019, respectively. Case fatality rate was higher in 2015 (2.3%) and 2017 (2.0%). The regression model showed 1°C increment in the daily average temperature might be associated with a 1.05-fold (95% CI 1.047-1.051) increase in the daily rate of VM cases, 1hPa increment in the average air pressure and 1% increment in the daily average humidity might contribute to a decrease in the daily rate of VM cases with IRRs of 0.997 (95% CI 0.995-0.998) and 0.982 (95% CI 0.981-0.983), respectively. In-hospital mortality was 35% higher in males compared to females. Patients residing in rural locations had a 2-fold higher risk of in-hospital death, compared to city residents. Elderly patients had a 14-fold higher risk of in-hospital mortality, compared to younger patients.

Conclusion

This is the first study in Kazakhstan investigating the epidemiology and impact of climate on VM using nationwide healthcare data. There was a tendency to decrease the incidence with outbreaks every 5 years, and mortality rates were higher for Russians and other ethnicities compared to Kazakhs, for males compared to females, for elder patients compared to younger patients, and for patients living in rural areas compared to city residents. The climatic parameters and the days of delay indicated a moderate interaction with the VM cases.

Amphotericin B plus fluorocytosine combined with voriconazole for the treatment of non-HIV and non-transplant-associated cryptococcal meningitis: a retrospective study

Background

Our previous study explored Amphotericin B (AMB) plus 5-flucytosine (5-FC) combined with fluconazole (FLU) therapy in the induction period, which seemed to be better than the previous AMB + 5-FC antifungal therapy in non-HIV and non-transplant-associated CM. However, based on our clinical finding, the outcomes of some CM patients who received AMB plus 5-FC combined with FLU antifungal therapy were still poor. Therefore, we need to explore new antifungal methods in non-HIV and non-transplant-associated CM during the induction period.

Methods

Clinical data from 148 patients admitted to the Third Affiliated Hospital of Sun Yat Sen University from January 2011 to December 2020 were collected. These patients were stratified based on antifungal treatment methods in the induction period (group I with AMB + 5-FC + VOR, group II with AMB + 5-FC + FLU, group III with AMB + 5-FC).

Results

The first hospitalization time of Group I (median: 25 days, IQR: 20–34.5) was significantly shorter than that of Group II (median: 43 days, IQR: 29–62) (p < 0.001) and Group III (median: 50.5 days, IQR: 43–77.5) (p < 0.001). After 2 weeks of follow-up, Group I (26/49) had more patients reaching CSF clearance (p = 0.004) than Group II (18/71) and Group III (7/28). In multivariable analysis, Group II (OR: 3.35, 95%CI 1.43–7.82, p = 0.005) and Group III (OR: 3.8, 95%CI 1.23–11.81, p = 0.021) were associated with higher risk about CSF clearance failure at 2 weeks follow-up than Group I. After 10 weeks of follow-up, the incidence of hypokalemia in Group I was significantly lower than that in Group II (p = 0.003) and Group III (p = 0.004), and the incidence of gastrointestinal discomfort in Group I was significantly lower than that in Group II (p = 0.004).

Conclusion

AMB plus 5-FC combined with VOR may rapidly improve clinical manifestation, decrease CSF OP and clear the cryptococci in CSF during the early phase, substantially shorten the hospitalization time, and reduce the incidences of hypokalemia and gastrointestinal discomfort.

Current methods for microbiological diagnosis of acute central nervous system infections

The incidence of infections affecting the central nervous system has increased in recent years, making neuroinfections a current global health problem. The central nervous system is quite well protected from the external and internal environments, although it is susceptible to infection by a wide variety of pathogens. The etiological diversity further complicates the management of such infections because it is important to identify correctly the specific cause in order to choose the most appropriate antimicrobial therapy. Diagnosis is made not only based on clinical and epidemiological data but also on the results of clinical laboratory and microbiological examination of cerebrospinal fluid. This article aims to review current microbiological methods in the diagnosis of acute central nervous system infections and help healthcare providers to recognize their advantages and limitations in order to manage their patients appropriately.

Cryptococcal meningitis in people living with Human Immunodeficiency Virus in Nepal: Perspectives from resource limited setting

Early diagnosis of cryptococcal meningitis among people living with HIV (PLHIV) is crucial for its therapeutic success. The objective of this study was to diagnose cryptococcal meningitis in PLHIV cases using the available laboratory techniques for its confirmation in resource limited setting. This cross-sectional prospective study was conducted among 72 PLHIV with clinical suspicion of meningitis. Each cerebrospinal fluid (CSF) sample received at National Public Health Laboratory, Kathmandu was processed for India ink staining, cryptococcal antigen lateral flow assay and fungal culture following standard protocols. The laboratory confirmed cryptococcal meningitis cases were between 24 and 69 years of age (median age 39 years) with 87.5% (12/14) of cases being male. Cryptococcus was detected in 22.22% (16/72) by any of the three tests, 19.44% (14/72) by cryptococcal antigen lateral flow assay, 16.66% (12/72) by India ink staining and 8.33% (6/72) by culture. High percentage of cryptococcal meningitis among PLHIV warrants early microbiological diagnosis for better case management. Cryptococcal antigen detection immunoassay should be the priority test for laboratory diagnosis of cryptococcal meningitis in PLHIV. Alternatively, very simple and economic India ink staining of CSF specimens could be used in resource limited settings.

Analysis of the association of HLA subtypes with cryptococcal meningitis in HIV-negative immunocompetent patients

Objective: We aimed to study the possible relationship between cryptococcal meningitis (CM) and HLA genotypes in HIV-negative immunocompetent patients. Methods: HLA loci of 53 HIV-negative immunocompetent Han Chinese CM patients were compared with those in 481 healthy individuals. Results: We found a significant association between DQB1*05:02 and CM patients compared with controls. There were no significant differences in the frequencies of HLA alleles between CM with and without postinfectious inflammatory response syndrome and controls. Correlation analysis showed DQB1*05:02 was correlated with susceptibility to CM. CM patients carrying the DQB1*05:02 allele had more severe focal neurological deficit, higher initial modified Rankin Scale and British Medical Research Council staging scores. Conclusion: This study provides the first evidence for the interaction between specific HLA class II alleles and HIV-negative immunocompetent CM patients.

Immunological Predictors of Post Infectious Inflammatory Response Syndrome in HIV-Negative Immunocompetent Cryptococcal Meningitis

Objective

This research aims to study the correlation between serum immune factors and post-infectious inflammatory response syndrome (PIIRS) in immunocompetent cryptococcal meningitis (CM), and explore whether serum immune factors could be used to predict the development of PIIRS.

Methods

A cohort of 30 patients with PIIRS and 87 patients without PIIRS was selected from 347 CM patients. We analyzed the general clinical information and immunological indexes (cytokines, complement, immunoglobulin, inflammation, related cytological and biochemical indexes). Spearman correlation analysis and principal component analysis were used to explore the effects of the variables on PIIRS. Additionally, the variables were identified by a random forest-based classifier for predicting the development of PIIRS. The clinical value of predictors was verified by survival analysis.

Results

Compared with patients without PIIRS, patients with PIIRS had lower baseline serum interleukin-6 (IL-6, P = 0.006), immunoglobulin M (IgM, P = 0.004), and a higher baseline neutrophil ratio (P <0.001). The baseline neutrophil ratio (r = 0.359, P = 0.001), IgM (r = −0.272, P = 0.025), and IL-6 (r = −0.259, P = 0.027) were significantly correlated with PIIRS. Combining principal component analysis and random forest results, neutrophil ratio, neutrophil count, IgM, IL-6, and D-dimer were useful predictors. The accuracy of random forest prediction was 75.00%, AUC, and sensitivity were 0.76 and 70%, respectively. Further survival analysis of the time from treatment to PIIRS revealed that the development of PIIRS was associated with IgM (more than 98 days of treatment) and neutrophil ratio/count.

Conclusion

Baseline neutrophils ratio, neutrophil count, IgM, IL-6, and D-dimer may be clinically useful predictors of PIIRS in HIV-negative immunocompetent CM patients.

Improving Technology to Diagnose Tuberculous Meningitis: Are We There Yet?

Diagnosis of tuberculous meningitis (TBM) remains challenging due to a paucity of high-performance diagnostics. Even those that have reasonable sensitivity are not adequate to 'rule out' TBM. Therefore, a combination of clinical factors alongside microbiological, molecular, and radiological investigations are utilized, depending on availability. A low threshold for starting empiric therapy in the appropriate clinical scenario remains crucial for good outcomes in many cases. Herein, we review the current TBM diagnostics landscape with a focus on limitations frequently encountered, such as diagnostic test performance, cost, laboratory infrastructure, and clinical expertise. Though molecular technologies, particularly GeneXpert MTB/Rif Ultra, have been a step forward, diagnosis of TBM remains difficult. We also provide an overview of promising technologies, such as cerebrospinal fluid (CSF) lactate, a new lipoarabinomannan test (FujiLAM), metagenomic next-generation sequencing, and transcriptomics that may further improve our TBM diagnostic capacity and lead to better outcomes.

Validation of host cerebrospinal fluid protein biomarkers for early diagnosis of tuberculous meningitis in children: a replication and new biosignature discovery study

The diagnosis of tuberculous meningitis (TBM) in children is often delayed due to diagnostic difficulties. New tools are urgently needed to improve the diagnosis of the disease in this vulnerable group. The present study aimed to validate the accuracy of recently identified host cerebrospinal (CSF) biomarkers as candidates for the diagnosis of TBM in children. We collected CSF samples from 87 children aged 3 months to 13 years, that were consecutively admitted at a tertiary hospital in Cape Town, South Africa, on suspicion of having TBM. We evaluated the concentrations of 67 selected host protein biomarkers using a multiplex platform. Previously identified 3-marker (VEGF-A + IFN-γ + MPO) and 4-marker (IFN-γ + MPO + ICAM-1 + IL-8) signatures diagnosed TBM with AUCs of 0.89 (95% CI, 0.81-0.97) and 0.87 (95% CI, 0.79-0.95) respectively; sensitivities of 80.6% (95% CI, 62.5-92.5%) and 81.6% (95% CI, 65.7-92.3%), and specificities of 86.8% (71.9-95.6%) and 83.7% (70.4-92.7%) respectively. Furthermore, a new combination between the analytes (CC4b + CC4 + procalcitonin + CCL1) showed promise, with an AUC of 0.98 (95% CI, 0.94-1.00). We have shown that the accuracies of previously identified candidate CSF biomarkers for childhood TBM was reproducible. Our findings augur well for the future development of a simple bedside test for the rapid diagnosis of TBM in children.

Integrating central nervous system metagenomics and host response for diagnosis of tuberculosis meningitis and its mimics

The epidemiology of infectious causes of meningitis in sub-Saharan Africa is not well understood, and a common cause of meningitis in this region, Mycobacterium tuberculosis (TB), is notoriously hard to diagnose. Here we show that integrating cerebrospinal fluid (CSF) metagenomic next-generation sequencing (mNGS) with a host gene expression-based machine learning classifier (MLC) enhances diagnostic accuracy for TB meningitis (TBM) and its mimics. 368 HIV-infected Ugandan adults with subacute meningitis were prospectively enrolled. Total RNA and DNA CSF mNGS libraries were sequenced to identify meningitis pathogens. In parallel, a CSF host transcriptomic MLC to distinguish between TBM and other infections was trained and then evaluated in a blinded fashion on an independent dataset. mNGS identifies an array of infectious TBM mimics (and co-infections), including emerging, treatable, and vaccine-preventable pathogens including Wesselsbron virus, Toxoplasma gondii, Streptococcus pneumoniae, Nocardia brasiliensis, measles virus and cytomegalovirus. By leveraging the specificity of mNGS and the sensitivity of an MLC created from CSF host transcriptomes, the combined assay has high sensitivity (88.9%) and specificity (86.7%) for the detection of TBM and its many mimics. Furthermore, we achieve comparable combined assay performance at sequencing depths more amenable to performing diagnostic mNGS in low resource settings.

Tuberculous meningitis is difficult to differentiate from meningitis caused by other pathogens. Here, the authors combine metagenomics-based pathogen detection in cerebrospinal fluid with a host gene expression-based machine learning classifier for diagnosis.

Tuberculosis Meningitis in People Living with HIV/AIDS in a Health Center in the Brazilian Amazon: A Silent Disease

Introduction

Tuberculosis (TB) is one of the ten leading causes of death worldwide and the leading cause of infection in people living with the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) (PLWHA). It is a major public health problem in Brazil and worldwide.

Methods

This was a case series study of five meningeal tuberculosis and PLWHA coinfection patients admitted between June 2019 and June 2020, in a public hospital in the northern region of Brazil. Associated with clinical cases, we propose a discussion of the different laboratory diagnostic methods available in Brazil, with the aim of increasing the diagnosis of this very serious disease, with high mortality.

Results

The diagnosis of tuberculous meningitis is a challenge in clinical practice; thus, the clinical cases presented help the physician to recognize the signs and symptoms of the disease and improve the confirmatory diagnosis through acid-alcoholic resistant bacilli techniques, molecular testing, and mycobacteria culture in the cerebrospinal fluid.

Conclusion

Knowing the diagnostic methods of tuberculous meningitis and its characteristics is of paramount importance to increase the correct diagnosis and reduce mortality in delayed treatment.

Diagnostic Model for Discrimination Between Tuberculous Meningitis and Bacterial Meningitis

Background

The differential diagnosis between tuberculous meningitis (TBM) and bacterial meningitis (BM) remains challenging in clinical practice. This study aimed to establish a diagnostic model that could accurately distinguish TBM from BM.

Methods

Patients with TBM or BM were recruited between January 2017 and January 2021 at Tongji Hospital (Qiaokou cohort) and Sino-French New City Hospital (Caidian cohort). The detection for indicators involved in cerebrospinal fluid (CSF) and T-SPOT assay were performed simultaneously. Multivariate logistic regression was used to create a diagnostic model.

Results

A total of 174 patients (76 TBM and 98 BM) and another 105 cases (39 TBM and 66 BM) were enrolled from Qiaokou cohort and Caidian cohort, respectively. Significantly higher level of CSF lymphocyte proportion while significantly lower levels of CSF chlorine, nucleated cell count, and neutrophil proportion were observed in TBM group when comparing with those in BM group. However, receiver operating characteristic (ROC) curve analysis showed that the areas under the ROC curve (AUCs) produced by these indicators were all under 0.8. Meanwhile, tuberculosis-specific antigen/phytohemagglutinin (TBAg/PHA) ratio yielded an AUC of 0.889 (95% CI, 0.840–0.938) in distinguishing TBM from BM, with a sensitivity of 68.42% (95% CI, 57.30%–77.77%) and a specificity of 92.86% (95% CI, 85.98%–96.50%) when a cutoff value of 0.163 was used. Consequently, we successfully established a diagnostic model based on the combination of TBAg/PHA ratio, CSF chlorine, CSF nucleated cell count, and CSF lymphocyte proportion for discrimination between TBM and BM. The established model showed good performance in differentiating TBM from BM (AUC: 0.949; 95% CI, 0.921–0.978), with 81.58% (95% CI, 71.42%–88.70%) sensitivity and 91.84% (95% CI, 84.71%–95.81%) specificity. The performance of the diagnostic model obtained in Qiaokou cohort was further validated in Caidian cohort. The diagnostic model in Caidian cohort produced an AUC of 0.923 (95% CI, 0.867–0.980) with 79.49% (95% CI, 64.47%–89.22%) sensitivity and 90.91% (95% CI, 81.55%–95.77%) specificity.

Conclusions

The diagnostic model established based on the combination of four indicators had excellent utility in the discrimination between TBM and BM.

Fujifilm SILVAMP TB LAM Assay on Cerebrospinal Fluid for the Detection of Tuberculous Meningitis in Adults With Human Immunodeficiency Virus

BACKGROUND

Tuberculous meningitis (TBM) has a high fatality rate, with inadequate diagnostic tests being a major contributor. The rollout of Xpert MTB/Rif and Xpert MTB/RIF Ultra (Xpert Ultra) have improved time-to-diagnosis with sensitivities similar to culture, yet test availability and sensitivity are inadequate. The TB lipoarabinomannan lateral flow assay (AlereLAM) offers ease of use, but its low sensitivity in cerebrospinal fluid (CSF) limits clinical utility for TBM. The Fujifilm SILVAMP TB LAM (FujiLAM) assay has excellent sensitivity in urine, but performance on cerebrospinal fluid is uncertain.

METHODS

We conducted a prospective cohort study at Kiruddu National Referral Hospital in Kampala, Uganda, enrolling patients suspected to have TBM. CSF was tested using AlereLAM, Xpert Ultra, culture, and FujiLAM. Results were compared with 2 reference standards: probable and definite TBM or definite TBM alone by the uniform TBM case definition.

RESULTS

Of 101 patients enrolled (95/101 HIV-positive), 34 had definite TBM and 24 had probable TBM. FujiLAM sensitivity on CSF was 52% (30/58) for definite or probable TBM compared with 55% (32/58) for Xpert Ultra. AlereLAM had lower sensitivity than FujiLAM in the subgroup of patients tested with both assays (14% [4/28] vs 50% [14/28]; P < .01). FujiLAM specificity was 98% (42/43) for patients without probable or definite TBM.

CONCLUSIONS

FujiLAM showed higher sensitivity than AlereLAM, with sensitivity potentially approaching that of Xpert Ultra. FujiLAM could improve time-to-treatment-initiation, especially in settings where the more technical Xpert Ultra system might not be feasible. Large confirmatory studies are needed.

Deciphering the role of nanoparticles for management of bacterial meningitis: an update on recent studies

Meningitis is an inflammation of the protective membranes called meninges and fluid adjacent the brain and spinal cord. The inflammatory progression expands all through subarachnoid space of the brain and spinal cord and occupies the ventricles. The pathogens like bacteria, fungi, viruses, or parasites are main sources of infection causing meningitis. Bacterial meningitis is a life-threatening health problem that which needs instantaneous apprehension and treatment. Nesseria meningitidis, Streptococcus pneumoniae, and Haemophilus flu are major widespread factors causing bacterial meningitis. The conventional drug delivery approaches encounter difficulty in crossing this blood-brain barrier (BBB) and therefore are insufficient to elicit the desired pharmacological effect as required for treatment of meningitis. Therefore, application of nanoparticle-based drug delivery systems has become imperative for successful dealing with this deadly disease. The nanoparticles have ability to across BBB via four important transport mechanisms, i.e., paracellular transport, transcellular (transcytosis), endocytosis (adsorptive transcytosis), and receptor-mediated transcytosis. In this review, we reminisce distinctive symptoms of meningitis, and provide an overview of various types of bacterial meningitis, with a focus on its epidemiology, pathogenesis, and pathophysiology. This review describes conventional therapeutic approaches for treatment of meningitis and the problems encountered by them while transmitting across tight junctions of BBB. The nanotechnology approaches like functionalized polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carrier, nanoemulsion, liposomes, transferosomes, and carbon nanotubes which have been recently evaluated for treatment or detection of bacterial meningitis have been focused. This review has also briefly summarized the recent patents and clinical status of therapeutic modalities for meningitis.

Autoimmune diseases in HIV-negative cryptococcal meningitis

Aim: The purpose of our study was to assess the differences between HIV-negative cryptococcal meningitis (CM) patients with and without autoimmune diseases. Methods: A total of 43 CM patients with autoimmune diseases and 67 without autoimmune diseases were enrolled for analysis. Results: CM patients with autoimmune diseases had higher fever, modified Rankin Scale scores, C-reactive protein and erythrocyte sedimentation rate, but had lower rates of visual and hearing symptoms, ventriculoperitoneal shunts, MRI meningeal enhancement and amphotericin B treatment, as well as lower cerebrospinal fluid pressure and fungal counts. When divided according to gender, each group had lower intracranial pressure and higher inflammation indicators. No differences in outcomes, sequelae and mortality hazard were found. Fluconazole treatment was a prognostic factor for CM without autoimmune diseases. Conclusions: Both antifungal and anti-inflammatory therapy should be considered in CM patients with autoimmune diseases.

Use of alternative cerebrospinal fluid-based biomarkers to help diagnose Xpert-negative tuberculous meningitis: A case report

The widely used Xpert MTB/RIF assay, limited by its suboptimal sensitivity, does not perform well as a rule-out test for tuberculous meningitis. Alternative CSF-based biomarkers can help determine the microbial etiology of clinical meningitis when standard diagnostic modalities fail.

Strategies for the diagnosis and management of meningitis in HIV-infected adults in resource limited settings

INTRODUCTION

The incidence of human immunodeficiency virus-1 (HIV-1) associated meningitis has been declining in the post-combination antiretroviral treatment (ART) era, although survival rates remain low for the common causes like tuberculosis and cryptococcal disease. Diagnosis and treatment of meningitis in HIV-1 is complicated by atypical clinical presentations, limited accuracy of diagnostic tests, access to diagnostic tests, and therapeutic agents in low- and middle-income countries (LMIC) and immune reconstitution inflammatory syndrome (IRIS).

AREAS COVERED

We provide an overview of the common etiologies of meningitis in HIV-1-infected adults, suggest a diagnostic approach based on readily available tests, and review specific chemotherapeutic agents, host-directed therapies, supportive care, timing of ART initiation, and considerations in the management of IRIS with a focus on resource-limited settings. They identify key knowledge gaps and suggest areas for future research.

EXPERT OPINION

Evidence-based management of HIV-1-associated meningitis is sparse for common etiologies. More readily available and sensitive diagnostic tests as well as standardized investigation strategies are required in LMIC. There is a lack of availability of recommended drugs in areas of high HIV-1 prevalence and a limited pipeline of novel chemotherapeutic agents. Host-directed therapies have been inadequately studied.

Epidemiology Profile of Viral Meningitis Infections Among Patients in Qatar (2015-2018)

Background: Little is known about the etiology of meningitis in the MENA region, including Qatar. Viral agents are considered the major cause for meningitis worldwide. Here, we present primary data about the etiology and clinical and demographic characteristics of viral meningitis (VM) in Qatar between 2015 and 2018.

Methods: We retrospectively collected data from Hamad Medical Corporation (HMC), which provides about 80% of healthcare services in Qatar. Data were collected for the period between 2015 and 2018. During this time period, 6,705 specimens were collected from patients with suspected meningitis attending HMC and primary healthcare centers. These specimens were tested for a panel of viruses using the “FTD Viral meningitis” multiplex real-time PCR kit that detects Adenovirus (ADV), Human herpesvirus 1&2 (HSV1 and HSV2), Epstein–Barr virus (EBV), Enteroviruses (EV), Cytomegalovirus (CMV), Varicella zoster virus (VZV), and Parechovirus (PV).

Results: Only 10.9% (732/6,705) of all suspected meningitis cases were caused by viral agents. 60.9% of the reported cases were males, compared to 39.1% in females. Most of the infections (73.9%) were reported in children younger than 10 years of age. EV were identified as the main causative agent (68.7%), followed by EBV (7.5%) and ADV (6.8%). Other viral agents including VZV, PV, HSV-1, and HSV-2 were also detected with a lower frequency. Confirmed VM were more prevalent among Qatari subjects compared to other nationalities. We observed no specific seasonality of viral agents, but a slight rise was recorded during the spring seasons (March to June). Fever (59.4%, 435/732) and acute central nervous system (CNS) infection (15.6%, 114/732) were initial symptoms of most cases.

Conclusion: This is the first report about the molecular epidemiology of VM in Qatar. In line with the international records, our data showed that EV is responsible for 68.7% of Qatar's VM cases. Further studies are needed to genotype and serotype the identified viruses.

Clinical usefulness of metagenomic next-generation sequencing for the diagnosis of central nervous system infection in people living with HIV

OBJECTIVES

To evaluate the clinical utility of metagenomic next-generation sequencing (mNGS) for the diagnosis of central nervous system (CNS) infection in people living with human immunodeficiency virus (PLWH) in a real-world situation.

METHODS

Cerebrospinal fluid (CSF) was sent for mNGS for PLWH who tested negative on all conventional tests but were still suspected to have CNS infection. A retrospective analysis was undertaken of the results and the clinical effect of mNGS on this cohort. The final diagnosis was adjudicated by a panel discussion following hospital discharge when the results of all tests and patients' responses to the empiric therapy were available.

RESULTS

Eighty-eight eligible PLWH, including 51 (58%) patients suspected of encephalitis and 34 (46.7%) patients suspected of meningitis, were included in the analysis. Sixty-eight (77.3%) patients were diagnosed with CNS infection, of which 50 were based on the pathogens identified by mNGS. The most common disease missed by mNGS was clinically suspected tuberculous meningitis, followed by clinically suspected non-tuberculous mycobacterial meningitis. The results from mNGS led to modification of treatment in 21 (23.9%) patients, and increased confidence in continuation of original therapy in 30 (34.1%) patients. During hospitalization, two (2.3%) patients died and 66 (75%) patients improved.

CONCLUSIONS

mNGS of CSF is a useful tool for the diagnosis of CNS infection among PLWH. Further investigations are warranted to improve its sensitivity.

Development and validation of a new scoring system for the early diagnosis of tuberculous meningitis in adults

We developed and validated a new diagnostic scoring system by simultaneously comparing 28 factors (including clinical, laboratory, and imaging) of HIV uninfected adult tuberculous meningitis (TBM) with viral meningitis (VM), bacterial meningitis (BM), and cryptococcal meningitis (CM). Predictors of TBM diagnosis obtained by logistic regression. A total of 382 patients with intracranial infection participated, and eight factors were independently associated with TBM diagnosis: symptom duration, evidence of extracranial tuberculosis, cerebrospinal fluid (CSF) leukocyte, CSF neutrophil, CSF protein, low serum sodium, meningeal enhancement, and tuberculomas. Factors are assigned according to weight, a score of ≥ 5 was suggestive of TBM with a sensitivity of 85.8% and a specificity of 87.7%, and the area under the receiver operating characteristic curve was 0.923. When applied to a prospective validation cohort, this scoring model showed robust performance. Our study suggests that the application of this score can help diagnose TBM more efficiently.

Neuroinfectious Disease Emergencies

Neuroinfectious diseases can affect immunocompetent and immunosuppressed individuals and cause a variety of emergencies including meningitis, encephalitis, and abscess. Neurologic infections are frequently complicated by secondary injuries that also present emergently such as cerebrovascular disease, acute obstructive hydrocephalus, and seizure. In most cases, timely recognition and early treatment of infection can improve the morbidity and mortality of infectious neurologic emergencies.

Tuberculous Meningitis: Pathogenesis, Immune Responses, Diagnostic Challenges, and the Potential of Biomarker-Based Approaches

Tuberculous meningitis (TBM) is the most devastating form of tuberculosis (TB), causing high mortality or disability. Clinical management of the disease is challenging due to limitations of the existing diagnostic approaches. Our knowledge on the immunology and pathogenesis of the disease is currently limited. More research is urgently needed to enhance our understanding of the immunopathogenesis of the disease and guide us toward the identification of targets that may be useful for vaccines or host-directed therapeutics.

Tuberculous meningitis (TBM) is the most devastating form of tuberculosis (TB), causing high mortality or disability. Clinical management of the disease is challenging due to limitations of the existing diagnostic approaches. Our knowledge on the immunology and pathogenesis of the disease is currently limited. More research is urgently needed to enhance our understanding of the immunopathogenesis of the disease and guide us toward the identification of targets that may be useful for vaccines or host-directed therapeutics. In this review, we summarize the current knowledge about the immunology and pathogenesis of TBM and summarize the literature on existing and new, especially biomarker-based, approaches that may be useful in the management of TBM. We identify research gaps and provide directions for research which may lead to the development of new tools for the control of the disease in the near future.

Diagnostic accuracy of Xpert MTB/RIF Ultra for tuberculous meningitis in a clinical practice setting of China

A comparative performance evaluation of the novel Xpert MTB/RIF Ultra (Xpert Ultra) and MTB/RIF Xpert (Xpert) for tuberculous meningitis (TBM) diagnosis was performed. The cerebrospinal fluids of suspected TBM patients were collected consecutively and subjected to smear microscopy, culture, Xpert, and Xpert Ultra. In total, 160 patients were recruited. Xpert Ultra produced a higher sensitivity (45%, 34 of 76) than Xpert (28%, 21 of 76; P = 0.001) and culture (18%, 14 of 76; P < 0.001), respectively. Inclusion of Xpert Ultra outcomes increased the percentage of definite TBM case from 36% (27 of 76) to 51% (39 of 76). Both Xpert Ultra and Xpert accurately identified the one rifampicin (RIF)-resistant and the 5 RIF-sensitive cases defined by phenotypic drug sensitivity test. The specificities of all of the culture, Xpert and Xpert Ultra were 100% (45 of 45). Xpert Ultra outperformed both Xpert and culture for TBM diagnosis, which may speed up the appropriate treatment of patients in clinical practice.

Metagenomic next generation sequencing for the diagnosis of tuberculosis meningitis: A systematic review and meta-analysis

Background

Tuberculous meningitis (TBM) is a severe form of extrapulmonary tuberculosis and its early diagnosis is very difficult leading to present with severe disability or die. The current study aimed to assess the accuracy of metagenomic next generation sequencing (mNGS) for TBM, and to identify a new test for the early diagnosis of TBM.

Methods

We searched for articles published in Embase, PubMed, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Data up to June 30, 2020 for studies that assessed the efficacy of mNGS for the diagnosis of TBM. Then, the accuracy between mNGS and a composite reference standard (CRS) in these articles was compared using the meta-analysis approach.

Results

Four independent studies with 342 samples comparing mNGS and a CRS were included in this study. The sensitivity of mNGS for TBM diagnosis ranged from 27% to 84%. The combined sensitivity of mNGS was 61%, and the I² value was 92%. Moreover, the specificity of mNGS for TBM diagnosis ranged from 96% to 100%. The combined specificity of mNGS was 98%, and the I² value was 74%. The heterogeneity between studies in terms of sensitivity and specificity was significant. The area under the curve (AUC) of the summary receiver operating characteristic curve (SROC) of mNGS for TBM was 0.98.

Conclusions

The sensitivity of mNGS for TBM diagnosis was moderate. Furthermore, the specificity was extremely high, and the AUC of the SROC indicated a very good diagnostic efficacy. mNGS could be used as an early diagnostic method for TBM, however, the results should be treated with caution for the heterogeneity between studies was extremely significant.

Systematic review registration

INPLASY202070100.

Challenges in the diagnosis of tuberculous meningitis

Tuberculosis (TB) continues to pose a significant public health problem. Tuberculous meningitis (TBM) is the most severe form of extra-pulmonary TB. TBM carries a high mortality rate, including for those receiving treatment for TB. Diagnosis of TBM is difficult for clinicians as it can clinically present similarly to other forms of meningitis. The difficulty in diagnosis often leads to a delay in treatment and subsequent mortality. Those who survive are left with long-term sequelae leading to lifelong disability. The microbiologic diagnosis of TBM requires the isolation of Mycobacterium tuberculosis from the cerebrospinal fluid (CSF) of an infected patient. The diagnosis of tuberculous meningitis continues to be challenging for clinicians. Unfortunately, many cases of TBM cannot be confirmed based on clinical and imaging findings as the clinical findings are nonspecific, while laboratory techniques are largely insensitive or slow. Until recently, the lack of accessible and timely tests has contributed to a delay in diagnosis and subsequent morbidity and mortality for many patients, particularly those in resourcelimited settings. The availability of Xpert Ultra and point-of-care lipoarabinomannan (LAM) testing could represent a new era of prompt diagnosis and early treatment of tuberculous meningitis. However, clinicians must be cautious when ruling out TBM with Xpert Ultra due to its low negative predictive value. Due to the limitations of current diagnostics, clinicians should utilize a combination of diagnostic modalities in order to prevent morbidity in patients with TBM.

Postinfectious inflammatory response syndrome in HIV-uninfected and nontransplant men after cryptococcal meningitis

Aim: The aim of our study was to describe the characteristics of postinfectious inflammatory response syndrome (PIIRS) in HIV-uninfected and nontransplant men after cryptococcal meningitis (CM). Patients & methods: A case-control study was designed to compare HIV-uninfected and nontransplant male CM patients with and without PIIRS. Results: CM-PIIRS patients had increased rates of hearing loss, V-P shunt placement, amphotericin B treatment, higher cerebrospinal fluid pressures and Cryptococcus counts in the first CM episode. CM-PIIRS episode was characterized by higher frequencies of headache and fever, higher C-reactive protein, erythrocyte sedimentation rate, cerebrospinal fluid white blood cell (WBC) counts and modified Rankin Score. Brain MRI scans revealed the high signal lesions on axial flair imaging. Receipt of corticosteroid therapy was associated with lower rates of fever and better modified Rankin Score scores at 1 month after treatment. Conclusion: CM-PIIRS episode differs to the initial presentation, may help to identify which patients are at risk to develop PIIRS. Steroids therapy could be beneficial.

Methods for rapid diagnosis of meningitis etiology in adults

Infectious meningitis can be caused by viral, bacterial or fungal pathogens. Despite widely available treatments, many types of infectious meningitis are still associated with significant morbidity and mortality. Delay in diagnosis contributes to poor outcomes. Cerebrospinal fluid cultures have been used traditionally but are time intensive and sensitivity is decreased by empiric treatment prior to culture. More rapid techniques such as the cryptococcal lateral flow assay (IMMY), GeneXpert MTB/Rif Ultra (Cepheid) and FilmArray multiplex-PCR (Biofire) are three examples that have drastically changed meningitis diagnostics. This review will discuss a holistic approach to diagnosing bacterial, mycobacterial, viral and fungal meningitis.

Comparison of acridine orange fluorescent microscopy and gram stain light microscopy for the rapid detection of bacteria in cerebrospinal fluid

OBJECTIVE

Bacterial meningitis is a life threatening condition that requires prompt recognition and treatment. Currently, Gram stain is widely used for the microscopic detection of bacterial pathogens in cerebrospinal fluid (CSF). In Nepal, fluorescent microscopes have been installed in laboratories as a part of the National tuberculosis control program. However, information on the utility of the acridine orange (AO) stain for the direct detection of bacteria in CSF samples in Nepal is not available. Therefore, this study aims to compare Gram stain and AO stain for the rapid detection of bacterial pathogens in CSF of clinically suspected meningitis cases in Kathmandu, Nepal.

RESULTS

Bacterial pathogens were detected in 9.30% (36/387) by either of the three tests, 9.04% (35/387) by AO stain, 8.27% (32/387) by culture and 6.46% (25/387) by Gram's stain. Considering culture as a gold standard, the sensitivity of AO stain was higher than Gram stain. The specificity of AO stain was 98.87%. Detection and differentiation of the bacteria was much clear in AO staining than Gram staining. AO is a better alternative to Gram stain in the rapid detection of bacterial pathogens in CSF in the setting where fluorescent microscope is available.

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.

Causes of Pediatric Meningitis in Botswana: Results From a 16-Year National Meningitis Audit

BACKGROUND

Central nervous system infections are an important cause of childhood morbidity and mortality in high HIV-prevalence settings of Africa. We evaluated the epidemiology of pediatric meningitis in Botswana during the rollout of antiretroviral therapy, pneumococcal conjugate vaccine and Haemophilus influenzae type B (HiB) vaccine.

METHODS

We performed a cross-sectional study of children (<15 years old) evaluated for meningitis by cerebrospinal fluid (CSF) examination from 2000 to 2015, with complete national records for 2013-2014. Clinical and laboratory characteristics of microbiologically confirmed and culture-negative meningitis were described and incidence of Streptococcus pneumoniae, H. influenzae and cryptococcal meningitis was estimated for 2013-2014.

RESULTS

A total of 6796 unique cases were identified. Median age was 1 year [interquartile range 0-3]; 10.4% (435/4186) of children with available HIV-related records were known HIV-infected. Overall, 30.4% (2067/6796) had abnormal CSF findings (positive microbiologic testing or CSF pleocytosis). Ten percent (651/6796) had a confirmed microbiologic diagnosis; including 26.9% (175/651) Cryptococcus, 18.9% (123/651) S. pneumoniae, 20.3% (132/651) H. influenzae and 1.1% (7/651) Mycobacterium tuberculosis. During 2013-2014, national cryptococcal meningitis incidence was 1.3 cases per 100,000 person-years (95% confidence interval, 0.8-2.1) and pneumococcal meningitis incidence 0.7 per 100,000 person-years (95% confidence interval, 0.3-1.3), with no HiB meningitis diagnosed.

CONCLUSIONS

Following HiB vaccination, a marked decline in microbiologically confirmed cases of H. influenzae meningitis occurred. Cryptococcal meningitis remains the most common confirmed etiology, demonstrating gaps in prevention-of-mother-to-child transmission and early HIV diagnosis. The high proportion of abnormal CSF samples with no microbiologic diagnosis highlights limitation in available diagnostics.

Diagnostic Testing of Neurologic Infections

Neuroinfectious diseases continue to cause morbidity and mortality worldwide, with many emerging or reemerging infections resulting in neurologic sequelae. Careful clinical evaluation coupled with appropriate laboratory investigations still forms the bedrock for making the correct etiologic diagnosis and implementing appropriate management. The treating physician needs to understand the individual test characteristics of each of the many conventional candidate-based diagnostics: culture, pathogen-specific polymerase chain reaction, antigen, antibody tests, used to diagnose the whole array of neuroinvasive infections. In addition, there is a growing need for more comprehensive, agnostic testing modalities that can identify a diversity of infections with a single assay.

Prospective Cohort Study on Performance of Cerebrospinal Fluid (CSF) Xpert MTB/RIF, CSF Lipoarabinomannan (LAM) Lateral Flow Assay (LFA), and Urine LAM LFA for Diagnosis of Tuberculous Meningitis in Zambia

Tuberculous meningitis (TBM) is a devastating infection of the central nervous system lacking an adequate point-of-care diagnostic test. We conducted a prospective cohort study of 550 Zambian adults with suspected TBM to determine the diagnostic accuracy of cerebrospinal fluid (CSF) Xpert MTB/RIF, CSF lipoarabinomannan (LAM), urine LAM, CSF total protein, and CSF glucose compared with the gold standard of CSF culture. We categorized patients with a positive CSF tuberculosis (TB) culture as definite TBM. We also assessed inpatient and 1-year mortality on definite TBM patients when CSF Xpert MTB/RIF results were available in real time to treating physicians relative to a historical comparison cohort in whom Xpert results were not available in real time. Of the 550 patients, 474 (86.2%) were HIV-infected and 105/550 (19.1%) had definite TBM based on a positive CSF culture. The sensitivity/specificity of the diagnostic tests were CSF Xpert MTB/RIF, 52.9%/94.2%; CSF LAM, 21.9%/94.2%; urine LAM, 24.1%/76.1%; and CSF glucose <40 mg/dl, and total protein, >100 mg/dl, 66.3%/90%. A model including CSF Xpert MTB/RIF, CSF LAM, CSF glucose, and CSF total protein demonstrated an area under the receiver operating curve of 0.90. The inpatient and 1-year mortality for definite TBM was 43% and 57%, respectively. There was low sensitivity for the diagnosis of TBM across all diagnostics tests. CSF Xpert MTB/RIF and CSF LAM are highly specific for the diagnosis of TBM. Despite the use of Xpert MTB/RIF for diagnostic purpose in real time, TBM was still associated with a high mortality in Zambian patients.

Fluconazole plus flucytosine is a good alternative therapy for non-HIV and non-transplant-associated cryptococcal meningitis: A retrospective cohort study

Cryptococcal meningitis (CM) carries a high risk of mortality with increasing incidences in immune competent hosts. Current treatments are not well tolerated, and evaluation of other treatments is needed. Fluconazole and 5‐flucytosine in treating immune competent hosts have not been characterised. To evaluate the efficacy of fluconazole and 5‐flucytosine in treating non‐HIV‐ and non‐transplant‐associated CM. We performed a retrospective cohort study of the outcomes in immune competent patients with CM treated with fluconazole and 5‐flucytosine or deoxycholate‐amphotericin B and 5‐flucytosine. The primary outcome was treatment response evaluated at the 12th week after initiation of antifungal therapy. A total of 43 and 47 patients received amphotericin B deoxycholate and 5‐flucytosine or fluconazole and 5‐flucytosine, respectively. A total of 38 (88.4%) patients cannot tolerate recommended doses of amphotericin B deoxycholate and 5‐flucytosine (patients needed dose reduction during the treatment). Patients given fluconazole and 5‐flucytosine had higher baseline cryptococcal burdens (median 3632 versus 900 cryptococci/mL, P = 0.008). No significant differences were seen in cryptococcus clearance (74.4% vs 70.2%, P = 0.814), treatment time (39 days, 20‐69 days vs 21 days, 7‐63 days, P = 0.107) and successful response (including complete and partial responses) rates (69.7% vs 72.3%, P = 0.820). Fluconazole and 5‐flucytosine treatment had lower total adverse events (19.1% vs 90.7%, P < 0.001). Fluconazole and 5‐flucytosine had relatively high efficacy with few adverse events in treating CM. Fluconazole and 5‐flucytosine therapy is promising in patients that do not tolerate or are not suited for amphotericin B deoxycholate treatment.

Economic analysis of rapid multiplex polymerase chain reaction testing for meningitis/encephalitis in adult patients

PURPOSE

Many patients with suspected meningitis do not require hospitalization yet are admitted, often resulting in unnecessary care and additional cost. We assessed the possible economic impact of a rapid multiplex test for suspected adult community-acquired meningitis/encephalitis.

METHODS

A model simulated diagnosis, clinical decisions, resource use/costs of standard of care (SOC) and two cerebrospinal fluid (CSF) testing strategies using the FDA-cleared BioFire® FilmArray® System (FA) which provides results in approximately one hour.

RESULTS

Pathogens detected by FA caused approximately 74% of cases, 97% of which would be accurately diagnosed with FA. False positives and false negatives more often led to extended/unnecessary admission than inappropriate discharge/missed admission. Mean cost per case ranged from 16829 to 20791. A strategy of testing all suspected cases yielded greater savings (2213/case) than testing only those with abnormal CSF (812/case) and both were less expensive than SOC.

CONCLUSION

This economic analysis demonstrates that FA can inform more appropriate clinician decisions resulting in cost savings with greater economic benefits achievable with syndromic testing of all cases, rather than SOC or targeted syndromic testing.

Metabolomic-Based Methods in Diagnosis and Monitoring Infection Progression

A robust biomarker screening and validation is crucial for overcoming the current limits in the clinical management of infectious diseases. In this chapter, a general workflow for metabolomics is summarized. Subsequently, an overview of the major contributions of this omics science to the field of biomarkers of infectious diseases is discussed. Different approaches using a variety of analytical platforms can be distinguished to unveil the key metabolites for the diagnosis, prognosis, response to treatment and susceptibility for infectious diseases. To allow the implementation of such biomarkers into the clinics, the performance of large-scale studies employing solid validation criteria becomes essential. Focusing on the etiological agents and after an extensive review of the field, we present a comprehensive revision of the main metabolic biomarkers of viral, bacterial, fungal, and parasitic diseases. Finally, we discussed several articles which show the strongest validation criteria. Following these research avenues, precious clinical resources will be revealed, allowing for reduced misdiagnosis, more efficient therapies, and affordable costs, ultimately leading to a better patient management.

Inadequate diagnostics: the case to move beyond the bacilli for detection of meningitis due to Mycobacterium tuberculosis

Tuberculosis (TB) meningitis is extremely difficult to diagnose due to its pauci-bacillary disease nature and new techniques are needed. Improved test sensitivity would allow for greater clinician confidence in diagnostic testing and has the potential to improve patient outcomes. Traditional microbiologic and molecular tests for TB meningitis focus on detection of TB bacilli and are inadequate. Smear microscopy is rapid but only ~10-15  % sensitive. Culture has 50-60  % sensitivity but is slow. Xpert MTB/Rif Ultra is a rapid, automated PCR-based assay with ~70  % sensitivity versus clinical case definition. Thus, even the best current testing may miss up to 30  % of cases. Clinicians are often left to treat empirically with prolonged regimens with significant side effects or risk a missed case that would result in death. Rather than relying strictly on microbiologic or molecular testing to diagnose TB meningitis, we propose that testing of CSF for biomarkers of host response may have an adjunctive role to play in improving the diagnosis of TB meningitis.

1H nuclear magnetic resonance-based metabolic profiling of cerebrospinal fluid to identify metabolic features and markers for tuberculosis meningitis

BACKGROUND

Tuberculosis meningitis (TBM) is the most severe form of tuberculosis, and currently lacks efficient diagnostic approaches. Metabolomics has the potential to differentiate patients with TBM from those with other forms of meningitis and meningitis-negative individuals. However, no systemic metabolomics research has compared the cerebrospinal fluid (CSF) of these patients.

METHODS

¹H nuclear magnetic resonance (NMR) was used for CSF metabolic profiling. Principal component analysis and orthogonal signal correction-partial least squares-discriminant analysis (OPLS-DA) were used to screen for important variables. The Human Metabolome Database was used to identify metabolites, and MetaboAnalyst 4.0 was used for pathway analysis and over-representation analysis.

RESULTS

OPLS-DA modeling could distinguish TBM from other forms of meningitis, and several significantly changed metabolites were identified. Additionally, 23, 6, and 21 metabolites were able to differentiate TBM from viral meningitis, bacterial meningitis, and meningitis-negative groups, respectively. Pathway analysis indicated that these metabolites were mainly involved in carbohydrate and amino acid metabolism, and over-representation analysis indicated that some of these pathways were over-represented.

CONCLUSIONS

The metabolites identified have the potential to serve as biomarkers for TBM diagnosis, and carbohydrate and amino acid metabolism are perturbed in the CSF of patents with TBM. Metabolomics is a valuable approach for screening TBM biomarkers. With further investigation, the metabolites identified in this study could aid in TBM diagnosis.

New molecular tools for meningitis diagnostics in Ethiopia - a necessary step towards improving antimicrobial prescription

BACKGROUND

Meningitis remains a top cause of premature death and loss of disability-adjusted life years in low-income countries. In resource-limited settings, proper laboratory diagnostics are often scarce and knowledge about national and local epidemiology is limited. Misdiagnosis, incorrect treatment and overuse of antibiotics are potential consequences, especially for viral meningitis.

METHODS

A prospective study was conducted over three months in a teaching hospital in Ethiopia with limited laboratory resources. Cerebrospinal fluid (CSF) samples from patients with suspected meningitis were analysed using a multiplex PCR-based system (FilmArray, BioFire), in addition to basic routine testing with microscopy and culture. Clinical data, as well as information on treatment and outcome were collected.

RESULTS

Two hundred and eighteen patients were included; 117 (54%) neonates (0-29 days), 63 (29%) paediatrics (1 month-15 years) and 38 (17%) adults (≥16 years). Of 218 CSF samples, 21 (10%) were PCR positive; 4% in neonates, 14% in paediatrics and 18% in adults. Virus was detected in 57% of the PCR positive samples, bacteria in 33% and fungi in 10%. All CSF samples that were PCR positive for a bacterial agent had a white cell count ≥75 cells/mm³ and/or turbid appearance. The majority (90%) of patients received more than one antibiotic for treatment of the meningitis episode. There was no difference in the mean number of different antibiotics received or in the cumulative number of days with antibiotic treatment between patients with a microorganism detected in CSF and those without.

CONCLUSIONS

A rapid molecular diagnostic system was successfully implemented in an Ethiopian setting without previous experience of molecular diagnostics. Viral meningitis was diagnosed for the first time in routine clinical practice in Ethiopia, and viral agents were the most commonly detected microorganisms in CSF. This study illustrates the potential of rapid diagnostic tests for reducing antibiotic usage in suspected meningitis cases. However, the cost of consumables for the molecular diagnostic system used in this study limits its use in low-income countries.

Ventriculoperitoneal shunts in non-HIV cryptococcal meningitis

Background

Persistent and uncontrollable intracranial hypertension (ICH) and difficulty in reducing Cryptococcus count are severe problems in cryptococcal meningitis (CM) patients. The therapeutic effects of ventriculoperitoneal shunts (VPS) in non-HIV CM patients are not fully known, and the procedure is somewhat unusual. Here, our study offers a review to investigate the role of VPS in non-HIV CM.

Methods

We retrospectively collected data on 23 non-HIV CM patients with and without ventriculomegaly from 2010 to 2016. Their demographic data, clinical manifestations, cerebrospinal fluid (CSF) features and outcomes were analysed.

Results

We found that non-HIV CM patients without ventriculomegaly were older, had earlier treatment times and had shorter symptom durations than CM patients with ventriculomegaly. In both groups, headache, vomiting, fever and loss of vision were the most common clinical features. CSF pressure and Cryptococcus count were significantly decreased after operation. VPS could provide sustained relief from ICH symptoms such as headache. 13% of patients had poor outcomes because of serious underlying disease, while 87% of patients had good outcomes.

Conclusions

The use of a VPS is helpful in decreasing ICH and fungal overload in non-HIV CM patients, and VPS should be performed before CM patients present with symptoms of severe neurological deficit.

Mass spectrometry-based metabolomics for tuberculosis meningitis

Tuberculosis meningitis (TBM) is a prevalent form of extra-pulmonary tuberculosis that causes substantial morbidity and mortality. Diagnosis of TBM is difficult because of the limited sensitivity of existing laboratory techniques. A metabolomics approach can be used to investigate the sets of metabolites of both bacteria and host, and has been used to clarify the mechanisms underlying disease development, and identify metabolic changes, leadings to improved methods for diagnosis, treatment, and prognostication. Mass spectrometry (MS) is a major analysis platform used in metabolomics, and MS-based metabolomics provides wide metabolite coverage, because of its high sensitivity, and is useful for the investigation of Mycobacterium tuberculosis (Mtb) and related diseases. It has been used to investigate TBM diagnosis; however, the processes involved in the MS-based metabolomics approach are complex and flexible, and often consist of several steps, and small changes in the methods used can have a huge impact on the final results. Here, the process of MS-based metabolomics is summarized and its applications in Mtb and Mtb-related diseases discussed. Moreover, the current status of TBM metabolomics is described.