Comparison of Cerebrospinal Fluid Biomarkers for Differential Diagnosis of Acute Bacterial and Viral Meningitis with Atypical Cerebrospinal Fluid Characteristics

Detection of intrathecal IgG antibody for varicella and measles diagnosis by evaluation and comparison of a commercial IgG chemiluminescent immunoassay with two ELISAs

OBJECTIVES

Analyse alternative methods of intrathecal antibody detection by comparing chemiluminescent immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) techniques to determine if CLIA can replace ELISA in the diagnosis of CNS infections.

METHODS

A panel of 280 paired samples-cerebrospinal fluid (CSF) and serum-with known antibody reactivities (Varicella, n = 60; Measles, n = 120) and negative samples (n = 100) were used to evaluate the performance of six serological test kits (Enzygnost, VirClia®, and Serion ELISA (Measles and Variella).

RESULTS

For Measles virus IgG, the VirClia® IgG monotest revealed 97% and 94% positive and negative agreement to the Enzygnost as reference test, respectively. In contrast, Serion ELISA kits yielded values of 18% and 90%. For the Varicella Zoster virus (VZV) IgG, the VirClia® IgG monotest showed 97% and 90% positive and negative agreement compared to Enzygnost. The Serion ELISA kits showed values of 55% and 86%, respectively. ROC analysis revealed that the areas under the curve for Measles and VZV IgGs were 0.7 and 0.852, respectively, using the Serion kit, and 0.963 and 0.955, for Vircell S.L CLIA technique. VirClia® monotest values were calculated using an antibody index cut-off of 1.3.

CONCLUSION

The findings indicate that CLIA testing can improve antibody detection in CSF samples, aiding the diagnosis of infectious neurological impairments.

Review of dengue, zika and chikungunya infections in nervous system in endemic areas

Dengue, zika, and chikungunya are arboviruses of great epidemiological relevance worldwide. The emergence and re-emergence of viral infections transmitted by mosquitoes constitute a serious human public health problem. The neurological manifestations caused by these viruses have a high potential for death or sequelae. The complications that occur in the nervous system associated with arboviruses can be a challenge for diagnosis and treatment. In endemic areas, suspected cases should include acute encephalitis, myelitis, encephalomyelitis, polyradiculoneuritis, and/or other syndromes of the central or peripheral nervous system, in the absence of a known explanation. The confirmation diagnosis is based on viral (isolation or RT-PCR) or antigens detection in tissues, blood, cerebrospinal fluid, or other body fluids, increase in IgG antibody titers between paired serum samples, specific IgM antibody in cerebrospinal fluid and serological conversion to IgM between paired serum samples (non-reactive in the acute phase and reactive in the convalescent). The cerebrospinal fluid examination can demonstrate: 1. etiological agent; 2. inflammatory reaction or protein-cytological dissociation depending on the neurological condition; 3. specific IgM, 4. intrathecal synthesis of specific IgG (dengue and chikungunya); 5. exclusion of other infectious agents. The treatment of neurological complications aims to improve the symptoms, while the vaccine represents the great hope for the control and prevention of neuroinvasive arboviruses. This narrative review summarizes the updated epidemiology, general features, neuropathogenesis, and neurological manifestations associated with dengue, zika, and chikungunya infection.

German guidelines on community-acquired acute bacterial meningitis in adults

INTRODUCTION

The incidence of community-acquired acute bacterial meningitis has decreased during the last decades. However, outcome remains poor with a significant proportion of patients not surviving and up to 50% of survivors suffering from long-term sequelae. These guidelines were developed by the Deutsche Gesellschaft für Neurologie (DGN) under guidance of the Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften (AWMF) to guide physicians through diagnostics and treatment of adult patients with acute bacterial meningitis.

RECOMMENDATIONS

The most important recommendations are: (i) In patients with suspected acute bacterial meningitis, we recommend that lumbar cerebrospinal fluid (with simultaneous collection of serum to determine the cerebrospinal fluid-serum glucose index and blood cultures) is obtained immediately after the clinical examination (in the absence of severely impaired consciousness, focal neurological deficits, and/or new epileptic seizures). (ii) Next, we recommend application of dexamethasone and empiric antibiotics intravenously. (iii) The recommended initial empiric antibiotic regimen consists of ampicillin and a group 3a cephalosporin (e.g., ceftriaxone). (iv) In patients with severely impaired consciousness, new onset focal neurological deficits (e.g. hemiparesis) and/or patients with newly occurring epileptic seizures, we recommend that dexamethasone and antibiotics are started immediately after the collection of blood; we further recommend that -if the imaging findings do not indicate otherwise -a lumbar CSF sample is taken directly after imaging. (v) Due to the frequent occurrence of intracranial and systemic complications, we suggest that patients with acute bacterial meningitis are treated at an intensive care unit in the initial phase of the disease. In the case of impaired consciousness, we suggest that this is done at an intensive care unit with experience in the treatment of patients with severe CNS diseases.

CONCLUSIONS

The German S2k-guidelines give up to date recommendations for workup, diagnostics and treatment in adult patients with acute bacterial meningitis.

Comparison between cerebrospinal fluid biomarkers for differential diagnosis of acute meningitis

OBJECTIVES

Given the difficulty in the differential diagnosis of acute bacterial meningitis (BM) and viral meningitis (VM), we aimed to compare the ability of cerebrospinal fluid (CSF) biomarkers, such as lactate, glucose, lactate dehydrogenase (LDH), C-reactive protein (CRP), total white blood cell count, and predominance of neutrophils, as single tests to differentiate microbiologically defined acute BM and VM.

METHODS

CSF samples were divided into three groups: BM (n=17), VM (n=14) (both with the etiological agent identified), and normal control groups (n=26).

RESULTS

All the biomarkers studied were significantly higher in the BM group than in the VM or control groups (p>0.05). CSF lactate showed the best diagnostic clinical performance characteristics: sensitivity (94.12%), specificity (100%), positive and negative predictive value (100 and 97.56%, respectively), positive and negative likelihood ratio (38.59 and 0.06, respectively), accuracy (98.25%), and AUC (0.97). CSF CRP is excellent for screening BM and VM, as its best feature is its specificity (100%). CSF LDH is not recommended for screening or case-finding. LDH levels were higher in Gram-negative diplococcus than in Gram-positive diplococcus. Other biomarkers were not different between Gram-positive and negative bacteria. The highest level of agreement between the CSF biomarkers was between CSF lactate and CRP [kappa coefficient, 0.91 (0.79; 1.00)].

CONCLUSIONS

All markers showed significant differences between the studied groups and were increased in acute BM. CSF lactate is better than the other biomarkers studied for screening acute BM due to its high specificity.

The usefulness of hematological parameters and cerebrospinal fluid indexes in the differential diagnosis of acute bacterial from viral meningitis

Central nervous system (CNS) infection is a medical emergency with an important cause of mortality worldwide. The 79 patients with confirmed acute CNS infection (48 bacterial and 31 viral meningitis) were evaluated. Bacterial meningitis score, cerebrospinal fluid (CSF)/serum glucose ratio, and CSF/serum albumin ratio had the highest area under the curves (0.873, 0.843, 0.810, respectively) for discriminating bacterial meningitis. Neutrophil-to-lymphocyte (NLR), platelet-to-lymphocyte ratio (PLR) and CSF lactate dehydrogenase have a good ability for the differential diagnosis of bacterial meningitis. CSF/serum glucose ratio, NLR (with a cut-off value> 8.87), large unstained cell, total protein, albumin, and procalcitonin levels were found to be predictors for mortality. NLR can be used as a biomarker to differentiate bacterial meningitis from viral meningitis and to predict the prognosis of CNS infection. CSF/serum albumin ratio and CSF lactate dehydrogenase can be used to predict bacterial meningitis as well as CSF/serum glucose ratio.

Cerebrospinal fluid lactate as a predictive biomarker for tuberculous meningitis diagnosis

Objectives

The definitive diagnosis of tuberculous meningitis (TBM) is achieved by identifying Mycobacterium tuberculosis (MTb) in cerebrospinal fluid (CSF); however, diagnostic confirmation is difficult due to the inability of current tests for an effective diagnosis. Our objective was to retrospectively assess the characteristics of CSF lactate (CSF-LA) as an adjunct biomarker in the diagnosis of TBM.

Methods

608 CSF laboratory reports were assessed. Of these, 560 had clinically suspected TBM. These were classified as definite (n=36), probable (23), possible (278), or non-TBM (223) according to the international consensus TBM case definitions. An additional 48 CSF samples were negative controls with normal CSF.

Results

Against a reference standard of definite TBM, the cut-off value for CSF-LA was 4.0 mmol/L, the area under the ROC curve was 0.88 (95% CI, 0.82–0.94; p=0.0001), sensitivity was 69%, specificity 90%, negative predictive value 98%. These diagnostic parameters decreased when calculated against those of the other categories of TBM. CSF-LA exhibited high specificity, efficiency, negative predictive value, and clinical utility index in all the groups studied.

Conclusions

CSF-LA is a useful diagnostic marker to rule out TBM when associated with conventional microbiology tests, nucleic acid amplification assays, and clinical algorithms, particularly in endemic areas.

The experience of using FilmArray Meningitis/Encephalitis Panel for the diagnosis of meningitis and encephalitis in pediatric patients

BACKGROUND/PURPOSE

Central nervous system infections can cause severe complications and even death in children. Early diagnosis of the causative pathogen can guide appropriate treatment and improve outcomes. The BioFire® FilmArray® Meningitis/Encephalitis Panel (FA-ME) is a multiplex polymerase chain reaction (PCR) assay targeting 14 pathogens. We aimed to examine FA-ME performance compared with conventional assays and its effect on antimicrobial usage.

METHODS

We prospectively enrolled 55 pediatric patients with suspected meningitis or encephalitis and simultaneously performed FA-ME and conventional assays. Sixty-three hospitalized patients with CNS infection before implementing FA-ME were considered controls. We compared the FA-ME results with conventional assays and the empiric antimicrobial usage and hospital stay between the two study groups.

RESULTS

Nine patients (16.4%) tested positive by FA-ME, four were bacterial, and five were viral. Three additional pathogens were detected by conventional assays: Enterococcus faecalis, Leptospira, and herpes simplex virus type 2. In the control group, two bacterial pathogens were detected by CSF culture and four viral pathogens by single PCRs. Compared with the control group, the FA-ME group had a shorter time for pathogen detection, but there were no significant differences in pathogen detection rate, duration of empiric antimicrobial therapy, and length of hospital stay.

CONCLUSION

Although no significant difference was found in empiric antimicrobial duration and length of stay between patients tested with FA-ME and conventional assays, FA-ME had the advantage of a shorter detection time and early exclusion of potential causative pathogens. The FA-ME results should be interpreted carefully based on the clinical presentation.

Application of Biomarkers in the Diagnostic Distinction of Bacterial and Viral Infections

Infectious diseases, which pose a great threat worldwide, have a significant impact on public health and the world economy. It contributes to increased healthcare costs, unnecessary drug-related side effects, and increased antimicrobial resistance. It is not always easy to distinguish the etiological differentiation of diseases that can develop with bacteria and viruses. Therefore, one of the biggest challenges in medicine is how to correctly distinguish between the different causes of these infections and how to manage the patient. Because bacterial and viral infections often present similar symptoms. The real decision is whether the infection is caused by bacteria or viruses and whether to treat the patient with antibiotics. There are many different methodological approaches to diagnosing infections. Biomarkers have been used in the diagnosis of diseases and other conditions for many years. Biomarkers are molecules found in blood and body fluids in measurable amounts, which can evaluate biological and pathological processes. These key indicators can provide vital information in determining disease prognosis, predicting response to treatments, adverse events and drug interactions, and identifying key risks. An effective biomarker is extremely important for the early diagnosis of various diseases. The explosion of interest in biomarker research is driving the development of new predictive, diagnostic, and prognostic products in modern medical practice. The purpose of this review is to demonstrate the use and diagnostic potential of current and investigational biomarkers in the distinction between bacterial and viral infections.

Heparin-Binding Protein (HBP), Neutrophil Gelatinase-Associated Lipocalin (NGAL) and S100 Calcium-Binding Protein B (S100B) Can Confirm Bacterial Meningitis and Inform Adequate Antibiotic Treatment

The empirical administration of antibiotics for suspected bacterial meningitis denotes a poor bacterial stewardship. In this context, the use of biomarkers can distinguish between bacterial and viral infections before deciding treatment. Our study assesses how levels of heparin-binding protein (HBP), neutrophil gelatinase-associated lipocalin (NGAL), S100 calcium-binding protein B (S100B), and neuron-specific enolase (NSE) in cerebrospinal fluid (CSF) and in blood can promptly confirm bacterial etiology and the need for antibiotic treatment. The CSF and blood levels of HBP, NGAL, S100B, and NSE of 81 patients with meningitis were measured and analyzed comparatively. Statistical sensitivity, specificity, and positive and negative predictive values were evaluated. CSF levels of HBP and NGAL and the blood level of S100B in the bacterial meningitis group were significantly higher (p < 0.05). The area under curve (AUC) for predicting bacterial meningitis was excellent for the CSF level of HBP (0.808 with 93.54% sensitivity and 80.64% specificity), good for the CSF level of NGAL (0.685 with 75.00% sensitivity and 65.62% specificity), and good for the blood level of S100B (0.652 with 65.90% sensitivity and 57.14% specificity). CSF levels of HBP and NGAL, as well as the blood level of S100B, could help discriminate between bacterial and viral meningitis before considering antibiotic treatment.

Clinical performance of amperometry compared with enzymatic ultra violet method for lactate quantification in cerebrospinal fluid

OBJECTIVES

The differential diagnosis between acute bacterial meningitis (BM) and viral meningitis (VM) is crucial for treatment and prognosis. Cerebrospinal fluid (CSF) lactate (LA) is considered a good biomarker for differentiating BM from VM. The objective of this study was to compare the clinical performance of amperometry, which is not validated for measurement of LA in CSF samples, with a validated method (enzymatic ultra violet), for their ability to discriminate between acute BM and VM.

METHODS

It was a retrospective, descriptive comparative study, 320 CSF reports were included; LA was quantified in CSF using either Dimension AR machine (Dade Behring) or amperometry (RAPID Point 500, Siemens). All samples with bacteria (n=54) or virus (n=139) identified, compared with a control with normal CSF (n=127).

RESULTS

CSF LA levels were comparable for amperometry or enzymatic methods on each group studied, in a wide range of LA levels; it was capable to distinguish BM from VM independent of the method used to quantify.

CONCLUSIONS

The findings support the use of the amperometric method in measuring LA concentrations in CSF in a wide range of values. Amperometry is a less expensive method, validated for blood, easily available in small laboratories including in limited resources countries.

Procalcitonin measurement using antibody-conjugated fluorescent microspheres distinguishes atypical bacterial meningitis from viral encephalitis in children

Examination of cerebrospinal fluid in atypical bacterial meningitis (ABM) is similar to that of viral encephalitis (VE), so ABM can easily be misdiagnosed as VE, which can delay diagnosis and treatment. We developed a simple, rapid hand-held lateral flow immunoassay detection system based on fluorescent microspheres (FMS) for procalcitonin (PCT) detection, which provides an indicator to differentiate between ABM and VE. With this novel method, the antigen-antibody reaction systems involve different species, making the test strips more stable than those utilizing one species. The strips exhibited a wide dynamic range (0.04-50 ng/mL) and good sensitivity (0.03 ng/mL). The function of PCT in the identification of ABM and VE in children was further studied. A significant difference in PCT levels was observed between the ABM and VE groups (P = 0.00) and between the ABM and the normal control groups (P = 0.00). PCT levels were not significantly different between the VE and normal control groups (P = 0.30). The area under the receiver operating characteristic curve of PCT for the diagnosis of ABM was 0.95. These findings collectively indicate the usefulness of the PCT detection method based on FMS for clinically differentiating between ABM and VE.

Advances in tuberculous meningitis diagnosis

Introduction: Tuberculous meningitis (TBM) is the most devastating form of central nervous system tuberculosis (TB) and causes high mortality worldwide. Nonspecific clinical manifestations and limited sensitivity of existing laboratory methods make the diagnosis elusive due to the paucibacillary nature of the infection. Areas Covered: We reviewed current literature on the adequacy and limitations of globally existing laboratory methods for diagnosing TBM. Expert opinion: TBM is deadliest among all TB forms, as the outcome may lead to death in 50% of cases, and survivors undergo irreversible neurological disorders. Therefore, early diagnosis and prompt treatment are cornerstones of effective disease management. Conventional microscopy and culture are widely used modalities but remain inadequate in most TBM cases. Although expanded use of rapid molecular tests such as real-time PCR and Xpert Ultra, even in resource-limited settings, hold promising results for TB diagnosis but need optimization for early detection of TBM. Moreover, CSF IGRA is also used but unable to differentiate between active and latent TB. Overall no single test for diagnosing TBM has adequate accuracy so, there is an urgent need to devise a point-of-care test.