Three-year follow-up of rheumatoid meningitis with matrix metalloprotease-9 levels in the serum and cerebrospinal fluid as indicators of disease activity: A case report.

Rheumatoid meningitis (RM) is an extra-articular complication of rheumatoid arthritis (RA). Although reports of RM sine arthritis exist, most patients with this presentation were diagnosed with RA within one year of RM onset. There are no established biomarkers reflecting the disease activity of RM. This case report highlights the elevation of matrix metalloprotease (MMP)-9 levels during the acute phase of RM and decline during remission. Additionally, this is the first case report of RA diagnosed three years after the onset of RM. It is important to further validate the utility of MMP-9 and conduct long-term follow-up of RM sine arthritis.

Evaluation of metagenomic and pathogen-targeted next-generation sequencing for diagnosis of meningitis and encephalitis in adults: A multicenter prospective observational cohort study in China.

BACKGROUND: Next-generation sequencing (NGS) might aid in the identification of causal pathogens. However, the optimal approaches applied to cerebrospinal fluid (CSF) for detection are unclear, and studies evaluating the application of different NGS workflows for the diagnosis of intracranial infections are limited. METHODS: In this multicenter, prospective observational cohort study, we described the diagnostic efficacy of pathogen-targeted NGS (ptNGS) and metagenomic NGS (mNGS) compared to that of composite microbiologic assays, for infectious meningitis/encephalitis (M/E). RESULTS: In total, 152 patients diagnosed with clinically suspected M/E at four tertiary hospitals were enrolled; ptNGS and mNGS were used in parallel for pathogen detection in CSF. Among the 89 patients who were diagnosed with definite infectious M/E, 57 and 39 patients had causal microbial detection via ptNGS and mNGS, respectively. The overall accuracy of ptNGS was 65.1%, with a positive percent agreement (PPA) of 64% and a negative percent agreement (NPA) of 66.7%; and the overall accuracy of mNGS was 47.4%, with a PPA of 43.8% and an NPA of 52.4% after discrepancy analysis. There was a significant difference in the detection efficiency between these two methods both for PPA (sensitivity) and overall accuracy for pathogen detection (P < 0.05). CONCLUSIONS: NGS tests have provided new information in addition to conventional microbiologic tests. ptNGS seems to have superior performance over mNGS for common causative pathogen detection in CSF for infectious M/E.

Hybrid capture shotgun sequencing detected unexpected viruses in the cerebrospinal fluid of children with acute meningitis and encephalitis.

PURPOSE: Investigation of undiagnosed cases of infectious neurological diseases, especially in the paediatric population, remains a challenge. This study aimed to enhance understanding of viruses in CSF from children with clinically diagnosed meningitis and/or encephalitis (M/ME) of unknown aetiology using shotgun sequencing enhanced by hybrid capture (HCSS). METHODS: A single-centre prospective study was conducted at Sant Joan de Déu University Hospital, Barcelona, involving 40 M/ME episodes of unknown aetiology, recruited from May 2021 to July 2022. All participants had previously tested negative with the FilmArray Meningitis/Encephalitis Panel. HCSS was used to detect viral nucleic acid in the patients' CSF. Sequencing was performed on Illumina NovaSeq platform. Raw sequence data were analysed using CZ ID metagenomics and PikaVirus bioinformatics pipelines. RESULTS: Forty episodes of M/ME of unknown aetiology in 39 children were analysed by HCSS. A significant viral detection in 30 CSF samples was obtained, including six parechovirus A, three enterovirus ACD, four polyomavirus 5, three HHV-7, two BKV, one HSV-1, one VZV, two CMV, one EBV, one influenza A virus, one rhinovirus, and 13 HERV-K113 detections. Of these, one sample with BKV, three with HHV-7, one with EBV, and all HERV-K113 were confirmed by specific PCR. The requirement for Intensive Care Unit admission was associated with HCSS detections. CONCLUSION: This study highlights HCSS as a powerful tool for the investigation of undiagnosed cases of M/ME. Data generated must be carefully analysed and reasonable precautions must be taken before establishing association of clinical features with unexpected or novel virus findings.

Elevated levels of ß2-microglobulin in cerebrospinal fluid in adult patients with viral encephalitis/meningitis.

BACKGROUND: Increased cerebrospinal fluid (CSF) ß2-microglobulin (ß2-MG) values are attributed to immune activation, lymphoid cell turnover and release of tissue destruction in the central nervous system (CNS). We investigated plasma and CSF ß2-MG levels in adult patients with viral encephalitis/meningitis and their correlations with clinical parameters. METHOD: CSF samples from 26 patients with viral encephalitis/meningitis were collected. Moreover, 24 CSF samples from patients with non-inflammatory neurological disorders (NIND) as controls were collected. Plasma samples from 22 enrolled patients and 20 healthy individuals were collected. The ß2-MG levels were measured by immunoturbidimetry on an automatic biochemical analyzer. Clinical data were extracted from an electronic patient documentation system. RESULT: CSF levels of ß2-MG, adenosine deaminase (ADA), white blood cell (WBC), lactate dehydrogenase (LDH), protein and lactate were significantly increased in patients with viral encephalitis/meningitis respectively (p < 0.001, p < 0.001, p < 0.001, p = 0.001, p < 0.001, p = 0.013). In contrast, no statistically significant difference was found in plasma levels of ß2-MG. Furthermore, CSF levels of ß2-MG were weakly correlated with WBC (r = 0.426, p = 0.030), lymphocyte percentage (r = 0.599, p = 0.018), ADA (r = 0.545, p = 0.004) and LDH (r = 0.414, p = 0.036), but not with lactate (r = 0.381, p = 0.055), protein (r = 0.179, p = 0.381) and plasma levels of ß2-MG (r = -0.156, p = 0.537) in viral encephalitis/meningitis patients. CONCLUSION: CSF ß2-MG may be a potential inflammatory marker for viral encephalitis/meningitis in adult patients diagnosed with viral encephalitis/meningitis.

A retrospective observational study of 1000 consecutive patients tested with the FilmArray® Meningitis/Encephalitis panel: clinical diagnosis at discharge and microbiological findings.

FilmArray® Meningitis/Encephalitis panel (FAME-p) is used to diagnose central nervous system (CNS) infections. In this study, we investigated performance of FAME-p compared to comparator assays (CA), and for the first time, clinical diagnosis at discharge (CDD). 1000 consecutive patients with a cerebrospinal fluid (CSF) sample analyzed with FAME-p were identified. As CA, culture, polymerase chain reaction and cryptococcal antigen test were used. Medical records of patients were obtained. A CDD of CNS infection was made in 139 of 1000 CSF samples. FAME-p was positive in 66 samples with 44 viral and 22 bacterial agents. Thirteen FAME-p findings were not confirmed by CA, with four discrepant results remaining after comparison with the CDD. Positive percentage agreement (PPA) calculated against CA was 100%. Negative percentage agreement (NPA) calculated against CA was 94.4-99.8% for Haemophilus influenzae, Listeria monocytogenes, Streptococcus agalactiae, S. pneumoniae and varicella-zoster virus (VZV). NPA calculated against CDD was higher (compared to CA) for L. monocytogenes, S. agalactiae and VZV (100%), and lower for Escherichia coli, enterovirus and herpes simplex virus 2 (50-83.3%). NPA of FAME-p for human herpes virus 6 was difficult to interpret. Eighty-four cases received diagnosis of CNS-infection despite negative FAME-p. The four most common non-infectious etiologies were primary headache disorders, cranial nerve palsies, neuroinflammatory disorders and seizure. Although FAME-p shows good performance in diagnosis of CNS infections, result of FAME-p should be interpreted carefully. Considering infectious diseases not covered by FAME-p as well as non-infectious differential diagnoses is important in this context.

C-reactive protein concentration has limited value in the diagnosis of meningoencephalitis of unknown origin in dogs.

OBJECTIVES: To evaluate blood and cerebrospinal fluid (CSF) concentrations of C-reactive protein (CRP) in dogs with meningoencephalitis of unknown origin (MUO); to evaluate whether blood CRP concentration is associated with epidemiological, clinicopathologic, and MRI findings; and to investigate blood CRP predictive power in survival. ANIMALS: 30 client-owned dogs with MUO, 15 client-owned dogs with steroid-responsive meningitis arteritis (SRMA; positive control group), and 15 healthy dogs (negative control group). METHODS: Blood CRP concentration was measured in each group, while it was performed in CSF only in the MUO and SRMA groups. The analysis of epidemiological data included breed, age, sex, duration of clinical signs, and history of seizures. Blinded analysis of MRI was performed based on a classification grid, and traditional CSF analysis parameters were assessed. The predictive power of blood CRP concentration regarding survival at 6 months was investigated. RESULTS: Of the 30 dogs with MUO, 9 (30%) had an increased CRP concentration in blood, and 3 (10%) showed a measurable CRP in CSF. Median blood CRP concentration in dogs with MUO was 0.1 mg/L (range, 0.1 to 102 mg/L), which was not statistically different from the healthy dog group but significantly lower than the SRMA control group. Only the duration of clinical signs was positively associated with an increased blood CRP level. Blood CRP concentration was not associated with survival at 6 months. CLINICAL RELEVANCE: Blood CRP concentration is of limited value for the diagnosis and prognosis of dogs with MUO. Chronicity of the disease may be associated with an increased concentration of blood CRP.

Myelomatous meningitis diagnosed by cerebrospinal fluid cytology examination.

Myelomatous meningitis diagnosed by CSF cytology. The combined use of cytology with immunocytochemistry can identify the presence of multiple myeloma cells in cerebrospinal fluid specimens.

Markedly Increased Mean Platelet Volume in Bacterial Meningitis.

BACKGROUND: Differentiating bacterial and viral meningitis is crucial, and this study explored the potential of mean platelet volume (MPV) as a marker for differentiation. METHODS: Blood samples were collected from patients with central nerve system related manifestations, and MPV was tested. Cerebrospinal fluid samples were obtained and bacterial culture and the FilmArray ME panel were performed. The distribution of MPV was compared between groups. RESULTS: The study included 8 patients in the bacterial meningitis group and 12 patients in the viral meningitis group. The bacterial meningitis group showed a significantly higher median MPV of 10.9 (9.2 - 11.6) fL compared to the viral meningitis group with 8.4 (8.1 - 8.8) fL (p < 0.0001). CONCLUSIONS: MPV could serve as a diagnostic indicator to differentiate between bacterial and viral meningitis. Larger studies are needed to validate these findings.

Elevated brain derived neurotrophic factor in plasma and interleukin-6 levels in cerebrospinal fluid in meningitis compared to cerebral malaria.

Neurological infections, such as Cerebral malaria (CM) and meningitis are associated with high mortality and in survivors, particularly young children, persistent neurologic deficits often remain. As brain inflammation plays a role in the development of these neurological sequelae, multiplex assays were used to assess a select set of immune mediators in both plasma and cerebrospinal fluid (CSF) from Zambian children with neurological infections. Both CM and meningitis patients showed high levels of markers for vascular inflammation, such as soluble ICAM-1 and angiopoietins. Although high levels of angiopoietin 1 and angiopoietin 2 were found in the meningitis group, their levels in the CSF were low and did not differ. As expected, there were high levels of cytokines and notably a significantly elevated IL-6 level in the CSF of the meningitis group. Interestingly, although elevated levels BDNF were found, BDNF levels were significantly higher in plasma of the meningitis group but similar in the CSF. The striking differences in plasma BDNF and IL-6 levels in the CSF point to markedly different neuro-pathological processes. Therefore, further investigations in the role of both IL-6 and BDNF in the neurological outcomes are needed.

Cerebrospinal fluid analysis in emergency patients with suspected infection of the central nervous system.

BACKGROUND AND PURPOSE: Meningitis and encephalitis are potentially life-threatening diseases that require fast and accurate diagnostics and therapy. The value of polymerase chain reaction (PCR) multiplex testing in clinical practice is still a matter of debate. This study aims to evaluate its benefits and limitations in emergency patients. METHODS: We assessed the value of a meningoencephalitis PCR array in the clinical routine of an emergency department. RESULTS: Of 1578 emergency patients who received a lumbar puncture, 43% received it for a clinically suspected central nervous system (CNS) infection. After initial workup for cerebrospinal fluid (CSF) cell count, protein and glucose, a CNS infection was still considered likely in 307 patients. In these patients, further microbiologic workup was performed. A total of 230 samples were examined by PCR and a pathogen was detected in 66 of these samples. In the case of a positive microbiologic result, a comparison between PCR array and standard method was available for 59 samples, which demonstrated an overcall agreement of 80% (n = 47/59). Of interest, exclusively array-positive results were observed for patients with meningitis found to be positive for Streptococcus pneumoniae; four out of five patients had been treated with antibiotics before the lumbar puncture. In samples with normal CSF cell count only two positive array results were obtained, both for human herpesvirus 6, and these were not clinically relevant. CONCLUSION: Our data suggest that the array substantially contributes to a detection of pathogens in patients with suspected CNS infection and seems of particular interest in patients with acute bacterial meningitis under empiric antibiotic treatment. In CSF samples with normal cell count, it might be dispensable.

Mycoplasma hominis Meningitis Diagnosed by Metagenomic Next-Generation Sequencing in a Preterm Newborn: a Case Report and Literature Review.

Mycoplasma hominis is mainly colonized in the genital tract and vertically transmitted to newborns; however, it rarely causes neonatal meningitis. We report a case of M. hominis meningitis in a premature infant. She was admitted to our hospital for treatment after 6 days of repeated fever. After admission, repeated cerebrospinal fluid (CSF) analysis showed that leukocytes and protein in CSF increased substantially and glucose decreased, but there was no growth in conventional CSF culture. The patient was diagnosed with M. hominis meningitis by metagenomic next-generation sequencing (mNGS). The antibiotic therapy used for the neonate was meropenem, vancomycin, and ampicillin against bacterial infection and azithromycin against mycoplasma infection. The child was subsequently considered cured and discharged from the hospital and followed up regularly in the neurology clinic. The mNGS may be a promising and effective diagnostic technique for identifying uncommon pathogens of meningitis in patients with meningitis symptoms and signs without microbial growth in routine CSF culture.

Pathogen and Antibody Identification in Children with Encephalitis in Myanmar.

OBJECTIVE: Prospective studies of encephalitis are rare in regions where encephalitis is prevalent, such as low middle-income Southeast Asian countries. We compared the diagnostic yield of local and advanced tests in cases of pediatric encephalitis in Myanmar. METHODS: Children with suspected subacute or acute encephalitis at Yangon Children's Hospital, Yangon, Myanmar, were prospectively recruited from 2016-2018. Cohort 1 (n = 65) had locally available diagnostic testing, whereas cohort 2 (n = 38) had advanced tests for autoantibodies (ie, cell-based assays, tissue immunostaining, studies with cultured neurons) and infections (ie, BioFire FilmArray multiplex Meningitis/Encephalitis multiplex PCR panel, metagenomic sequencing, and pan-viral serologic testing [VirScan] of cerebrospinal fluid). RESULTS: A total of 20 cases (13 in cohort 1 and 7 in cohort 2) were found to have illnesses other than encephalitis. Of the 52 remaining cases in cohort 1, 43 (83%) had presumed infectious encephalitis, of which 2 cases (4%) had a confirmed infectious etiology. Nine cases (17%) had presumed autoimmune encephalitis. Of the 31 cases in cohort 2, 23 (74%) had presumed infectious encephalitis, of which one (3%) had confirmed infectious etiology using local tests only, whereas 8 (26%) had presumed autoimmune encephalitis. Advanced tests confirmed an additional 10 (32%) infections, 4 (13%) possible infections, and 5 (16%) cases of N-methyl-D-aspartate receptor antibody encephalitis. INTERPRETATION: Pediatric encephalitis is prevalent in Myanmar, and advanced technologies increase identification of treatable infectious and autoimmune causes. Developing affordable advanced tests to use globally represents a high clinical and research priority to improve the diagnosis and prognosis of encephalitis. ANN NEUROL 2023;93:615-628.

Impact of CSF Meningitis and Encephalitis Panel on Resource Use for Febrile Well-Appearing Infants.

OBJECTIVES: To determine whether the BioFire FilmArray Meningitis/Encephalitis (ME) panel is associated with decreased resource use for febrile infants. The ME panel has a rapid turnaround time (1-2 hours) and may shorten length of stay (LOS) and antimicrobial use for febrile well-appearing infants. METHODS: Retrospective cohort study of febrile well-appearing infants ≤60 days with cerebrospinal fluid culture sent in the emergency department from July 2017 to April 2019. We examined the frequency of ME panel use and its relationship with hospital LOS and initiation and duration of antibiotics and acyclovir. We used nonparametric tests to compare median durations. RESULTS: The ME panel was performed for 85 (36%) of 237 infants. There was no difference in median hospital LOS for infants with versus without ME panel testing (42 hours, interquartile range [IQR] 36-52 vs 40 hours, IQR: 35-47, P = .09). More than 97% of infants with and without ME panel testing were initiated on antibiotics. Patients with ME panel were more likely to receive acyclovir (33% vs 18%; odds ratio: 2.2, 95%: confidence interval 1.2-4.0). There was no difference in median acyclovir duration with or without ME panel testing (1 hour, IQR: 1-7 vs 4.2 hours, IQR: 1-21, P = .10). When adjusting for potential covariates, these findings persisted. CONCLUSIONS: ME panel use was not associated with differences in hospital LOS, antibiotic initiation, or acyclovir duration in febrile well-appearing infants. ME panel testing was associated with acyclovir initiation.

Ion Mobility Mass Spectrometry Reveals Rare Sialylated Glycosphingolipid Structures in Human Cerebrospinal Fluid.

Gangliosides (GGs) represent an important class of biomolecules associated with the central nervous system (CNS). In view of their special role at a CNS level, GGs are valuable diagnostic markers and prospective therapeutic agents. By ion mobility separation mass spectrometry (IMS MS), recently implemented by us in the investigation of human CNS gangliosidome, we previously discovered a similarity between GG profiles in CSF and the brain. Based on these findings, we developed IMS tandem MS (MS/MS) to characterize rare human CSF glycoforms, with a potential biomarker role. To investigate the oligosaccharide and ceramide structures, the ions detected following IMS MS separation were submitted to structural analysis by collision-induced dissociation (CID) MS/MS in the transfer cell. The IMS evidence on only one mobility feature, together with the diagnostic fragment ions, allowed the unequivocal identification of isomers in the CSF. Hence, by IMS MS/MS, GalNAc-GD1c(d18:1/18:1) and GalNAc-GD1c(d18:1/18:0) having both Neu5Ac residues and GalNAc attached to the external galactose were for the first time discovered and structurally characterized. The present results demonstrate the high potential of IMS MS/MS for biomarker discovery and characterization in body fluids, and the perspectives of method implementation in clinical analyses targeting the early diagnosis of CNS diseases through molecular fingerprints.

Clinical Significance of Positive Results of the BioFire Cerebrospinal Fluid FilmArray Meningitis/Encephalitis Panel at a Tertiary Medical Center in the United States.

CONTEXT.­: The FilmArray Meningitis/Encephalitis (ME) panel is the first US Food and Drug Administration-cleared multiplex polymerase chain reaction panel for the detection of central nervous system infections. While the assay's performance characteristics have been described, the real-world significance of positive results has not been fully characterized. OBJECTIVE.­: To evaluate the clinical significance of positive ME panel results in a tertiary care medical center in New York, New York. DESIGN.­: Four physicians independently performed retrospective clinical assessments of all positive ME panel results at Columbia University Irving Medical Center, including the Children's Hospital of New York, during an 18-month period. Each reviewer determined the likelihood of central nervous system infection for all cases and whether cases fit Brighton diagnostic criteria for meningitis, encephalitis, or meningoencephalitis. RESULTS.­: Among 119 cases, there was 75% positive agreement (95% CI, 54%-89%) between ME panel results and clinical consensus, which varied among panel targets. CONCLUSIONS.­: The ME panel showed good agreement with expert clinical consensus for patients presenting with acute meningitis/encephalitis. Factors contributing to clinically insignificant ME positive results included low pretest probability, traumatic lumbar puncture, specimen contamination, and detection of incidental viral targets such as human herpesvirus 6. Notably, the ME panel detected more than twice the number of cases of bacterial meningitis detected by culture alone, particularly among patients receiving empiric antimicrobial therapy before lumbar puncture. Appropriate test use and contextual interpretation of results are critical to leveraging the advantages of the platform while avoiding potential pitfalls.

Assessment of the FilmArray ME panel in 4199 consecutively tested cerebrospinal fluid samples.

OBJECTIVES: In central nervous system infections, early and correct management is of utmost importance. Rapid syndromic panel testing can potentially provide valuable guidance. The FilmArray meningitis/encephalitis (ME) panel detects 14 pathogens through multiplex PCR. Our study objectives were to assess its performance compared with established diagnostic procedures, especially real-time quantitative PCR for detection of viruses, and to determine the diagnostic and clinical significance of discrepant results. METHODS: All cerebrospinal fluid samples sent for viral diagnostics to our microbiological laboratory over 34 months were analysed with the ME panel and in-house real-time PCR for herpes simplex virus type 1 (HSV-1), HSV-2, varicella zoster virus and enteroviruses. Other pathogens detected by the panel were confirmed by routine diagnostic procedures. Discrepant results were analysed through interpretation of biological and clinical data, and performance data were calculated for individual pathogens. RESULTS: Altogether, 315 pathogens were detected by the ME panel in 4199 cerebrospinal fluid samples (7.5%) and an additional 21 viral targets were identified using real-time PCR. Thirty-four ME panel detections were not confirmed, totalling 55 discrepant results. After discrepancy analysis, 20 false-positive and 21 false-negative ME panel results remained. Performance varied between pathogens. Sensitivity for HSV-1 was calculated at 82.4% (59.0%-93.8%) with three false-negative results. Also noteworthy were 13 false-negative enterovirus and eight false-positive Streptococcus pneumoniae results. CONCLUSIONS: Our analysis shows good performance for the ME panel in diagnosing central nervous system infection. The risk of false-negative HSV-1 results, however, warrants additional testing when encephalitis is suspected. Uncertainties in interpretation of enterovirus and S. pneumoniae results represent other limitations.

Normal Values for Cerebrospinal Fluid in Neonates: A Systematic Review.

BACKGROUND: The diagnosis of neonatal meningitis often rests on microscopic and biochemical findings in the cerebrospinal fluid (CSF). There is ongoing uncertainty about age-related normal values for CSF findings in neonates, and many previous studies have included infants in whom antibiotics were administered before lumbar puncture or in whom viral meningitis was not excluded. METHODS: A systematic search was done using MEDLINE and EMBASE to identify original studies which investigated CSF normal values in either healthy neonates or febrile neonates in whom bacterial and viral meningitis were reliably excluded. RESULTS: We identified seven studies investigating 270 term and 96 preterm neonates. There were minimal differences between preterm and term neonates in the CSF white blood cell (WBC) count and glucose concentration. In contrast, the CSF neutrophil count and protein concentration were influenced by gestational and chronological age. In the four studies that reported individual patient data, in 95% of cases the CSF WBC count was <12 cells/µL in preterm and <10 cells/µL in term neonates, the neutrophil count was <16 and 8 cells/µL, and the protein concentration was <210 and 110 mg/dL, respectively. CONCLUSION: The normal range for CSF parameters in neonates is different to that in older infants, and some parameters are influenced by gestational and chronological age. CSF parameters alone are not sufficiently reliable to exclude meningitis.

Enhanced Virus Detection and Metagenomic Sequencing in Patients with Meningitis and Encephalitis.

Meningitis and encephalitis are leading causes of central nervous system (CNS) disease and often result in severe neurological compromise or death. Traditional diagnostic workflows largely rely on pathogen-specific tests, sometimes over days to weeks, whereas metagenomic next-generation sequencing (mNGS) profiles all nucleic acid in a sample. In this single-center, prospective study, 68 hospitalized patients with known (n = 44) or suspected (n = 24) CNS infections underwent mNGS from RNA and DNA to identify potential pathogens and also targeted sequencing of viruses using hybrid capture. Using a computational metagenomic classification pipeline based on KrakenUniq and BLAST, we detected pathogen nucleic acid in cerebrospinal fluid (CSF) from 22 subjects, 3 of whom had no clinical diagnosis by routine workup. Among subjects diagnosed with infection by serology and/or peripheral samples, we demonstrated the utility of mNGS to detect pathogen nucleic acid in CSF, importantly for the Ixodes scapularis tick-borne pathogens Powassan virus, Borrelia burgdorferi, and Anaplasma phagocytophilum. We also evaluated two methods to enhance the detection of viral nucleic acid, hybrid capture and methylated DNA depletion. Hybrid capture nearly universally increased viral read recovery. Although results for methylated DNA depletion were mixed, it allowed the detection of varicella-zoster virus DNA in two samples that were negative by standard mNGS. Overall, mNGS is a promising approach that can test for multiple pathogens simultaneously, with efficacy similar to that of pathogen-specific tests, and can uncover geographically relevant infectious CNS disease, such as tick-borne infections in New England. With further laboratory and computational enhancements, mNGS may become a mainstay of workup for encephalitis and meningitis. IMPORTANCE Meningitis and encephalitis are leading global causes of central nervous system (CNS) disability and mortality. Current diagnostic workflows remain inefficient, requiring costly pathogen-specific assays and sometimes invasive surgical procedures. Despite intensive diagnostic efforts, 40 to 60% of people with meningitis or encephalitis have no clear cause of CNS disease identified. As diagnostic uncertainty often leads to costly inappropriate therapies, the need for novel pathogen detection methods is paramount. Metagenomic next-generation sequencing (mNGS) offers the unique opportunity to circumvent these challenges using unbiased laboratory and computational methods. Here, we performed comprehensive mNGS from 68 prospectively enrolled patients with known (n = 44) or suspected (n = 24) CNS viral infection from a single center in New England and evaluated enhanced methods to improve the detection of CNS pathogens, including those not traditionally identified in the CNS by nucleic acid detection. Overall, our work helps elucidate how mNGS can become integrated into the diagnostic toolkit for CNS infections.

Antiviral Cytokine Response in Neuroinvasive and Non-Neuroinvasive West Nile Virus Infection.

Data on the immune response to West Nile virus (WNV) are limited. We analyzed the antiviral cytokine response in serum and cerebrospinal fluid (CSF) samples of patients with WNV fever and WNV neuroinvasive disease using a multiplex bead-based assay for the simultaneous quantification of 13 human cytokines. The panel included cytokines associated with innate and early pro-inflammatory immune responses (TNF-α/IL-6), Th1 (IL-2/IFN-γ), Th2 (IL-4/IL-5/IL-9/IL-13), Th17 immune response (IL-17A/IL-17F/IL-21/IL-22) and the key anti-inflammatory cytokine IL-10. Elevated levels of IFN-γ were detected in 71.7% of CSF and 22.7% of serum samples (p = 0.003). Expression of IL-2/IL-4/TNF-α and Th1 17 cytokines (IL-17A/IL-17F/IL-21) was detected in the serum but not in the CSF (except one positive CSF sample for IL-17F/IL-4). While IL-6 levels were markedly higher in the CSF compared to serum (CSF median 2036.71, IQR 213.82-6190.50; serum median 24.48, IQR 11.93-49.81; p < 0.001), no difference in the IL-13/IL-9/IL-10/IFN-γ/IL-22 levels in serum/CSF was found. In conclusion, increased concentrations of the key cytokines associated with innate and early acute phase responses (IL-6) and Th1 type immune responses (IFN-γ) were found in the CNS of patients with WNV infection. In contrast, expression of the key T-cell growth factor IL-2, Th17 cytokines, a Th2 cytokine IL-4 and the proinflammatory cytokine TNF-α appear to be concentrated mainly in the periphery.