Parechovirus infection in human brain organoids: host innate inflammatory response and not neuro-infectivity correlates to neurologic disease

Picornaviruses are a leading cause of central nervous system (CNS) infections. While genotypes such as parechovirus A3 (PeV-A3) and echovirus 11 (E11) can elicit severe neurological disease, the highly prevalent PeV-A1 is not associated with CNS disease. Here, we expand our current understanding of these differences in PeV-A CNS disease using human brain organoids and clinical isolates of the two PeV-A genotypes. Our data indicate that PeV-A1 and A3 specific differences in neurological disease are not due to infectivity of CNS cells as both viruses productively infect brain organoids with a similar cell tropism. Proteomic analysis shows that PeV-A infection significantly alters the host cell metabolism. The inflammatory response following PeV-A3 (and E11 infection) is significantly more potent than that upon PeV-A1 infection. Collectively, our findings align with clinical observations and suggest a role for neuroinflammation, rather than viral replication, in PeV-A3 (and E11) infection.

A prospective study of nanopore-targeted sequencing in the diagnosis of central nervous system infections

Central nervous system (CNS) infections are a leading cause of death in patients. Nanopore-targeted sequencing (NTS) has begun to be used for pathogenic microbial detection. This study aims to evaluate the ability of NTS in the detection of pathogens in cerebrospinal fluid (CSF) through a prospective study. Fifty CSF specimens collected from 50 patients with suspected CNS infections went through three methods including NTS, metagenomic next-generation sequencing (mNGS), and microbial culture in parallel. When there was an inconsistency between NTS results and the results of the mNGS, the 16S rDNA gene was amplified followed by Sanger sequencing to further verify pathogens detected by NTS. Among 50 CSF specimens, 76% were NTS-positive, which is lower than mNGS (94.0%), yet higher than microbial culture (16.0%). The overall validation rate, diagnostic accordance rate (DAR), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of NTS were 86.7%, 50.0%, 71.0%, 15.8%, 57.9%, and 25.0%, respectively. In the CSF total nucleated cell (TNC) number ≤10 cells/µL, DAR, specificity, and PPV were 20%, 11.1%, and 11.1%, whereas in that with CSF TNC number >10 cells/µL, DAR, sensitivity, specificity, PPV, and NPV were 57.5%, 70.0%, 20.0%, 72.4%, and 18.2%, respectively. Although NTS has a higher microbial detection rate than microbial culture, it should combine CSF TNC result to evaluate the value of NTS for the diagnosis of CNS infections.

IMPORTANCE

This study aims to prospectively evaluate the ability of nanopore-targeted sequencing (NTS) in the detection of pathogens in cerebrospinal fluid (CSF). It was the first time combining mNGS and microbial culture to verify the NTS-positive results also using 16S rDNA amplification with Sanger sequencing. Although microbial culture was thought to be the gold standard for pathogens detection and diagnosis of infectious diseases, this study suggested that microbial culture of CSF is not the most appropriate way for diagnosing central nervous system (CNS) infection. NTS should be recommended to be used in CSF for diagnosing CNS infection. When evaluating the value of NTS for diagnosis of CNS infections, the results of CSF TNC should be combined, and NTS-positive result is observed to be more reliable in patients with CSF TNC level >10 cells/μL.

Transcranial direct current stimulation (tDCS) in the treatment of neuropsychiatric symptoms of long COVID

The study aimed to assess the efficacy of transcranial direct current stimulation (tDCS) in the treatment of neuropsychiatric (NP) symptoms of the post-acute sequelae of SARS-CoV-2 infection (PASC), known as the long COVID. A double-blind, randomized, sham-controlled study compared the efficacy and safety of prefrontal cortex active tDCS to sham-tDCS in treating NP-PASC. Patients diagnosed with NP-PASC, with a Fatigue Impact Scale (FIS) score ≥ 40, were eligible for the study. Twenty tDCS sessions were administered within four weeks, with continuous, end-of-treatment, and follow-up measurements. The primary outcome was a change in the FIS at the end-of-treatment, analyzed in the intention-to-treat population. Data from 33 patients assigned to active (n = 16) or sham-tDCS (n = 17) were analyzed. After the treatment, a decrease in the FIS score was more pronounced in the sham than in the active group, yet the intergroup difference was insignificant (11.7 [95% CI -11.1 to 34.5], p = 0.6). Furthermore, no significant intergroup differences were observed regarding anxiety, depression, quality of life, and cognitive performance. The small cohort sample, differences in baseline FIS scores between groups (non-stratified randomization), or chosen stimulation parameters may have influenced our findings. However, it might also be possible that the expected mechanism of action of tDCS is insufficient to treat these conditions.

Pegivirus Detection in Cerebrospinal Fluid from Patients with Central Nervous System Infections of Unknown Etiology in Brazil by Viral Metagenomics

Metagenomic next-generation sequencing (mNGS) methodology serves as an excellent supplement in cases where diagnosis is challenging to establish through conventional laboratory tests, and its usage is increasingly prevalent. Examining the causes of infectious diseases in the central nervous system (CNS) is vital for understanding their spread, managing outbreaks, and effective patient care. In a study conducted in the state of São Paulo, Brazil, cerebrospinal fluid (CSF) samples from 500 patients with CNS diseases of indeterminate etiology, collected between 2017 and 2021, were analyzed. Employing a mNGS approach, we obtained the complete coding sequence of Pegivirus hominis (HPgV) genotype 2 in a sample from a patient with encephalitis (named IAL-425/BRA/SP/2019); no other pathogen was detected. Subsequently, to determine the extent of this virus's presence, both polymerase chain reaction (PCR) and/or real-time PCR assays were utilized on the entire collection. The presence of the virus was identified in 4.0% of the samples analyzed. This research constitutes the first report of HPgV detection in CSF samples in South America. Analysis of the IAL-425 genome (9107 nt) revealed a 90% nucleotide identity with HPgV strains from various countries. Evolutionary analyses suggest that HPgV is both endemic and extensively distributed. The direct involvement of HPgV in CNS infections in these patients remains uncertain.

Economic impact of metagenomic next-generation sequencing versus traditional bacterial culture for postoperative central nervous system infections using a decision analysis mode: study protocol for a randomized controlled trial

IMPORTANCE

Diagnosing and treating postoperative central nervous system infections (PCNSIs) remains challenging due to the low detection rate and time-consuming nature of traditional methods for identifying microorganisms in cerebrospinal fluid. Metagenomic next-generation sequencing (mNGS) technology provides a rapid and comprehensive understanding of microbial composition in PCNSIs by swiftly sequencing and analyzing the microbial genome. The current study aimed to assess the economic impact of using mNGS versus traditional bacterial culture-directed PCNSIs diagnosis and therapy in post-neurosurgical patients from Beijing Tiantan Hospital. mNGS is a relatively expensive test item, and whether it has the corresponding health-economic significance in the clinical application of diagnosing intracranial infection has not been studied clearly. Therefore, the investigators hope to explore the clinical application value of mNGS detection in PCNSIs after neurosurgery.

Development of a murine model to study the cerebral pathogenesis of Aspergillus fumigatus

IMPORTANCE

Molds are environmental fungi that can cause disease in immunocompromised individuals. The most common pathogenic mold is Aspergillus fumigatus, which is typically inhaled into the lungs and causes invasive pulmonary disease. In a subset of these patients, this infection can spread from the lungs to other organs including the brain, resulting in cerebral aspergillosis. How A. fumigatus causes brain disease is not well understood and these infections are associated with extremely high mortality rates. Thus, we developed an animal model to study the pathogenesis of cerebral aspergillosis to better understand this disease and develop better treatments for these life-threatening infections.

Toxoplasma rhoptry proteins that affect encephalitis outcome

Toxoplasma gondii, a widespread obligate intracellular parasite, can infect almost all warm-blooded animals, including humans. The cellular barrier of the central nervous system (CNS) is generally able to protect the brain parenchyma from infectious damage. However, T. gondii typically causes latent brain infections in humans and other vertebrates. Here, we discuss how T. gondii rhoptry proteins (ROPs) affect signaling pathways in host cells and speculate how this might affect the outcome of Toxoplasma encephalitis.

Predictors of unfavourable outcome in adults with suspected central nervous system infections: a prospective cohort study

Suspected central nervous system (CNS) infections may pose a diagnostic challenge, and often concern severely ill patients. We aim to identify predictors of unfavourable outcome to prioritize diagnostics and treatment improvements. Unfavourable outcome was assessed on the Glasgow Outcome Scale at hospital discharge, defined by a score of 1 to 4. Of the 1152 episodes with suspected CNS infection, from two Dutch prospective cohorts, the median age was 54 (IQR 37-67), and 563 episodes (49%) occurred in women. The final diagnoses were categorized as CNS infection (N = 358 episodes, 31%), CNS inflammatory disease (N = 113, 10%), non-infectious non-inflammatory neurological disorder (N = 388, 34%), non-neurological infection (N = 252, 22%), and other systemic disorder (N = 41, 4%). Unfavourable outcome occurred in 412 of 1152 (36%), and 99 died (9%). Predictors for unfavourable outcomes included advanced age, absence of headache, tachycardia, altered mental state, focal cerebral deficits, cranial nerve palsies, low thrombocytes, high CSF protein, and the final diagnosis of CNS inflammatory disease (odds ratio 4.5 [95% confidence interval 1.5-12.6]). Episodes suspected of having a CNS infection face high risk of experiencing unfavourable outcome, stressing the urgent need for rapid and accurate diagnostics. Amongst the suspected CNS infection group, those diagnosed with CNS inflammatory disease have the highest risk.

Reduced neural progenitor cell count and cortical neurogenesis in guinea pigs congenitally infected with Toxoplasma gondii

Toxoplasma (T.) gondii is an obligate intracellular parasite with a worldwide distribution. Congenital infection can lead to severe pathological alterations in the brain. To examine the effects of toxoplasmosis in the fetal brain, pregnant guinea pigs are infected with T. gondii oocysts on gestation day 23 and dissected 10, 17 and 25 days afterwards. We show the neocortex to represent a target region of T. gondii and the parasite to infect neural progenitor cells (NPCs), neurons and astrocytes in the fetal brain. Importantly, we observe a significant reduction in neuron number at end-neurogenesis and find a marked reduction in NPC count, indicating that impaired neurogenesis underlies the neuronal decrease in infected fetuses. Moreover, we observe focal microglioses to be associated with T. gondii in the fetal brain. Our findings expand the understanding of the pathophysiology of congenital toxoplasmosis, especially contributing to the development of cortical malformations.

Gummatous Neurosyphilis With Transient Worsening of Neurological Symptoms After Treatment Initiation

Cerebral syphilitic gumma is an atypical presentation of neurosyphilis, the clinical manifestations of which depend on the size and location of the lesions. It radiologically presents as enhancing nodular lesion(s) in brain parenchyma. We present a case of a patient with cerebral syphilitic gummas who had worsening neurological symptoms a few hours after initiation of anti-syphilitic antibiotic treatment. We aim to illustrate the clinical and radiological characteristics that might be helpful to clinicians when approaching the challenges they might encounter while treating neurosyphilis.

Investigation of risk factors for external ventricular drainage‑associated central nervous system infections in patients undergoing neurosurgery

Meningitis/ventriculitis (MV) is an illness which can occur as a complication following neurosurgical procedures. Devices such as an external ventricular drain (EVD) are also related to considerable complications, such as infections. The present study examined the risk factors associated with central nervous system (CNS) infections associated with the external ventricle drainage system. The present retrospective study included all patients hospitalized between April, 2011 and August, 2018 who had been receiving therapy with EVD for developed hydrocephalus. A total of 48 out of 65 patients were classified into two groups as follows: Patients without MV (group A) and patients who developed MV (group B). The durations of hospital stay and intensive care unit (ICU) stay were significantly lower in group A (32.4±24 and 21.1±11 days, respectively) compared to group B (54.7±37 and 42±24 days, respectively) (P=0.027 and P=0.001, respectively). The Acute Physiological and Chronic Health Evaluation II (APACHE II) score and EVD distance from the wound exit side to the burr hole were significantly lower in the survivors compared to the non-survivors (17.5±6 and 15.4±4 vs. 22.5±6 and 39.8±38, respectively). Receiver operating characteristic analysis revealed that the APACHE II score with an area under the curve [(AUC) of 0.677, P=0.044, and 95% confidence interval (CI) of (0.516-0.839)] and a cut-off value of 14 could predict mortality with a sensitivity of 100% and a specificity of 71%; the EVD distance from the wound exit side from the burr hole with an AUC of 0.694 (P=0.028), 95% CI of 0.521-0.866 and a cut-off value of 11.5 mm could predict mortality with a sensitivity of 88% and a specificity of 83%. On the whole, the present study demonstrates that the EVD-related distance from the wound exit side of the burr hole can predict poor outcomes due to CNS infections in patients undergoing neurosurgery.

Altered structural connectivity in olfactory disfunction after mild COVID-19 using probabilistic tractography

We aimed to investigate changes in olfactory bulb volume and brain network in the white matter (WM) in patients with persistent olfactory disfunction (OD) following COVID-19. A cross-sectional study evaluated 38 participants with OD after mild COVID-19 and 24 controls, including Sniffin' Sticks identification test (SS-16), MoCA, and brain magnetic resonance imaging. Network-Based Statistics (NBS) and graph theoretical analysis were used to explore the WM. The COVID-19 group had reduced olfactory bulb volume compared to controls. In NBS, COVID-19 patients showed increased structural connectivity in a subnetwork comprising parietal brain regions. Regarding global network topological properties, patients exhibited lower global and local efficiency and higher assortativity than controls. Concerning local network topological properties, patients had reduced local efficiency (left lateral orbital gyrus and pallidum), increased clustering (left lateral orbital gyrus), increased nodal strength (right anterior orbital gyrus), and reduced nodal strength (left amygdala). SS-16 test score was negatively correlated with clustering of whole-brain WM in the COVID-19 group. Thus, patients with OD after COVID-19 had relevant WM network dysfunction with increased connectivity in the parietal sensory cortex. Reduced integration and increased segregation are observed within olfactory-related brain areas might be due to compensatory plasticity mechanisms devoted to recovering olfactory function.

Lyme neuroborreliosis: A case report

KEY CLINICAL MESSAGE

Lyme neuroborreliosis is the manifestation of Lyme borreliosis that impacts the nervous system. It gives rise to various neurological and psychiatric conditions, and its diagnosis is challenging. The timely administration of antibiotics is effective.

ABSTRACT

A male patient, aged 55, was admitted to the emergency department due to the sudden onset of tonic-clonic seizures. All standard laboratory examinations yielded unremarkable outcomes, except a favorable Wright and 2-mercaptoethanol test. The examination of cerebrospinal fluid revealed the presence of 380 white blood cells per milliliter. The protein level was also elevated, while the glucose level was within the normal range. The results of the serologic tests indicated the presence of both IgG and IgM antibodies to Borrelia burgdorferi. Following the administration of ceftriaxone, a significant improvement was observed in the patient's medical status, and he was subsequently discharged. Lyme neuroborreliosis is the manifestation of Lyme borreliosis that impacts the nervous system. It gives rise to various neurological and psychiatric conditions, and its diagnosis is challenging. The timely administration of antibiotics is effective in treating patients.

Evaluation of the Novel CE-IVD-Marked Multiplex PCR QIAstat-Dx Meningitis/Encephalitis Panel

Central nervous system (CNS) infections such as meningitis and encephalitis are life-threatening conditions that demand hospital care and prompt identification of the causative agent. Since 2015, there has been only one CE-IVD-marked rapid multiplexed diagnostic assay in cassette format for bacterial and viral detection from cerebrospinal fluid (CSF): the BioFire FilmArray meningitis/encephalitis (ME) panel. In the beginning of 2022, Qiagen introduced the QIAstat-Dx meningitis/encephalitis panel. It is a CE-IVD-marked multiplex PCR cassette test intended for the identification of suspected infectious meningitis, encephalitis, or meningoencephalitis caused by bacterial, viral, or fungal pathogens. In this study, we evaluated patient and quality control samples using the QIAstat-Dx meningitis/encephalitis panel and compared the results to those of the BioFire FilmArray meningitis/encephalitis panel and reference methods (current routine analysis methods in our laboratory, PCR, or cultivation). The combined positive percent agreement between the two panel assays was 100%, and the negative percent agreement was 94%. We further compared specifically herpes simplex virus 1 (HSV-1), HSV-2, and varicella-zoster virus (VZV) dilution series using six commercial herpesvirus assays, including the two cassette tests. The results suggested that real-time PCR methods (with separate extraction) were the most sensitive methods. When comparing the cassette tests, the BioFire FilmArray meningitis/encephalitis panel produced more positive results than the QIAstat-Dx meningitis/encephalitis panel in the herpesvirus analyses. IMPORTANCE The diagnosis of infectious meningitis and encephalitis relies mostly on specific PCR and culturing methods, but commercial syndromic panel assays are bringing a change in diagnostics. With multiplexed analysis, the identification of the pathogen is potentially faster, and less sample material is needed. The novel QIAstat-Dx meningitis/encephalitis panel assay is intended for the rapid identification of pathogens from cerebrospinal fluid for suspected central nervous system (CNS) infection, which is a life-threatening condition and difficult to diagnose. We studied the performance of this panel assay using patient samples and dilution series of selected viruses. The evaluation data for this novel meningitis/encephalitis panel assay are useful for other clinical laboratories and organizations using or considering using this test.

SARS-CoV-2 Infection of Human Neurons Is TMPRSS2 Independent, Requires Endosomal Cell Entry, and Can Be Blocked by Inhibitors of Host Phosphoinositol-5 Kinase

2019 coronavirus disease (COVID-19) is a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition to respiratory illness, COVID-19 patients exhibit neurological symptoms lasting from weeks to months (long COVID). It is unclear whether these neurological manifestations are due to an infection of brain cells. We found that a small fraction of human induced pluripotent stem cell (iPSC)-derived neurons, but not astrocytes, were naturally susceptible to SARS-CoV-2. Based on the inhibitory effect of blocking antibodies, the infection seemed to depend on the receptor angiotensin-converting enzyme 2 (ACE2), despite very low levels of its expression in neurons. The presence of double-stranded RNA in the cytoplasm (the hallmark of viral replication), abundant synthesis of viral late genes localized throughout infected cells, and an increase in the level of viral RNA in the culture medium (viral release) within the first 48 h of infection suggested that the infection was productive. Productive entry of SARS-CoV-2 requires the fusion of the viral and cellular membranes, which results in the delivery of the viral genome into the cytoplasm of the target cell. The fusion is triggered by proteolytic cleavage of the viral surface spike protein, which can occur at the plasma membrane or from endosomes or lysosomes. We found that SARS-CoV-2 infection of human neurons was insensitive to nafamostat and camostat, which inhibit cellular serine proteases, including transmembrane serine protease 2 (TMPRSS2). Inhibition of cathepsin L also did not significantly block infection. In contrast, the neuronal infection was blocked by apilimod, an inhibitor of phosphatidyl-inositol 5 kinase (PIK5K), which regulates early to late endosome maturation. IMPORTANCE COVID-19 is a disease caused by the coronavirus SARS-CoV-2. Millions of patients display neurological symptoms, including headache, impairment of memory, seizures, and encephalopathy, as well as anatomical abnormalities, such as changes in brain morphology. SARS-CoV-2 infection of the human brain has been documented, but it is unclear whether the observed neurological symptoms are linked to direct brain infection. The mechanism of virus entry into neurons has also not been characterized. Here, we investigated SARS-CoV-2 infection by using a human iPSC-derived neural cell model and found that a small fraction of cortical-like neurons was naturally susceptible to infection. The productive infection was ACE2 dependent and TMPRSS2 independent. We also found that the virus used the late endosomal and lysosomal pathway for cell entry and that the infection could be blocked by apilimod, an inhibitor of cellular PIK5K.

Association of Scrub Typhus in Children with Acute Encephalitis Syndrome and Meningoencephalitis, Southern India

Scrub typhus is an established cause of acute encephalitis syndrome (AES) in northern states of India. We systematically investigated 376 children with AES in southern India, using a stepwise diagnostic strategy for the causative agent of scrub typhus, Orientia tsutsugamushi, including IgM and PCR testing of blood and cerebrospinal fluid (CSF) to grade its association with AES. We diagnosed scrub typhus in 87 (23%) children; of those, association with AES was confirmed in 16 (18%) cases, probable in 55 (63%), and possible in 16 (18%). IgM detection in CSF had a sensitivity of 93% and specificity of 82% compared with PCR. Our findings suggest scrub typhus as an emerging common treatable cause of AES in children in southern India and highlight the importance of routine testing for scrub typhus in diagnostic algorithms. Our results also suggest the potential promise of IgM screening of CSF for diagnosis of AES resulting from scrub typhus.

Rash, Facial Droop, and Multifocal Intracranial Stenosis Due to Varicella Zoster Virus Vasculitis

Background: This is a case of multifocal intracranial stenosis in a 74 year old male ultimately discovered to be due to Varicella Zoster Virus infection. Purpose: We highlight the importance of a broad differential diagnosis, even when the most likely etiology of intracranial stenosis is atherosclerosis. Our paper reviews the differential diagnosis as well as "red flags" for intracranial vasculopathy. Even though intracranial atherosclerotic disease is the most common cause of vasculopathy, infectious or inflammatory vasculitis should be considered on the differential. Conclusions: Before considering bypass surgery or other invasive neurosurgical procedures, ensure reversible causes of vasculopathy have been ruled out. The presence of cranial neuropathies, rash, and/or elevated inflammatory markers should be red flags for vasculitis in patients presenting with stroke.

Chronic flaccid quadriparesis from tract specific myelopathy in neurosyphilis

INTRODUCTION

Tract-specific myelopathies with distinctive imaging features are uncommon and typically occur with metabolic or paraneoplastic syndromes. We report a unique case of tract-specific myelopathy with neurosyphilis.

CASE PRESENTATION

A 53-year-old male presented with a four-month history of flaccid quadriparesis, sensory loss, and bladder dysfunction. His MRIs revealed striking symmetric T2-weighted hyperintensities in the lateral corticospinal tracts and dorsal columns of the cervical spinal cord that extended rostrally into the pyramidal decussation and medial lemnisci of the medulla oblongata. Nerve conduction and needle electromyography studies excluded axonal or demyelinating lower motor neuron disorders. The patient reported previous untreated primary syphilis and was seropositive on the T.pallidum hemagglutination assay. Penicillin therapy resulted in substantial clinical improvement.

DISCUSSION

Although syphilitic meningomyelitis is well-reported, our patient was unique because of the persistent flaccidity (possibly suggesting prolonged spinal shock) and striking tract-specific MRI patterns. These features are novel in syphilitic myelitis and suggest unknown mechanisms of tract-specific tropism and neuronal injury.

CONCLUSIONS

"Tract-specific" complete transverse myelopathy with persistent flaccid weakness and areflexia is a novel presentation of neurosyphilis. Early recognition and crystalline penicillin therapy can alleviate morbidity. Our report describes this patient's findings and discusses the differential diagnoses of tract-specific myelopathies.

A novel machine learning-based web application for field identification of infectious and inflammatory disorders of the central nervous system in cattle

BACKGROUND

Central nervous system (CNS) infections in cattle are a major cause of economic loss and mortality. Machine learning (ML) techniques are gaining widespread application in solving predictive tasks in both human and veterinary medicine.

OBJECTIVES

Our primary aim was to develop and compare ML models that could predict the likelihood of a CNS disorder of infectious or inflammatory origin in neurologically-impaired cattle. Our secondary aim was to create a user-friendly web application based on the ML model for the diagnosis of infection and inflammation of the CNS.

ANIMALS

Ninety-eight cattle with CNS infection and 86 with CNS disorders of other origin.

METHODS

Retrospective observational study. Six different ML methods (logistic regression [LR]; support vector machine [SVM]; random forest [RF]; multilayer perceptron [MLP]; K-nearest neighbors [KNN]; gradient boosting [GB]) were compared for their ability to predict whether an infectious or inflammatory disease was present based on demographics, neurological examination findings, and cerebrospinal fluid (CSF) analysis.

RESULTS

All 6 methods had high prediction accuracy (≥80%). The accuracy of the LR model was significantly higher (0.843 ± 0.005; receiver operating characteristic [ROC] curve 0.907 ± 0.005 ) than the other models and was selected for implementation in a web application.

CONCLUSION AND CLINICAL IMPORTANCE

Our findings support the use of ML algorithms as promising tools for veterinarians to improve diagnosis. The open-access web application may aid clinicians in achieving correct diagnosis of infectious and inflammatory neurological disorders in livestock, with the added benefit of promoting appropriate use of antimicrobials.

The Contribution of Multiplex Polymerase Chain Reaction in the Diagnosis of Central Nervous System Infections in Intensive Care Units

Introduction The aim of this study was to evaluate the contribution and limits of BioFire® FilmArray® meningitis/encephalitis panel (FA MEP) polymerase chain reaction (PCR) (bioMérieux, Marcy-l'Étoile, France) (product references: LLC RFIT-ASY-0118) coupled with bacterial and fungal culture in the diagnosis of central nervous system infections (CNSIs). Methods This was a retrospective observational study including all patients (adults and children) hospitalized in the intensive care units (ICUs) of a Moroccan university hospital, who benefited from multiplex PCR on a cerebrospinal fluid (CSF) sample. Results A total of 112 PCRs were performed, with a positivity rate of 18%. Bacterial etiology was the most frequent (70%), represented mainly by Streptococcus pneumoniae (45%), followed by viruses (25%), with four isolates of Herpes simplex virus (HSV) 1. On 94 samples, there was an agreement between the culture and PCR results. Their discordance was found in 18 cases, including 16 suspected CNSIs recovered only by PCR and two diagnoses confirmed only by bacterial culture. Conclusion This study revealed the significant impact of multiplex PCR on the early and targeted diagnostic and therapeutic management of infectious meningitis and meningoencephalitis in intensive care unit patients.

Clinical application value of metagenomic next-generation sequencing in the diagnosis of central nervous system infections

Objectives: The purpose of this study is to evaluate the clinical application value of metagenomic next-generation sequencing (mNGS) in central nervous system (CNS) infections. Methods: Both mNGS and routine examination of cerebrospinal fluid (CSF) samples from patients with CNS infections retrospectively analyzed the efficacy of mNGS in this cohort and were ultimately compared with a clinical diagnosis. Results: A total of 94 cases consistent with CNS infections were included in the analysis. The positive rate for mNGS is 60.6% (57/94), which is significantly higher than 20.2% (19/94; p < 0.01) detected using conventional methods. mNGS detected 21 pathogenic strains that could not be detected by routine testing. Routine tests were positive for two pathogens but negative for mNGS. The sensitivity and specificity of mNGS in the diagnosis of central nervous system infections were 89.5% and 44%, respectively, when compared with traditional tests. At discharge, 20 (21.3%) patients were cured, 55 (58.5%) patients showed improvements, five (5.3%) patients did not recover, and two (2.1%) patients died. Conclusion: mNGS has unique advantages in the diagnosis of central nervous system infections. mNGS tests can be performed when patients are clinically suspected of having a central nervous system infection but no pathogenic evidence.

Diagnostic Significance of Targeted Next-Generation Sequencing in Central Nervous System Infections in Neurosurgery of Pediatrics

Background

Cerebrospinal fluid (CSF) pathogen culture suffers from the drawbacks of prolonged cycle time and a low positivity rate in diagnosing intracranial infections in children. This study aims to investigate the diagnostic potential of targeted next-generation sequencing (tNGS) in pediatric neurosurgery for central nervous system (CNS) infections.

Methods

A retrospective study was conducted on children under 14 with suspected intracranial infections following craniocerebral trauma or surgery between November 2018 and August 2020. Routine, biochemical, smear, and pathogen culture tests were performed on CSF during treatment. The main parameters of CSF analysis encompassed white blood cells (WBC, ×10⁶/L) count, percentage of multinucleated cells (%), protein levels (g/L), glucose concentration (GLU, mmol/L), chloride levels (mmol/L), and pressure (mmH2O). The outcomes of tNGS were assessed through the Receiver Operating Characteristic (ROC) curve and pertinent diagnostic parameters.

Results

Among the 35 included pediatric patients, 22 were clinically diagnosed with CNS infection in neurosurgery, tNGS was confirmed in 18 cases. The sensitivity and specificity of tNGS were 81.8% and 76.9%, respectively, while the traditional method of CSF cultures and smears exhibited a sensitivity of 13.6% and a specificity of 100%. ROC curve analysis indicated an area under the curve (AUC) of 0.794 for tNGS and 0.568 for the CSF cultures and smears. CSF analysis indicated that the two groups exhibited statistically significant differences in terms of WBC count [330.0 (110.00-2639.75) vs 14.00 (4.50-26.50), P<0.001] and percentage of multinuclear cells (%) [87.50 (39.75-90.00) vs 0 (0-10.00), P<0.001]. However, the remaining parameters did not statistically significant differences between the groups (all P>0.05).

Conclusion

tNGS demonstrates a high degree of diagnostic accuracy when detecting infections within the CNS of pediatric neurosurgery patients. tNGS can effectively establish for diagnosing CNS infections by detecting pathogenic microorganisms and their corresponding virulence and/or resistance genes within the test samples.

Dynamic 18F-Pretomanid PET imaging in animal models of TB meningitis and human studies

Pretomanid is a nitroimidazole antimicrobial active against drug-resistant Mycobacterium tuberculosis and approved in combination with bedaquiline and linezolid (BPaL) to treat multidrug-resistant (MDR) pulmonary tuberculosis (TB). However, the penetration of these antibiotics into the central nervous system (CNS), and the efficacy of the BPaL regimen for TB meningitis, are not well established. Importantly, there is a lack of efficacious treatments for TB meningitis due to MDR strains, resulting in high mortality. We have developed new methods to synthesize ¹⁸F-pretomanid (chemically identical to the antibiotic) and performed cross-species positron emission tomography (PET) imaging to noninvasively measure pretomanid concentration-time profiles. Dynamic PET in mouse and rabbit models of TB meningitis demonstrates excellent CNS penetration of pretomanid but cerebrospinal fluid (CSF) levels does not correlate with those in the brain parenchyma. The bactericidal activity of the BPaL regimen in the mouse model of TB meningitis is substantially inferior to the standard TB regimen, likely due to restricted penetration of bedaquiline and linezolid into the brain parenchyma. Finally, first-in-human dynamic ¹⁸F-pretomanid PET in six healthy volunteers demonstrates excellent CNS penetration of pretomanid, with significantly higher levels in the brain parenchyma than in CSF. These data have important implications for developing new antibiotic treatments for TB meningitis.

Treatment of Carbapenem-Resistant Multidrug-Resistant Gram-Negative Bacilli with Intracerebroventricular Injection of Polymyxin B: A Retrospective Study

Purpose

We evaluated the efficacy and administration time of intraventricular (IVT) polymyxin B in the treatment of carbapenem-resistant and multidrug-resistant/extensively drug-resistant (MDR/XDR) Gram-negative bacilli in central nervous system (CNS) infections and investigated prognostic factors.

Patients and Methods

This retrospective analysis comprised 41 post-surgical carbapenem-resistant CNS infections from October 2016 to October 2021. All patients were treated with effective intravenous antibiotics and IVT polymyxin B. Patient characteristics, therapeutic procedure, symptoms, cerebrospinal fluid (CSF) examination, laboratory tests, and complications were recorded. The effectiveness of IVT polymyxin B was evaluated using temperature, Glasgow Coma Scale, CSF contents, bacterial clearance rate, cure rate, and mortality. Mortality between early (7 days) and late administration of IVT polymyxin B was compared. Prognostic factors were evaluated using the pupillary light reflex and multiloculated hydrocephalus.

Results

The 41 patients acquired carbapenem-resistant MDR/XDR bacteria, including 24 Klebsiella pneumoniae, 15 Acinetobacter baumannii, 3 Pseudomonas aeruginosa, and 1 Enterobacter cloacae. The bacterial clearance rate was 32/41 (78.0%), and 9 patients (22.0%) with uncured bacterial infections died. Adverse events included 1 case of skin pigmentation. Among the 32 cured patients, 31 received a ventriculoperitoneal shunt, and 1 patient had an extraventricular drainage tube removed. Mortality in the late (>7 days) group was higher (39.1% vs 0%, P < 0.05). The group without pupillary light reflex showed a higher death rate (41.2% vs 8.3%; P < 0.05). The multiloculated hydrocephalus group had a higher mortality rate than that of the normal group (34.8% vs 5.6%, P < 0.05). All 32 cured patients were followed up for 9 to 66 months, and all survived without recurrent infections.

Conclusion

Intraventricular polymyxin B is an effective treatment for carbapenem-resistant MDR/XDR Gram-negative bacilli, with a 78% cure rate and significant mortality reduction if administered within 7 days of bacterial identification. Multiloculated hydrocephalus and the pupillary light reflex may be used as prognostic indicators of mortality.

The Glymphatic System: a Potential Key Player in Bacterial Meningitis

The glial-lymphatic system (glymphatic system) is a recently characterized fluid clearance pathway of the central nervous system. Glymphatic system disfunctions leading to defects in drainage of the cerebrospinal fluid have been associated with several neurological disorders. In their article, J. S. Generoso, S. Thorsdottir, A. Collodel, R. R. E. Santo, et al. (mBio 13:e01886-22, 2022, https://doi.org/10.1128/mBio.01886-22) have now associated impaired glymphatic system functionality to neurological sequelae of murine meningitis caused by Streptococcus pneumoniae. Their work provides an initial and important step into the systematic evaluation of a potential impact of glymphatic system functionality on disease severity and sequelae in meningitis.

Toxoplasma gondii Dissemination in the Brain Is Facilitated by Infiltrating Peripheral Immune Cells

Despite recent advances in our understanding of pathogenic access to the central nervous system (CNS), the mechanisms by which intracellular pathogens disseminate within the dense cellular network of neural tissue remain poorly understood. To address this issue, longitudinal analysis of Toxoplasma gondii dissemination in the brain was conducted using 2-photon imaging through a cranial window in living mice that transgenically express enhanced green fluorescent protein (eGFP)-claudin-5. Extracellular T. gondii parasites were observed migrating slowly (1.37 ± 1.28 μm/min) and with low displacement within the brain. In contrast, a population of highly motile infected cells transported vacuoles of T. gondii significantly faster (6.30 ± 3.09 μm/min) and with a higher displacement than free parasites. Detailed analysis of microglial dynamics using CX3CR1-GFP mice revealed that T. gondii-infected microglia remained stationary, and infection did not increase the extension/retraction of microglial processes. The role of infiltrating immune cells in shuttling T. gondii was examined by labeling of peripheral hematopoietic cells with anti-CD45 antibody. Infected CD45⁺ cells were found crawling along the CNS vessel walls and trafficked T. gondii within the brain parenchyma at significantly higher speeds (3.35 ± 1.70 μm/min) than extracellular tachyzoites. Collectively, these findings highlight a dual role for immune cells in neuroprotection and in facilitating parasite dissemination within the brain. IMPORTANCE T. gondii is a foodborne parasite that infects the brain and can cause fatal encephalitis in immunocompromised individuals. However, there is a limited understanding of how the parasites disseminate through the brain and evade immune clearance. We utilized intravital imaging to visualize extracellular T. gondii tachyzoites and infected cells migrating within the infected mouse brain during acute infection. The infection of motile immune cells infiltrating the brain from the periphery significantly increased the dissemination of T. gondii in the brain compared to that of free parasites migrating using their own motility: the speed and displacement of these infected cells would enable them to cover nearly 1 cm of distance per day! Among the infiltrating cells, T. gondii predominantly infected monocytes and CD8⁺ T cells, indicating that the parasite can hijack immune cells that are critical for controlling the infection in order to enhance their dissemination within the brain.

The Blood-Brain Barrier and Pharmacokinetic/Pharmacodynamic Optimization of Antibiotics for the Treatment of Central Nervous System Infections in Adults

Bacterial central nervous system (CNS) infections are serious and carry significant morbidity and mortality. They encompass many syndromes, the most common being meningitis, which may occur spontaneously or as a consequence of neurosurgical procedures. Many classes of antimicrobials are in clinical use for therapy of CNS infections, some with established roles and indications, others with experimental reporting based on case studies or small series. This review delves into the specifics of the commonly utilized antibacterial agents, updating their therapeutic use in CNS infections from the pharmacokinetic and pharmacodynamic perspectives, with a focus on the optimization of dosing and route of administration that have been described to achieve good clinical outcomes. We also provide a concise synopsis regarding the most focused, clinically relevant information as pertains to each class and subclass of antimicrobial therapeutics. CNS infection morbidity and mortality remain high, and aggressive management is critical in ensuring favorable patient outcomes while averting toxicity and upholding patient safety.

Neuroimmune Responses in a New Experimental Animal Model of Cerebral Aspergillosis

Exposure of immunosuppressed individuals to the opportunistic fungal pathogen Aspergillus fumigatus may result in invasive pulmonary aspergillosis (IPA), which can lead to the development of cerebral aspergillosis (CA), a highly lethal infection localized in the central nervous system (CNS). There are no experimental models of CA that effectively mimic human disease, resulting in a considerable knowledge gap regarding mechanisms of neurological pathogenicity and neuroimmune responses during infection. In this report, immunosuppressed mice (via acute, high-dose corticosteroid administration) challenged with A. fumigatus resting conidia intranasally, followed a day later by a 70-fold lower inoculum of pre-swollen conidia intravenously (IN + IV + steroid), demonstrated increased weight loss, signs of severe clinical disease, increased fungal burden in the brain, and significant reduction in survival compared to immunosuppressed mice challenged intranasally only (IN + steroid) or non-immunosuppressed mice challenged both intranasally and intravenously (IN + IV). The IN + IV + steroid group demonstrated significant decreases in monocytes, eosinophils, dendritic cells (DCs), and invasive natural killer T (iNKT) cells, but not neutrophils or γδ T cells, in the brain compared to the IN + IV group. Likewise, the IN + IV + steroid group had significantly lower levels of interleukin (IL)-1β, IL-6, IL-17A, CC motif chemokine ligand 3 (CCL3), CXC chemokine ligand 10 (CXCL10), and vascular endothelial growth factor (VEGF) in the brain compared to the IN + IV group. IN + IV + steroid was superior to both IN + IV + chemotherapy (cytarabine + daunorubicin) and IN + IV + neutropenia for the development of CA. In conclusion, we have developed a well-defined, physiologically relevant model of disseminated CA in corticosteroid-induced immunosuppressed mice with a primary pulmonary infection. This model will serve to advance understanding of disease mechanisms, identify immunopathogenic processes, and help define the protective neuroinflammatory response to CA. IMPORTANCE Invasive fungal infections (IFIs) result in significant mortality in immunosuppressed individuals. Of these, invasive pulmonary aspergillosis (IPA), caused by the opportunistic mold Aspergillus fumigatus, is the most lethal. Lethality in IPA is due to two main factors: destruction of the lung leading to compromised pulmonary function, and dissemination of the organism to extrapulmonary organs. Of these, the CNS is the most common site of dissemination. However, very little is known regarding the pathogenesis of or immune response during cerebral aspergillosis, which is directly due to the lack of an animal model that incorporates immunosuppression, lung infection, and consistent dissemination to the CNS/brain. In this report, we have developed a new experimental animal model of CA which includes the above parameters and characterized the neuroimmune response. We further compared this disseminated CA model to two additional immunosuppressive strategies. Overall, this model of disseminated CA following IPA in an immunosuppressed host provides a novel platform for studying the efficacy of antifungal drugs and immunotherapies for improving disease outcomes.

Detection of multidrug-resistant Acinetobacter baumannii by metagenomic next-generation sequencing in central nervous system infection after neurosurgery: A case report

Background

Central nervous system (CNS) infection is one of the most serious complications after neurosurgery. Traditional clinical methods are difficult to diagnose the pathogen of intracranial infection. Due to recent advances in genomic approaches, especially sequencing technologies, metagenomic next-generation sequencing (mNGS) has been applied in many research and clinical settings.

Case presentation

Here, we report a case of CNS infection with Acinetobacter baumannii in a 15-year-old woman, who previously underwent surgery for recurrence of ependymoma in the fourth ventricle. On the eleventh postoperative day, the patient had a high fever and leukocytosis in the cerebrospinal fluid (CSF). mNGS using CSF rapidly and accurately identified the causative pathogen as A. baumannii with carbapenem resistance genes blaOXA-23 and blaOXA-51, which were confirmed by subsequent culture and susceptibility tests within 5 days. During the disease, mNGS, culture, and drug susceptibility testing were continued to monitor changes in pathogenic bacteria and adjust medication. At present, there are no case reports on to the use of mNGS for detecting pathogens in postoperative infection with ependymoma and guide medication.

Conclusion

mNGS has great advantages in pathogen identification and even pathogen resistance prediction. Multiple mNGS examinations during the course of the disease play an important role in the dynamic monitoring of pathogens.

A Role for Basigin in Toxoplasma gondii Infection

The role of specific host cell surface receptors during Toxoplasma gondii invasion of host cells is poorly defined. Here, we interrogated the role of the well-known malarial invasion receptor, basigin, in T. gondii infection of astrocytes. We found that primary astrocytes express two members of the BASIGIN (BSG) immunoglobulin family, basigin and embigin, but did not express neuroplastin. Antibody blockade of either basigin or embigin caused a significant reduction of parasite infectivity in astrocytes. The specific role of basigin during T. gondii invasion was further examined using a mouse astrocytic cell line (C8-D30), which exclusively expresses basigin. CRISPR-mediated deletion of basigin in C8-D30 cells resulted in decreased T. gondii infectivity. T. gondii replication and invasion efficiency were not altered by basigin deficiency, but parasite attachment to astrocytes was markedly reduced. We also conducted a proteomic screen to identify T. gondii proteins that interact with basigin. Toxoplasma-encoded cyclophilins, the protein 14-3-3, and protein disulfide isomerase (TgPDI) were among the putative basigin-ligands identified. Recombinant TgPDI produced in E. coli bound to basigin and pretreatment of tachyzoites with a PDI inhibitor decreased parasite attachment to host cells. Finally, mutagenesis of the active site cysteines of TgPDI abolished enzyme binding to basigin. Thus, basigin and its related immunoglobulin family members may represent host receptors that mediate attachment of T. gondii to diverse cell types.

Meropenem Population Pharmacokinetics and Simulations in Plasma, Cerebrospinal Fluid, and Brain Tissue

Meropenem is a broad spectrum carbapenem used for the treatment of cerebral infections. There is a need for data describing meropenem pharmacokinetics (PK) in the brain tissue to optimize therapy in these infections. Here, we present a meropenem PK model in the central nervous system and simulate dosing regimens. This was a population PK analysis of a previously published prospective study of patients admitted to the neurointesive care unit between 2016 and 2019 who received 2 g of meropenem intravenously every 8 h. Meropenem concentration was determined in blood, cerebrospinal fluid (CSF), and brain microdialysate. Meropenem was described by a six-compartment model: two compartments in the blood, two in the CSF, and two in the brain tissue. Creatinine clearance and brain glucose were included as covariates. The median elimination rate constant was 1.26 h^-1, the central plasma volume was 5.38 L, and the transfer rate constants from the blood to the CSF and from the blood to the brain were 0.001 h^-1 and 0.02 h^-1, respectively. In the first 24 h, meropenem 2 g, administered every 8 h via intermittent and extended infusions achieved good target attainment in the CSF and brain, but continuous infusion (CI) was better at steady-state. Administering a 3 g loading dose (LD) followed by 8 g CI was beneficial for early target attainment. In conclusion, a meropenem PK model was developed using blood, CSF, and brain microdialysate samples. An 8 g CI may be needed for good target attainment in the CSF and brain. Giving a LD prior to the CI improved the probability of early target attainment.

Intravenous plus intraventricular tigecycline-amikacin therapy for the treatment of carbapenem-resistant Klebsiella pneumoniae ventriculitis: A case report

RATIONALE

Central nervous system infections (CNSIs) are one of the most serious complications after neurosurgery, especially carbapenem-resistant bacterial meningitis. Owing to the poor blood-brain barrier permeability of most antibiotics, the treatment of CNSIs by intraventricular (IVT) administration is becoming a hot topic in clinical research. Currently, the treatment of CNSIs caused by carbapenem-resistant Klebsiella pneumoniae is mainly based on intraventricular injection of an antibiotic combined with one or more other systemic intravenous (IV) antibiotics, whereas there are few case reports of intraventricular injection of 2 antibiotics.

PATIENT CONCERNS

A 57-year-old man with an open craniocerebral injury presented with dyspnea, high fever, and seizures associated with surgery.

DIAGNOSIS

Intracranial infection caused by carbapenem-resistant K. pneumoniae was diagnosed.

INTERVENTIONS

On the advice of a clinical pharmacist, the patient was given tigecycline (100 mg IV + 3 mg IVT q12h) combined with amikacin (0.8 g IV + 30 mg IVT qd) antiinfective therapy. Ultimately, the pathogens in the cerebrospinal fluid were eradicated after 7 days, and the CNSIs were completely cured after 14 days.

OUTCOMES

The patient recovered and was discharged from the hospital without adverse reactions.

LESSONS

A series of in vitro and in vivo synergy tests of carbapenem-resistant K. pneumoniae showed that tigecycline combined with aminoglycosides had good synergistic effects and effectively suppressed bacterial resistance selection. Intravenous plus intraventricular tigecycline-amikacin seems to be a safe and effective treatment option for carbapenem-resistant K. pneumoniae CNSIs.

Norvancomycin for the Treatment of Central Nervous System MRSA Infections: a Randomized Controlled Trial: Norvancomycin for the Treatment of Central nervous system MRSA infections

Combined intravenous and intrathecal administration of norvancomycin (NVCM) is routinely employed in treating methicillin-resistant Staphylococcus aureus (MRSA) ventriculitis in patients following craniotomy. However, the optimal dosing regimen, the pharmacokinetics (PK) of NVCM in cerebrospinal fluid (CSF), and the clinical outcome are yet to be elucidated. Herein, a single-center randomized controlled trial was conducted in the Neurosurgery Department of the Second Hospital of Hebei Medical University (Shijiazhuang, China). Patients with MRSA ventriculitis after craniotomy were randomly assigned to two groups. The control group received 800 mg NVCM intravenously every 12 h, and the experimental group received 800 mg NVCM intravenously every 12 h and 16 mg NVCM intrathecal administration every 24 h. The primary outcome was the length of therapy, while the secondary outcomes included the area under the concentration-time curve in 0-24 h/minimum inhibitory concentration ratio (AUC_0-24h/MIC) of NVCM in CSF. A total of 29 patients (14 in the experimental group and 15 in the control group) were included in this study. Of these, 24 constituted the final analysis population, with 12 in each group. The average length of therapy in the experimental group was markedly shorter than that of the control group (11.2 ± 2.6 days vs. 16.6 ± 5.2 days, P = 0.005), while the AUC_0-24h/MIC in the experimental group was significantly higher than that in the control group (2306.57 ± 928.58 vs. 46.83 ± 27.48, P <0.001) with no increase in adverse reactions. Combined intravenous and intrathecal administration can shorten the treatment time of intracranial infection without higher adverse reaction risks in our research. Further studies with larger sample size are warranted to verify its safety and efficacy.

Tick-borne encephalitis vaccine effectiveness and barriers to vaccination in Germany

Tick-borne encephalitis (TBE) vaccination coverage remains low in Germany. Our case-control study (2018-2020) aimed to examine reasons for low vaccine uptake, vaccine effectiveness (VE), and vaccine breakthrough infections (VBIs). Telephone interviews (581 cases, 975 matched controls) covered vaccinations, vaccination barriers, and confounders identified with directed acyclic graphs. Multivariable logistic regression determined VE as 1-odds ratio with 95% confidence intervals (CI). We additionally calculated VE with the Screening method using routine surveillance and vaccination coverage data. Main vaccination barriers were poor risk perception and fear of adverse events. VE was 96.6% (95% CI 93.7-98.2) for ≥ 3 doses and manufacturer-recommended dosing intervals. Without boosters, VE after ≥ 3 doses at ≤ 10 years was 91.2% (95% CI 82.7-95.6). VE was similar for homologous/heterologous vaccination. Utilising routine surveillance data, VE was comparable (≥ 3 doses: 92.8%). VBIs (n = 17, 2.9% of cases) were older, had more comorbidities and higher severity than unvaccinated cases. However, only few VBIs were diagnostically confirmed; 57% of re-tested vaccinated cases (≥ 1 dose, n = 54) proved false positive. To increase TBE vaccine uptake, communication efforts should address complacency and increase confidence in the vaccines' safety. The observed duration of high VE may inform decision-makers to consider extending booster intervals to 10 years.

Serum Neurogranin Measurement as a Biomarker of Central Nervous System Infections: A Preliminary Study

The early diagnosis of central nervous system infections is of great importance to minimize morbidity and mortality. Neurogranin is a postsynaptic neural protein, and when the blood-brain barrier is damaged, neurogranin levels increase in both the cerebrospinal fluid and serum. The aim of this study was to evaluate the level of serum neurogranin and to investigate its utility in the diagnosis of central nervous system infections. This study was conducted as a prospective case-control study of patients diagnosed with meningitis. The study initially included 55 patients, and 15 patients with proven central nervous system infection were ultimately included in the patient group. The results in the patient group were compared with those of the control group of 15 healthy subjects. The 15 patients comprised 4 women and 11 men with a mean cerebrospinal fluid neurogranin level of 432.4 ± 123.5 ng/ml. Correlation analysis revealed a moderate positive correlation between cerebrospinal fluid neurogranin levels and serum neurogranin levels. The mean serum neurogranin level was 198.6 ± 51.7 ng/ml in the control group but was significantly higher at 429.2 ± 104.3 ng/ml in the patient group. In conclusion, it may be useful to measure blood neurogranin levels in patients suspected of having central nervous system infections, especially in those for whom computed tomography, magnetic resonance imaging, or lumbar puncture cannot be performed.

Thyroid hypogenesis is associated with a novel AKT3 germline variant that causes megalencephaly and cortical malformation

The molecular mechanisms involved in thyroid organogenesis have not been fully elucidated. We report a patient with a de novo germline AKT3 variant, NM_005465.7:c.233A > G, p.(Gln78Arg), who presented with congenital hypothyroidism in addition to typical AKT3-related brain disorders. The report of this patient contributes to delineating the associated yet uncertain endocrine complications of this AKT3 disease-causing variant.

Group B Streptococcal Neonatal Meningitis

Neonatal bacterial meningitis is a devastating disease, associated with high mortality and neurological disability, in both developed and developing countries. Streptococcus agalactiae, commonly referred to as group B Streptococcus (GBS), remains the most common bacterial cause of meningitis among infants younger than 90 days. Maternal colonization with GBS in the gastrointestinal and/or genitourinary tracts is the primary risk factor for neonatal invasive disease. Despite prophylactic intrapartum antibiotic administration to colonized women and improved neonatal intensive care, the incidence and morbidity associated with GBS meningitis have not declined since the 1970s. Among meningitis survivors, a significant number suffer from complex neurological or neuropsychiatric sequelae, implying that the pathophysiology and pathogenic mechanisms leading to brain injury and devastating outcomes are not yet fully understood. It is imperative to develop new therapeutic and neuroprotective approaches aiming at protecting the developing brain. In this review, we provide updated clinical information regarding the understanding of neonatal GBS meningitis, including epidemiology, diagnosis, management, and human evidence of the disease's underlying mechanisms. Finally, we explore the experimental models used to study GBS meningitis and discuss their clinical and physiologic relevance to the complexities of human disease.

Metagenomic Next-Generation Sequencing vs. Traditional Pathogen Detection in the Diagnosis of Infection After Allogeneic Hematopoietic Stem Cell Transplantation in Children

Infection is a severe complication of allo-HSCT in children, however, the accurate detection of the infection is hard. In this study, we traced the records of 101 pediatric recipients with allo-HSCT to investigate the pathogens of infection, and collected 54 bronchoalveolar lavage fluid, 32 blood, and 15 cerebrospinal fluid samples. In these samples, 87 was with post-transplant infection and 14 without infection. Using the metagenomic next-generation sequencing (mNGS) and traditional pathogen detection, we compared their sensitivity and specificity to detect pathogens of infection. Our results showed that mNGS was more sensitive (89.7%) than conventional pathogen detection (21.8%), with a difference of 67.9% (P < 0.001), However, mNGS was less specific (78.5%) than traditional methods (92.9%), with a difference of 14.4% (P = 0.596). The sensitivity of mNGS for diagnosing pulmonary infections, bloodstream infections or viremia, and CNS infections post-transplant were 91.7, 85.7, and 90.9%, respectively. In contrast, the sensitivity of conventional testing for diagnosing pulmonary infections, bloodstream infections or viremia, and CNS infections post-transplant were 22.9, 21.4, and 18.2%, respectively. There were significant differences in the sensitivity of mNGS and conventional testing in BALF, blood, and CSF samples, with P values of 0.000, 0.000, and 0.002 respectively. Among the patients with pulmonary infection, 11 pathogens were both identified by mNGS and conventional testing, and 33 by mNGS only. The percentage with the mNGS-positive result was 44/48 (91.7%), including viruses (n = 12), bacteria (n = 17), fungi (n = 9) and mixed infections (n = 6). Among the patients diagnosed with fungal pneumonia (n = 9), the most prevalent pathogenic fungi were Pneumocystis jiroveci (n = 6), which were also detected in 4 patients with mixed infectious pneumonia. In the 28 blood specimens of patients with bloodstream infections or viremia, five patients were positive by both mNGS and conventional testing, 19 were positive by mNGS, and 1 was positive by traditional testing only. The percentage with the mNGS-positive results was 24/28 (85.7%), including viruses (n = 12), bacteria (n = 4), fungi (n = 3), and mixed infections (n = 5). Of the 15 CSF specimens enrolled, 11 patients were eventually diagnosed with CNS infections. Ten pathogens were identified by mNGS in the 11 patients, including viruses (n = 8), bacteria (n = 1), and fungi (n = 1). These results suggest that mNGS is more sensitive than conventional pathogen detection for diagnosing infections post HSCT in children which may help the clinic diagnosis. Pneumocystis jiroveci was the most frequent pathogen of pulmonary infections post-transplant, while viruses were the most common pathogens of CNS infections in allo-HSCT recipients.

Diagnostic criteria of CNS infection in patients with external ventricular drainage after traumatic brain injury: a pilot study

BACKGROUND

Ventriculostomy-related infection (VRI) is a common complication in patients with traumatic brain injury (TBI) treated with an external ventricular drain (EVD). The aim of this study was to investigate incidence and characteristics of patients with VRI, and to explore diagnostic criteria to confidently rule out VRI in patients with TBI.

METHODS

This retrospective cohort pilot study included adults with severe TBI who were admitted to the ICU and received an EVD, during a 26-month period. Patients were categorized as having Culture-positive VRI, Culture-negative VRI, or No VRI. Variables that were potentially associated with Culture-positive VRI was analyzed, and predictive values were calculated.

RESULTS

75 of 215 patients with severe TBI (35%) underwent EVD placement; nine of these (12%) were classified as Culture-negative VRI and eight (11%) as Culture-positive VRI. The CSF cell counts that led to VRI treatment were compared with 46 CSF cell counts from No VRI patients. A CSF/plasma glucose ratio below 0.6 had a negative predictive value (NPV) for culture-verified VRI of 0.97 (95% CI: 0.85-1), whereas a combination of three CSF-derived biomarkers within the reference limits (white/red blood cell ratio, CSF/plasma glucose ratio, and protein content) ruled out Culture-positive VRI in this cohort (PPV 0, 95% CI: 0-0.14). C-reactive protein did not reliably predict VRI.

CONCLUSIONS

In this pilot study of patients after severe, a combination of biomarkers within reference limits ruled out VRI (PPV 0, CI: 0-0.14). Hypoglycorrhachia was a sensitive marker of VRI (NPV 0.97, CI: 0.85-1). Systemic signs and markers of infection did not predict VRI.

Nosocomial meningitis in intensive care: a 10-year retrospective study and literature review

Background

Nosocomial meningitis is a medical emergency that requires early diagnosis, prompt initiation of therapy, and frequent admission to the intensive care unit (ICU).

Methods

A retrospective study was conducted in adult patients diagnosed with nosocomial meningitis who required admission to the ICU between April 2010 and March 2020. Meningitis/ventriculitis and intracranial infection were defined according to Centers for Disease Control and Prevention guidelines.

Results

An incidence of 0.75% of nosocomial meningitis was observed among 70 patients. The mean patient age was 59 years and 34% were ≥65 years. Twenty-two percent of patients were in an immunocompromised state. A clear predisposing factor for nosocomial meningitis (traumatic brain injury, basal skull fracture, brain hemorrhage, central nervous system [CNS] invasive procedure or device) was present in 93% of patients. Fever was the most frequent clinical feature. A microbiological agent was identified in 30% of cases, of which 27% were bacteria, with a predominance of Gram-negative over Gram-positive. Complications developed in 47% of cases, 24% of patients were discharged with a Glasgow coma scale <14, and 37% died. There were no clear clinical predictors of complications. Advanced age (≥65 years old) and the presence of complications were associated with higher hospital mortality.

Conclusions

Nosocomial meningitis in critical care has a low incidence rate but high mortality and morbidity. In critical care patients with CNS-related risk factors, a high level of suspicion for meningitis is warranted, but diagnosis can be hindered by several confounding factors.

Using the Acute Flaccid Paralysis Surveillance System to Identify Cases of Acute Flaccid Myelitis, Australia, 2000‒2018

Since 2012, the United States has reported a distinct syndrome of acute flaccid paralysis (AFP) with anterior myelitis, predominantly in children. This polio-like syndrome was termed acute flaccid myelitis (AFM). Australia routinely conducts AFP surveillance to exclude poliomyelitis. We reviewed 915 AFP cases in Australia for children <15 years of age during 2000‒2018 and reclassified a subset to AFM by using the US Council of State and Territorial Epidemiologists case definition. We confirmed 37 AFM cases by using magnetic resonance imaging findings and 4 probable AFM cases on the basis of cerebrospinal fluid pleocytosis. Nonpolio enteroviruses were detected in 33% of AFM cases from which stool samples were tested. Average annual AFM incidence was 0.07 cases/100,000 person-years in children <15 years of age. AFM occurred sporadically in Australia before 2010 but regularly since then, indicating sustained, albeit rare, clinical manifestation in children. The AFP surveillance system in Australia is well-positioned to identify future AFM cases.

Cryptococcal Meningoencephalitis During Convalescence From Severe COVID-19 Pneumonia

Invasive cryptococcal infection in a previously immunocompetent patient complicating coronavirus disease 2019 (COVID-19) pneumonia has not been described before. In this report, a 76-year-old woman survived a bout of respiratory failure from severe COVID-19 pneumonia, during which she received remdesivir, convalescent plasma, corticosteroids, and tocilizumab. Soon after discharge, she developed acute encephalopathy and multifocal ischemic strokes. CSF and blood cultures were positive for Cryptococcus neoformans. Cryptococcal meningoencephalitis should be considered in the differential diagnosis of encephalopathy in a patient with COVID-19. Treatment with high-dose steroids and tocilizumab may be predisposing factors.

Lentiviral Infections Persist in Brain despite Effective Antiretroviral Therapy and Neuroimmune Activation

HIV infection persists in different tissue reservoirs among people with HIV (PWH) despite effective antiretroviral therapy (ART). In the brain, lentiviruses replicate principally in microglia and trafficking macrophages. The impact of ART on this viral reservoir is unknown. We investigated the activity of contemporary ART in various models of lentivirus brain infection. HIV-1 RNA and total and integrated DNA were detected in cerebral cortex from all PWH (n = 15), regardless of ART duration or concurrent plasma viral quantity and, interestingly, integrated proviral DNA levels in brain were significantly higher in the aviremic ART-treated group (P < 0.005). Most ART drugs tested (dolutegravir, ritonavir, raltegravir, and emtricitabine) displayed significantly lower 50% effective concentration (EC₅₀) values in lymphocytes than in microglia, except tenofovir, which showed 1.5-fold greater activity in microglia (P < 0.05). In SIV-infected Chinese rhesus macaques, despite receiving suppressive (n = 7) or interrupted (n = 8) ART, brain tissues had similar SIV-encoded RNA and total and integrated DNA levels compared to brains from infected animals without ART (n = 3). SIV and HIV-1 capsid antigens were immunodetected in brain, principally in microglia/macrophages, regardless of ART duration and outcome. Antiviral immune responses were comparable in the brains of ART-treated and untreated HIV- and SIV-infected hosts. Both HIV-1 and SIV persist in brain tissues despite contemporary ART, with undetectable virus in blood. ART interruption exerted minimal effect on the SIV brain reservoir and did not alter the neuroimmune response profile. These studies underscore the importance of augmenting ART potency in different tissue compartments. IMPORTANCE Antiretroviral therapy (ART) suppresses HIV-1 in plasma and CSF to undetectable levels. However, the impact of contemporary ART on HIV-1 brain reservoirs remains uncertain. An active viral reservoir in the brain during ART could lead to rebound systemic infection after cessation of therapy, development of drug resistance mutations, and neurological disease. ART's impact, including its interruption, on brain proviral DNA remains unclear. The present studies show that in different experimental platforms, contemporary ART did not suppress viral burden in the brain, regardless of ART component regimen, the duration of therapy, and its interruption. Thus, new strategies for effective HIV-1 suppression in the brain are imperative to achieve sustained HIV suppression.

Healthcare-Associated Ventriculitis and Meningitis: A Retrospective Analysis

Background and objective Healthcare-associated ventriculitis and meningitis (HAVM) is frequent in neurocritical patients and associated with significant mortality. Surgery and intracranial devices are usually necessary and may lead to infection. Classical clinical signs and cerebral spinal fluid (CSF) analysis may be unreliable. The purpose of this study was to characterize the prevalence of HAVM, risk factors, and interventions in the neurocritical population admitted in the ICU. Methods This was a retrospective single-center analysis of all adult neurocritical patients admitted to an ICU during a three-year period. Results A total of 218 neurocritical patients were included. The prevalence of HAVM was 13% and it was found to be associated with mortality. When suspected, it was not possible to exclude HAVM in 30% of the patients. HAVM was significantly associated with surgery, surgical reintervention, and brain devices. Sustained fever was the most frequent clinical sign, and it was significantly associated with unexcluded HAVM. CSF cell count was significantly higher in HAVM, though without microbiological isolation in most of the cases. Conclusion Brain damage, interventions, and devices may significantly alter cerebral homeostasis. Sustained fever is very frequent and may be attributed to several conditions. CSF cell count is useful for the diagnosis of HAVM. HAVM is a clinical challenge in the management of neurocritical patients with important therapeutic and prognostic implications.

Case Report: A Candida Meningitis in an Immunocompetent Patient Detected Through the Next-Generation Sequencing

Background: Fungal infections of the central nervous system (CNS) are not commonly seen clinically. Clinical diagnosis of fungal infections often depend on the pathogen culture and the clinical features. This method is time-consuming and insensitive, which can lead to misdiagnosis. The authors introduce an adult patient with fungal infections diagnosed by next-generation sequencing (NGS).

Case: The patient was a 60-year-old male Chinese who had both hypermyotonia of the lower extremities and fever. The auxiliary examinations such as MRI, CT, and cerebrospinal fluid (CSF) analysis showed obvious abnormalities. Because of the difficulties in diagnosis, it was hard to determine the treatment plan. The NGS detected specific sequences of Candida albicans in 3 days. The patient was then treated with liposomal amphotericin B and fluconazole. About 3 weeks later, the symptoms of the patient improved significantly and he was discharged from the hospital.

Conclusion: Compared with the routine cultural method, NGS has made a huge advancement in infection diagnosis and targeting antimicrobial therapy for CNS infection.

Inositol Metabolism Regulates Capsule Structure and Virulence in the Human Pathogen Cryptococcus neoformans

The environmental yeast Cryptococcus neoformans is the most common cause of deadly fungal meningitis in primarily immunocompromised populations. A number of factors contribute to cryptococcal pathogenesis. Among them, inositol utilization has been shown to promote C. neoformans development in nature and invasion of central nervous system during dissemination. The mechanisms of the inositol regulation of fungal virulence remain incompletely understood. In this study, we analyzed inositol-induced capsule growth and the contribution of a unique inositol catabolic pathway in fungal development and virulence. We found that genes involved in the inositol catabolic pathway are highly induced by inositol, and they are also highly expressed in the cerebrospinal fluid of patients with meningoencephalitis. This pathway in C. neoformans contains three genes encoding myo-inositol oxygenases that convert myo-inositol into d-glucuronic acid, a substrate of the pentose phosphate cycle and a component of the polysaccharide capsule. Our mutagenesis analysis demonstrates that inositol catabolism is required for C. neoformans virulence and deletion mutants of myo-inositol oxygenases result in altered capsule growth as well as the polysaccharide structure, including O-acetylation. Our study indicates that the ability to utilize the abundant inositol in the brain may contribute to fungal pathogenesis in this neurotropic fungal pathogen. IMPORTANCE The human pathogen Cryptococcus neoformans is the leading cause of fungal meningitis in primarily immunocompromised populations. Understanding how this environmental organism adapts to the human host to cause deadly infection will guide our development of novel disease control strategies. Our recent studies revealed that inositol utilization by the fungus promotes C. neoformans development in nature and invasion of the central nervous system during infection. The mechanisms of the inositol regulation in fungal virulence remain incompletely understood. In this study, we found that C. neoformans has three genes encoding myo-inositol oxygenase, a key enzyme in the inositol catabolic pathway. Expression of these genes is highly induced by inositol, and they are highly expressed in the cerebrospinal fluid of patients with meningoencephalitis. Our mutagenesis analysis indeed demonstrates that inositol catabolism is required for C. neoformans virulence by altering the growth and structure of polysaccharide capsule, a major virulence factor. Considering the abundance of free inositol and inositol-related metabolites in the brain, our study reveals an important mechanism of host inositol-mediated fungal pathogenesis for this neurotropic fungal pathogen.

Multiple brain abscesses due to Listeria monocytogenes infection in a patient with systemic lupus erythematosus: A case report and literature review

AIM

To review the clinical features of systemic lupus erythematosus (SLE) complicated by central nervous system (CNS) infection due to Listeria monocytogenes.

METHOD

A patient with SLE receiving high-dose glucocorticoids combined with cyclophosphamide who developed multiple brain abscesses due to Listeria infection is described. The case is compared with known cases in a literature review.

RESULTS

A review of the literature showed that CNS infections are rare bacterial complications of SLE, but they can be a significant cause of mortality, especially those due to L. monocytogenes. The most significant risk factor for listerial meningitis is a prior history of receiving immunosuppressive therapy. At-risk patients should avoid unpasteurized milk and soft cheeses along with deli-style, ready-to-eat prepared meats, particularly poultry products. The case we report is the fifth SLE patient with multiple brain abscesses due to L. monocytogenes, and the first to be discharged with no sequelae. Timely and accurate identification and treatment of CNS infections and neuropsychiatric lupus are very important for favorable disease prognosis.

CONCLUSION

Repeated blood culture is helpful for early diagnosis, and empirical anti-infective treatment that covers L. monocytogenes is recommended for SLE patients with risk factors when CNS infection occurs. A comprehensive assessment might be helpful to distinguish CNS infections from neuropsychiatric SLE. For severe infection, the dosage of steroids does not need to be reduced immediately but can be gradually adjusted based on the results of a comprehensive evaluation of the disease.

Early Hydromyelia as a Rare Complication of Tuberculous Meningitis

Syringomyelia is an uncommon late complication of tuberculous meningitis with a latency period of up to 18 years. Acute hydromyelia is exceedingly rare with few case reports occuring within the first 6 weeks. We present a case and magnetic resonance imaging of a 38-year-old immunocompetent woman with this rare complication of early hydromyelia due to tuberculous meningitis which responded to ventriculoperitoneal shunting, highlighting that early detection and treatment may improve prognosis.

Suspected Central Nervous System Infections in HIV-Infected Adults

Objectives: To study the differential diagnosis of HIV-infected patients with suspected central nervous system (CNS) infections and the association of CD4 counts with the final diagnosis. Methods: We analyzed HIV-infected patients from a prospective cohort study on the diagnostic accuracy of clinical and laboratory characteristics in adults with suspected CNS infections in an academic hospital in Amsterdam, the Netherlands, who underwent cerebrospinal fluid (CSF) examination. Results: Thirty-four (9.4%) out of 363 patients with suspected CNS infections were HIV-positive of whom 18 (53%) were diagnosed to have CNS infection, with median CD4 counts of 255 cells/μl. The spectrum of CNS infections consisted of progressive multifocal leukoencephalopathy in three patients (17%); cryptococcal meningoencephalitis, toxoplasma encephalitis, angiostrongylus eosinophilic meningitis, and HIV encephalitis each in two (11%); and cytomegalovirus encephalitis, neurosyphilis, tuberculous meningoencephalitis, histoplasma encephalitis, and varicella-zoster virus meningitis each in one (6%). Clinical characteristics and blood parameters did not differ between HIV-infected patients with CNS infections and other diagnoses. The best predictor for CNS infections was the CSF leukocyte count (AUC = 0.77, 95 CI% 0.61-0.94). The diagnosis of CNS infection was not associated with the CD4 count (median 205 vs. 370, p = 0.21). Two patients (11%) with CNS infections died and two (11%) had neurological sequelae. Conclusions: Half of the patients with suspected CNS infections are diagnosed with a CNS infection, and this was not related to CD4 counts. The best predictor for CNS infections was the CSF leukocyte count.