Pathophysiology of neonatal acute bacterial meningitis

Sudden death in a newborn from cerebral venous sinus thrombosis resulting from meningitis

Septic cerebral venous sinus thrombosis is a rare but often fatal complication caused by bacterial meningitis and paranasal sinusitis.We report a particular case of the sudden and unexpected death of a six-day-old infant from unrecognised acute meningitis that caused a thrombotic occlusion of the venous sinuses (with the particular involvement of the torcular Herophili at the confluence of sinuses) resulting in subdural haemorrhage.This case report alerts paediatricians and neonatologists to the importance of promptly considering a possible diagnosis of meningitis without delay to avoid the fatal complications described here. As in all cases of sudden infant death our case study underlines the need for a thorough autopsy, accompanied by histological analysis, in order to identify the causes of the underlying pathological mechanisms causing death and to ensure an adequate differential diagnosis.

Self-Reported Executive Functioning in Young Adult Survivors of Childhood Bacterial Meningitis

OBJECTIVE

This study investigated executive functions (EFs) in young adult survivors of childhood bacterial meningitis (BM). These skills are important for normal development, and their potential vulnerability in early years suggests that childhood BM could affect executive functions in the longer term.

METHOD

The adult self-report Behavior Rating Inventory of Executive Function was administered to 474 young adult survivors of childhood BM who participated in the 20|30 Dutch Postmeningitis study. Average scores were compared to population-norm group scores. Subgroup scores were compared according to causative pathogen and age at onset.

RESULTS

Young adult survivors of childhood BM scored lower on overall metacognition than the age-matched population norm group. Young adult survivors of childhood BM caused by Streptococcus pneumoniae, S. agalactiae, or Escherichia coli had lower scores than cases caused by Neisseria meningitidis. Survivors with age-at-onset below 12 months had a higher (worse) overall EF score than survivors with age-at-onset above 12 months.

CONCLUSIONS

Young adult survivors of childhood BM experience difficulties in EF. However, most of the self-reported EF scores were within the norm. Future studies need to additionally assess EF in adult survivors of childhood BM using performance-based tests.

Unmasking the invisible enemy: A case report of metagenomics-guided diagnosis and treatment of neonatal septic meningitis caused by Corynebacterium aurimucosum in a preterm infant with neonatal lupus erythematosus

RATIONALE

Neonatal septic meningitis is a serious condition that can be caused by various pathogens, including Corynebacterium aurimucosum, a rare and opportunistic bacterium. We reports a case of infectious meningitis in a premature infant with neonatal lupus erythematosus caused by C aurimucosum. The purpose of this study is to explore the occurrence of meningitis caused by C aurimucosum in preterm infants with neonatal lupus erythematosus. We found that early diagnosis and treatment are crucial for this type of meningitis, especially for infants with impaired immunity or mothers receiving immunosuppressive therapy. This bacterium is rare in clinical practice, but it needs to be taken seriously.

PATIENT CONCERNS

The infant was born to a mother with systemic lupus erythematosus who had a history of long-term immunosuppressive therapy. The infant presented with preterm birth, purplish-red skin, fever, and widespread scarlet dermatitis. He also had positive anti-Ro/SSA and anti-La/SSB antibodies.

DIAGNOSIS

The infant was diagnosed with neonatal lupus erythematosus based on clinical and serological features. A lumbar puncture revealed septic meningitis with high levels of total nucleated cells, protein, and Pan's test in the CSF. The macrogenic examination identified C aurimucosum as the causative agent. The culture of the mother's vaginal secretion also revealed the same bacterium.

INTERVENTIONS

The infant was treated with anti-infective therapy with ceftriaxone, ampicillin, vancomycin, and meropenem. He also received prednisone and gammaglobulin infusion for neonatal lupus erythematosus.

OUTCOMES

The infant's temperature returned to normal, and his general condition and responsiveness improved. The CSF cytology and biochemistry normalized, and the culture was negative. The cranial MRI examination showed no abnormalities. The red rash disappeared, and the follow-ups after discharge revealed no complications.

LESSONS

This case highlights the importance of early diagnosis and treatment of neonatal septic meningitis caused by C aurimucosum, especially in infants with immunocompromised conditions or maternal history of immunosuppressive therapy. C aurimucosum should not be overlooked as a potential pathogen in neonatal septic meningitis.

Long-Term Neurodevelopmental Impairment among Very Preterm Infants with Sepsis, Meningitis, and Intraventricular Hemorrhage

INTRODUCTION

Sepsis and intraventricular hemorrhage (IVH) are associated with poorer long-term neurodevelopmental outcomes in very preterm infants (VPIs), but less is known about the long-term effect of meningitis and the combined impact of both meningitis and IVH. Our objective was to examine the long-term neurodevelopmental outcomes of VPIs with late onset sepsis and meningitis, with and without IVH, in Canada.

METHODS

We conducted a retrospective cohort study of all infants <29 weeks GA who were admitted to 26 tertiary-level neonatal intensive care units in the Canadian Neonatal Network (CNN) and Canadian Neonatal Follow-Up Network (CNFUN) databases, from January 1, 2010, to December 31, 2016.

RESULTS

Of the 6,322 infants in the cohort, 4,575 had no infection, 1,590 had late onset culture-positive bloodstream infection (CPBSI) only, and 157 had late onset meningitis. There was a significant (p < 0.05) trend of increasing rates of significant neurodevelopmental delay (sNDI) when comparing infants with no infection (sNDI rate 15.0%), late onset CPBSI (sNDI rate 22.9%), and late onset meningitis (sNDI rate 32.0%), even after adjustment for infant characteristics. Similar trends were observed for neurodevelopmental impairment, cerebral palsy, and individual Bayley-III scores <85 for cognitive, language, and motor development. There was an additive effect of IVH in all infant categories, but there was no multiplicative effect between IVH and late onset meningitis.

CONCLUSION

There was an increasing trend of adverse neurodevelopmental outcomes when infants with no infection, late onset CPBSI and late onset meningitis are compared. IVH had an additive effect.

Immaturity of immune cells around the dural venous sinuses contributes to viral meningoencephalitis in neonates

High neonatal susceptibility to meningitis has been attributed to the anatomical barriers that act to protect the central nervous system (CNS) from infection being immature and not fully developed. However, the mechanisms by which pathogens breach CNS barriers are poorly understood. Using the Armstrong strain of lymphocytic choriomeningitis virus (LCMV) to study virus propagation into the CNS during systemic infection, we demonstrate that mortality in neonatal, but not adult, mice is high after infection. Virus propagated extensively from the perivenous sinus region of the dura mater to the leptomeninges, choroid plexus, and cerebral cortex. Although the structural barrier of CNS border tissues is comparable between neonates and adults, immunofluorescence staining and single-cell RNA sequencing analyses revealed that the neonatal dural immune cells are immature and predominantly composed of CD206hi macrophages, with major histocompatibility complex class II (MHCII)hi macrophages being rare. In adults, however, perivenous sinus immune cells were enriched in MHCIIhi macrophages that are specialized for producing antiviral molecules and chemokines compared with CD206hi macrophages and protected the CNS against systemic virus invasion. Our findings clarify how systemic pathogens enter the CNS through its border tissues and how the immune barrier at the perivenous sinus region of the dura blocks pathogen access to the CNS.

Factors associated with afebrile presentation and delayed defervescence of bacterial meningitis in children under 3 years of age: a multi-centre retrospective analysis

BACKGROUND

This multi-center study aimed to identify factors affecting fever and delayed defervescence in bacterial meningitis (BM) patients under 3 years of age because of the variability of fever in this patient population.

METHODS

Only BM patients under 3 years treated at 49 centers in China from November 2018 to end-April 2021 were included in the study. Univariate and multivariate logistic regression analyses were performed to determine factors associated with afebrile presentation and fever of delayed defervescence.

RESULTS

A total of 863 BM patients under 3 years were included in the study. Coagulase negative staphylococcus was associated with afebrile presentation (OR = 1.176), while septicaemia and ear-nose-throat infections were associated with fever (P < 0.05). The patients with fever were assigned into early and delayed defervescence groups based on defervescence time (less than and more than or equal to one week). Furthermore, Streptococcus agalactiae meningitis (OR = 1.124), concomitant gastrointestinal infection (OR = 1.276), encephalomalacia (or = 1.339), and subdural effusion (OR = 1.454) were independently associated with delayed defervescence (all P < 0.05).

CONCLUSIONS

The findings can aid in the efficient utilization of fever in auxiliary diagnosis and evaluating the condition of the disease.

Phage Interactions with the Nervous System in Health and Disease

The central nervous system manages all of our activities (e.g., direct thinking and decision-making processes). It receives information from the environment and responds to environmental stimuli. Bacterial viruses (bacteriophages, phages) are the most numerous structures occurring in the biosphere and are also found in the human organism. Therefore, understanding how phages may influence this system is of great importance and is the purpose of this review. We have focused on the effect of natural bacteriophages in the central nervous system, linking them to those present in the gut microbiota, creating the gut-brain axis network, as well as their interdependence. Importantly, based on the current knowledge in the field of phage application (e.g., intranasal) in the treatment of bacterial diseases associated with the brain and nervous system, bacteriophages may have significant therapeutic potential. Moreover, it was indicated that bacteriophages may influence cognitive processing. In addition, phages (via phage display technology) appear promising as a targeted therapeutic tool in the treatment of, among other things, brain cancers. The information collected and reviewed in this work indicates that phages and their impact on the nervous system is a fascinating and, so far, underexplored field. Therefore, the aim of this review is not only to summarize currently available information on the association of phages with the nervous system, but also to stimulate future studies that could pave the way for novel therapeutic approaches potentially useful in treating bacterial and non-bacterial neural diseases.

Bacterial meningitis in the early postnatal mouse studied at single-cell resolution

Bacterial meningitis is a major cause of morbidity and mortality, especially among infants and the elderly. Here, we study mice to assess the response of each of the major meningeal cell types to early postnatal E. coli infection using single nucleus RNA sequencing (snRNAseq), immunostaining, and genetic and pharamacologic perturbations of immune cells and immune signaling. Flatmounts of the dissected leptomeninges and dura were used to facilitiate high-quality confocal imaging and quantification of cell abundances and morphologies. Upon infection, the major meningeal cell types - including endothelial cells (ECs), macrophages, and fibroblasts - exhibit distinctive changes in their transcriptomes. Additionally, ECs in the leptomeninges redistribute CLDN5 and PECAM1, and leptomeningeal capillaries exhibit foci with reduced blood-brain barrier integrity. The vascular response to infection appears to be largely driven by TLR4 signaling, as determined by the nearly identical responses induced by infection and LPS administration and by the blunted response to infection in Tlr4^-/- mice. Interestingly, knocking out Ccr2, encoding a major chemoattractant for monocytes, or acute depletion of leptomeningeal macrophages, following intracebroventricular injection of liposomal clodronate, had little or no effect on the response of leptomeningeal ECs to E. coli infection. Taken together, these data imply that EC responses to infection are largely driven by the intrinsic EC response to LPS.

Bacterial meningitis in Africa

Bacterial meningitis differs globally, and the incidence and case fatality rates vary by region, country, pathogen, and age group; being a life-threatening disease with a high case fatality rate and long-term complications in low-income countries. Africa has the most significant prevalence of bacterial meningitis illness, and the outbreaks typically vary with the season and the geographic location, with a high incidence in the meningitis belt of the sub-Saharan area from Senegal to Ethiopia. Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) are the main etiological agents of bacterial meningitis in adults and children above the age of one. Streptococcus agalactiae (group B Streptococcus), Escherichia coli, and Staphylococcus aureus are neonatal meningitis's most common causal agents. Despite efforts to vaccinate against the most common causes of bacterial neuro-infections, bacterial meningitis remains a significant cause of mortality and morbidity in Africa, with children below 5 years bearing the heaviest disease burden. The factors attributed to this continued high disease burden include poor infrastructure, continued war, instability, and difficulty in diagnosis of bacterial neuro-infections leading to delay in treatment and hence high morbidity. Despite having the highest disease burden, there is a paucity of African data on bacterial meningitis. In this article, we discuss the common etiologies of bacterial neuroinfectious diseases, diagnosis and the interplay between microorganisms and the immune system, and the value of neuroimmune changes in diagnostics and therapeutics.

Isolation and Characterization of Lytic Bacteriophages Active against Clinical Strains of E. coli and Development of a Phage Antimicrobial Cocktail

Pathogenic E. coli cause urinary tract, soft tissue and central nervous system infections, sepsis, etc. Lytic bacteriophages can be used to combat such infections. We investigated six lytic E. coli bacteriophages isolated from wastewater. Transmission electron microscopy and whole genome sequencing showed that the isolated bacteriophages are tailed phages of the Caudoviricetes class. One-step growth curves revealed that their latent period of reproduction is 20-30 min, and the average value of the burst size is 117-155. During co-cultivation with various E. coli strains, the phages completely suppressed bacterial host culture growth within the first 4 h at MOIs 10^-7 to 10^-3. The host range lysed by each bacteriophage varied from six to two bacterial strains out of nine used in the study. The cocktail formed from the isolated bacteriophages possessed the ability to completely suppress the growth of all the E. coli strains used in the study within 6 h and maintain its lytic activity for 8 months of storage. All the isolated bacteriophages may be useful in fighting pathogenic E. coli strains and in the development of phage cocktails with a long storage period and high efficiency in the treatment of bacterial infections.

High-throughput sequencing unravels the cell heterogeneity of cerebrospinal fluid in the bacterial meningitis of children

Bacterial meningitis (BM) is a common life-threatening infection in children that occurs in the central nervous system (CNS). The cytologic examination of cerebrospinal fluid (CSF) is a key parameter in the diagnosis of BM, but the heterogeneity of cells in the CSF has not been elucidated, which limits the current understanding of BM neuroinflammation. In this study, CSF samples were collected from a number of BM patients who were in different stages of disease progression. Single-cell RNA-sequencing (scRNA-seq), with additional bulk transcriptome sequencing, was conducted to decipher the characteristics of CSF cells in BM progression. A total of 18 immune cell clusters in CSF were identified, including two neutrophils, two monocytes, one macrophage, four myeloid dendritic cells, five T cells, one natural killer cell, one B cell, one plasmacytoid dendritic cell, and one plasma cell subtype. Their population profiles and dynamics in the initial onset, remission, and recovery stages during BM progression were also characterized, which showed decreased proportions of myeloid cells and increased proportions of lymphoid cells with disease progression. One novel neutrophil subtype, FFAR2+TNFAIP6+ neutrophils, and one novel monocyte subtype, THBS1+IL1B+ monocytes, were discovered, and their quantity changes positively correlated with the intensity of the inflammatory response in the CSF during BM. In addition, the CSF of BM patients with unsatisfactory therapeutic responses presented with different cell heterogeneity compared to the CSF of BM patients with satisfactory therapeutic responses, and their CSF featured altered intercellular communications and increased proportions of type II myeloid dendritic cells and plasmacytoid dendritic cells. Moreover, the bulk transcriptome profiles of autologous CSF cells and peripheral blood leukocytes of BM patients showed that the immune cells in these two physiological compartments exhibited distinct immune responses under different onset conditions. In particular, the CSF cells showed a high expression of macrophage characteristic genes and a low expression of platelet characteristic genes compared with peripheral blood leukocytes. Our study conducted an in-depth exploration of the characteristics of CSF cells in BM progression, which provided novel insights into immune cell engagement in acute CNS infection.

Quantitative proteomics on the cerebrospinal fluid of hydrocephalus in neonatal bacterial meningitis

Objective

Hydrocephalus in bacterial meningitis (BM) is a devastating infectious neurological disease and the proteins and pathways involved in its pathophysiology are not fully understood.

Materials and methods

Label-free quantitative (LFQ) proteomics analyses was used to identify differentially expressed proteins (DEPs) in cerebrospinal fluid (CSF) samples from infants with hydrocephalus and bacterial meningitis (HBM group, N = 8), infants with bacterial meningitis (BM group, N = 9); and healthy infants (N group, N = 11). Bioinformatics analysis was subsequently performed to investigate Gene Ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enriched signaling pathways of these DEPs. Six proteins (AZU1, COX4I1, EDF1, KRT31, MMP12, and PRG2) were selected for further validation via enzyme-linked immunosorbent assay (ELISA).

Results

Compared with BM group and N group, HBM group had a higher whole CSF protein level (5.6 ± 2.7 vs. 1.7 ± 1.0 vs. 1.2 ± 0.5 g/l) and lower whole CSF glucose level (0.8 ± 0.6 vs. 1.8 ± 0.7 vs. 3.3 ± 0.8 mmol/l) (both P < 0.05). Over 300 DEPs were differentially expressed in HBM group compared with BM group and BM compared with N group, of which 78% were common to both. Cluster analysis indicated that the levels of 226 proteins were increased in BM group compared with N group and were decreased in HBM group compared with BM group. Bioinformatics analysis indicated the involvement of the cell adhesion, immune response and extracellular exosome signaling were significantly enriched in HBM compared with BM group and BM compared with N group. 267 DEPs were identified between HBM group with N group, KEGG analysis indicated that DEPs mainly involved in filament cytoskeleton and immune response. The ELISA results further verified that the expression levels of AZU1 were significantly different from among three groups (both P < 0.05).

Conclusion

This is the first reported characterization of quantitative proteomics from the CSF of infants with HBM. Our study also demonstrated that AZU1 could be a potential biomarker for the diagnosis of hydrocephalus in bacterial meningitis.

Mesenchymal-Stem-Cell-Derived Extracellular Vesicles Attenuate Brain Injury in Escherichia coli Meningitis in Newborn Rats

We recently reported that transplantation of mesenchymal stem cells (MSCs) significantly reduced bacterial growth and brain injury in neonatal meningitis induced by Escherichia coli (E. coli) infection in newborn rats. As a next step, to verify whether the MSCs protect against brain injury in a paracrine manner, this study was designed to estimate the efficacy of MSC-derived extracellular vesicles (MSC-EVs) in E. coli meningitis in newborn rats. E. coli meningitis was induced without concomitant bacteremia by the intra-cerebroventricular injection of 5 × 10² colony-forming units of K1 (-) E. coli in rats, at postnatal day 11. MSC-EVs were intra-cerebroventricularly transplanted 6 h after the induction of meningitis, and antibiotics were administered for three consecutive days starting at 24 h after the induction of meningitis. The increase in bacterial growth in the cerebrospinal fluid measured at 24 h after the meningitis induction was not significantly reduced following MSC-EV transplantation. However, an increase in brain cell death, reactive gliosis, and inflammation following meningitis were significantly attenuated after MSC-EV transplantation. Taken together, our results indicate that MSCs show anti-apoptotic, anti-gliosis, and anti-inflammatory, but not antibacterial effects, in an EV-mediated paracrine manner in E. coli-induced neonatal meningitis.

YbdO Promotes the Pathogenicity of Escherichia coli K1 by Regulating Capsule Synthesis

Escherichia coli K1 is the most popular neonatal meningitis-causing Gram-negative bacterium. As a key virulence determinant, the K1 capsule enhances the survival of E. coli K1 in human brain microvascular endothelial cells (HBMECs) upon crossing the blood–brain barrier; however, the regulatory mechanisms of capsule synthesis during E. coli K1 invasion of HBMECs remain unclear. Here, we identified YbdO as a transcriptional regulator that promotes E. coli K1 invasion of HBMECs by directly activating K1 capsule gene expression to increase K1 capsule synthesis. We found that ybdO deletion significantly reduced HBMEC invasion by E. coli K1 and meningitis occurrence in mice. Additionally, electrophoretic mobility shift assay and chromatin immunoprecipitation–quantitative polymerase chain reaction analysis indicated that YbdO directly activates kpsMT and neuDBACES expression, which encode products involved in K1 capsule transport and synthesis by directly binding to the kpsM promoter. Furthermore, ybdO transcription was directly repressed by histone-like nucleoid structuring protein (H-NS), and we observed that acidic pH similar to that of early and late endosomes relieves this transcriptional repression. These findings demonstrated the regulatory mechanism of YbdO on K1 capsule synthesis, providing further insights into the evolution of E. coli K1 pathogenesis and host–pathogen interaction.

Lipopolysaccharide From E. coli Increases Glutamate-Induced Disturbances of Calcium Homeostasis, the Functional State of Mitochondria, and the Death of Cultured Cortical Neurons

Lipopolysaccharide (LPS), a fragment of the bacterial cell wall, specifically interacting with protein complexes on the cell surface, can induce the production of pro-inflammatory and apoptotic signaling molecules, leading to the damage and death of brain cells. Similar effects have been noted in stroke and traumatic brain injury, when the leading factor of death is glutamate (Glu) excitotoxicity too. But being an amphiphilic molecule with a significant hydrophobic moiety and a large hydrophilic region, LPS can also non-specifically bind to the plasma membrane, altering its properties. In the present work, we studied the effect of LPS from Escherichia coli alone and in combination with the hyperstimulation of Glu-receptors on the functional state of mitochondria and Ca2+ homeostasis, oxygen consumption and the cell survival in primary cultures from the rats brain cerebellum and cortex. In both types of cultures, LPS (0.1–10 μg/ml) did not change the intracellular free Ca2+ concentration ([Ca2+]i) in resting neurons but slowed down the median of the decrease in [Ca2+]i on 14% and recovery of the mitochondrial potential (ΔΨm) after Glu removal. LPS did not affect the basal oxygen consumption rate (OCR) of cortical neurons; however, it did decrease the acute OCR during Glu and LPS coapplication. Evaluation of the cell culture survival using vital dyes and the MTT assay showed that LPS (10 μg/ml) and Glu (33 μM) reduced jointly and separately the proportion of live cortical neurons, but there was no synergism or additive action. LPS-effects was dependent on the type of culture, that may be related to both the properties of neurons and the different ratio between neurons and glial cells in cultures. The rapid manifestation of these effects may be the consequence of the direct effect of LPS on the rheological properties of the cell membrane.

Decreasing Trend in Incidence of Late Onset Culture Positive Bloodstream Infections but Not Late Onset Meningitis in Preterm Infants <33 Weeks Gestation in Canadian Neonatal Intensive Care Unit

INTRODUCTION

Recent studies reported decreased incidence of late onset sepsis in the neonatal intensive care unit (NICU), but it is unclear whether this is also true for late onset meningitis. Recent reports that both meningitis and intraventricular hemorrhage (IVH) are associated with systemic inflammation also raise questions about an association between the 2.

METHODS

All preterm infants <33 weeks gestational age admitted to CNN NICUs from 2010 to 2018 were included. We compared incidence trends of late onset culture positive bloodstream infection (CPBSI) and late onset meningitis, and examined the association of meningitis and IVH (exposure), after adjustment for potential confounders.

RESULTS

Of 36,573 infants included, 32,198 had no infection, 3,977 had only late onset CPBSI and 398 had late onset meningitis. There was significant decrease in incidence of late onset CPBSI (14%-10%; adjusted odds ratio (AOR) = 0.93; 95% confidence interval [CI] 0.92, 0.95) but not late onset meningitis (1.6%-1.2%; AOR = 0.98; 95% CI 0.94, 1.01). Compared to infants with no IVH grade 3 or above, infants with IVH grade 3, or above had higher odds of late onset meningitis versus no infection (AOR 4.16; 95% CI 3.17, 5.44), and higher odds of late onset meningitis versus late onset CPBSI (AOR 4.11; 95% CI 3.08, 5.50).

CONCLUSIONS

There was a decreasing trend of late onset CPBSI but not late onset meningitis. An association between late onset meningitis and IVH grade 3 or above was observed. Late onset CPBSI and meningitis may have different risk factors and require different prevention strategies.

Cerebrospinal fluid culture-positive bacterial meningitis increases the risk for neurologic damage among neonates

OBJECTIVE

This study aimed to compare the clinical features and outcomes of neonatal bacterial meningitis (NBM) between patients with positive and negative cerebrospinal fluid (CSF) cultures and determine the risk factors for CSF culture-positive NBM.

METHODS

We retrospectively reviewed the medical records of all patients with NBM. Perinatal clinical data, laboratory results, and cranial radiographs were obtained.

RESULTS

Among the 186 neonates who met the inclusion criteria. The risk factors for positive CSF culture results were analysed using multiple logistic regression. The multivariable logistic regression analysis showed that the possible risk factors of NBM with positive CSF culture in this study were: Length of fever [OR = 1.126; 95% CI (0.999-1.268)], Neurologic symptoms [OR = 3.043; 95% CI (1.164-7.959)], Cerebrospinal fluid protein [OR = 1.001; 95% CI (1.000-1.001)]. Cases of NBM with a longer duration of fever, more neurologic symptoms, and higher levels of CSF protein were more likely to demonstrate positive results on CSF culture.

CONCLUSION

Cases of NBM with CSF culture-positive results were more likely to have severe clinical manifestations and develop more serious neurologic damage. Patients with NBM who have longer durations of fever, more neurologic symptoms, and higher levels of CSF protein were more likely to have CSF culture-positive results, who should be followed up more closely.Key MessageBacterial meningitis is clinically defined as a serious inflammation of meningitis, usually caused by a variety of bacterial infections that may leave sequelae and long-term complications and high mortality rates. Early diagnosis is often difficult, particularly when the patient has been treated with antimicrobials.

Inflammatory hydrocephalus

Reparative inflammation is an important protective response that eliminates foreign organisms, damaged cells, and physical irritants. However, inappropriately triggered or sustained inflammation can respectively initiate, propagate, or prolong disease. Post-hemorrhagic (PHH) and post-infectious hydrocephalus (PIH) are the most common forms of hydrocephalus worldwide. They are treated using neurosurgical cerebrospinal fluid (CSF) diversion techniques with high complication and failure rates. Despite their distinct etiologies, clinical studies in human patients have shown PHH and PIH share similar CSF cytokine and immune cell profiles. Here, in light of recent work in model systems, we discuss the concept of "inflammatory hydrocephalus" to emphasize potential shared mechanisms and potential therapeutic vulnerabilities of these disorders. We propose that this change of emphasis could shift our thinking of PHH and PIH from a framework of life-long neurosurgical disorders to that of preventable conditions amenable to immunomodulation.

Microglia-leucocyte axis in cerebral ischaemia and inflammation in the developing brain

Development of the Central Nervous System (CNS) is reliant on the proper function of numerous intricately orchestrated mechanisms that mature independently, including constant communication between the CNS and the peripheral immune system. This review summarizes experimental knowledge of how cerebral ischaemia in infants and children alters physiological communication between leucocytes, brain immune cells, microglia and the neurovascular unit (NVU)-the "microglia-leucocyte axis"-and contributes to acute and long-term brain injury. We outline physiological development of CNS barriers in relation to microglial and leucocyte maturation and the plethora of mechanisms by which microglia and peripheral leucocytes communicate during postnatal period, including receptor-mediated and intracellular inflammatory signalling, lipids, soluble factors and extracellular vesicles. We focus on the "microglia-leucocyte axis" in rodent models of most common ischaemic brain diseases in the at-term infants, hypoxic-ischaemic encephalopathy (HIE) and focal arterial stroke and discuss commonalities and distinctions of immune-neurovascular mechanisms in neonatal and childhood stroke compared to stroke in adults. Given that hypoxic and ischaemic brain damage involve Toll-like receptor (TLR) activation, we discuss the modulatory role of viral and bacterial TLR2/3/4-mediated infection in HIE, perinatal and childhood stroke. Furthermore, we provide perspective of the dynamics and contribution of the axis in cerebral ischaemia depending on the CNS maturational stage at the time of insult, and modulation independently and in consort by individual axis components and in a sex dependent ways. Improved understanding on how to modify crosstalk between microglia and leucocytes will aid in developing age-appropriate therapies for infants and children who suffered cerebral ischaemia.

Epidemiology and Trends of Infective Meningitis in Neonates and Infants Less than 3 Months of Age in Hong Kong

INTRODUCTION AND AIMS

Meningitis in neonates and young infants leads to significant morbidity and mortality worldwide. This study aims to investigate pathogens, antibiotics resistance and secular change of incidence in Hong Kong.

METHODS

We performed a retrospective search on meningitis in neonates and infants <3 months old in three Hong Kong public hospitals from 2004 to 2019. Medical charts were reviewed, focusing on the identification and antibiotics resistance of the pathogens.

RESULTS

200 cases of meningitis were identified (67% were bacterial). Group B Streptococcus (GBS) and Escherichia coli (E. coli) were the commonest bacterial pathogens. The annual rates of early-onset GBS meningitis decreased since the implementation of the universal GBS screening and intrapartum antibiotics prophylaxis (IAP) in 2012, while that of late-onset GBS meningitis remained similar. A significant portion of E. coli isolates were resistant to ampicillin and/or gentamicin.

CONCLUSION

GBS and E. coli remained the commonest bacteria for meningitis in this age group. The annual rate of bacterial meningitis in Hong Kong declined in recent years, which was attributed by the decline in that of early-onset GBS meningitis due to the universal GBS screening and IAP. Antimicrobial-resistant bacterial strains that caused meningitis require further clinical and public health attention.

Neuronal Damage and Neuroinflammation, a Bridge Between Bacterial Meningitis and Neurodegenerative Diseases

Bacterial meningitis is an inflammation of the meninges which covers and protects the brain and the spinal cord. Such inflammation is mostly caused by blood-borne bacteria that cross the blood-brain barrier (BBB) and finally invade the brain parenchyma. Pathogens such as Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae are the main etiological causes of bacterial meningitis. After trafficking across the BBB, bacterial pathogens in the brain interact with neurons, the fundamental units of Central Nervous System, and other types of glial cells. Although the specific molecular mechanism behind the interaction between such pathogens with neurons is still under investigation, it is clear that bacterial interaction with neurons and neuroinflammatory responses within the brain leads to neuronal cell death. Furthermore, clinical studies have shown indications of meningitis-caused dementia; and a variety of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease and Huntington's disease are characterized by the loss of neurons, which, unlike many other eukaryotic cells, once dead or damaged, they are seldom replaced. The aim of this review article is to provide an overview of the knowledge on how bacterial pathogens in the brain damage neurons through direct and indirect interactions, and how the neuronal damage caused by bacterial pathogen can, in the long-term, influence the onset of neurodegenerative disorders.

Etiology of Neonatal Bacterial Meningitis and Their Antibiotic Susceptibility Pattern at the University of Gondar Comprehensive Specialized Hospital, Ethiopia: A Seven-Year Retrospective Study

Background

Meningitis, which is mostly caused by infectious agents, occurs more commonly during the first month of life. Bacterial meningitis is an important source of mortality and morbidity, especially in neonates of resource-limited countries. We aimed to determine the prevalence and etiological agents of bacterial meningitis and their antibiotic susceptibility pattern in neonates at the University of Gondar Comprehensive Specialized Hospital.

Methods

We collected retrospective data from bacteriological results of cerebrospinal fluid of meningitis suspected neonates from 2013 to 2019. Sample collection, culture preparation, bacterial identification, and susceptibility testing were performed using standard microbiological techniques. We extracted data on socio-demographic characteristics and culture and antibiotic susceptibility testing results. We inputted the data using Epi-info version 7 and exported it to SPSS version 20 for analysis.

Results

In this study, 1101 cerebrospinal fluid samples, 595 (54%) male and 506 (46%) female neonates, were cultured to look for meningitis-causing bacteria. Of 1101 cerebrospinal fluid, 19 (1.73%) were culture positive for meningitis-causing bacteria. The common etiological agents were Klebsiella pneumoniae 36.8% (7), non-lactose-fermenter Gram-negative rods 21% (4), and Group B streptococcus 15.8% (3). The overall resistance rate among cephalosporin, cotrimoxazole, penicillin, and aminoglycosides classes were 90%, 88.9%, 77.3%, and 54.54%, respectively. Of all isolates, 58% (11) were multidrug-resistant, including all the non-lactose-fermenter Gram-negative rods and 71.4% of the Klebsiella pneumonia isolates.

Conclusion

The prevalence of neonatal bacterial meningitis was 1.73%. Klebsiella pneumonia and other Gram-negative rods, with a high multidrug-resistant rate, were the leading cause of neonatal bacterial meningitis. Further studies are needed to explore the source of infection, incidence, and risk factors of neonatal bacterial meningitis.

The role of the microbiota-gut-brain axis in neuropsychiatric disorders

The microbiota-gut-brain axis is a bidirectional signaling mechanism between the gastrointestinal tract and the central nervous system. The complexity of the intestinal ecosystem is extraordinary; it comprises more than 100 trillion microbial cells that inhabit the small and large intestine, and this interaction between microbiota and intestinal epithelium can cause physiological changes in the brain and influence mood and behavior. Currently, there has been an emphasis on how such interactions affect mental health. Evidence indicates that intestinal microbiota are involved in neurological and psychiatric disorders. This review covers evidence for the influence of gut microbiota on the brain and behavior in Alzheimer disease, dementia, anxiety, autism spectrum disorder, bipolar disorder, major depressive disorder, Parkinson's disease, and schizophrenia. The primary focus is on the pathways involved in intestinal metabolites of microbial origin, including short-chain fatty acids, tryptophan metabolites, and bacterial components that can activate the host's immune system. We also list clinical evidence regarding prebiotics, probiotics, and fecal microbiota transplantation as adjuvant therapies for neuropsychiatric disorders.

Unexpected and Sudden Death Due to Undiagnosed Moraxella catarrhalis Meningoencephalitis in a 40-day-old Infant: Case Report and Literature Review

Acute bacterial meningitis in infants and newborns represents a medical emergency and a significant cause of mortality and morbidity worldwide. Moraxella catarrhalis has been considered a microorganism with low pathogenic potential, and only in exceptional cases has it been found to cause meningitis in infants and immunocompetent people. We will now document an unusual case of an unexpected and sudden death of a 40-day-old infant due to acute meningitis from M. catarrhalis, apparently asymptomatic and subsequently diagnosed by an autopsy. According to our knowledge this is the first case of unexpected infant death due to undiagnosed M. catarrhalis meningitis.The suggested case, as well as for the rarity of such a fatal event, should be considered a caution to pediatrics and neonatologists for M. catarrhalis can cause paucisymptomatic meningoencephalitis in infants which can be potentially fatal.From a forensic point of view, an autopsy accompanied by a multidisciplinary assessment is always necessary in cases of unexpected infant deaths to identify the causes.

Epidemiology and antimicrobial susceptibility of invasive Escherichia coli infection in neonates from 2012 to 2019 in Xiamen, China

BACKGROUND

Escherichia coli (E. coli) is one of the important causative pathogens of neonatal invasive infection. The epidemiological and clinical profile of invasive E. coli infection in Chinese newborns is not well characterized.

METHODS

Ninety-four infants with invasive E. coli infection were categorized into E. coli early onset disease (EOD) group (onset ≤72 h after birth) (n = 46) and E. coli late onset disease (LOD) group (onset > 72 h) (n = 48). We compared and analyzed the clinical characteristics and drug sensitivity profile of early-onset and late-onset E. coli invasive infection in neonates.

RESULTS

The incidence of E. coli-EOD and E.coli-LOD was 0.45/1000 live births (LBs) and 0.47/1000 LBs, respectively. The incidence of gestational diabetes mellitus, perinatal fever, urinary tract infection, chorioamnionitis, and positive E. coli culture among mothers in the E. coli-EOD group were significantly higher than that in E. coli-LOD group. The incidence of premature birth, low-birth-weight, nosocomial infection, and hospitalization time were significantly higher in the E. coli-LOD group. The main disease in E. coli-EOD group was pneumonia (main clinical manifestation: dyspnea). The main disease in E. coli-LOD group was sepsis (main clinical manifestation: fever). The sensitivity rates of E. coli strains to ampicillin and piperacillin were low (25.00-28.79%); sensitivity to cephalosporins was also low except ceftazidime (lowest sensitivity rate: 57.14%). Sensitivity to compound preparations containing β-lactamase inhibitors was high, even for extended spectrum β-lactamase-positive strains (nearly 100%).

CONCLUSION

E. coli is an important cause of invasive infection of newborns in Xiamen, China. E. coli-EOD was largely attributable to perinatal factors, while E. coli-LOD was largely related to nosocomial infection. Compound preparations containing β-lactamase inhibitor or carbapenem antibiotics should be preferred for neonatal invasive infection by E. coli.

A Mitocentric View of the Main Bacterial and Parasitic Infectious Diseases in the Pediatric Population

Infectious diseases occur worldwide with great frequency in both adults and children. Both infections and their treatments trigger mitochondrial interactions at multiple levels: (i) incorporation of damaged or mutated proteins to the complexes of the electron transport chain, (ii) mitochondrial genome (depletion, deletions, and point mutations) and mitochondrial dynamics (fusion and fission), (iii) membrane potential, (iv) apoptotic regulation, (v) generation of reactive oxygen species, among others. Such alterations may result in serious adverse clinical events with great impact on children's quality of life, even resulting in death. As such, bacterial agents are frequently associated with loss of mitochondrial membrane potential and cytochrome c release, ultimately leading to mitochondrial apoptosis by activation of caspases-3 and -9. Using Rayyan QCRI software for systematic reviews, we explore the association between mitochondrial alterations and pediatric infections including (i) bacterial: M. tuberculosis, E. cloacae, P. mirabilis, E. coli, S. enterica, S. aureus, S. pneumoniae, N. meningitidis and (ii) parasitic: P. falciparum. We analyze how these pediatric infections and their treatments may lead to mitochondrial deterioration in this especially vulnerable population, with the intention of improving both the understanding of these diseases and their management in clinical practice.

Neonatal Ureaplasma parvum meningitis complicated with subdural hematoma: a case report and literature review

BACKGROUND

Neonatal meningitis is a severe infectious disease of the central nervous system with high morbidity and mortality. Ureaplasma parvum is extremely rare in neonatal central nervous system infection.

CASE PRESENTATION

We herein report a case of U. parvum meningitis in a full-term neonate who presented with fever and seizure complicated with subdural hematoma. After hematoma evacuation, the seizure disappeared, though the fever remained. Cerebrospinal fluid (CSF) analysis showed inflammation with CSF pleocytosis (1135-1319 leukocytes/μl, mainly lymphocytes), elevated CSF protein levels (1.36-2.259 g/l) and decreased CSF glucose (0.45-1.21 mmol/l). However, no bacterial or viral pathogens in either CSF or blood were detected by routine culture or serology. Additionally, PCR for enteroviruses and herpes simplex virus was negative. Furthermore, the CSF findings did not improve with empirical antibiotics, and the baby experienced repeated fever. Thus, we performed metagenomic next-generation sequencing (mNGS) to identify the etiology of the infection. U. parvum was identified by mNGS in CSF samples and confirmed by culture incubation on mycoplasma identification medium. The patient's condition improved after treatment with erythromycin for approximately 5 weeks.

CONCLUSIONS

Considering the difficulty of etiological diagnosis in neonatal U. parvum meningitis, mNGS might offer a new strategy for diagnosing neurological infections.

Bacteriophage K1F targets Escherichia coli K1 in cerebral endothelial cells and influences the barrier function

Bacterial neonatal meningitis results in high mortality and morbidity rates for those affected. Although improvements in diagnosis and treatment have led to a decline in mortality rates, morbidity rates have remained relatively unchanged. Bacterial resistance to antibiotics in this clinical setting further underlines the need for developing other technologies, such as phage therapy. We exploited an in vitro phage therapy model for studying bacterial neonatal meningitis based on Escherichia coli (E. coli) EV36, bacteriophage (phage) K1F and human cerebral microvascular endothelial cells (hCMECs). We show that phage K1F is phagocytosed and degraded by constitutive- and PAMP-dependent LC3-assisted phagocytosis and does not induce expression of inflammatory cytokines TNFα, IL-6, IL-8 or IFNβ. Additionally, we observed that phage K1F temporarily decreases the barrier resistance of hCMEC cultures, a property that influences the barrier permeability, which could facilitate the transition of immune cells across the endothelial vessel in vivo. Collectively, we demonstrate that phage K1F can infect intracellular E. coli EV36 within hCMECs without themselves eliciting an inflammatory or defensive response. This study illustrates the potential of phage therapy targeting infections such as bacterial neonatal meningitis and is an important step for the continued development of phage therapy targeting antibiotic-resistant bacterial infections generally.

Inflammation in acquired hydrocephalus: pathogenic mechanisms and therapeutic targets

Hydrocephalus is the most common neurosurgical disorder worldwide and is characterized by enlargement of the cerebrospinal fluid (CSF)-filled brain ventricles resulting from failed CSF homeostasis. Since the 1840s, physicians have observed inflammation in the brain and the CSF spaces in both posthaemorrhagic hydrocephalus (PHH) and postinfectious hydrocephalus (PIH). Reparative inflammation is an important protective response that eliminates foreign organisms, damaged cells and physical irritants; however, inappropriately triggered or sustained inflammation can respectively initiate or propagate disease. Recent data have begun to uncover the molecular mechanisms by which inflammation - driven by Toll-like receptor 4-regulated cytokines, immune cells and signalling pathways - contributes to the pathogenesis of hydrocephalus. We propose that therapeutic approaches that target inflammatory mediators in both PHH and PIH could address the multiple drivers of disease, including choroid plexus CSF hypersecretion, ependymal denudation, and damage and scarring of intraventricular and parenchymal (glia-lymphatic) CSF pathways. Here, we review the evidence for a prominent role of inflammation in the pathogenic mechanism of PHH and PIH and highlight promising targets for therapeutic intervention. Focusing research efforts on inflammation could shift our view of hydrocephalus from that of a lifelong neurosurgical disorder to that of a preventable neuroinflammatory condition.

Bacterial meningitis: new treatment options to reduce the risk of brain damage

Introduction: Bacterial meningitis (BM) is a medical emergency and its etiology varies according to the age group and geographic area. Studies have shown that brain damage, sequelae and neuropsychological deficits depend not only on the direct deleterious action of the pathogens, but also on the host defenses themselves.Areas covered: Corticosteroids (CS) were the first drugs used with the intent to limit the exaggerated host response. However, as steroid addition to antibiotics is frequently unsatisfactory, other measures have been suggested. In this study, the most important adjuvant therapies that are potentially useful to limit the neuropsychological damage of BM are discussed.Expert opinion: The pathophysiological mechanisms leading to the development of brain damage are not completely defined. Moreover, the efficacy of adjuvant therapies can vary according to the aetiologic cause of BM, and differences in immune system function of the host can play a relevant role in the expression of inflammation and related problems. It is likely that none of the measures with demonstrated efficacy in animal models can be translated into clinical practice in the next few years, suggesting that to reduce the total burden of BM, the increased use of vaccines seems to be the best solution.

Rickettsial infections of the central nervous system

As a result of migrations and globalization, people may face a possible increase in the incidence of central nervous system rickettsial infections (CNS R). These diseases, caused by Rickettsia species and transmitted to humans by arthropod bites, are putatively lethal. However, the diagnosis of CNS R is challenging and often delayed due to their nonspecific clinical presentation and the strict intracellular nature of rickettsiae. Furthermore, transfer of rickettsiae to the brain parenchyma is not yet understood. The aim of this review is to analyze and summarize the features and correlated findings of CNS R in order to focus attention on these intriguing but frequently neglected illnesses. We also incorporated data on CNS infections caused by Rickettsia-related microorganisms.

Ureaplasma Species Modulate Cytokine and Chemokine Responses in Human Brain Microvascular Endothelial Cells

Ureaplasma species are common colonizers of the adult genitourinary tract and often considered as low-virulence commensals. Intraamniotic Ureaplasma infections, however, facilitate chorioamnionitis and preterm birth, and cases of Ureaplasma-induced neonatal sepsis, pneumonia, and meningitis raise a growing awareness of their clinical relevance. In vitro studies are scarce but demonstrate distinct Ureaplasma-driven impacts on immune mechanisms. The current study addressed cytokine and chemokine responses upon exposure of native or lipopolysaccharide (LPS) co-stimulated human brain microvascular endothelial cells (HBMEC) to Ureaplasma urealyticum or U. parvum, using qRT-PCR, RNA sequencing, multi-analyte immunoassay, and flow cytometry. Ureaplasma exposure in native HBMEC reduced monocyte chemoattractant protein (MCP)-3 mRNA expression (p < 0.01, vs. broth). In co-stimulated HBMEC, Ureaplasma spp. attenuated LPS-evoked mRNA responses for C-X-C chemokine ligand 5, MCP-1, and MCP-3 (p < 0.05, vs. LPS) and mitigated LPS-driven interleukin (IL)-1α protein secretion, as well as IL-8 mRNA and protein responses (p < 0.05). Furthermore, Ureaplasma isolates increased C-X-C chemokine receptor 4 mRNA levels in native and LPS co-stimulated HBMEC (p < 0.05). The presented results may imply immunomodulatory capacities of Ureaplasma spp. which may ultimately promote chronic colonization and long-term neuroinflammation.

Prognostic factors in pediatric pneumococcal meningitis patients in mainland China: a retrospective multicenter study

Background: Prognosis of pneumococcal meningitis (PM) remains very poor, especially in less developed countries. Currently, few multi-centric studies on pediatric PM have been reported in mainland China.

Objectives: This study aimed to explore the correlation of clinical and laboratory findings with complications and prognosis in pediatric PM.

Methods: The pediatric PM patients were retrospectively recruited from ten pediatric tertiary hospitals across China between January 2013 and June 2018. Clinical, biochemical, and microbiological data and follow-up information were collected. Predictive factors for complications and prognostic factors for overall survival (OS) and sequelae-free survival (SFS) were analyzed.

Results: A total of 132 pediatric PM patients were included. Seventy-one patients had complications, 25 patients died, and 39 patients had neurological sequelae. Multivariate logistic regression suggested that age less than 28 months (adjusted OR=2.654, 95%CI=1.067–6.600, P=0.036) and lower white blood cells in blood (aOR=3.169, 95%CI=1.395–7.202, P=0.006) were associated with high risk of complications. Multivariate Cox’s proportional hazard regression suggested that age less than 28 months (aHR=6.479, 95%CI=1.153–36.404, P=0.034), coma (aHR=9.808, 95%CI=2.802–34.323, P=0.000), and non-adjuvant steroid therapy (aHR=4.768 95%CI=1.946–11.678, P=0.001) were independent prognostic factors for poor OS; coma (aHR=5.841, 95%CI=2.652–12.864, P=0.000), septic shock on admission (aHR=2.949, 95%CI=1.049–8.290, P=0.040), and lower glucose level in cerebrospinal fluid (CSF) (aHR=2.523, 95%CI=1.336–4.765, P=0.004) were independent prognostic factors for poor SFS.

Conclusion: Age, coma, and adjuvant steroid therapy were independent factors for OS, while coma, septic shock on admission, and lower glucose level in CSF were independent factors for SFS in pediatric PM patients. These factors might be used to identify PM patients with poor prognosis and guide individual treatment.

Clinical presentations, Laboratory analysis and Linear Growth in 50 Neonates and Young Infants with Acute Meningitis: One Year Experience of a Single Center in Qatar

Background

Meningitis frequently occurs in neonates and can lead to a number of acute, severe complications and long-term disabilities. Although, long term growth delay and abnormal weight gain appear to be risk factors following an acute attack of both bacterial and aseptic meningitis in children, especially during the fast phase of infantile growth, the long-term effects of acute meningitis occurring during the neonatal and early infantile periods on linear growth (length, weight and head growth) have not fully reported.

Aim of the study

The objective of this study is to describe the clinical presentation of neonates and young infants with acute meningitis with different etiologies and to determine the clinical impact of the effect of acute meningitis on growth parameters.

Material and methods

We analyzed the clinical data and the growth parameters of 50 newborns and young infants (age: 1.6 ± 0.9 months) admitted to our hospital (Al Wakhra Hospital, Department of Pediatrics, Doha, Qatar), between 1-1-2016 to 1-1-2017, with acute meningitis. Anthropometric measurements included weight, length, and head circumference. Length SDS (L-SDS) and body-mass-index (BMI) were calculated and recorded at every clinic visit, every 3 months for 8 ± 2 months.

Results

In this age group of neonates and young infants with acute meningitis fever (84%) and hypoactivity (64%) were the major presenting manifestations. Acute bacterial meningitis (n: 10) was associated with higher morbidity [shock (n: 1), subdural empyema (n: 1) and hydrocephalus (n: 1)]. Cerebrospinal fluid (CSF) examinations showed that infants with bacterial meningitis had significantly higher pleiocytosis of mainly polymorphic leukocytes and protein levels, compared to those with aseptic meningitis.

All infants showed normal linear growth and weight gain during the follow-up period (8 ± 2 months). The annualized growth rate of infants was 25.3 ± 3.5 cm per year. All had normal length standard deviation scores (LSDS) (−0.2 ± 0.9) and none of them had LSDS < −2. All infants had a normal BMI (16.7 ± 1.8 kg/m²). Head circumference growth was normal in 49/50 infants (43.8 ± 1.8 cm) at 8 ± 2 months. One infant developed hydrocephalus after group B streptococcus (GBS) meningitis. There was no statistical difference in linear growth between infants with aseptic and bacterial meningitis.

Conclusion

Acute bacterial meningitis in newborns and young infants is still associated with considerably high morbidity and complications. Infantile linear growth appears to be normal in all newborns and young infants with both bacterial and aseptic meningitis.

More than just inflammation: Ureaplasma species induce apoptosis in human brain microvascular endothelial cells

Background

Ureaplasma species (spp.) are commonly regarded as low-virulent commensals but may cause invasive diseases in immunocompromised adults and in neonates, including neonatal meningitis. The interactions of Ureaplasma spp. with host defense mechanisms are poorly understood. This study addressed Ureaplasma-driven cell death, concentrating on apoptosis as well as inflammatory cell death.

Methods

Human brain microvascular endothelial cells (HBMEC) were exposed to Ureaplasma (U.) urealyticum serovar 8 (Uu8) and U. parvum serovar 3 (Up3). Resulting numbers of dead cells as well as mRNA levels and enzyme activity of key agents in programmed cell death were assessed by flow cytometry, RNA sequencing, and qRT-PCR, respectively. xCELLigence data were used for real-time monitoring of changes in cell adhesion properties.

Results

Both Ureaplasma isolates induced cell death (p < 0.05, vs. broth). Furthermore, Ureaplasma spp. enhanced mRNA levels for genes in apoptosis, including caspase 3 (Up3 p < 0.05, vs. broth), caspase 7 (p < 0.01), and caspase 9 (Up3 p < 0.01). Caspase 3 activity was increased upon Uu8 exposure (p < 0.01). Vice versa, Ureaplasma isolates downregulated mRNA levels for proteins involved in inflammatory cell death, namely caspase 1 (Uu8 p < 0.01, Up3 p < 0.001), caspase 4 (Uu8 p < 0.05, Up3 p < 0.01), NOD-like receptor pyrin domain-containing 3 (Uu8 p < 0.05), and receptor-interacting protein kinase 3 (p < 0.05).

Conclusions

By inducing apoptosis in HBMEC as main constituents of the blood-brain barrier, Ureaplasma spp. may provoke barrier breakdown. Simultaneous suppression of inflammatory cell death may additionally attenuate host defense strategies. Ultimate consequence could be invasive and long-term CNS infections by Ureaplasma spp.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1413-8) contains supplementary material, which is available to authorized users.

Turkish Neonatal Society guideline on neonatal infections-diagnosis and treatment

Neonatal infections are a major cause of morbidity and mortality in the first month of life, especially in developing countries. Despite advances in neonatology, neonatal infections still haves clinical importance because of nonspecific signs and symptoms, no perfect diagnostic marker, and interference with non-infectious diseases of newborns. Diagnosis is typically made by clinical and laboratory findings. Empiric antibiotic therapy should be started in a newborn with signs and symptoms of infection after cultures are taken according to the time of the signs and symptoms, risk factors, admission from community or hospital, focus of infection, and antibiotic susceptibility estimation. Treatment should be continued according to clinical findings and culture results. Intrapartum antibiotic prophylaxis, proper hand washing, aseptic techniques for invasive procedures, appropriate neonatal intensive care unit design, isolation procedures, and especially breast milk use are needed to prevent infections. The use of diagnosis and treatment protocols increases clinical success.

Risk Factors in Predicting Prognosis of Neonatal Bacterial Meningitis-A Systematic Review

Background: Neonatal bacterial meningitis is a severe infection with high mortality and morbidity. It is necessary to identify factors associated with a high risk of a poor prognosis so that we can prevent them with more appropriate treatments. This study was performed to summarize the prognostic factors known to predict adverse outcomes in neonatal bacterial meningitis.

Methods: The Medline/PubMed, Cochrane Library and Embase databases were searched for studies of prognostic risk factors in neonates with bacterial meningitis. Studies published from the initiation of the database to April 30th, 2017 were included. The quality of cohort studies was assessed by the Newcastle-Ottawa Scale (NOS). The quality of cross-section studies was assessed by the Agency for Healthcare Research and Quality (AHRQ) scale. Each prognostic factor known to cause adverse outcomes is summarized.

Results: Sixteen studies were identified, including 7 cohort studies and 9 cross section studies. Seizure and high protein levels in the cerebrospinal fluid (CSF) predict a poor prognosis in this disease. Coma, the need for ventilation support, and leukopenia also had some value for predicting poor prognoses. A bulging anterior fontanelle was valuable for predicting mortality. Low CSF glucose levels, thrombocytopenia, gestational age (GA) < 37 weeks and an altered sensorium were correlated with a poor prognosis. A birth weight < 2500 g, early onset meningitis and positive CSF cultures were correlated with mortality.

Conclusions: This study provides a preliminary exploration of prognostic factors in neonatal bacterial meningitis and thereby fills some of the gaps in the study of prognoses in this disease. These prognostic factors can be used to predict and estimate outcomes in neonatal bacterial meningitis. Without a meta-analysis, the reliability of these factors cannot be assured. In addition, these results emphasize that there is an urgent need for a standardized protocol for follow-up and well-designed prognostic studies in neonatal bacterial meningitis.

Neurological Complications in Young Infants With Acute Bacterial Meningitis

We aimed to evaluate the occurrence, treatment, and outcomes of neurological complications after bacterial meningitis in young infants. A case series study from a retrospective cohort from two tertiary-level medical centers in Taiwan between 2007 and 2016 was conducted. Eighty-five young infants aged < 90 days with bacterial meningitis were identified. 25 (29.4%) were born at preterm. Group B Streptococcus (GBS) and Escherichia coli caused 74.1% of identified cases. Despite the majority (90.6%) initially received microbiologically appropriate antibiotics, 65 (76.5%) had experienced at least one neurological complication identified at a median of 6 days (range: 1–173) after onset of bacterial meningitis. The most common neurological complication was seizure (58.8%), followed by subdural effusion (47.1%), ventriculomegaly (41.2%), subdural empyema (21.2%), hydrocephalus (18.8%), ventriculitis (15.3%), periventricular leukomalacia (11.8%), and encephalomalacia (10.6%). Nine patients (10.6%) died (including 4 had critical discharge on request) and 29/76 (38.2%) of the survivors had major neurological sequelae at discharge. Nighteen (22.4%) received surgical intervention due to these complications. After multivariate logistic regression, initial seizure (adjusted odds ratio [aOR]: 4.76, 95% confidence interval [CI]: 1.7–13.0, P = 0.002) and septic shock (aOR: 6.04; 95% CI: 1.35–27.0, P = 0.019) were independent predictors for final unfavorable outcomes.

Conclusions: Neurological complications and sequelae are common in young infants after bacterial meningitis. Patients presented with early seizure or septic shock can be an early predictor of final unfavorable outcomes and require close monitoring. Further research regarding how to improve clinical management and outcomes is warranted.

A mouse model reproducing the pathophysiology of neonatal group B streptococcal infection

Group B streptococcal (GBS) meningitis remains a devastating disease. The absence of an animal model reproducing the natural infectious process has limited our understanding of the disease and, consequently, delayed the development of effective treatments. We describe here a mouse model in which bacteria are transmitted to the offspring from vaginally colonised pregnant females, the natural route of infection. We show that GBS strain BM110, belonging to the CC17 clonal complex, is more virulent in this vertical transmission model than the isogenic mutant BM110∆cylE, which is deprived of hemolysin/cytolysin. Pups exposed to the more virulent strain exhibit higher mortality rates and lung inflammation than those exposed to the attenuated strain. Moreover, pups that survive to BM110 infection present neurological developmental disability, revealed by impaired learning performance and memory in adulthood. The use of this new mouse model, that reproduces key steps of GBS infection in newborns, will promote a better understanding of the physiopathology of GBS-induced meningitis.

Animal models of group-B streptococcal infections are needed to develop effective therapies. Here, Andrade et al. present a mouse model in which the bacteria are transmitted from vaginally colonised pregnant females to their offspring, causing neonatal meningitis and neurological developmental disabilities.

Relevant analyses of pathogenic bacteria and inflammatory factors in neonatal purulent meningitis

Pathogenic bacteria and inflammatory factors in neonatal purulent meningitis (PM) were investigated to explore the diagnostic value of inflammatory factors in PM, to clarify the etiology, and to provide evidence for rational clinical treatment. Seventy-four neonates who were diagnosed with PM and were bacteriogically positive in Daqing Longnan Hospital from January 2012 to December 2015 were retrospectively analyzed and used as observation group. Another 74 neonates simultaneously hospitalized with non-PM factors were selected as control group. The levels of C-reactive protein (CRP) and β 2 microglobulin (β2MG) in cerebrospinal fluid in pediatric patients were measured, and the separation culture and identification of pathogenic bacteria were carried out at the same time. The results showed that i) neonatal PM often lacked specific clinical manifestations; ii) high risk factors of neonatal PM included gestational age, body weight <2,500 g, neonatal asphyxia, premature rupture of membranes, and umbilical or pulmonary infection; iii) the levels of CRP and β2MG in the cerebrospinal fluid in the neonatal PM group were significantly higher than those in the control group (P<0.05), and the neonatal PM group had obviously decreased levels of CRP and β2MG in the cerebrospinal fluid after treatment compared with those before treatment (P<0.05); iv) the positive rate of Gram-negative bacilli (G-bacilli) showed an increasing trend year by year in the past 4 years. Seventy-four strains of bacteria were isolated from the cerebrospinal fluid in neonatal PM group, including 45 strains of Gram-positive cocci (G+cocci, accounting for 60.81%) and 29 strains of G-bacilli (accounting for 39.19%). Among them, the top three were Escherichia coli, coagulase-negative staphylococci (CNS) and Streptococcus. These findings indicated that for suspected PM pediatric patients with high risk factors, the inflammatory factors in cerebrospinal fluid and the etiology should be investigated via lumbar puncture as early as possible to confirm the diagnosis. Pathogenic bacteria of meningitis mainly are Escherichia coli, CNS and Streptococcus, and the characteristics of pathogenic bacteria should be considered during experiential medication. The incidence rate of PM due to Streptococcus has an upward tendency and great damage, needing to arouse high attention in clinic.

Novel insights into neuroinflammation: bacterial lipopolysaccharide, tumor necrosis factor α, and Ureaplasma species differentially modulate atypical chemokine receptor 3 responses in human brain microvascular endothelial cells

BACKGROUND

Atypical chemokine receptor 3 (ACKR3, synonym CXCR7) is increasingly considered relevant in neuroinflammatory conditions, in which its upregulation contributes to compromised endothelial barrier function and may ultimately allow inflammatory brain injury. While an impact of ACKR3 has been recognized in several neurological autoimmune diseases, neuroinflammation may also result from infectious agents, including Ureaplasma species (spp.). Although commonly regarded as commensals of the adult urogenital tract, Ureaplasma spp. may cause invasive infections in immunocompromised adults as well as in neonates and appear to be relevant pathogens in neonatal meningitis. Nonetheless, clinical and in vitro data on Ureaplasma-induced inflammation are scarce.

METHODS

We established a cell culture model of Ureaplasma meningitis, aiming to analyze ACKR3 variances as a possible pathomechanism in Ureaplasma-associated neuroinflammation. Non-immortalized human brain microvascular endothelial cells (HBMEC) were exposed to bacterial lipopolysaccharide (LPS) or tumor necrosis factor-α (TNF-α), and native as well as LPS-primed HBMEC were cultured with Ureaplasma urealyticum serovar 8 (Uu8) and U. parvum serovar 3 (Up3). ACKR3 responses were assessed via qRT-PCR, RNA sequencing, flow cytometry, and immunocytochemistry.

RESULTS

LPS, TNF-α, and Ureaplasma spp. influenced ACKR3 expression in HBMEC. LPS and TNF-α significantly induced ACKR3 mRNA expression (p < 0.001, vs. control), whereas Ureaplasma spp. enhanced ACKR3 protein expression in HBMEC (p < 0.01, vs. broth control). Co-stimulation with LPS and either Ureaplasma isolate intensified ACKR3 responses (p < 0.05, vs. LPS). Furthermore, stimulation wielded a differential influence on the receptor's ligands.

CONCLUSIONS

We introduce an in vitro model of Ureaplasma meningitis. We are able to demonstrate a pro-inflammatory capacity of Ureaplasma spp. in native and, even more so, in LPS-primed HBMEC, underlining their clinical relevance particularly in a setting of co-infection. Furthermore, our data may indicate a novel role for ACKR3, with an impact not limited to auto-inflammatory diseases, but extending to infection-related neuroinflammation as well. AKCR3-induced blood-brain barrier breakdown might constitute a potential common pathomechanism.

The myth of the immature barrier systems in the developing brain: role in perinatal brain injury

Central nervous system homeostasis is maintained by cellular barriers that protect the brain from external environmental changes and protect the CNS from harmful molecules and pathogens in the blood. Historically, for many years these barriers were thought of as immature, with limited functions, during brain development. In this review, we will present advances in the understanding of the barrier systems during development and evidence to show that in fact the barriers serve many important neurodevelopmental functions and that fetal and newborn brains are well protected. We will also discuss how ischaemic injury or systemic inflammation may breach the integrity of the barriers in the developing brain.

Temporal changes of oxidative stress markers in Escherichia coli K1-induced experimental meningitis in a neonatal rat model

Despite advances in antimicrobial therapy and advanced critical care neonatal bacterial meningitis has a mortality rate of over 10% and induces neurological sequelae in 20-50% of cases. Escherichia coli K1 (E. coli K1) is the most common gram-negative organism causing neonatal meningitis and is the second most common cause behind group B streptococcus. We previously reported that an E. coli K1 experimental meningitis infection in neonatal rats resulted in habituation and aversive memory impairment and a significant increase in cytokine levels in adulthood. In this present study, we investigated the oxidative stress profile including malondialdehyde (MDA) levels, carbonyl protein formation, myeloperoxidase activity (MPO) activity, superoxide dismutase (SOD) activity and catalase (CAT) activity 6, 12, 24, 48, 72 and 96h after E. coli K1 experimental meningitis infection. In addition, sulfhydryl groups, nitrite and nitrate levels and activity of the mitochondrial respiratory chain enzymes were also measured in the frontal cortex and hippocampus of neonatal rats. The results from this study demonstrated a significant increase in MDA, protein carbonyls and MPO activity and a simultaneous decrease in SOD activity in the hippocampus of the neonatal meningitis survivors but the same was not observed in frontal cortex. In addition, we also observed a significant increase in complex IV activity in the hippocampus and frontal cortex of meningitis survivor rats. Thus, the results from this study reaffirmed the possible role of oxidative stress, nitric oxide and its related compounds in the complex pathophysiology of E. coli K1-induced bacterial meningitis.

Epidemiology of Cerebrospinal Fluid Cultures and Time to Detection in Term Infants

BACKGROUND

Although meningitis is rare in previously healthy term infants, lumbar puncture is often performed to evaluate for source of illness. This study was performed to determine the time to detection for positive cerebrospinal fluid (CSF) cultures and to provide an update on the current epidemiology of bacterial meningitis in term infants.

METHODS

This study was a multicenter, retrospective review of positive CSF cultures in infants ≤90 days of age. Specimens were drawn in the emergency department or inpatient setting between January 2000 and December 2013. Cultures were deemed true pathogens or contaminant species based on the attending physician's treatment plan. Cultures from premature infants, an operative source, or those with significant medical history were excluded.

RESULTS

A total of 410 positive CSF culture results were included, with 53 (12.9%) true pathogens and 357 (87.1%) contaminant species. The mean ± SD time to detection for true pathogens was 28.6 ± 16.8 hours (95% confidence interval, 24-33.2); for contaminant species, it was 68.1 ± 36.2 hours (95% confidence interval, 64.3-71.9). Forty-three true-positive cases (81.1%) were positive in ≤36 hours. The most common pathogen was group B Streptococcus (51%), followed by Escherichia coli (13%) and Streptococcus pneumoniae (9%).

CONCLUSIONS

The majority of pathogenic bacteria in CSF exhibit growth within 36 hours. Most growth from CSF cultures in febrile infants is treated as contamination. The epidemiology of meningitis has remained constant, with group B Streptococcus as the predominant pathogen, despite changes noted in the epidemiology of bacteremia in this population.

Of the Phrensy: an update on the epidemiology and pathogenesis of bacterial meningitis in the pediatric population

In the past century, advances in antibiotics and vaccination have dramatically altered the incidence and clinical outcomes of bacterial meningitis. We review the shifting epidemiology of meningitis in children, including after the implementation of vaccines that target common meningitic pathogens and the introduction of intrapartum antibiotic prophylaxis offered to mothers colonized with Streptococcus agalactiae. We also discuss what is currently known about the pathogenesis of meningitis. Recent studies of the human microbiome have illustrated dynamic relationships of bacterial and viral populations with the host, which may potentiate the risk of bacterial meningitis.

The effects of cytotoxic necrotizing factor 1 expression in the uptake of Escherichia coli K1 by macrophages and the onset of meningitis in newborn mice

Macrophages are a permissive niche for E. coli K1 multiplication for which the interaction of the bacterial outer membrane protein A and its cognate receptor CD64 are critical. Using in vitro immunofluorescence and live microscopy with ex vivo macrophage cultures from RFP-Lifeact mice, we show that cytotoxic necrotizing factor 1 (CNF1) secreted by E. coli K1 sequesters cellular actin toward microspike formation, thereby limiting actin availability for OmpA-mediated bacterial invasion. Surprisingly, the observed effects of CNF1 occur despite the absence of 67-kDa laminin receptor in macrophages. Concomitantly, the CNF1 deletion mutant of E. coli K1 (Δcnf1) invades macrophages and the brains of newborn mice in greater numbers compared to wild-type. However, the Δcnf1 strain induces less severe pathology in the brain. These results suggest a novel role for CNF1 in limiting E. coli K1 entry into macrophages while exacerbating disease severity in the brains of newborn mice.