Infantile and childhood bacterial meningitis. Pediatric Neurology Part II. Elsevier; 2013. pp. 1115-25. [DOI: 10.1016/b978-0-444-52910-7.00031-3]

Non-contrast Enhancing Group A Streptococcus Subdural Empyema: An Illustrative Case Report of a Potential Radiographic Pitfall

Subdural empyemas (SDEs) are an uncommon complication of intracranial infection, typically presenting as a hypodense collection with peripheral contrast enhancement. Herein, we report two rare cases of SDE without contrast enhancement, both secondary to group A streptococcus. The first is a 27-year-old previously healthy female, at 27 weeks of gestational age who presented with fever, headache, neurological decline, and blood cultures positive for gram-positive cocci. The second case is a previously healthy 48-year-old male who presented with left-sided otalgia, fever, headache, and precipitous decline in altered mental status and hemiplegia. Computed tomography (CT) and magnetic resonance imaging (MRI) in both cases showed a subdural collection without contrast enhancement and without diffusion restriction. Despite appearances similar to subdural effusion, because of a heightened suspicion due to clinical decline, both were taken to surgery for irrigation and debridement which confirmed SDE. Both patients were treated with six weeks of intravenous antibiotics and eventually recovered without neurological deficits. SDEs are uncommon but clinically significant phenomena. These two cases demonstrate that SDEs in rare circumstances may present as non-enhancing subdural collections. Missing the diagnosis of SDE can have significant consequences to patient morbidity and mortality and as such, it not be excluded based on radiographic findings alone.

Neurological sequelae remain frequent after bacterial meningitis in children

AIM

To examine the incidence, clinical presentation and risk factors for neurological sequelae following childhood community-acquired bacterial meningitis (CABM).

METHODS

We included all children aged 1 month to 15 years old with CABM in North Denmark Region, 1998-2016. Using medical records, we registered baseline demographics, signs and symptoms at admission, laboratory investigations, and outcome assessed by the Glasgow Outcome Scale (GOS). A GOS score of 1-4 was considered an unfavourable outcome. We used modified Poisson regression to examine predefined risk factors for neurological sequelae among survivors.

RESULTS

We identified 88 cases of CABM in 86 patients (45 female) with a median age of 1.4 years (interquartile range 0.7-4.6). Neisseria meningitidis was the most common pathogen (48/88). Neurological sequelae occurred in 23 (27%) as hearing deficits in 13 (15%), cognitive impairment in 10 (12%) and motor or sensory nerve deficits in 8 (9%). Unfavourable outcome was observed in 16 (18%) patients and three (3%) patients died. Abnormalities on cranial imaging remained the only independent risk factor for developing neurological sequelae in adjusted analysis.

CONCLUSION

Neurological sequelae following CABM in children remain frequent and abnormal cranial imaging may be an independent risk factor.

The cerebral protective effect and mechanism of action of vitamin B6 adjuvant ceftriaxone in experimental pneumococcal meningitis

BACKGROUND

Pneumococcal meningitis is one of the most common infectious diseases with a high-mortality rate and long-term neurological sequelae, affecting up to 50% of survivors. Pneumococcal compounds are pro-inflammatory mediators that induce an innate immune response and tryptophan degradation through the kynurenine pathway. Vitamin B6 (vitB6) is an important vitamin which acts as a cofactor at the active sites of enzymes that catalyze a great number of reactions involved in the metabolism of tryptophan through the kynurenine pathway and may thus limit the accumulation of neurotoxic metabolites and preserve the cellular energy status. The aim of this study was to investigate the neuroprotective effect of adjuvant treatment with vitB6 in pneumococcal meningitis.

METHODS

The effects of vitB6 on the clinical symptoms, the expression of kynureninase (KYN), Kynurenic acid (KYNA), nicotinamide adenine dinucleotide (NAD) and cytokines in brain tissue and memory of infant Wistar rats subjected to pneumococcal meningitis were researched. At the same time, Kynurenine 3-monooxygenase (KMO) inhibitor Ro 61-8048 was applied in order to further investigate the brain protective effect of vitB6 in bacterial meningitis.

RESULTS

Adjuvant therapy of bacterial meningitis with vitB6 could improve the clinical symptoms, learning performance, lead to the maintenance of cellular NAD+ and ATP homeostasis and significantly down-regulate the levels of cytokines in the brain tissue by affecting the KYN pathway.

CONCLUSIONS

Adjuvant treatment with vitB6 in pneumococcal meningitis could exert neuroprotective effect via increasing the preservation of cellular energy through affecting the KYN pathway and reducing of the inflammatory response.

Increased Intracranial Pressure in the Setting of Enterovirus and Other Viral Meningitides

Increased intracranial pressure due to viral meningitis has not been widely discussed in the literature, although associations with Varicella and rarely Enterovirus have been described. Patients with increased intracranial pressure and cerebrospinal fluid analysis suggestive of a viral process are sometimes classified as having atypical idiopathic intracranial hypertension (IIH). However, a diagnosis of IIH requires normal cerebrospinal fluid, and therefore in these cases an infection with secondary intracranial hypertension may be a more likely diagnosis. Here seven patients are presented with elevated intracranial pressure and cerebrospinal fluid suggestive of viral or aseptic meningitis. Of these, 1 had Enterovirus and the remainder were diagnosed with nonspecific viral meningitis. These data suggest that viral meningitis may be associated with elevated intracranial pressure more often than is commonly recognized. Enterovirus has previously been associated with increased intracranial pressure only in rare case reports.

Pathogenic Triad in Bacterial Meningitis: Pathogen Invasion, NF-κB Activation, and Leukocyte Transmigration that Occur at the Blood-Brain Barrier

Bacterial meningitis remains the leading cause of disabilities worldwide. This life-threatening disease has a high mortality rate despite the availability of antibiotics and improved critical care. The interactions between bacterial surface components and host defense systems that initiate bacterial meningitis have been studied in molecular and cellular detail over the past several decades. Bacterial meningitis commonly exhibits triad hallmark features (THFs): pathogen penetration, nuclear factor-kappaB (NF-κB) activation in coordination with type 1 interferon (IFN) signaling and leukocyte transmigration that occur at the blood-brain barrier (BBB), which consists mainly of brain microvascular endothelial cells (BMEC). This review outlines the progression of these early inter-correlated events contributing to the central nervous system (CNS) inflammation and injury during the pathogenesis of bacterial meningitis. A better understanding of these issues is not only imperative to elucidating the pathogenic mechanism of bacterial meningitis, but may also provide the in-depth insight into the development of novel therapeutic interventions against this disease.

The kynurenine pathway is involved in bacterial meningitis

BACKGROUND

Bacterial meningitis (BM) is characterized by an intense host inflammatory reaction, which contributes to the development of brain damage and neuronal sequelae. Activation of the kynurenine (KYN) pathway (KP) has been reported in various neurological diseases as a consequence of inflammation. Previously, the KP was shown to be activated in animal models of BM, and the association of the SNP AADAT + 401C/T (kynurenine aminotransferase II - KAT II) with the host immune response to BM has been described. The aim of this study was to investigate the involvement of the KP during BM in humans by assessing the concentrations of KYN metabolites in the cerebrospinal fluid (CSF) of BM patients and their relationship with the inflammatory response compared to aseptic meningitis (AM) and non-meningitis (NM) groups.

METHODS

The concentrations of tryptophan (TRP), KYN, kynurenic acid (KYNA) and anthranilic acid (AA) were assessed by HPLC from CSF samples of patients hospitalized in the Giselda Trigueiro Hospital in Natal (Rio Grande do Norte, Brazil). The KYN/TRP ratio was used as an index of indoleamine 2,3-dioxygenase (IDO) activity, and cytokines were measured using a multiplex cytokine assay. The KYNA level was also analyzed in relation to AADAT + 401C/T genotypes.

RESULTS

In CSF from patients with BM, elevated levels of KYN, KYNA, AA, IDO activity and cytokines were observed. The cytokines INF-γ and IL-1Ra showed a positive correlation with IDO activity, and TNF-α and IL-10 were positively correlated with KYN and KYNA, respectively. Furthermore, the highest levels of KYNA were associated with the AADAT + 401 C/T variant allele.

CONCLUSION

This study suggests a downward modulatory effect of the KP on CSF inflammation during BM.