Long-term outcomes of pneumococcal meningitis in childhood and adolescence

Neuroinfectious Diseases in Children: Pathophysiology, Outcomes, and Global Challenges

Pathogens with affinity for the central nervous system (CNS) in children are diverse in their mechanisms of infecting and attacking the brain. Infections can reach the CNS via hematogenous routes, transneurally thereby avoiding the blood-brain barrier, and across mucosal or skin surfaces. Once transmission occurs, pathogens can wreak havoc both by direct action on host cells and via an intricate interplay between the protective and pathologic actions of the host's immune system. Pathogen prevalence varies depending on region, and susceptibility differs based on epidemiologic factors such as age, immune status, and genetics. In addition, some infectious diseases are monophasic, whereas others may lie dormant for years, thereby causing a dynamic effect on outcomes. Outcomes in survivors are highly variable for each particular pathogen and depend on the vaccination and immune status of the patient as well as the speed by which the patient receives evidence-based treatments. Given pathogens cause communicable diseases that can cause morbidity and mortality on a population level when spread, the burden is often the greatest and the outcomes the worst in low-resource settings. Here we will focus on the most common infections with a propensity to affect a child's brain, the pathologic mechanisms by which they do so, and what is known about the developmental outcomes in children who are affected by these infections.

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.

Monetary Valuation of Children's Cognitive Outcomes in Economic Evaluations from a Societal Perspective: A Review

Cognitive ability in childhood is positively associated with economic productivity in adulthood. Expected gains in economic output from interventions that protect cognitive function can be incorporated in benefit-cost and cost-effectiveness analyses conducted from a societal perspective. This review summarizes estimates from high-income countries of the association of general cognitive ability, standardized as intelligence quotient (IQ), with annual and lifetime earnings among adults. Estimates of the association of adult earnings with cognitive ability assessed in childhood or adolescence vary from 0.5% to 2.5% per IQ point. That range reflects differences in data sources and analytic methods. We take a conservative published estimate of a 1.4% difference in market productivity per IQ point in the United States from a recent study that controlled for confounding by family background and behavioral attributes. Using that estimate and the present value of lifetime earnings calculated using a 3% discount rate, the implied lifetime monetary valuation of an IQ point in the United States is USD 10,600-13,100. Despite uncertainty and the exclusion of non-market productivity, incorporation of such estimates could lead to a fuller assessment of the benefits of public health and clinical interventions that protect the developing brains of fetuses, infants, and young children.

Mini-Review: Bioactivities of Bacterial Cell Envelopes in the Central Nervous System

During acute bacterial meningitis, recognition of the bacterial envelope by immune cells of the central nervous system (CNS) generates a robust response that is essential to clear bacteria. This response is further amplified during treatment when lytic antibiotics, required for cure, also generate a burst of highly inflammatory cell envelope debris. Different peptidoglycan (PG) subcomponents interact with neurons, glia, and the blood brain barrier resulting in the entire symptom complex of meningitis. Recently, this CNS-cell envelope signaling axis has been extended to non-inflammatory recognition of cell wall components circulating from endogenous bacteria to the brain resulting in both benefit and chronic damage. This review will describe the molecular details of a broad array of cell envelope-induced responses in the CNS and what current strategies can be implemented to improve clinical outcome.

Pneumococcal Meningitis and Its Sequelae - A Devastating CNS Disease

Introduction

In countries where Haemophilus influenzae type B vaccine is used, Streptococcus pneumoniae is the most common cause of bacterial meningitis in young children and notable cause of morbidity/mortality. The authors present material of magnetic resonance imaging (MRI) of patients with pneumococcal meningitis from archive of Department of Diagnostic Imaging of Institute of Mother and Child in Warsaw.

Materials and methods

We performed 27 brain MRI scans and 1 follow-up computed tomography (CT) in 10 children (2 girls and 8 boys) aged from neonate to 5 years at disease onset with proven pneumococcal infection.

Results

Follow-up period range was 0–12 years. Two children underwent only one MRI, one of them died before follow-up and the other was lost from further observation. There was one case of relatively benign disease course with mild changes on MRI. In another seemingly benign case, acute transient hydrocephalus was observed. Six children developed hydrocephalus, and two required ventriculoperitoneal shunting complicated by neuroinfection, shunt malfunction and revisions. Two patients developed epilepsy. In six children, spastic paresis of various severity was diagnosed, up to quadriplegia in one who is under the longest observation (>12 years) and survived in vegetative state. Three other children suffer from delayed psychomotor development to severe intellectual disability.

Conclusions

MRI shows perfectly the degree of central nervous system (CNS) damage during and after pneumococcal invasion. Despite appropriate treatment, disease course may be unpredictably serious. Attempts to eliminate the obligation to vaccinate are extremely irresponsible taking into account potential danger of death, vegetative state or another form of severe damage to CNS. Social and financial costs of care of survivors are very high with shunts placements and changes, (neuro)infections, rehabilitation, families breakdown, etc.

Study protocol: The Dutch 20|30 Postmeningitis study: a cross-sectional follow-up of two historical childhood bacterial meningitis cohorts on long-term outcomes

Background

Bacterial meningitis (BM) is a serious, life-threatening infectious disease of the central nervous system that often occurs in young children. The most common severe to moderate sequelae following BM are sensorineural hearing loss, neuromotor disabilities and mental retardation, while subtle sequelae include academic and behavioral disabilities. It is largely unknown whether these more subtle sequelae persist into adolescence and adulthood. Therefore, this study will investigate the very long-term effects of childhood BM in later life. Better understanding of long-term effects and early identification of adverse outcomes after BM are essential for more timely interventions. Additionally, certain single nucleotide polymorphisms (SNPs) are associated with disease severity and might predict adverse sequelae. These include SNPs in genes encoding for pathogen recognition and immune response upon infection. Accordingly, a secondary objective of this study is to investigate the role of genetic variation in BM and use any insights to predict short- and long-term outcomes.

Methods

In the Dutch 20|30 Postmeningitis study, adolescents and young adults (n = 947) from two historical cohorts with a prior episode of BM during childhood will be enrolled into a cross-sectional follow-up investigation using mainly questionnaires that examine executive and behavioral functioning, health-related quality of life, subjective hearing, mood and sleeping disorders, academic performance, and economic self-sufficiency. The results will be compared to normative data by one-sample t-tests. Multivariable regression analysis will be used to assess for any associations with causative pathogens and severity of BM. Participants that complete the questionnaires will be approached to provide a swab for buccal DNA and subsequent sequencing analyses. Logistic regression models will be used to predict sequelae.

Discussion

The unique follow-up duration of this cohort will enable us to gain insights into the possible very long-term adverse effects of childhood BM and how these might impact on quality of life. The investigation of host genetic factors will contribute to the development of prediction models which will serve as prognostic tools to identify children who are at high risk of adverse outcome after BM.

Trial Registration

Dutch Trial Register NTR-6891. Retrospectively registered 28 December 2017.

Double deficiency of toll-like receptors 2 and 4 alters long-term neurological sequelae in mice cured of pneumococcal meningitis

Toll-like receptor (TLR) 2 and 4 signalling pathways are central to the body’s defence against invading pathogens during pneumococcal meningitis. Whereas several studies support their importance in innate immunity, thereby preventing host mortality, any role in protecting neurological function during meningeal infection is ill-understood. Here we investigated both the acute immunological reaction and the long-term neurobehavioural consequences of experimental pneumococcal meningitis in mice lacking both TLR2 and TLR4. The absence of these TLRs significantly impaired survival in mice inoculated intracerebroventricularly with Streptococcus pneumoniae. During the acute phase of infection, TLR2/4-deficient mice had lower cerebrospinal fluid concentrations of interleukin-1β, and higher interferon-γ, than their wild-type counterparts. After antibiotic cure, TLR2/4 double deficiency was associated with aggravation of behavioural impairment in mice, as shown by diurnal hypolocomotion throughout the adaptation phases in the Intellicage of TLR-deficient mice compared to their wild-type counterparts. While TLR2/4 double deficiency did not affect the cognitive ability of mice in a patrolling task, it aggravated the impairment of cognitive flexibility. We conclude that TLR2 and TLR4 are central to regulating the host inflammatory response in pneumococcal meningitis, which may mediate diverse compensatory mechanisms that protect the host not only against mortality but also long-term neurological complications.

Recurrent Pneumococcal Meningitis in Children: A Multicenter Case-control Study

BACKGROUND

Pneumococcal meningitis (PM) is a serious disease that can rarely recur at a later time after the initial episode.

METHODS

A retrospective multicenter case-control study was conducted with data for children 18 years of age or younger obtained from the National Observatory of Bacterial Meningitis in Children between January 2001 and September 2015. Cases were all patients with RPM. Each case was matched with 2 randomized controls with a single PM episode in the year of the first episode of PM in the case and born the same year. Case and control data were compared.

RESULTS

Among the 1634 PM episodes in children 18 years of age or younger, 24 (1.5%) children had RPM. RPM cases were significantly less frequent than single PM cases in winter (27% vs. 48%; P=0.03) and showed significantly less concomitant ear, nose and throat infections when considering the first episode (30% vs. 56%, P = 0.04) and all episodes (28% vs. 56%, P < 0.01). Cerebrospinal fluid leakage was frequent in RPM cases versus controls (83% vs. 10%, P < 0.01), including 25% discovered after the third PM episode. Immune deficiency was absent in cases and present in 15% of controls. Cases and controls did not differ in death rate or neurologic outcome.

CONCLUSIONS

RPM is rare in children. Cerebrospinal fluid leakage must be considered.

Blood‒Brain Barrier Pathology and CNS Outcomes in Streptococcus pneumoniae Meningitis

Streptococcus pneumoniae is a major meningitis-causing pathogen globally, bringing about significant morbidity and mortality, as well as long-term neurological sequelae in almost half of the survivors. Subsequent to nasopharyngeal colonisation and systemic invasion, translocation across the blood‒brain barrier (BBB) by S. pneumoniae is a crucial early step in the pathogenesis of meningitis. The BBB, which normally protects the central nervous system (CNS) from deleterious molecules within the circulation, becomes dysfunctional in S. pneumoniae invasion due to the effects of pneumococcal toxins and a heightened host inflammatory environment of cytokines, chemokines and reactive oxygen species intracranially. The bacteria‒host interplay within the CNS likely determines not only the degree of BBB pathological changes, but also host survival and the extent of neurological damage. This review explores the relationship between S. pneumoniae bacteria and the host inflammatory response, with an emphasis on the BBB and its roles in CNS protection, as well as both the acute and long-term pathogenesis of meningitis.

Systematic Review: Incidence and Course of Hearing Loss Caused by Bacterial Meningitis: In Search of an Optimal Timed Audiological Follow-up

OBJECTIVE

The objective of this study was to clarify the incidence and course of hearing loss after bacterial meningitis to optimize the audiological follow-up.

DATA SOURCES

The databases Embase, Medline (OvidSP), Web-of-science, Scopus, Cinahl, Cochrane, PubMed publisher, and Google Scholar were used. Only articles written in English were included.

STUDY SELECTION

Articles published from 1985 until March 2015 describing the incidence, risk factors, or course of hearing loss after meningitis were used.

DATA EXTRACTION

The quality of the studies was assessed on three aspects: quality of audiometry, number of patients, and methodological quality.

DATA SYNTHESIS

For each publication, data were entered in spreadsheet software for analysis. The data were analyzed and interpreted using best evidence synthesis.

CONCLUSIONS

The overall quality of the included studies was poor. A major drawback was the quality of the (description of) audiometry, severity, and timing of hearing loss.A systematic review of the literature showed an incidence of hearing loss (>25 ± 5  dB) of 14% and an incidence of 5% for profound hearing loss (>90  dB). Patients with initial normal hearing after meningitis showed stable normal hearing over time. However, initial hearing loss related to meningitis can improve or deteriorate over time.We therefore recommend early audiological testing of all patients who suffered bacterial meningitis. However, long-term audiological follow-up is only needed for patients with early onset hearing loss and not for patients with normal hearing at the first hearing test.

Antibody-induced neutrophil depletion prior to the onset of pneumococcal meningitis influences long-term neurological complications in mice

During pneumococcal meningitis, clearance of bacteria by recruited neutrophils is crucial for host protection. However, these innate immune mechanisms are often insufficient and treatment with antibiotics is necessary to prevent death. Despite this antibiotic treatment, approximately half of all survivors suffer lifelong neurological problems. There is growing evidence indicating the harmful effects of neutrophils on CNS integrity. Therefore, the present study investigated the roles of neutrophils in the acute inflammatory response and the resulting long-term neuropsychological effects in murine pneumococcal meningitis. Long-term behavioural and cognitive functions in mice were measured using an automated IntelliCage system. Neutrophil depletion with antibody 1A8 as adjunctive therapy was shown to remarkably impair survival in meningitic C57BL/6J mice despite antibiotic (ceftriaxone) treatment. This was accompanied by increased bacterial load in the cerebrospinal fluid (CSF) and an increase in IL-1β, but decrease in TNF, within the CSF at 20h after bacterial inoculation. In the longer term, the surviving neutrophil-depleted post-meningitic (PM) mice displayed reduced diurnal hypolocomotion compared to PM mice treated with an isotype antibody. However, they showed nocturnal hyperactivity, and greater learning impairment in a patrolling task that is believed to depend upon an intact hippocampus. The data thus demonstrate two important mechanisms: 1. Neutrophil extravasation into the CNS during pneumococcal meningitis influences the pro-inflammatory response and is central to control of the bacterial load, an increase in which may lead to death. 2. Neutrophil-mediated changes in the acute inflammatory response modulate the neuropsychological sequelae in mice that survive pneumococcal meningitis.

The Burden of Pediatric Invasive Meningococcal Disease in Spain (2008-2013)

BACKGROUND

Invasive meningococcal disease remains a rare infectious disease not only with high mortality but also with important morbidity. Until recently no universal vaccine existed against serogroup B, which explains most of the cases in settings like Europe. The objective of this study was to analyze the clinical course and sequelae of meningococcal disease in Spain.

METHODS

Retrospective review of all children younger than 15 years admitted to any of the 36 hospitals in the MENDICOS Spanish network (www.mendicos.org) with confirmed or probable invasive meningococcal disease in children between January 2008 and December 2013.

RESULTS

A total of 458 cases were identified across the country, most of them occurring in previously healthy children (91.5%; n = 419/458). Median (interquartile range) age was 1.7 (0.7 and 4.6) years, with 53.1% of the cases occurring in children younger than 2 years; 82.1% (n = 368) were laboratory confirmed cases; 95.2% (n = 256) of those serogrouped were serogroup B. The diagnosis was meningitis in 24.9% (n = 114) of the cases, sepsis in 37.1% (n = 170) and both in 38.0% (n = 174). Mean hospital length of stay was 11.6 (10.9) days; 79.2% (n = 354) of the patients required pediatric intensive care unit admission, with a mean pediatric intensive care unit stay of 3.9 (4.9) days; 3.5% (n = 16) died; 12.9% (n = 59) of the survivors were discharged with some kind of physical sequelae, mainly neurological (n = 23).

CONCLUSIONS

Serogroup B invasive meningococcal infection explains substantial morbidity and mortality in Spain, occurring mainly in infants. The recent availability of a vaccine against serogroup B may change this scenario. Given that the vast majority of the cases occur in otherwise healthy children, inclusion of the meningococcal B vaccine in the national immunization program should be carefully considered.

Outcomes of bacterial meningitis in children

OBJECTIVE

Pediatricians are well aware of the immediate risks of bacterial meningitis in children. However, the long-term outcome of the disease has not been extensively studied. We aimed: (i) to evaluate the duration and quality of the long-term follow-up of children diagnosed with bacterial meningitis in a general pediatric department, (ii) to estimate the incidence of sequelae at the various stages of follow-up, and (iii) to compare our data with that of other studies.

METHODS

We conducted a retrospective study and included 34 children (3 months-15 years) who had been hospitalized for bacterial meningitis in the pediatric department of a University Hospital between January 1st, 2001 and December 31st, 2013.

RESULTS

Overall, 32% of patients presented with sequelae and 15% with seizures. Only one patient presented with hearing loss, but 23.5% of patients did not have any hearing test performed. Seven patients had a neuropsychological assessment performed and no severe neuropsychological sequela was observed in this group. The average follow-up duration increased during the study period (from 23 to 49months). The long-term follow-up modalities observed in other studies were highly variable. Assessing the incidence and severity of sequelae was therefore difficult.

CONCLUSION

A standardized follow-up should be implemented by way of a national surveillance network of children presenting with bacterial meningitis.

Assessing Patient-Reported Outcomes in Pediatric Populations With Vaccine-Preventable Infectious Diseases: A Systematic Review of the Literature (the PROCHID Study)

OBJECTIVE

To investigate the use of patient-reported outcomes (PROs) in pediatric populations with vaccine-preventable infectious diseases in high-income Western countries.

METHODS

Systematic review of PRO use in populations younger than 18 years with any of 17 infectious diseases for which vaccines are available or in development. The search was limited to studies performed in Europe, North America, Australia, and New Zealand and published between January 1, 1990, and July 31, 2013. Searches were conducted in Scopus and PsycINFO, and reference lists were manually searched. Results are reported using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Of 6410 titles and abstracts and 174 full-text articles reviewed, 17 full-text articles were included for data extraction. The largest number of PRO studies was carried out in patients with anogenital warts and rotavirus gastroenteritis. No PRO studies were identified for nine conditions. A total of 24 PRO measures (12 generic and 12 disease-specific) were used in the studies reviewed. Most of the instruments used were of high quality. Proxy responses were occasionally obtained when self-report would have been feasible. No validated disease-specific instruments for children with any of the conditions studied were found.

CONCLUSIONS

The paucity of studies and PRO instruments to assess pediatric health status in vaccine-preventable infectious diseases, and the lack of a standardized approach to measurement, makes it difficult to capture the impact of disease and the benefit of vaccination and could potentially hinder decision making. Guidelines from relevant bodies to steer research in this area would be useful.

A population-based prospective birth cohort study of childhood neurocognitive and psychological functioning in healthy survivors of early life meningitis

PURPOSE

To determine neurocognitive, educational, and psychological functioning during childhood and early adolescence among survivors of early life meningitis who are apparently healthy.

METHODS

In the general population-based Avon Longitudinal Study of Parents and Children birth cohort, meningitis exposure was determined at age of 18 months. The outcomes of intelligence quotient, short-term memory, working memory, reading and spelling abilities, psychological and behavioral problems, depressive and anxiety symptoms, and psychotic experiences at ages 9 to 13 years were compared between those exposed and unexposed to meningitis. Individuals with special educational needs were excluded.

RESULTS

By age of 18 months, 67 of 11,035 children were reported to have suffered from meningitis (0.61%). These children, compared with the unexposed, performed worse on all neurocognitive and educational measures; mean difference in total intelligence quotient 7.36 (95% confidence interval, 1.60-13.11). Meningitis was associated with higher depressive and anxiety symptoms (P = .02), psychological and behavioral problems (P = .09), and increased risk of psychotic experiences; risk ratio 2.22 (95% confidence interval, 1.12-4.38).

CONCLUSIONS

Exposure to meningitis in the early life is associated with neurocognitive, educational, and psychological difficulties during childhood and early adolescence among survivors who are apparently healthy. Therefore, focusing only on serious neurologic disabilities may underestimate the true impact of early life meningitis.

The burden of pneumococcal meningitis in Austrian children between 2001 and 2008

The present study was conducted to evaluate the burden of pneumococcal meningitis in Austrian children between 2001 and 2008. Clinical outcome was retrospectively analyzed both on discharge and on follow-up investigations. This study was based on a prospective multicentre surveillance study on hospitalized invasive pneumococcal infections in Austrian children with a total annual "study population" of about 399,000 children aged below 5 years per year. Between 2001 and 2008, 74 cases of pneumococcal meningitis were identified in children aged below 5 years. The mean annual incidence rate for pneumococcal meningitis was 2.3 per 100,000 children in this age group. In 57/74 children (mean age on admission 14.5 ± 13.3 months), outcome data on hospital discharge were available: 5 deaths (8.8%), 20 children (35.1%) with sequelae and 32 children (56.1%) without sequelae were observed. Sequelae on discharge included motor impairment in 8 children (14.0%), hearing impairment in 9 children (15.8%) and/or other complications in 14 children (24.6%). In 7/8 children with motor deficits, matching cerebral lesions were identified by neuroimaging: cerebral infarction in five children, cerebral vasculitis and cerebral abscess in one child each. In 40/57 children, long-term outcome (18.9 ± 20.2 months after discharge) could be assessed: 1 child (2.5%) died 9 months after hospital discharge, 11 children (27.5%) had one or two long-term sequelae and 28 children (70.0%) had no sequelae. Long-term sequelae included motor impairment in three children (7.5%), hearing impairment in nine children (22.5%) and other deficits in two children (5.0%).

CONCLUSION

Our study confirms that pneumococcal meningitis causes high mortality and severe long-term sequelae. On long-term follow-up, we observed improvements of motor impairment, but not of hearing impairment.

The kynurenine pathway contributes to long-term neuropsychological changes in experimental pneumococcal meningitis

Pneumococcal meningitis is a lethal form of bacterial infection in the central nervous system that often causes lifelong neurological sequelae, despite therapeutic advances. The contemporary view is that the inflammatory response to infection contributes to the functional disabilities among survivors of this disease. We previously have established a mouse model of neurobehavioural deficits, using an automated IntelliCage™ system that revealed long-term behavioural and cognitive deficits in C57BL/6J female mice cured of meningitis by ceftriaxone treatment. We now have investigated the roles of two kynurenine pathway enzymes, indoleamine dioxygenase-1 (IDO1) and tryptophan dioxygenase-2 (TDO2), in the pathomechanisms of pneumococcal meningitis. Since tryptophan metabolism has long been implicated in behavioural and cognitive modulation through the production of neuroactive compounds, we hypothesised that preventing the actions of these enzymes through gene knockout would be beneficial in mice subjected to pneumococcal infection. We found no significant effect of IDO1 or TDO2 on mortality. Post-meningitic wild-type mice showed long-term diurnal hypoactivity and nocturnal hyperactivity when they were exposed to an Intellicage adaptation test throughout both the light and dark phases. These changes were not apparent in IDO1(-/-) survivors, but were present in the TDO2(-/-) survivors. Both IDO1(-/-) and TDO2(-/-) survivors were not protected against developing long-term cognitive deficits as measured in IntelliCage-based patrolling or reversal tasks. Collectively, these observations suggest (i) involvement of the kynurenine pathway in causing some behavioural sequelae of pneumococcal meningitis and (ii) that this pathway might operate synergistically with, or independently of, other pathways to cause other aspects of neurological sequelae.

Interleukin-18 deficiency and its long-term behavioural and cognitive impacts in a murine model of pneumococcal meningitis

Pneumococcal meningitis often results in death or neurological sequelae, but the underlying pathogenetic mechanisms remain poorly understood. In C57BL/6J mice subjected to intracerebroventricular (icv) challenge with Streptococcus pneumoniae, the chemokine CCL2 and cytokines interferon-γ, interleukin (IL)-1β, IL-6 and tumour necrosis factor were prominently expressed in the brain during the acute phase of the disease. The upregulation of these immune mediators was markedly diminished in IL-18-deficient mice. Uninfected IL-18(-/-) mice exhibited decreases in anxiety phenotype and licking behaviour, and an increase in behavioural habituation, in an automated monitoring system (the IntelliCage). Without antibiotic intervention, a majority of IL-18(+/+) mice developed irreversible disease after icv S. pneumoniae but this was significantly improved by deleting IL-18 gene function. IL-18(+/+) mice cured of pneumococcal meningitis with four doses of ceftriaxone, initiated at 20 h post-inoculation, showed enduring sequelae. These included abnormal behavioural phenotypes featuring diurnal hypoactivity and nocturnal hyperactivity, light phobia and disrupted cognitive function. While the hyperactive phenotype was absent in the corresponding IL-18(-/-) survivors, cognitive impairments and behavioural deficits were still present. Overall, the results suggest that the high levels of cytokines and/or chemokines released after pneumococcal challenge provoked a series of pathological events, ultimately causing acute death. Furthermore, since only a subset of behavioural phenotypes were ameliorated in the pneumococcus-infected IL-18(-/-) mice, the pathological pathways causing mortality may be, at least in part, distinct from those leading to long-term neurological sequelae.

A novel automated test battery reveals enduring behavioural alterations and cognitive impairments in survivors of murine pneumococcal meningitis

Pneumococcal meningitis, caused by Streptococcus pneumoniae infection, is a major form of lethal bacterial meningitis. Survivors are predisposed to developing lifelong disabling sequelae, including cognitive impairment, psychological problems and motor deficits. In our experimental model, ventricular inoculation of 10(5) colony-forming units of S. pneumoniae type 3 caused 90% of mice to develop life-threatening meningitis within 48 h. Antibiotic treatment with ceftriaxone 20 h post infection reduced the incidence of severe meningitis to <10%. At the time of treatment, upregulation of pro-inflammatory cytokines was detected, including interleukin-1β, interleukin-6 and tumour necrosis factor. We evaluated the long-term behavioural and cognitive sequelae in control mice and those surviving meningitis using an automated system (the IntelliCage) in which mice perform a range of behavioural and spatial tasks to obtain water rewards from conditioning units in their home cage. Surviving mice showed a number of altered behaviours relative to controls, including (i) hypoexploration when first exposed to the IntelliCage, (ii) altered activity patterns (fewer visits to conditioning stations during the light phase and more in the dark phase), (iii) avoidance of light (a constant or flashing LED stimulus), (iv) impaired spatial learning (a complex patrolling task), and (v) impaired discrimination reversal learning. Overall these results suggest photophobia and weakened learning ability in post-meningitic mice, particularly on tasks engaging hippocampal and prefrontal neural substrates. This study also demonstrates a standardised and comprehensive battery of tests that can be readily used to investigate neurological sequelae in undisturbed mice residing in a complex home cage environment.

The health, social and educational needs of children who have survived meningitis and septicaemia: the parents' perspective

Background

Survivors of bacterial meningitis and septicaemia can experience a range of after-effects. There is little published research on the needs and provision of aftercare for children surviving bacterial meningitis and septicaemia.

Methods

Mixed methods study employing a survey and follow-up interviews with a sample of survey participants recruited from Meningitis Research Foundation’s member database and social media.

Results

Of 194 eligible survey respondents, 77% reported at least moderate short-term after-effects, and 57% a need for aftercare or support. Most parents reported that their child received a hearing test (98%) and follow-up appointment with a paediatrician (66%). Psychosocial after-effects were most common and the greatest need was for educational support. About half of participants felt their children’s needs for aftercare were met. We conducted interviews with 18 parents. Findings suggest access could be limited by: parents’ inability to navigate systems in place, child’s age, and delayed identification of sequelae. Parents felt a comprehensive explanation of possible after-effects on discharge from hospital was required, and found uncertain prognoses difficult. Good communication between professionals enabled a service tailored to the child’s needs.

Conclusions

Our study supports the NICE and SIGN guidelines and highlights areas for improvement in the aftercare of these children.

Cost-effectiveness of vaccination against meningococcal B among Dutch infants: Crucial impact of changes in incidence

OBJECTIVE

Recently, a vaccine with the capacity to protect against serogroup B meningococcal (MenB) disease received a positive opinion of the European Medicines Agency. Previously, such a vaccine was estimated to be cost-effective. However, since then, the MenB disease incidence has declined drastically in the Netherlands. Therefore, we re-assessed the potential incremental cost-effectiveness ratio (ICER) of vaccinating infants in the Netherlands with a MenB vaccine.

RESULTS

Routine infant vaccination (2, 3, 4+11 mo) could prevent 39 cases of MenB disease in a single birth cohort, corresponding to a total gain of 133 quality-adjusted life years (QALYs). However, this strategy is unlikely to be cost-effective if the vaccine costs €40 per dose (€243,778 per QALY). At a disease incidence of 5.7 per 100,000 person-years or a vaccine price of €10 per dose including administration costs, the ICER becomes more acceptable and remains below a threshold of €50,000 per QALY.

METHODS

A cohort of 185,000 Dutch newborns was followed in a Markov model to compare routine vaccination against MenB disease with no vaccination. The ICER was estimated for different disease incidences. The study was performed from a societal perspective.

CONCLUSIONS

At the current low level of disease incidence, introduction of routine infant vaccination, following a 2, 3, 4+11 mo schedule, against MenB disease is unlikely cost-effective in the Netherlands. If the MenB disease incidence increases or the vaccine price is substantially lower than €40, routine infant vaccination has the potential to be cost-effective.

Childhood infection and adult schizophrenia: a meta-analysis of population-based studies

OBJECTIVE

To determine whether exposures to infectious illness during childhood involving the CNS or elsewhere is associated with adult schizophrenia or other psychoses.

METHOD

Systematic review and meta-analysis of published literature identified by electronic and manual search meeting three inclusion criteria: population-base, objective assessment of childhood infection at the individual level, standard definition of adult psychotic outcomes. We calculated risk ratio for all CNS infection, and separately for viral and bacterial infection in relation to non-affective psychosis and schizophrenia, which was combined in meta-analysis.

RESULTS

Seven studies were included. Meta-analysis involving 2424 cases and over 1.2 million controls showed CNS viral infection was associated with nearly two-fold increased risk of adult non-affective psychosis (risk ratio 1.70; 95% CI 1.13-2.55; p=0.01). There was no significant heterogeneity between studies (p=0.26; I(2)=20%). Separate meta-analysis involving 1035 cases and over 1.2 million controls suggested all childhood CNS infections, particularly viral infections, may be associated with nearly two-fold risk of adult schizophrenia. However, there was evidence of some heterogeneity between these studies (p=0.07; I(2)=70%). CNS bacterial infections were not associated with risk of psychosis. Data on childhood infections with no obvious involvement of the CNS is insufficient.

CONCLUSIONS

These findings indicate childhood CNS viral infections increase the risk of adult psychotic illness. Possible mechanisms may include both direct effects of pathogens, and the effects of inflammatory response on the developing brain.

Cognitive deficits following exposure to pneumococcal meningitis: an event-related potential study

BACKGROUND

Pneumococcal meningitis (PM) is a severe and life-threatening disease that is associated with cognitive impairment including learning difficulties, cognitive slowness, short-term memory deficits and poor academic performance. There are limited data on cognitive outcomes following exposure to PM from Africa mainly due to lack of culturally appropriate tools. We report cognitive processes of exposed children as measured by auditory and visual event-related potentials.

METHODS

Sixty-five children (32 male, mean 8.4 years, SD 3.0 years) aged between 4-15 years with a history of PM and an age-matched control group of 93 children (46 male; mean 8.4 years, SD 2.7 years) were recruited from a well-demarcated study area in Kilifi. In the present study, both baseline to peak and peak-to-peak amplitude differences are reported.

RESULTS

Children with a history of pneumococcal meningitis had significantly longer auditory P1 and P3a latencies and smaller P1 amplitudes compared to unexposed children. In the visual paradigm, children with PM seemingly lacked a novelty P3a component around 350 ms where control children had a maximum, and showed a lack of stimulus differentiation at Nc. Further, children with exposure to PM had smaller peak to peak amplitude (N2-P1) compared to unexposed children.

CONCLUSION

The results suggest that children with a history of PM process novelty differently than do unexposed children, with slower latencies and reduced or absent components. This pattern suggests poorer auditory attention and/or cognitive slowness and poorer visual attention orienting, possibly due to disruption in the functions of the lateral prefrontal and superior temporal cortices. ERPs may be useful for assessment of the development of perceptual-cognitive functions in post brain-injury in African children by providing an alternate way of assessing cognitive development in patient groups for whom more typical standardized neuropsychological assessments are unavailable.