Epidemiology of community-acquired bacterial meningitis

Burden and bacterial etiology of neonatal meningitis at Hawassa University Comprehensive Specialized Hospital, Hawassa, Ethiopia

BACKGROUND

Meningitis poses a significant challenge to public health in low-income nations, such as Ethiopia, with a particular impact on newborns. The magnitude and etiologies of meningitis vary based on geographic location and age of patients. There is limited data regarding the magnitude and etiology of meningitis from Sidama Regional State, Ethiopia. This study aimed to determine the magnitude and bacterial profile of meningitis among newborns aged less than 90 days at Hawassa University Comprehensive Specialized Hospital (HUCSH).

METHODS

A retrospective cross-sectional study was conducted among newborns under 90 days who were suspected of meningitis at HUCSH from January 2019 to July 2023, and for whom Cerebrospinal fluid (CSF) culture was performed. At HUCSH, bacteria are isolated and identified using standard microbiological techniques. Socio-demographic characteristics and culture results were extracted from the laboratory register. Data were entered into Excel and exported it to SPSS version 20 for analysis.

RESULTS

Overall 1061 newborns suspected of meningitis were included in the study. Among the participants, 767 individuals (72.3%) fell within the age range of 8 to 90 days. Of the total participants, 437 (41.2%) were females. The magnitude of culture-confirmed meningitis was 90(8.5%) 95% CI: 6.8%-10.1%. The magnitude of culture-confirmed meningitis among newborns aged 0-7 days and 8-90 days were 1.6% and 6.9% respectively. The proportion of bacteria among newborns aged 0-7 days and 8-90 days were 18.9% and 81.1% respectively. Coagulase-negative Staphylococci (CONS) were the most common bacteria (n = 26; 28.9%) recovered followed by Acinetobacter species (n = 12, 13.3%), Escherichia coli (n = 9; 10%), and Klebsiella pneumoniae (n = 7; 7.8%). K. pneumoniae was the predominant bacteria among newborns within the age group of 0 to 7 days while Acinetobacter species was the most common among newborns within the 8 to 90 days age group. The prevalence of culture-confirmed neonatal meningitis was found to be greater in male newborns (x2 = 1.74, p = 0.18), newborns aged between 8 to 90 days (x2 = 0.07, p = 3.4), and newborns admitted in 2022 (x2 = 2.4, p = 0.66).

CONCLUSIONS

In this study, the overall magnitude of culture-confirmed meningitis was relatively high. Culture-confirmed meningitis was high in newborns within the age range of 8 to 90 days. The most common bacteria were CONS in both age groups followed by Acinetobacter species, E. coli, and K. pneumoniae.

Epidemiology and antimicrobial resistance patterns of bacterial meningitis among hospitalized patients at a tertiary care hospital in Saudi Arabia: a six-year retrospective study

INTRODUCTION

Bacterial meningitis poses significant medical challenges due to its acute inflammatory nature and potential for severe neurological complications, emphasizing the need for prompt diagnosis and treatment. Limited data exists on its epidemiology and antimicrobial resistance trends among hospitalized patients in Saudi Arabia. This study aimed to investigate these factors at a tertiary care hospital over six years.

METHODS

A retrospective analysis was conducted on cerebrospinal fluid samples results from 222 bacterial meningitis cases among hospitalized patients between 2018 and 2023. Demographic, clinical, microbiological data, and antibiotic susceptibility patterns were collected and analyzed.

RESULTS

Pseudomonas aeruginosa (43%) was the predominant pathogen isolated. Neonates (16%) and children (47%) were most affected population. Nosocomial meningitis accounted for 92% of cases, mainly in the intensive care settings (50.45%). Extended-spectrum beta-lactamase was the leading resistance pattern (12.2%). Seasonal variation was observed, with a peak incidence in October-November.

CONCLUSION

The study highlights the substantial burden of bacterial meningitis among hospitalized patients, especially among high-risk groups. Emerging antimicrobial resistance emphasizes the need for optimized surveillance and stewardship. Future prospective research employing molecular techniques across multiple centers in the country is warranted to enhance understanding and guide public health strategies in Saudi Arabia.

PCR-positive meningococcal CSF infection without pleocytosis but high IL-6 and IL-8

BACKGROUND

Meningococcal meningitis is still a severe disease causing high mortality and morbidity rates. Early diagnosis is crucial to ensure prompt antibiotic therapy. However, identification of the pathogen can be challenging.

CASE PRESENTATION

A 32-year-old male patient with systemic lupus erythematosus (SLE) presented to the emergency room with fever, nausea, vomiting, headache and lower back pain as well as multiple petechial bleedings. On suspicion of meningococcal infection, the emergency doctor had already administered one dose of ceftriaxone before arrival to the clinic. Blood works showed massive inflammation due to bacterial infection. Cerebrospinal fluid (CSF) analysis showed normal cell count, protein and glucose levels but PCR was positive for Neisseria meningitis and IL-6 as well as IL-8 were elevated. On antibiotic therapy with ceftriaxone, the patient's condition improved quickly.

CONCLUSIONS

We present a rare case of meningococcal infection of the CSF in a SLE patient without further CSF abnormalities. We discuss the involvement of early antibiotic treatment and the role of the patient's immune status in the normal CSF findings of this case. Moreover, this case demonstrates the importance of early antibiotic therapy in bacterial meningitis for the clinical outcome.

Characterization and diagnosis spectrum of patients with cerebrospinal fluid pleocytosis

PURPOSE

There is an overlap in the cerebrospinal fluid (CSF) characteristics of patients presenting with different etiologies of CSF pleocytosis. Here, we characterized patients with CSF pleocytosis treated in a large hospital.

METHODS

A retrospective cohort study of 1150 patients with an elevated CSF leukocyte count > 5 cells/µl treated at a university hospital in Germany from January 2015 to December 2017 was performed. Information on clinical presentation, laboratory parameters, diagnosis and outcome was collected. Clinical and laboratory features were tested for their potential to differentiate between bacterial meningitis (BM) and other causes of CSF pleocytosis.

RESULTS

The most common etiologies of CSF pleocytosis were CNS infections (34%: 20% with detected pathogen, 14% without), autoimmune (21%) and neoplastic diseases (16%). CSF cell count was higher in CNS infections with detected pathogen (median 82 cells/µl) compared to autoimmune (11 cells/µl, p = 0.001), neoplastic diseases (19 cells/µl, p = 0.01) and other causes (11 cells/µl, p < 0.001). The CHANCE score was developed to differentiate BM from other causes of CSF pleocytosis: Multivariate regression revealed that CSF cell count > 100 cells/µl, CSF protein > 100 mg/dl, CRP > 5 mg/dl, elevated white blood cell count, abnormal mental status and nuchal rigidity are important indicators. The CHANCE score identified patients with BM with high sensitivity (92.1%) and specificity (90.9%) (derivation cohort: AUC: 0.955, validation cohort: AUC: 0.956).

CONCLUSION

Overall, the most common causes for CSF pleocytosis include infectious, neoplastic or autoimmune CNS diseases in ~ 70% of patients. The CHANCE score could be of help to identify patients with high likelihood of BM and support clinical decision making.

Recurrent bacterial meningitis in children in the Netherlands: a nationwide surveillance study

OBJECTIVES

This study aimed to estimate the recurrence rate of culture-positive bacterial meningitis in children in the Netherlands.

DESIGN

Nationwide surveillance study, using the database of the Netherlands Reference Laboratory for Bacterial Meningitis to identify patients with culture-positive bacterial meningitis during childhood.

SETTING

The study was based in the Netherlands.

PARTICIPANTS

A total of 9731 children with a first bacterial meningitis episode between 1 July 1987 and 30 June 2019 were identified.

PRIMARY AND SECONDARY OUTCOME MEASURES

Recurrence was defined as a subsequent episode >28 days, or caused by a different pathogen. Annual incidence and incidence rate ratios (IRRs) comparing the periods 1988-2003 and 2004-2019 were calculated. Predictors of recurrent meningitis were assessed using Cox proportional hazards regression.

RESULTS

Sixty-three (0.6%) of the 9731 children with a first bacterial meningitis episode contracted recurrent meningitis. Neisseria meningitidis was the leading pathogen for first meningitis episodes (52%) and Streptococcus pneumoniae for recurrent episodes (52%). The median annual incidence of first episodes per 100 000 children decreased from 11.81 (IQR 11.26-17.60) in 1988-2003 to 2.60 (IQR 2.37-4.07) in 2004-2019 (IRR 0.25, 95% CI 0.23 to 0.26). The incidence of recurrences did not change: 0.06 (IQR 0.02-0.11) in 1988-2003 to 0.03 (IQR 0.00-0.06) in 2004-2019 (IRR 0.65, 95% CI 0.39 to 1.1). Age above 5 years (OR 3.6 (95% CI 1.5 to 8.3)) and a first episode due to Escherichia coli (OR 25.7 (95% CI 7.2 to 92.0)) were associated with higher risks of recurrence.

CONCLUSION

The recurrence rate of childhood bacterial meningitis in the Netherlands was 0.6%. While the incidence rate of first episodes decreased substantially, this was not the case for recurrent episodes. Older age and a first episode due to E. coli were associated with higher recurrence risks.

Application of parametric survival analysis to women patients with breast cancer at Jimma University Medical Center

Public health systems in both industrialized and undeveloped countries continue to struggle with the worldwide problem of breast cancer. In sub-Saharan African countries, notably Ethiopia, it is the form of cancer that strikes women the most commonly. Despite the extreme difficulties, the causes of mortality in Ethiopia have not yet been identified. In addition, little study has been done in this area. Therefore, the major objective of this analysis was to pinpoint the factors that were most responsible for the decreased life expectancy of breast cancer patients at the University of Jimma Medical Center. 552 women who had been treated for breast cancer at Jimma University Medical Center between October 2018 and December 2022 were included in this study, which used a retrospective cohort study design and five-year follow-up data. The most frequent and widely used test for comparing the probability of survival curves between several categorical independent variables was the log-rank test. Next, semi-parametric methods for multivariable analysis using the Cox proportional hazards model were used. Furthermore, a parametric strategy that includes fully parametric survival models better achieves the goal of the analysis. Among covariate, age of patient (ϕ = 254.06; 95% CI (3.95, 7.13), P-value = 0.000), patient live in urban (ϕ = 0.84; 95% CI (-0.35,-0.00), P-value = 0.047), preexisting comorbidity (ϕ = 2.46; 95% CI (0.39, 1.41), P-value = 0.001), overweight women cancer patient (ϕ = 0.05; 95% CI(-4.41,-1.57), P-value = 0.000, positive Axillary Node status cancer patient (ϕ = 0.04; 95% CI(-4.45,-1.88), P-value = 0.000), both surgery and chemotropic baseline treatment patient (ϕ = 0.53; 95% CI(-1.12,-0.16), P-value = 0.009) significantly affected the survival of women breast cancer. Age of breast cancer patient, patient education level, place of residence, marital status, pre-existing comorbidity, axillary node status, estrogen receptor, tumor size, body mass index at diagnosis, stage of cancer, and baseline treatment were found to have a significant effect on time to survive for women with breast cancer at the University of Jimma Medical Center, Oromia region, Ethiopia. However, the covariate histologic grade, number of positive lymph nodes involved, and type of hormone used were insignificant to the survival of breast cancer patients.

Persistent headaches one year after bacterial meningitis: prevalence, determinants and impact on quality of life

BACKGROUND

Little is known on headaches long-term persistence after bacterial meningitis and on their impact on patients' quality of life.

METHODS

In an ancillary study of the French national prospective cohort of community-acquired bacterial meningitis in adults (COMBAT) conducted between February 2013 and July 2015, we collected self-reported headaches before, at onset, and 12 months (M12) after meningitis. Determinants of persistent headache (PH) at M12, their association with M12 quality of life (SF 12), depression (Center for Epidemiologic Studies Depression Scale) and neuro-functional disability were analysed.

RESULTS

Among the 277 alive patients at M12 87/274 (31.8%), 213/271 (78.6%) and 86/277 (31.0%) reported headaches before, at the onset, and at M12, respectively. In multivariate analysis, female sex (OR: 2.75 [1.54-4.90]; p < 0.001), pre-existing headaches before meningitis (OR: 2.38 [1.32-4.30]; p < 0.01), higher neutrophilic polynuclei percentage in the CSF of the initial lumbar puncture (OR: 1.02 [1.00-1.04]; p < 0.05), and brain abscess during the initial hospitalisation (OR: 8.32 [1.97-35.16]; p < 0.01) were associated with M12 persistent headaches. Neither the responsible microorganism, nor the corticoids use were associated with M12 persistent headaches. M12 neuro-functional disability (altered Glasgow Outcome Scale; p < 0.01), M12 physical handicap (altered modified Rankin score; p < 0.001), M12 depressive symptoms (p < 0.0001), and M12 altered physical (p < 0.05) and mental (p < 0.0001) qualities of life were associated with M12 headaches.

CONCLUSION

Persistent headaches are frequent one year after meningitis and are associated with quality of life alteration.

CLINICAL TRIAL

NCT01730690.

Cholesterol dependent cytolysins and the brain: Revealing a potential therapeutic avenue for bacterial meningitis

Bacterial meningitis is a catastrophic nervous system disorder with high mortality and wide range of morbidities. Some of the meningitis-causing bacteria occupy cholesterol dependent cytolysins (CDCs) to increase their pathogenicity and arrange immune-evasion strategy. Studies have observed that the relationship between CDCs and pathogenicity in these meningitides is complex and involves interactions between CDC, blood-brain barrier (BBB), glial cells and neurons. In BBB, these CDCs acts on capillary endothelium, tight junction (TJ) proteins and neurovascular unit (NVU). CDCs also observed to elicit intriguing effects on brain inflammation which involves microglia and astrocyte activations, along with neuronal damage as the end-point of pathological pathways in bacterial meningitis. As some studies mentioned potential advantage of CDC-targeted therapeutic mechanisms to combat CNS infections, it might be a fruitful avenue to deepen our understanding of CDC as a candidate for adjuvant therapy to combat bacterial meningitis.

Trends in Pneumococcal and Bacterial Meningitis in Brazil from 2007 to 2019

The pneumococcal conjugate vaccination (PCV) was introduced into the Brazilian Childhood National Immunization Program in 2010; however, universal pneumococcal vaccination for older adults has not been implemented yet. Our aim is to evaluate the trends in pneumococcal meningitis incidence and case fatality rate (CFR) across all age groups from 2007 to 2019 using data from the National Surveillance System. The pre-PCV (2007-2009) and post-PCV (2011-2019) periods were compared; changes in incidence and CFR were assessed by joinpoint regression. Additional analyses of bacterial meningitis were performed to compare the patterns and trends. Over the 13-year period, 81,203 and 13,837 cases were classified as bacterial and pneumococcal meningitis, respectively. S. pneumoniae was the main etiological agent of bacterial meningitis in adults aged ≥50 years and the most lethal in all age groups. In the post-PCV period, a 56.5% reduction in the average incidence was seen in pneumococcal meningitis in the pediatric population. In contrast, there was an increasing trend among adults. The CFR for pneumococcal and bacterial meningitis remained stable in most age groups during the study period. These findings highlight the value of expanding pneumococcal vaccination policies, including vaccines that provide better indirect protection from children to adults and broadening vaccination to older adults.

Epidemiology, clinical features and outcome of adults with meningococcal meningitis: a 15-year prospective nationwide cohort study

Background

We describe the epidemiology, clinical features and outcome of adult meningococcal meningitis in the Netherlands over a 15-year period.

Methods

We studied adults (age ≥ 16 years) who were listed by the Netherlands Reference Laboratory for Bacterial Meningitis and/or included in the prospective nationwide cohort study (MeninGene) between January 2006 and July 2021. Incidences were calculated per epidemiological year (July-June).

Findings

We identified 442 episodes of adult meningococcal meningitis. The median patient age was 32 years (IQR 18-55) and 226 episodes (51%) occurred in female patients. The annual incidence per 100,000 adults fluctuated, from 0.33 in 2006-2007 to 0.05 in 2020-2021, with a temporal increase up to 0.30 from 2016 to 2018, driven by an outbreak of serogroup W (MenW). Of 442 episodes, 274 episodes (62%) in 273 patients were included in the clinical cohort study. The overall case fatality rate was 4% (10 of 274) and 16% (43 of 274) had an unfavourable outcome (Glasgow Outcome Scale score 1-4). Compared to other serogroups, MenW was associated with higher rates of unfavourable outcome (6 of 16 [38%] vs. 37 of 251 [15%], P = 0.03) and death (4 of 16 [25%] vs. 6 of 251 [2%], P = 0.001).

Interpretation

The overall incidence of adult meningococcal meningitis in the Netherlands is low and outcome is generally favourable. An increase of MenW meningitis occurred from 2016 to 2018, which was associated with more unfavourable outcome and death.

Funding

Netherlands Organisation for Health Research and Development, European Research Council, National Institute of Public Health and Environmental protection.

Meningitis after elective intracranial surgery: a systematic review and meta-analysis of prevalence

Meningitis is a potential complication of elective intracranial surgery (EIS). The prevalence of meningitis after EIS varies greatly in the literature. The objective of this study was to estimate the overall pooled prevalence of meningitis following EIS. Four databases (PubMed, Scopus, Web of Science, and Embase) were searched to identify relevant studies. Meta-analyses of proportions were used to combine data. Cochran's Q and I2 statistics were used to assess and quantify heterogeneity. Additionally, several subgroup analyses were conducted to investigate the source of heterogeneity and examine differences in the prevalence based on variables such as geographical regions, income level, and meningitis type. The meta-analysis included 83 studies (30 959 patients) from 26 countries. The overall pooled prevalence of meningitis after EIS was 1.6% (95% CI 1.1-2.1), with high heterogeneity present (I2 = 88%). The pooled prevalence in low- to middle-income countries and high-income countries was 2.7% (95% CI 1.6-4.1) and 1.2% (95% CI 0.8-1.7), respectively. Studies that reported only aseptic meningitis had a pooled prevalence of 3.2% (95% CI 1.3-5.8). The pooled prevalence was 2.8% (95% CI 1.5-4.5) in studies that reported only bacterial meningitis. Similar prevalence rates of meningitis were observed in the subgroups of tumor resection, microvascular decompression, and aneurysm clipping. Meningitis is a rare but not exceptional complication following EIS, with an estimated prevalence of 1.6%.

Cerebrovascular complications in patients with community-acquired bacterial meningitis: occurrence and associated factors in the COMBAT multicenter prospective cohort

BACKGROUND

Community-acquired bacterial meningitis is a rare but severe central nervous system infection that may be associated with cerebrovascular complications (CVC). Our objective is to assess the prevalence of CVC in patients with community-acquired bacterial meningitis and to determine the first-48 h factors associated with CVC.

METHODS

We analyzed data from the prospective multicenter cohort study (COMBAT) including, between February 2013 and July 2015, adults with community-acquired bacterial meningitis. CVC were defined by the presence of clinical or radiological signs (on cerebral CT or MRI) of focal clinical symptom. Factors associated with CVC were identified by multivariate logistic regression.

RESULTS

CVC occurred in 128 (25.3%) of the 506 patients in the COMBAT cohort (78 (29.4%) of the 265 pneumococcal meningitis, 17 (15.3%) of the 111 meningococcal meningitis, and 29 (24.8%) of the 117 meningitis caused by other bacteria). The proportion of patients receiving adjunctive dexamethasone was not statistically different between patients with and without CVC (p = 0.84). In the multivariate analysis, advanced age (OR = 1.01 [1.00-1.03], p = 0.03), altered mental status at admission (OR = 2.23 [1.21-4.10], p = 0.01) and seizure during the first 48 h from admission (OR = 1.90 [1.01-3.52], p = 0.04) were independently associated with CVC.

CONCLUSIONS

CVC were frequent during community-acquired bacterial meningitis and associated with advanced age, altered mental status and seizures occurring within 48 h from admission but not with adjunctive corticosteroids.

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.

Specificities of Meningitis and Meningo-Encephalitis After Kidney Transplantation: A French Retrospective Cohort Study

Kidney transplant recipients develop atypical infections in their epidemiology, presentation and outcome. Among these, meningitis and meningoencephalitis require urgent and adapted anti-infectious therapy, but published data is scarce in KTRs. The aim of this study was to describe their epidemiology, presentation and outcome, in order to improve their diagnostic and management. We performed a retrospective, multicentric cohort study in 15 French hospitals that included all 199 cases of M/ME in KTRs between 2007 and 2018 (0.9 case per 1,000 KTRs annually). Epidemiology was different from that in the general population: 20% were due to Cryptococcus neoformans, 13.5% to varicella-zoster virus, 5.5% to Mycobacterium tuberculosis, and 4.5% to Enterobacteria (half of which produced extended spectrum beta-lactamases), and 5% were Post Transplant Lymphoproliferative Disorders. Microorganisms causing M/ME in the general population were infrequent (2%, for Streptococcus pneumoniae) or absent (Neisseria meningitidis). M/ME caused by Enterobacteria, Staphylococci or filamentous fungi were associated with high and early mortality (50%-70% at 1 year). Graft survival was not associated with the etiology of M/ME, nor was impacted by immunosuppression reduction. Based on these results, we suggest international studies to adapt guidelines in order to improve the diagnosis and the probabilistic treatment of M/ME in SOTRs.

Dendritic spine loss deep in the neocortex and dendrite distortion with diffusion disturbances occur early in experimental pneumococcal meningitis

Introduction

Streptococcus pneumoniae (pneumococcus) meningitis is a serious disease with substantial lethality and long-term disability in survivors. Loss of synaptic staining in the superficial layers of the neocortex in rodent models and in humans, and pneumolysin (a major pneumococcal toxin)-dependent dendritic spine collapse in brain slices have been described. It remains unclear how deep in the neocortex more discrete changes are present, how soon after disease onset these changes occur, and whether other properties of dendrites are also affected.

Methods

Using a mouse model of pneumococcal meningitis, we studied changes in the neocortex shortly (3-6 h) after the onset of clinical symptoms via modified Golgi-Cox silver staining.

Results

Dendritic changes were present in areas with otherwise unchanged cell numbers and no signs of necrosis or other apparent neuronal pathology. Mature dendritic spines were reduced in the pyramidal neurons running through layers 1-5. Additionally, spine morphology changes (swelling, spine neck distortion), were also observed in the deeper layers 4 and 5 of the neocortex. Immature spines (filopodia) remained unchanged between groups, as well as the dendritic arborization of the analyzed neurons. In a third of the animals with meningitis, massive mechanical distortion of the primary dendrites of most of the pyramidal neurons through layers 1-5 was observed. This distortion was reproduced in acute brain slices after exposure to pneumolysin-containing bacterial lysates (S. pneumoniae D39 strain), but not to lysates of pneumolysin-deficient bacteria, which we explain by the tissue remodeling effect of the toxin. Experimental mechanical dendrite distortion in primary neural cultures demonstrated diminished FRAP diffusion of neuronally-expressed enhanced green fluorescent protein (eGFP), indicative of disturbed dendritic diffusion.

Discussion

Our work extends earlier knowledge of synaptic loss in the superficial cortical layers during meningitis to deeper layers. These changes occurred surprisingly early in the course of the disease, substantially limiting the effective therapeutic window. Methodologically, we demonstrate that the dendritic spine collapse readout is a highly reliable and early marker of neural damage in pneumococcal meningitis models, allowing for reduction of the total number of animals used per a group due to much lower variation among animals.

Progress and Challenges in Bacterial Meningitis: A Review

IMPORTANCE

Bacterial meningitis is a worldwide health problem, with incidence rates ranging from approximately 0.9 per 100 000 individuals per year in high-income countries to 80 per 100 000 individuals per year in low-income countries. In low-income countries, bacterial meningitis has a mortality rate of up to 54%. Up to 24% of those who survive develop chronic neurological sequelae, such as hearing loss or focal neurological deficits.

OBSERVATIONS

Streptococcus pneumoniae causes about 72% and Neisseria meningitidis causes about 11% of cases of bacterial meningitis in people older than 16 years. Escherichia coli and Streptococcus agalactiae cause about 35% of cases of early-onset neonatal meningitis. In adults, risk factors for bacterial meningitis include older age and immunosuppressive conditions. The most common symptoms are headache (84%), fever (74%), stiff neck (74%), altered mental status (median [IQR] Glasgow Coma Scale score of 11 [9-14] on a scale ranging from 3-15), and nausea (62%). Brain imaging should be performed before lumbar puncture if patients present with altered mental status, focal neurological deficits, papilledema, or history of immunocompromising conditions or central nervous system disease. Bacterial meningitis should be suspected if any of the following are present on admission: serum leukocytes greater than 10.0 ×109/L, cerebrospinal fluid (CSF) leukocytes greater than 2000/μL, CSF granulocytes greater than 1180/μL, CSF protein greater than 2.2 g/L, CSF glucose less than 34.23 mg/dL, or fever. A positive Gram stain result for bacteria is diagnostic, but the sensitivity of a positive Gram stain result for bacterial meningitis ranges from 50% to 90%. In countries in which the prevalence of ceftriaxone-resistant Streptococcus pneumoniae exceeds 1%, vancomycin and ceftriaxone are the empirical antibiotics of choice, with the addition of ampicillin in neonates, older patients, and immunocompromised patients. Adjunctive dexamethasone should be used in patients with bacterial meningitis but stopped if Listeria monocytogenes is confirmed.

CONCLUSIONS AND RELEVANCE

Bacterial meningitis affects approximately 0.9 per 100 000 individuals to 80 per 100 000 individuals per year and has a mortality rate as high as 54%. First-line therapy is prompt empirical intravenous antibiotic therapy and adjunctive dexamethasone.

Diagnosis of bacterial meningitis caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae using a multiplex real-time PCR technique

Bacterial meningitis is one of the diseases that, despite the introduction of several vaccines, remains a serious public health concern. Streptococcus pneumoniae (Spn), Neisseria meningitidis (Nm), and Haemophilus influenzae (Hi) are responsible for most cases diagnosed in children, adolescents, and adult population. Rapid, sensitive, and specific laboratory assays are critical for effective diagnosis and treatment, particularly in countries like Mexico in which culture positivity rates are very low due to the use of antibiotics prior to sample collection and to delay in transporting samples to the laboratory. The aim of this study was to evaluate the use of real-time polymerase chain reaction (RT-PCR) of cerebrospinal fluid (CSF) as a rapid diagnostic test for bacterial meningitis and compare these results with bacterial culture in three general hospitals in Mexico. During a 5-year period (2014-2018), a total of 512 CSF samples obtained from patients in whom infectious meningitis was suspected as initial clinical diagnosis were tested with RT-PCR with species-specific targets for the three pathogens. For Spn, 5.07% samples were RT-PCR positive; 0.39% for Nm and none for Hi. Only five RT-PCR Spn positive samples had a positive culture. Sensitivity and specificity estimates for RT-PCR are 100% and 95.46%, respectively. DNA amplification methods can provide better sensitive diagnostic tests than the reference standard, which is culture, particularly when antimicrobial treatment is initiated before clinical samples can be obtained.

Dysfunctional Glymphatic System with Disrupted Aquaporin 4 Expression Pattern on Astrocytes Causes Bacterial Product Accumulation in the CSF during Pneumococcal Meningitis

Pneumococcal meningitis, inflammation of the meninges due to an infection of the Central Nervous System caused by Streptococcus pneumoniae (the pneumococcus), is the most common form of community-acquired bacterial meningitis globally. Aquaporin 4 (AQP4) water channels on astrocytic end feet regulate the solute transport of the glymphatic system, facilitating the exchange of compounds between the brain parenchyma and the cerebrospinal fluid (CSF), which is important for the clearance of waste away from the brain. Wistar rats, subjected to either pneumococcal meningitis or artificial CSF (sham control), received Evans blue-albumin (EBA) intracisternally. Overall, the meningitis group presented a significant impairment of the glymphatic system by retaining the EBA in the CSF compartments compared to the uninfected sham group. Our results clearly showed that during pneumococcal meningitis, the glymphatic system does not function because of a detachment of the astrocytic end feet from the blood-brain barrier (BBB) vascular endothelium, which leads to misplacement of AQP4 with the consequent loss of the AQP4 water channel's functionality. IMPORTANCE The lack of solute drainage due to a dysfunctional glymphatic system leads to an increase of the neurotoxic bacterial material in the CSF compartments of the brain, ultimately leading to brain-wide neuroinflammation and neuronal damage with consequent impairment of neurological functions. The loss of function of the glymphatic system can therefore be a leading cause of the neurological sequelae developing post-bacterial meningitis.

One-Year Sequelae and Quality of Life in Adults with Meningococcal Meningitis: Lessons from the COMBAT Multicentre Prospective Study

INTRODUCTION

COMBAT is a prospective, multicentre cohort study that enrolled consecutive adults with community-acquired bacterial meningitis (CABM) in 69 participating centres in France between February 2013 and July 2015 and followed them for 1 year.

METHODS

Patients aged at least 18 years old, hospitalised with CABM were followed during their hospitalisation and then contacted by phone 12 months after enrolment. Here we present the prevalence of sequelae at 12 months in a subgroup of patients with meningococcal meningitis.

RESULTS

Five of the 111 patients with meningococcal meningitis died during initial hospitalisation and two died between discharge and 12 months, leaving 104 patients alive 1 year after enrolment, 71 of whom provided 12-month follow-up data. The median age was 30.0 years and 54.1% of the patients had no identified risk factor for meningitis. More than 30% reported persistent headache, more than 40% were not satisfied with their sleep and 10% had concentration difficulties. Hearing loss was present in about 15% of the patients and more than 30% had depressive symptoms. About 13% of the patients with a previous professional activity had not resumed work. On the SF-12 Health Survey, almost 50% and 30% had physical component or mental component scores lower than the 25th percentile of the score distribution in the French general population. There was a non-significant improvement in the patients' disability scores from hospital discharge to 12 months (p = 0.16), but about 10% of the patients had residual disability.

CONCLUSIONS

Although most patients in our cohort survive meningococcal meningitis, the long-term burden is substantial and therefore it is important to ensure a prolonged follow-up of survivors and to promote preventive strategies, including vaccination.

TRIAL REGISTRATION

ClinicalTrial.Gov identification number NCT01730690.

Neuroprotective effects of CysLTR antagonist on Streptococcus pneumoniae‑induced meningitis in rats

Cysteinyl leukotrienes (CysLTs) modulate central nervous system inflammatory responses via their receptors, CysLT₁R and CysLT₂R. It has been demonstrated that CysLTR participates in the infection process of Streptococcus pneumoniae (SP)-induced meningitis. In the present study, the effects and possible underlying mechanisms of CysLTR antagonists (pranlukast and HAMI 3379) on SP meningitis were further determined. SP meningitis was induced by intracerebroventricular injection of serotype III SP in Sprague-Dawley rats which were administrated intraperitoneally with 0.1 mg/kg antagonists. The clinical disease status of rats was evaluated by body weight and behavioral changes with neurological scoring. Survival neuron density, activated microglial and astrocytes were assessed by Nissl staining and immunohistochemical staining. The expression levels of inflammatory cytokines and NLRP3 inflammasome were detected by reverse transcription-quantitative PCR and western blotting, respectively. Pranlukast and HAMI 3379 treatment markedly alleviated the clinical disease status, which was manifested by improving body weight loss and neurological deficit. Furthermore, pranlukast and HAMI 3379 treatment ameliorated neuronal injury and inhibited microgliosis and astrogliosis. In addition, significant downregulation of inflammatory cytokines and NLRP3 expression was observed in pranlukast and HAMI 3379-treated rats. These in vivo findings indicated the neuroprotective effects of CysLTR antagonists against experimental SP-induced meningitis, and the mechanism of anti-inflammatory effects may partly be by inhibiting NLRP3 inflammasome overactivation.

Clinical Features and Outcomes of Streptococcus pneumoniae Meningitis in Children: A Retrospective Analysis of 26 Cases in China

BACKGROUND

Streptococcus pneumoniae is an important cause of pediatric meningitis.

OBJECTIVE

The aim of this study was to analyze the clinical features and outcomes of children with pneumococcal meningitis at our hospital in China, so as to provide basis for improving the clinical treatment effect.

METHODS

This retrospective analysis included patients aged <16 years treated for pneumococcal meningitis at the Department of Neurology, Children's Hospital of Shanxi (January 2014-February 2016). Clinical data were extracted from the medical records. Patients were followed up for 6 months after discharge.

RESULTS

The analysis included 26 children aged 2 months to 13 years, with 17 (65.4%) aged <3 years. Presenting symptoms included fever (100%), lethargy (100%), impaired consciousness (88.5%), neck stiffness (69.2%), seizures (53.8%), and headache (50.0%). All patients had positive cerebrospinal fluid (CSF) cultures. The final treatment was vancomycin combined with a third-generation cephalosporin or other antibiotics in 25 patients. Eleven patients (42.3%) were recovered, 3 (11.5%) had neurological sequelae, and 12 (46.2%) died. Impaired consciousness (p = 0.035), cerebral hernia (p = 0.037), respiratory failure (p = 0.004), heart failure (p = 0.044), septic shock (p = 0.037), low CSF white blood cell count (p = 0.036), high CSF protein levels (p = 0.028), low white blood cell count (p = 0.036), and low blood neutrophil ratio (p = 0.016) are associated with a poor prognosis to pneumococcal meningitis.

CONCLUSION

Pneumococcal meningitis is associated with a poor prognosis in many children. Poor prognosis might be related to early ineffective antibiotic therapy, a combination of systemic failure, neurological problems, and changed inflammatory response. It is important to rapid initiation of appropriate antibiotic therapy if meningitis is suspected.

Antimicrobial use in central nervous system infections

PURPOSE OF REVIEW

Central nervous system (CNS) infections are associated with high rates of morbidity and mortality. The purpose of this review is to summarize current antimicrobial therapies, as well as, updates in the management of community-acquired meningitis and healthcare-associated meningitis and ventriculitis.

RECENT FINDINGS

Due to the increasing rates of multidrug resistant and extensively-drug resistant organisms, available antimicrobials are limited. Novel treatment options include newer systemic antimicrobials and antimicrobials that have previously limited data in the management of CNS infections. Although limited by retrospective data, intrathecal (IT) and intraventricular (IVT) routes of administration offer the opportunity for antimicrobials that conventionally have minimal cerebrospinal fluid (CSF) penetration to achieve high CSF concentrations while minimizing systemic exposure.

SUMMARY

Updates in the use of systemic, IT, and IVT antimicrobials offer promise as therapeutic options for CNS infections. Additional pharmacokinetic and prospective data are needed to confirm these findings.

SOP: emergency workup in patients with suspected acute bacterial meningitis

Introduction

Despite antibiotic therapy, adjunctive treatment with dexamethasone, and care on modern intensive care units, bacterial meningitis remains a life-threatening disease with a high mortality and morbidity. One of most critical factors that influences outcome is a targeted quick but profound workup and early initiation of therapy in the Emergency Department. This standardized operating procedure was designed to guide physicians through the workup of patients with suspected acute bacterial meningitis.

First steps

In patients with suspected community-acquired bacterial meningitis, the first steps aim at establishing a diagnosis and at starting empiric therapy without delay. Therefore, physicians need to seek for an early lumbar puncture that can be done safely without prior imaging if clinical signs that point at contraindications of a lumbar puncture are absent. Immediately after lumbar puncture, empiric therapy with ceftriaxone, ampicillin and dexamethasone should be started. In regions with a critical resistance rate of pneumococci against third generation cephalosporines, vancomycin or rifampicin need to be added.

Comments

Clinical signs that are associated with intracranial conditions that are a contraindication for a lumbar puncture are severely decreased consciousness, new onset focal neurological signs, and epileptic seizures. If any of these clinical signs are present, cerebral imaging is recommended before lumbar puncture. Whenever lumbar puncture is delayed, empiric therapy needs to be begun before cerebrospinal fluid is obtained.

Conclusion

Suspected acute bacterial meningitis is an emergency and requires attention with high priority in the emergency department to ensure a quick workup and early start of therapy.

Community-acquired bacterial meningitis in adults: emergency department management protocol

Acute bacterial meningitis (ABM) is a rare but disabling infectious condition that requires a performant multidisciplinary management approach. Between 70 and 90 adult patients are diagnosed with community-acquired ABM in Belgium annually, and reported case fatality rates range from 17 to 40%. The currently available guidelines provide evidence-based guidance on how to manage this disease. However, these guidelines do not translate the evidence to the daily practice at the emergency department in a Belgian healthcare context. We created a taskforce in University Hospitals Leuven consisting of experts with complementary expertise in managing this disease: neurology, neurosurgery, intensive care medicine, microbiology and infectious diseases. The taskforce agreed upon a flowchart containing seven management steps encompassing all relevant phases in emergency ABM management. In addition to the focus on timely and adequate initiation of antimicrobial treatment, the flowchart and protocol also provide guidance on practical hurdles such as how to assess the safety of performing a lumbar puncture and when to refer patients to the intensive care department. This protocol was implemented in University Hospitals Leuven and fosters inter-disciplinary coordination of ABM care.

Pediatric bacterial meningitis and meningococcal disease profile in a Brazilian General Hospital

Objective

To evaluate the clinical and epidemiological profile of bacterial meningitis and meningococcal disease in pediatric patients admitted to a Brazilian Secondary Public Hospital.

Methods

A descriptive observational study was conducted. Microbiologically proven bacterial meningitis or meningococcal disease diagnosed from 2008 to 2018 were included.

Results

A total of 90 patients were diagnosed with proven bacterial meningitis. There were 64 confirmed cases of meningococcal disease. The prevalence was higher in boys (n = 38), median age 30 months (1–185). The main clinical manifestations were: meningococcal meningitis (n = 27), meningococcemia without meningitis (n = 14), association of meningococcemia with meningitis (n = 13), and fever without a known source in infants (n = 7).

Admissions to intensive care unit were necessary for 45 patients. Three deaths were notified. Serogroup C was the most prevalent (n = 32) followed by serogroup B (n = 12).

Pneumococcal meningitis was identified in 21 cases; out of the total, 10 were younger than two years. The identified serotypes were: 18C, 6B, 15A, 28, 7F, 12F, 15C, 19A and 14. Pneumococcal conjugate 10-valent vaccine covered four of the nine identified serotypes.

Haemophilus influenzae meningitis serotype IIa was identified in three patients, median age 4 months (4–7). All of them needed intensive care. No deaths were notified.

Conclusion

Morbidity and mortality rates from bacterial meningitis and meningococcal disease remain high, requiring hospitalization and leading to sequelae. Our study observed a reduced incidence of bacterial disease over the last decade, possibly reflecting the impact of vaccination.

Update and advances in community acquired bacterial meningitis

PURPOSE OF REVIEW

Community-acquired bacterial meningitis continues to occur and be associated with significant morbidity and mortality despite the availability of effective conjugate vaccines for the three most important meningeal pathogens.

RECENT FINDINGS

Indications for cranial imaging in suspected bacterial meningitis varies significantly between guidelines. Cranial imaging is of no clinical utility in those patients without indications and fosters delays in performing a lumbar puncture. Delaying lumbar puncture is associated with increased costs in both adults and children with meningitis and previous antibiotic therapy impacts the yield of microbiological results. Delaying antibiotic therapy is associated with worse clinical outcomes. Adjunctive steroids have reduced the mortality of adults with pneumococcal meningitis but have been associated with increased adverse outcomes in Listeria monocytogenes and Cryptococcus neoformans.

SUMMARY

Community-acquired bacterial meningitis remains a global health concern with high morbidity and mortality especially in low-income countries. Cranial imaging should be done only in patients with an indication with an attempt to do a prompt lumbar puncture and to initiate antibiotic therapy and adjunctive steroids as soon as possible to improve clinical outcomes.

Targeting the complement system in bacterial meningitis

Bacterial meningitis is most commonly caused by Streptococcus pneumoniae and Neisseria meningitidis and continues to pose a major public health threat. Morbidity and mortality of meningitis are driven by an uncontrolled host inflammatory response. This comprehensive update evaluates the role of the complement system in upregulating and maintaining the inflammatory response in bacterial meningitis. Genetic variation studies, complement level measurements in blood and CSF, and experimental work have together led to the identification of anaphylatoxin C5a as a promising treatment target in bacterial meningitis. In animals and patients with pneumococcal meningitis, the accumulation of neutrophils in the CSF was mainly driven by C5-derived chemotactic activity and correlated positively with disease severity and outcome. In murine pneumococcal meningitis, adjunctive treatment with C5 antibodies prevented brain damage and death. Several recently developed therapeutics target C5 conversion, C5a, or its receptor C5aR. Caution is warranted because treatment with C5 antibodies such as eculizumab also inhibits the formation of the membrane attack complex, which may result in decreased meningococcal killing and increased meningococcal disease susceptibility. The use of C5a or C5aR antagonists to specifically target the harmful anaphylatoxins-induced effects, therefore, are most promising and present opportunities for a phase 2 clinical trial.

Streptococcus pneumoniae Meningitis Associated With Over-the-Counter Sinus Irrigation

We present the first reported case of Streptococcus pneumoniae bacterial meningitis that may be associated with use of an over-the-counter sinus irrigation. Sinus rinse or “Neti Pot” use is a common remedy for sinus congestion and is felt to be relatively safe. Given its widespread use, it is important to report possible associations with disease, in this case Streptococcus pneumoniae meningitis. A 50-year-old male with a history of sinusitis presented to the emergency department with a headache and altered mental status and was ultimately diagnosed with Streptococcus pneumoniae meningitis and sepsis. He had been using over-the-counter sinus rinses several times daily with distilled water. The patient had no radiographic evidence of contiguous spread or traumatic injury that would make him susceptible to direct cerebrospinal fluid infection. Inquiring about sinus irrigation use should be considered in patients with suspected meningitis. Emergency clinicians must consider meningitis in patients with Neti Pot use.

The Strengthening of Laboratory Systems in the Meningitis Belt to Improve Meningitis Surveillance, 2008-2018: A Partners' Perspective

Laboratories play critical roles in bacterial meningitis disease surveillance in the African meningitis belt, where the highest global burden of meningitis exists. Reinforcement of laboratory capacity ensures rapid detection of meningitis cases and outbreaks and a public health response that is timely, specific, and appropriate. Since 2008, joint efforts to strengthen laboratory capacity by multiple partners, including MenAfriNet, beginning in 2014, have been made in countries within and beyond the meningitis belt. Over the course of 10 years, national reference laboratories were supported in 5 strategically targeted areas: specimen transport systems, laboratory procurement systems, laboratory diagnosis, quality management, and laboratory workforce with substantial gains made in each of these areas. To support the initiative to eliminate meningitis by 2030, continued efforts are needed to strengthen laboratory systems.

Methods for rapid diagnosis of meningitis etiology in adults

Infectious meningitis can be caused by viral, bacterial or fungal pathogens. Despite widely available treatments, many types of infectious meningitis are still associated with significant morbidity and mortality. Delay in diagnosis contributes to poor outcomes. Cerebrospinal fluid cultures have been used traditionally but are time intensive and sensitivity is decreased by empiric treatment prior to culture. More rapid techniques such as the cryptococcal lateral flow assay (IMMY), GeneXpert MTB/Rif Ultra (Cepheid) and FilmArray multiplex-PCR (Biofire) are three examples that have drastically changed meningitis diagnostics. This review will discuss a holistic approach to diagnosing bacterial, mycobacterial, viral and fungal meningitis.

Vitamin B12 is neuroprotective in experimental pneumococcal meningitis through modulation of hippocampal DNA methylation

Background

Bacterial meningitis (BM) causes apoptotic damage to the hippocampus and homocysteine (Hcy) accumulation to neurotoxic levels in the cerebrospinal fluid of children. The Hcy pathway controls bioavailability of methyl, and its homeostasis can be modulated by vitamin B₁₂, a cofactor of the methionine synthase enzyme. Herein, the neuroprotective potential and the underlying mode of action of vitamin B₁₂ adjuvant therapy were assessed in an infant rat model of BM.

Methods

Eleven-day old rats were intracysternally infected with Streptococcus pneumoniae serotype 3, or saline, treated with B₁₂ or placebo, and, 24 h after infection, their hippocampi were analyzed for apoptosis in the dentate gyrus, sulfur amino acids content, global DNA methylation, transcription, and proximal promoter methylation of candidate genes. Differences between groups were compared using 2-way ANOVA followed by Bonferroni post hoc test. Correlations were tested with Spearman’s test.

Results

B₁₂ attenuated BM-induced hippocampal apoptosis in a Hcy-dependent manner (r = 0.80, P < 0.05). BM caused global DNA hypomethylation; however, B₁₂ restored this parameter. Accordingly, B₁₂ increased the methylation capacity of hippocampal cells from infected animals, as inferred from the ratio S-adenosylmethionine (SAM):S-adenosylhomocysteine (SAH) in infected animals. BM upregulated selected pro-inflammatory genes, and this effect was counteracted by B₁₂, which also increased methylation of CpGs at the promoter of Ccl3 of infected animals.

Conclusion

Hcy is likely to play a central role in hippocampal damage in the infant rat model of BM, and B₁₂ shows an anti-inflammatory and neuroprotective action through methyl-dependent epigenetic mechanisms.

Community-acquired bacterial meningitis in adults: in-hospital prognosis, long-term disability and determinants of outcome in a multicentre prospective cohort

OBJECTIVES

To identify factors associated with unfavourable in-hospital outcome (death or disability) in adults with community-acquired bacterial meningitis (CABM).

METHODS

In a prospective multicentre cohort study (COMBAT; February 2013 to July 2015), all consecutive cases of CABM in the 69 participating centres in France were enrolled and followed up for 12 months. Factors associated with unfavourable outcome were identified by logistic regression and long-term disability was analysed.

RESULTS

Among the 533 individuals enrolled, (Streptococcus pneumoniae 53.8% (280/520 isolates identified), Neisseria meningitidis 21.3% (111/520), others 24.9% (129/520)), case fatality rate was 16.9% (90/533) and unfavourable outcome occurred in 45.0% (225/500). Factors independently associated with unfavourable outcome were: age >70 years (adjusted odds ratio (aOR) 4.64; 95% CI 1.93-11.15), male gender (aOR 2.11; 95% CI 1.25-3.57), chronic renal failure (aOR 6.65; 95% CI 1.57-28.12), purpura fulminans (aOR 4.37; 95% CI 1.38-13.81), localized neurological signs (aOR 3.72; 95% CI 2.29-6.05), disseminated intravascular coagulation (aOR 3.19; 95% CI 1.16-8.79), cerebrospinal fluid (CSF) white-cell count <1500 cells/μL (aOR 2.40; 95% CI 1.42-4.03), CSF glucose concentration (0.1-2.5 g/L: aOR 1.92; 95% CI 1.01-3.67; <0.1 g/L: aOR 2.24; 95% CI 1.01-4.97), elevated CSF protein concentration (aOR 1.09; 95% CI 1.03-1.17), time interval between hospitalization and lumbar puncture >1 day (aOR 2.94; 95% CI 1.32-6.54), and S. pneumoniae meningitis (aOR 4.99; 95% CI 1.98-12.56), or meningitis other than N. meningitidis (aOR 4.54; 95% CI 1.68-12.27). At 12 months, 26.7% (74/277) had hearing loss, 32.8% (87/265) depressive symptoms, 31.0% (86/277) persistent headache, and 53.4% had a physical health-related quality of life (142/266) <25th centile of the distribution of the score in the general French population (p < 0.0001).

CONCLUSIONS

The burden of CABM (death, disability, depression, impaired quality of life and hearing loss) is high. Identification of cases from the first symptoms may improve prognosis.

CLINICALTRIAL

Gov identification number: NCT01730690.

Sex-based differences in the response to dexamethasone in bacterial meningitis: Analysis of the European dexamethasone in adulthood bacterial meningitis study

Inflammatory markers have been found at higher concentrations in women than men with bacterial meningitis. To investigate sex‐based differences in the response to dexamethasone, we performed a post hoc analysis of a double‐blind, randomised multicentre trial of dexamethasone (10 mg, 4 times daily for 4 days) vs placebo in adults with bacterial meningitis. The primary outcome measure was the Glasgow outcome scale score at 8 weeks and interaction tests were used to examine subgroup differences. Between June 1993 and December 2001, 301 patients (56% male) were randomly assigned to a treatment group: 157 received dexamethasone and 144 placebo. Although dexamethasone reduced the risk of unfavourable outcome to a greater extent in women (relative risk [RR] 0.42, 95% confidence interval [CI] 0.21–0.86, P = .02) than men (RR 0.79, 95% CI 0.41–1.51, P = .55), on interaction testing (ratio of RR women:men 0.53, 95% CI 0.20–1.39, P = .19) patient sex was not a significant modifier of the effect of dexamethasone.

Neuroinflammation trajectories precede cognitive impairment after experimental meningitis-evidence from an in vivo PET study

Background

Bacterial meningitis is a devastating central nervous system (CNS) infection with acute and long-term neurological consequences, including cognitive impairment. The aim of this study was to understand the association between activated microglia-induced neuroinflammation and post-meningitis cognitive impairment.

Method

Meningitis was induced in male Wistar rats by injecting Streptococcus pneumoniae into the brain through the cisterna magna, and rats were then treated with ceftriaxone. Twenty-four hours and 10 days after meningitis induction, rats were imaged with positron emission tomography (PET) using [¹¹C]PBR28, a specific translocator protein (TSPO) radiotracer, to determine in vivo microglial activation. Following imaging, the expression of TSPO, cardiolipin, and cytochrome c, inflammatory mediators, oxidative stress markers, and glial activation markers were evaluated in the prefrontal cortex and hippocampus. Ten days after meningitis induction, animals were subjected to behavioral tests, such as the open-field, step-down inhibitory avoidance, and novel object recognition tests.

Results

Both 24-h (acute) and 10-day (long-term) groups of rats demonstrated increased [¹¹C]PBR28 uptake and microglial activation in the whole brain compared to levels in the control group. Although free from infection, 10-day group rats exhibited increased expression levels of cytokines and markers of oxidative stress, microglial activation (IBA-1), and astrocyte activation (GFAP) similar to those seen in the 24-h group. Acute meningitis induction also elevated TSPO, cytochrome c, and caspase-3 levels with no change in caspase-9 levels. Furthermore, upregulated levels of TSPO, cytochrome c, and caspase-3 and caspase-9 were observed in the rat hippocampus 10 days after meningitis induction with a simultaneous reduction in cardiolipin levels. Animals showed a cognitive decline in all tasks compared with the control group, and this impairment may be at least partially mediated by activating a glia-mediated immune response and upregulating TSPO.

Conclusions

TSPO-PET could potentially be used as an imaging biomarker for microglial activation and long-term cognitive impairment post-meningitis. Additionally, this study opens a new avenue for the potential use of TSPO ligands after infection-induced neurological sequelae.

Isolation and identification of Streptococcus suis from sick pigs in Bali, Indonesia

Objective

Streptococcus suis (S. suis) is a causative agent for various syndromes in pigs. It can be transmitted to humans with typical symptoms of meningitis and death. Although human infections have been confirmed at Bali Referral Hospital, Indonesia, since 2014, the bacteria have not been isolated from pigs. Here, we provide confirmation of the presence of the bacteria in sick pigs in the province.

Results

Streptococcus suis was confirmed in 8 of 30 cases. The final confirmation was made using PCR and sequencing of the glutamate dehydrogenase (GDH) and recombination/repair protein (recN) gene fragments. Upon PCR serotyping, two were confirmed to be serotype 2 or 1/2. Prominent histopathological lesions of confirmed cases were meningitis, endocarditis, pericarditis, bronchopneumonia, enteritis and glomerulonephritis. The dominant inflammatory cells were neutrophils and macrophages. Further research is needed to understand the risk factors for human infection. Community awareness on the risk of contracting S. suis and vaccine development are needed to prevent human infections.

Development of practical recommendations for diagnostic accuracy studies in low-prevalence situations

OBJECTIVE

Low disease prevalence poses challenges for diagnostic accuracy studies because of the large sample sizes that are required to obtain sufficient precision. The aim is to collate and discuss designs of diagnostic accuracy studies suited for use in low-prevalence situations.

STUDY DESIGN AND SETTING

We conducted a literature search including backward citation tracking and expert consultation. Two reviewers independently selected studies on designs for estimating diagnostic accuracy in a low-prevalence situation. During a 1-day expert meeting, all designs were discussed and recommendations were formulated.

RESULTS

We identified six designs for diagnostic accuracy studies that are suitable in low-prevalence situations because they reduced the total sample size or the number of patients undergoing the index test or reference standard depending on which poses the highest burden. We described the advantages and limitations of these designs and evaluated efficiencies in sample sizes, risk of bias, and alignment with the clinical pathway for applicability in routine care.

CONCLUSION

Choosing a study design for diagnostic accuracy studies in low-prevalence situations should depend on whether the aim is to limit the number of patients undergoing the index test or reference standard, and the risk of bias associated with a particular design type.

Enhanced safety and immunogenicity of a pneumococcal surface antigen A mutant whole-cell inactivated pneumococcal vaccine

Existing capsular polysaccharide-based vaccines against pneumococcal disease are highly effective against vaccine-included serotypes, but they are unable to combat serotype replacement. We have developed a novel pneumococcal vaccine that confers serotype-independent protection, and could therefore constitute a "universal" vaccine formulation. This preparation is comprised of whole un-encapsulated pneumococci inactivated with gamma irradiation (γ-PN), and we have previously reported induction of cross-reactive immunity after nonadjuvanted intranasal vaccination. To further enhance vaccine immunogenicity and safety, we modified the pneumococcal vaccine strain to induce a stressed state during growth. Specifically, the substrate binding component of the psaBCA operon for manganese import was mutated to create a pneumococcal surface antigen A (psaA) defective vaccine strain. psaA mutation severely attenuated the growth of the vaccine strain in vitro without negatively affecting pneumococcal morphology, thereby enhancing vaccine safety. In addition, antibodies raised against vaccine preparations based on the modified strain [γ-PN(ΔPsaA)] showed more diversified reactivity to wild-type pneumococcal challenge strains compared to those induced by the original formulation. The modified vaccine also induced comparable protective T_H 17 responses in the lung, and conferred greater protection against lethal heterologous pneumococcal challenge. Overall, the current study demonstrates successful refinement of a serotype-independent pneumococcal vaccine candidate to enhance safety and immunogenicity.

Pneumolysin and the bacterial capsule of Streptococcus pneumoniae cooperatively inhibit taxis and motility of microglia

Background

Streptococcus pneumoniae is the cause of a highly lethal form of meningitis in humans. Microglial cells in the brain represent the first line of defense against pathogens, and they participate in the inflammatory response. The cholesterol-dependent cytolysin pneumolysin and the bacterial capsule are key pathogenic factors, known to exacerbate the course of pneumococcal meningitis.

Methods

We utilized live imaging and immunostaining of glial cells in dissociated and acute brain slice cultures to study the effect of pneumococcal factors, including the cholesterol-dependent cytolysin pneumolysin and the pneumococcal capsule, on microglial motility and taxis.

Results

In brain tissue, primary microglia cells showed an enhanced response towards lysates from bacteria lacking capsules and pneumolysin as they moved rapidly to areas with an abundance of bacterial factors. The presence of bacterial capsules and pneumolysin cumulatively inhibited microglial taxis. In mixed cultures of astrocytes and microglia, the motility of microglia was inhibited by capsular components within minutes after exposure. The reduced motility was partially reversed by mannan, a mannose receptor inhibitor. The effects on microglia were not mediated by astrocytes because pure microglial cells responded to various pneumococcal lysates similarly with distinct cell shape changes as seen in mixed cultures.

Conclusions

Our data indicate that microglia possess the capacity for a very agile response towards bacterial pathogens, but key pathogenic factors, such as pneumococcal capsules and pneumolysin, inhibited this response shortly after a bacterial challenge. Furthermore, we demonstrate for the first time that the bacterial capsule affects cellular behaviors such as motility and taxis.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1491-7) contains supplementary material, which is available to authorized users.

Immunogenicity and safety of the Haemophilus influenzae type b and Neisseria meningitidis serogroups C and Y-tetanus toxoid conjugate vaccine co-administered with human rotavirus, hepatitis A and 13-valent pneumococcal conjugate vaccines: results from a phase III, randomized, multicenter study in infants

This phase III, open-label, randomized study (NCT01978093) evaluated the immunogenicity and safety of co-administered Haemophilus influenzae type b–Neisseria meningitidis serogroups C and Y–tetanus toxoid conjugate vaccine (Hib-MenCY-TT) with human rotavirus vaccine (HRV), hepatitis A vaccine (HAV) and 13-valent pneumococcal conjugate vaccine (PCV13). We randomized 600 infants (1:1) to receive 4 doses of Hib-MenCY-TT at 2, 4, 6 and 12–15 months of age or 3 doses of Hib vaccine conjugated to N. meningitidis outer membrane protein complex (Hib-OMP) at 2, 4 and 12–15 months of age. All infants received HRV at 2 and 4 months of age, PCV13 at 2, 4, 6 and 12–15 months of age, HAV at 12–15 and 18–21 months of age, and diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus vaccine at 2, 4 and 6 months of age. We measured immune responses against HRV, HAV and Hib with enzyme-linked immunosorbent assays, and against MenC/MenY with serum bactericidal assays using human complement. The 4-dose vaccination series with Hib-MenCY-TT induced a robust immune response against Hib, which was non-inferior to that induced by a 3-dose vaccination series with Hib-OMP, and against MenC and MenY. Hib-MenCY-TT did not interfere with immune responses to concomitantly administered HRV, PCV13 and HAV. We did not identify any safety concern. In conclusion, we showed that 4-dose vaccination series with Hib-MenCY-TT during infancy did not interfere with immune responses of co-administered HRV, PCV13 and HAV, induced robust immune responses against Hib, MenC and MenY, and had a clinically acceptable safety profile.

Bactericidal Activity of a Cationic Peptide on Neisseria meningitidis

BACKGROUND

The increasing prevalence of antibiotic resistant bacteria has raised an urgent need for substitute remedies. Antimicrobial peptides (AMPs) are considered promising candidates to address infections by multidrug-resistant bacteria through new mechanisms of action that require a careful evaluation of their performance.

OBJECTIVE

Identification of effective AMPs against Neisseria meningitidis, which represents a pathogen of great public health importance worldwide that is intrinsically resistant to some AMPs, such as polymyxin B.

METHODS

A cationic 11-residue peptide (KLKLLLLLKLK), referred to as poly-Leu, was synthesized and its antimeningococcal activity was compared to cecropin A and poly-P (KLKPPPPPKLK) through a variety of assays. Flow cytometry was used to measure propidium iodide uptake by N. meningitidis serotype B as an indicator of the effectiveness of each peptide when added to cultures at different concentrations.

RESULTS

The addition of the poly-Leu peptide led to a 90.3% uptake of the dye with an EC50 value of 7.9 µg mL-1. In contrast, uptake was <10% in cells grown in the absence of peptides or with an identical concentration of cecropin and poly-Pro peptides. Electron micrographs indicated that the integrity of the cellular wall and internal membrane was impacted in relation to peptide concentrations, which was confirmed by the detection of released alkaline phosphatase from the periplasmic space due to disruption of the external membrane.

CONCLUSION

Poly-Leu peptide demonstrated definitive antimicrobial activity against N. meningitidis.