Hearing loss in adults surviving pneumococcal meningitis is associated with otitis and pneumococcal serotype

Hearing loss after bacterial meningitis, a retrospective study

BACKGROUND

Hearing loss is a common sequela after bacterial meningitis, but risk factors for this are poorly studied, particularly in relation to concurrent acute otitis media (AOM).

AIMS

The aim of this study was to investigate incidence and risk factors for hearing loss in patients treated for bacterial meningitis.

METHODS

In this retrospective study, medical records for patients admitted to hospital with bacterial meningitis in Skåne county, Sweden, between 2000 and 2017 were retrieved. The association between risk factors and hearing loss was estimated using logistic regression.

RESULTS

During the 18 years, 187 cases of meningitis were identified. Hearing loss was confirmed in 71 of the 119 patients who had done an audiometry. It was significantly more common in adults. There was also evidence of an association between hearing loss and AOM, and between hearing loss and pneumococcal infection.

CONCLUSION

Age, concurrent AOM and pneumococcal infection were risk factors for developing hearing loss. Despite being recommended in the national guidelines, more than a third of the patients had not done a hearing test after recovering from bacterial meningitis. The findings strengthen the demand for prompt ear examination and - if needed - tympanocentesis in meningitis patients.

Community-acquired bacterial meningitis

Progress has been made in the prevention and treatment of community-acquired bacterial meningitis during the past three decades but the burden of the disease remains high globally. Conjugate vaccines against the three most common causative pathogens (Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae) have reduced the incidence of disease, but with the replacement by non-vaccine pneumococcal serotypes and the emergence of bacterial strains with reduced susceptibility to antimicrobial treatment, meningitis continues to pose a major health challenge worldwide. In patients presenting with bacterial meningitis, typical clinical characteristics (such as the classic triad of neck stiffness, fever, and an altered mental status) might be absent and cerebrospinal fluid examination for biochemistry, microscopy, culture, and PCR to identify bacterial DNA are essential for the diagnosis. Multiplex PCR point-of-care panels in cerebrospinal fluid show promise in accelerating the diagnosis, but diagnostic accuracy studies to justify routine implementation are scarce and randomised, controlled studies are absent. Early administration of antimicrobial treatment (within 1 hour of presentation) improves outcomes and needs to be adjusted according to local emergence of drug resistance. Adjunctive dexamethasone treatment has proven efficacy beyond the neonatal age but only in patients from high-income countries. Further progress can be expected from implementing preventive measures, especially the development of new vaccines, implementation of hospital protocols aimed at early treatment, and new treatments targeting checkpoints of the inflammatory cascade.

A Review of Adult-Onset Hearing Loss: A Primer for Neurologists

Purpose of the Review

The goal of this review is to highlight current approaches to diagnosis and treatment for adult-onset hearing loss in patients likely to present to a neurologist's office. The review will discuss primary and secondary causes of acute and chronic hearing loss, and will discuss common situations that can be managed by a neurologist as well as situations that require immediate care and referral for further management by an otolaryngologist-head and neck surgeon.

Recent Findings

Hearing screening assessments using mobile applications and tablet devices are now available and can be integrated into many clinical practice settings, including in the evaluation of hearing concerns related to various neurological pathologies. For patients presenting with a sudden worsening in hearing, bedside evaluation, including with objective measures of hearing, can inform neurologists about diagnosis and subsequent management. For patients who present with gradual worsening in hearing, particularly those related to neurologic disorders, hearing care can be an important adjunct to ongoing neurologic care. More commonly encountered, age-related hearing loss is highly prevalent among older adults and may affect overall neurological assessment, including neurocognitive testing, as well as patient-provider communication, patient satisfaction, and care outcomes. Hearing loss is increasingly recognized as a potentially modifiable risk factor for dementia. Neurologists can support the hearing health of their patients through the routine use of communication strategies and by integrating simple, low-cost technology with their current clinical practices.

Summary

Both acute and chronic hearing loss can be a symptom of many conditions managed by neurologists. Few conditions are emergent, requiring immediate referral to and treatment by an otolaryngologist-head and neck surgeon. Despite the range of hearing interventions available, including hearing aids, over-the-counter devices, and aural rehabilitation, hearing loss is a common and under-treated chronic health condition. By promptly addressing a patient's hearing concerns, neurologists can improve patients' awareness of the deficit and support the overall importance of maintaining sensory health across the life course.

Otoacoustic emissions in patients with bacterial meningitis

Objective: Systematic evaluation of studies using otoacoustic emissions (OAEs) to monitor cochlear damage in patients with bacterial meningitis.Design: Systematic review. This includes articles retrieved from PUBMED and EMBASE. The search-strategy was based on the PICO-model. Data processing involved Cochrane Public Health Data Extraction template in addition to assessment of risk of bias and applicability with the Second Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool.Study samples: Thirty-eight articles were identified with 6 studies comprising 391 children and 17 adult patients eligible for full assessment.Results: Studies were heterogenic and the timing of OAE was incomparable between studies. The frequency of severe loss of hearing was reported to occur between 1.6 and 21% of the patients with culture-proven meningitis. The included studies, albeit heterogenic, found OAE-screening feasible and sensitive in children recovering from bacterial meningitis.Conclusion: No children with hearing loss were reported to pass an OAE screening in any of the included studies. The timing, sensitivity and extent of sensorineural hearing loss determined by OAE could not be assessed from the included studies. Levels of risk of bias were inconsistent and the clinical feasibility for routine inclusion of patients with bacterial meningitis was uncertain. The technological development within this field implies the need for further research.

Neuroinflammation and ER-stress are key mechanisms of acute bilirubin toxicity and hearing loss in a mouse model

Hyperbilirubinemia (jaundice) is caused by raised levels of unconjugated bilirubin in the blood. When severe, susceptible brain regions including the cerebellum and auditory brainstem are damaged causing neurological sequelae such as ataxia, hearing loss and kernicterus. The mechanism(s) by which bilirubin exerts its toxic effect have not been completely understood to date. In this study we investigated the acute mechanisms by which bilirubin causes the neurotoxicity that contributes to hearing loss. We developed a novel mouse model that exhibits the neurological features seen in human Bilirubin-Induced Neurological Dysfunction (BIND) syndrome that we assessed with a behavioural score and auditory brainstem responses (ABR). Guided by initial experiments applying bilirubin to cultured cells in vitro, we performed whole genome gene expression measurements on mouse brain tissue (cerebellum and auditory brainstem) following bilirubin exposure to gain mechanistic insights into biochemical processes affected, and investigated further using immunoblotting. We then compared the gene changes induced by bilirubin to bacterial lipopolysaccharide (LPS), a well characterized inducer of neuroinflammation, to assess the degree of similarity between them. Finally, we examined the extent to which genetic perturbation of inflammation and both known and novel anti-inflammatory drugs could protect hearing from bilirubin-induced toxicity. The in vitro results indicated that bilirubin induces changes in gene expression consistent with endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR). These gene changes were similar to the gene expression signature of thapsigargin–a known ER stress inducer. It also induced gene expression changes associated with inflammation and NF-κB activation. The in vivo model showed behavioural impairment and a raised auditory threshold. Whole genome gene expression analysis confirmed inflammation as a key mechanism of bilirubin neurotoxicity in the auditory pathway and shared gene expression hallmarks induced by exposure to bacterial lipopolysaccharide (LPS) a well-characterized inducer of neuroinflammation. Interestingly, bilirubin caused more severe damage to the auditory system than LPS in this model, but consistent with our hypothesis of neuroinflammation being a primary part of bilirubin toxicity, the hearing loss was protected by perturbing the inflammatory response. This was carried out genetically using lipocalin-2 (LCN2)-null mice, which is an inflammatory cytokine highly upregulated in response to bilirubin. Finally, we tested known and novel anti-inflammatory compounds (interfering with NF-κB and TNFα signalling), and also demonstrated protection of the auditory system from bilirubin toxicity. We have developed a novel, reversible, model for jaundice that shows movement impairment and auditory loss consistent with human symptoms. We used this model to establish ER-stress and inflammation as major contributors to bilirubin toxicity. Because of the rapid and reversible onset of toxicity in this novel model it represents a system to screen therapeutic compounds. We have demonstrated this by targeting inflammation genetically and with anti-inflammatory small molecules that offered protection against bilirubin toxicity. This also suggests that anti-inflammatory drugs could be of therapeutic use in hyperbilirubinemia.

Variation in coagulation and fibrinolysis genes evaluated for their contribution to cerebrovascular complications in adults with bacterial meningitis in the Netherlands

OBJECTIVE

To study whether genetic variation in coagulation and fibrinolysis genes contributes to cerebrovascular complications in bacterial meningitis.

METHODS

We performed a nationwide prospective genetic association study in adult community-acquired bacterial meningitis patients. The exons and flanking regions of 16 candidate genes involved in coagulation and fibrinolysis pathways were sequenced. We analyzed whether genetic variation in these genes resulted in a higher risk of cerebrovascular complications, unfavorable outcome and differences in thrombocyte count on admission.

RESULTS

From 2006 to 2011, a total of 1101 bacterial meningitis patients were identified of whom 622 supplied DNA for genotyping and passed genetic quality control steps. In 139 patients (22%) the episode of bacterial meningitis was complicated by cerebral infarction, and 188 (30%) had an unfavorable outcome. We identified the functional variant rs494860 in the protein Z (PROZ) gene as our strongest association with occurrence of cerebral infarction (odds ratio (OR) 0.49 (95% confidence interval 0.33-0.73), p = 5.2 × 10^-4). After Bonferroni correction for multiple testing no genetic variant was significantly associated (p-value threshold 2.7 × 10^-4).

CONCLUSION

Our study suggests a functional genetic variation in the PROZ gene, rs494860, may be of importance in bacterial meningitis pathogenesis and cerebral infarction risk. Replication of this finding in other cohort studies populations is needed.

The Severity of Infection Determines the Localization of Damage and Extent of Sensorineural Hearing Loss in Experimental Pneumococcal Meningitis

Hearing loss is an important sequela of pneumococcal meningitis (PM), occurring in up to 30% of survivors. The role of the severity of infection on hearing function and pathomorphological consequences in the cochlea secondary to PM have not been investigated to date. Using a well-established model of PM, we systematically investigated the functional hearing outcome and the long-term fate of neurosensory cells in the cochlea, i.e., hair cells and spiral ganglion neurons (SGNs), with a focus on their tonotopic distribution. Intracisternal infection of infant rats with increasing inocula of Streptococcus pneumoniae resulted in a dose-dependent increase in CSF levels of interleukin-1β, interleukin-6, tumor necrosis factor α, interleukin-10, and interferon-γ in acute disease. The severity of long-term hearing loss at 3 weeks after infection, measured by auditory brainstem response recordings, correlated to the initial inoculum dose and to the levels of proinflammatory cytokines determined in the acute phase of PM. Quantitative cochlear histomorphology revealed a significant loss of SGNs and outer hair cells that strongly correlated to the level of infection, with the most severe damage occurring in the basal part of the cochlea. Inner hair cells (IHCs) were not significantly affected throughout the entire cochlea. However, surviving IHCs lost synaptic connectivity to remaining SGNs in all cochlear regions. These findings provide evidence that the inoculum concentration, i.e., severity of infection, is the major determinant of long-term morphological cell pathologies in the cochlea and functional hearing loss.

SIGNIFICANCE STATEMENT

Hearing loss is a neurofunctional deficit occurring in up to 30% of patients surviving pneumococcal meningitis (PM). Here, we analyze the correlation between the severity of infection and the inflammatory response in the CSF, the tonotopic distribution of neurosensory pathologies in the cochlea, and the long-term hearing function in a rat model of pneumococcal meningitis. Our study identifies the severity of infection as the key determinant of long-term hearing loss, underlining the importance of the prompt institution of antibiotic therapy in patients suffering from PM. Furthermore, our findings reveal in detail the spatial loss of cochlear neurosensory cells, providing new insights into the pathogenesis of meningitis-associated hearing loss that reveal new starting points for the development of otoprotective therapies.

Streptococcus pneumoniae-induced ototoxicity in organ of Corti explant cultures

Hearing loss remains the most common long-term complication of pneumococcal meningitis (PM) reported in up to 30% of survivors. Streptococcus pneumoniae have been shown to possess different ototoxic properties. Here we present a novel ex vivo experimental setup to examine in detail the pattern of hair cell loss upon exposure to different S. pneumoniae strains, therefore recapitulating pathogen derived aspects of PM-induced hearing loss. Our results show a higher susceptibility towards S. pneumoniae-induced cochlear damage for outer hair cells (OHC) compared to inner hair cells (IHC), which is consistent with in vivo data. S. pneumoniae-induced hair cell loss was both time and dose-dependent. Moreover, we have found significant differences in the level of cell damage between tissue from the basal and the apical turns. This shows that the higher vulnerability of hair cells located at high frequency regions observed in vivo cannot be explained solely by the spatial organisation and bacterial infiltration from the basal portion of the cochlea. Using a wild type D39 strain and a mutant defective for the pneumolysin (PLY) gene, we also have shown that the toxin PLY is an important factor involved in ototoxic damages. The obtained results indicate that PLY can cause both IHC and OHC loss. Finally, we are reporting here for the first time a higher vulnerability of HC located at the basal and middle cochlear region to pneumolysin-induced damage. The detailed description of the susceptibility of hair cells to Streptococcus pneumoniae provided in this report can in the future determine the choice and the development of novel otoprotective therapies during pneumococcal meningitis.

Sex-based differences in adults with community-acquired bacterial meningitis: a prospective cohort study

OBJECTIVES

To investigate sex-based differences in clinical features, causative pathogens, outcome and treatment of adult community-acquired meningitis.

METHODS

From January 2006 to July 2014, we prospectively investigated sex-based differences in clinical features, causative pathogens, outcome and treatment of adult community-acquired meningitis in a nationwide cohort study in the Netherlands. Sex was analysed along with known predictors of unfavourable outcome using logistic regression.

RESULTS

We evaluated 1412 episodes of meningitis, 707 (50%) in men. Men more often presented with a history of remote head injury (41/667 (6%) versus 14/658 (2%) women, p 0.0002) or alcoholism (61/652 (9%) versus 21/660 (3%) women, p <0.0001). Neck stiffness was less common in men (453/651 (70%) versus 524/671 (78%) women, p 0.0004). Despite greater illness severity, women were less likely to receive treatment in an intensive care unit (odds ratio (OR) 0.72, 95% CI 0.58-0.89, p 0.003) or mechanical ventilation (OR 0.67, 95% CI 0.54-0.85, p 0.001). Women exhibited higher serum inflammatory parameters than men (median C-reactive protein 211 versus 171, p 0.0001; median erythrocyte sedimentation rate 48 versus 33, p <0.0001). Corticosteroids improved prognosis in both sexes, but absolute risk reduction was higher in women (20% versus 15%, p 0.001), although we found no significant interaction between sex and dexamethasone (p 0.38). In the multivariable analysis, male sex was an independent predictor of unfavourable outcome (OR 1.34, 95% CI 1.03-1.75, p 0.03) and death (OR 1.47, 95% CI 1.04-2.07, p 0.03).

CONCLUSIONS

Our findings show sex-based differences in adults with community-acquired bacterial meningitis. Male sex is an independent risk factor for adverse outcome. It is possible that sex-based differences in immune reaction could determine a distinct response to corticosteroids.

Community-acquired bacterial meningitis

Meningitis is an inflammation of the meninges and subarachnoid space that can also involve the brain cortex and parenchyma. It can be acquired spontaneously in the community - community-acquired bacterial meningitis - or in the hospital as a complication of invasive procedures or head trauma (nosocomial bacterial meningitis). Despite advances in treatment and vaccinations, community-acquired bacterial meningitis remains one of the most important infectious diseases worldwide. Streptococcus pneumoniae and Neisseria meningitidis are the most common causative bacteria and are associated with high mortality and morbidity; vaccines targeting these organisms, which have designs similar to the successful vaccine that targets Haemophilus influenzae type b meningitis, are now being used in many routine vaccination programmes. Experimental and genetic association studies have increased our knowledge about the pathogenesis of bacterial meningitis. Early antibiotic treatment improves the outcome, but the growing emergence of drug resistance as well as shifts in the distribution of serotypes and groups are fuelling further development of new vaccines and treatment strategies. Corticosteroids were found to be beneficial in high-income countries depending on the bacterial species. Further improvements in the outcome are likely to come from dampening the host inflammatory response and implementing preventive measures, especially the development of new vaccines.

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.

Neurological sequelae of bacterial meningitis

OBJECTIVES

We reported on occurrence and impact of neurological sequelae after bacterial meningitis.

METHODS

We reviewed occurrence of neurological sequelae in children and adults after pneumococcal and meningococcal meningitis.

RESULTS

Most frequently reported sequelae are focal neurological deficits, hearing loss, cognitive impairment and epilepsy. Adults with pneumococcal meningitis have the highest risk of developing focal neurological deficits, which are most commonly caused by cerebral infarction, but can also be due to cerebritis, subdural empyema, cerebral abscess or intracerebral bleeding. Focal deficits may improve during clinical course and even after discharge, but a proportion of patients will have persisting focal neurological deficits that often interfere in patient's daily life. Hearing loss occurs in a high proportion of patients with pneumococcal meningitis and has been associated with co-existing otitis. Children and adults recovering from bacterial meningitis without apparent neurological deficits are at risk for long-term cognitive deficits. Early identification of neurological sequelae is important for children to prevent additional developmental delay, and for adults to achieve successful return in society after the disease.

CONCLUSIONS

Neurological sequelae occur in a substantial amount of patients following bacterial meningitis. Most frequently reported sequelae are focal neurological deficits, hearing loss, cognitive impairment and epilepsy.

Functional polymorphisms of macrophage migration inhibitory factor as predictors of morbidity and mortality of pneumococcal meningitis

Pneumococcal meningitis is the most frequent and critical type of bacterial meningitis. Because cytokines play an important role in the pathogenesis of bacterial meningitis, we examined whether functional polymorphisms of the proinflammatory cytokine macrophage migration inhibitory factor (MIF) were associated with morbidity and mortality of pneumococcal meningitis. Two functional MIF promoter polymorphisms, a microsatellite (-794 CATT5-8; rs5844572) and a single-nucleotide polymorphism (-173 G/C; rs755622) were genotyped in a prospective, nationwide cohort of 405 patients with pneumococcal meningitis and in 329 controls matched for age, gender, and ethnicity. Carriages of the CATT7 and -173 C high-expression MIF alleles were associated with unfavorable outcome (P= 0.005 and 0.003) and death (P= 0.03 and 0.01). In a multivariate logistic regression model, shock [odds ratio (OR) 26.0, P= 0.02] and carriage of the CATT7 allele (OR 5.12,P= 0.04) were the main predictors of mortality. MIF levels in the cerebrospinal fluid were associated with systemic complications and death (P= 0.0002). Streptococcus pneumoniae strongly up-regulated MIF production in whole blood and transcription activity of high-expression MIF promoter Luciferase reporter constructs in THP-1 monocytes. Consistent with these findings, treatment with anti-MIF immunoglogulin G (IgG) antibodies reduced bacterial loads and improved survival in a mouse model of pneumococcal pneumonia and sepsis. The present study provides strong evidence that carriage of high-expression MIF alleles is a genetic marker of morbidity and mortality of pneumococcal meningitis and also suggests a potential role for MIF as a target of immune-modulating adjunctive therapy.

Community-acquired bacterial meningitis in adults in the Netherlands, 2006-14: a prospective cohort study

BACKGROUND

We studied causative pathogens, clinical characteristics, and outcome of adult community-acquired bacterial meningitis after the introduction of adjunctive dexamethasone treatment and nationwide implementation of paediatric conjugate vaccines.

METHODS

In this cohort study, we prospectively assessed adults (age >16 years) with community-acquired bacterial meningitis in the Netherlands, identified through the National Reference Laboratory for Bacterial Meningitis or individual physicians between Jan 1, 2006, and July 1, 2014. We identified independent predictors of an unfavourable outcome (Glasgow Outcome Scale score 1-4) by logistic regression.

FINDINGS

We assessed 1412 episodes of community-acquired bacterial meningitis. Incidence declined from 1·72 cases per 100,000 adults per year in 2007-08, to 0·94 per 100,000 per year in 2013-14. Streptococcus pneumoniae caused 1017 (72%) of 1412 episodes. Rates of adult bacterial meningitis decreased most sharply among pneumococcal serotypes included in paediatric conjugate vaccine, and in meningococcal meningitis. We found no evidence of serotype or serogroup replacement. The overall case fatality rate was 244 (17%) of 1412 episodes and unfavourable outcome occurred in 531 (38%) of 1412 episodes. Predictors of unfavourable outcome were advanced age, absence of otitis or sinusitis, alcoholism, tachycardia, lower score on the Glasgow Coma Scale, cranial nerve palsy, a cerebrospinal fluid white-cell count lower than 1000 cells per μL, a positive blood culture, and a high serum C-reactive protein concentration. Adjunctive dexamethasone was administered for 1234 (89%) of 1384 assessed episodes. The multivariable adjusted odds ratio of dexamethasone treatment for unfavourable outcome was 0·54 (95% CI 0·39-0·73).

INTERPRETATION

The incidence of adult bacterial meningitis has decreased substantially, which is partly explained by herd protection by paediatric conjugate vaccines. Adjunctive dexamethasone treatment was associated with substantially improved outcome.

FUNDING

European Research Council, National Institute of Public Health and the Environment, European Union, Academic Medical Center, and Netherlands Organization for Health Research and Development.

Thrombin-activatable fibrinolysis inhibitor influences disease severity in humans and mice with pneumococcal meningitis

BACKGROUND

Mortality and morbidity in patients with bacterial meningitis result from the proinflammatory response and dysregulation of coagulation and fibrinolysis. Thrombin-activatable fibrinolysis inhibitor (TAFI) is activated by free thrombin or thrombin in complex with thrombomodulin, and plays an antifibrinolytic role during fibrin clot degradation, but also has an anti-inflammatory role by inactivating proinflammatory mediators, such as complement activation products.

OBJECTIVE

To assess the role of TAFI in pneumococcal meningitis.

METHODS

We performed a prospective nationwide genetic association study in patients with bacterial meningitis, determined TAFI and complement levels in cerebrospinal fluid (CSF), and assessed the function of TAFI in a pneumococcal meningitis mouse model by using Cpb2 (TAFI) knockout mice.

RESULTS

Polymorphisms (reference sequences: rs1926447 and rs3742264) in the CPB2 gene, coding for TAFI, were related to the development of systemic complications in patients with pneumococcal meningitis. Higher protein levels of TAFI in CSF were significantly associated with CSF complement levels (C3a, iC3b, and C5b-9) and with more systemic complications in patients with bacterial meningitis. The risk allele of rs1926447 (TT) was associated with higher levels of TAFI in CSF. In the murine model, consistent with the human data, Cpb2-deficient mice had decreased disease severity, as reflected by lower mortality, and attenuated cytokine levels and bacterial outgrowth in the systemic compartment during disease, without differences in the brain compartment, as compared with wild-type mice.

CONCLUSIONS

These findings suggest that TAFI plays an important role during pneumococcal meningitis, which is likely to be mediated through inhibition of the complement system, and influences the occurrence of systemic complications and inflammation.

Corticosteroids for acute bacterial meningitis

BACKGROUND

In experimental studies, the outcome of bacterial meningitis has been related to the severity of inflammation in the subarachnoid space. Corticosteroids reduce this inflammatory response.

OBJECTIVES

To examine the effect of adjuvant corticosteroid therapy versus placebo on mortality, hearing loss and neurological sequelae in people of all ages with acute bacterial meningitis.

SEARCH METHODS

We searched CENTRAL (2015, Issue 1), MEDLINE (1966 to January week 4, 2015), EMBASE (1974 to February 2015), Web of Science (2010 to February 2015), CINAHL (2010 to February 2015) and LILACS (2010 to February 2015).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of corticosteroids for acute bacterial meningitis.

DATA COLLECTION AND ANALYSIS

We scored RCTs for methodological quality. We collected outcomes and adverse effects. We performed subgroup analyses for children and adults, causative organisms, low-income versus high-income countries, time of steroid administration and study quality.

MAIN RESULTS

We included 25 studies involving 4121 participants (2511 children and 1517 adults; 93 mixed population). Four studies were of high quality with no risk of bias, 14 of medium quality and seven of low quality, indicating a moderate risk of bias for the total analysis. Nine studies were performed in low-income countries and 16 in high-income countries.Corticosteroids were associated with a non-significant reduction in mortality (17.8% versus 19.9%; risk ratio (RR) 0.90, 95% confidence interval (CI) 0.80 to 1.01, P value = 0.07). A similar non-significant reduction in mortality was observed in adults receiving corticosteroids (RR 0.74, 95% CI 0.53 to 1.05, P value = 0.09). Corticosteroids were associated with lower rates of severe hearing loss (RR 0.67, 95% CI 0.51 to 0.88), any hearing loss (RR 0.74, 95% CI 0.63 to 0.87) and neurological sequelae (RR 0.83, 95% CI 0.69 to 1.00).Subgroup analyses for causative organisms showed that corticosteroids reduced mortality in Streptococcus pneumoniae (S. pneumoniae) meningitis (RR 0.84, 95% CI 0.72 to 0.98), but not in Haemophilus influenzae (H. influenzae) orNeisseria meningitidis (N. meningitidis) meningitis. Corticosteroids reduced severe hearing loss in children with H. influenzae meningitis (RR 0.34, 95% CI 0.20 to 0.59) but not in children with meningitis due to non-Haemophilus species.In high-income countries, corticosteroids reduced severe hearing loss (RR 0.51, 95% CI 0.35 to 0.73), any hearing loss (RR 0.58, 95% CI 0.45 to 0.73) and short-term neurological sequelae (RR 0.64, 95% CI 0.48 to 0.85). There was no beneficial effect of corticosteroid therapy in low-income countries.Subgroup analysis for study quality showed no effect of corticosteroids on severe hearing loss in high-quality studies.Corticosteroid treatment was associated with an increase in recurrent fever (RR 1.27, 95% CI 1.09 to 1.47), but not with other adverse events.

AUTHORS' CONCLUSIONS

Corticosteroids significantly reduced hearing loss and neurological sequelae, but did not reduce overall mortality. Data support the use of corticosteroids in patients with bacterial meningitis in high-income countries. We found no beneficial effect in low-income countries.

Magnetic resonance imaging in the evaluation of patients with sensorineural hearing loss caused by meningitis: implications for cochlear implantation

OBJECTIVES

To determine the role of MRI in the evaluation of patients with sensorineural hearing loss (SNHL) caused by meningitis. Gadolinium-enhanced T1-weighted MRI (GdMRI) and 3D heavily weighted T2-weighted MRI (T2MRI) were associated with the occurrence of SNHL and the peroperative surgical findings during cochlear implantation, respectively.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral otology and cochlear implant center.

PATIENTS

Seventeen patients who developed SNHL after bacterial meningitis were evaluated with MRI. Twenty-one cochlear implantations were performed in 11 patients with severe bilateral SNHL. Six patients developed unilateral SNHL and did not receive a CI.

INTERVENTIONS

MRI scans were independently scored by 3 observers. Sensitivity, specificity, positive predictive value, negative predictive value, and interobserver reproducibility were calculated.

RESULTS

Cochlea enhancement on GdMRI was present in 87% of the ears affected by SNHL. In patients with unilateral SNHL, a nonenhancing cochlea predicted the preservation of hearing on the ipsilateral side. In all cases with an incomplete electrode insertion (6/21), loss of cochlear patency was already seen on T2MRI. However, loss of fluid was also found in 29% of the cases in which full electrode insertion was achieved.

CONCLUSION

MRI is crucial for decision making in patients with SNHL after meningitis. Diminished cochlear patency, as seen on T2MRI, is related to electrode insertion difficulty but does not always preclude full electrode insertion in cochlear implantation. Cochlear enhancement on GdMRI is associated with the occurrence of SNHL.

Pneumococcal meningitis, cerebral venous thrombosis, and cervical arterial dissection: a run of bad luck?

BACKGROUND

Pneumococcal meningitis in adults is widely associated with intracranial complications, which occur in up to 74.7% of the patients.

METHOD

Case report.

RESULTS

We report the case of a 40-year-old white female with pneumococcal meningitis after a sinus surgery, who developed a concomitant cerebral venous thrombosis and multiple cervical artery dissections. Following treatment with antibiotics and intravenous heparin, she had complete neurological recovery.

CONCLUSIONS

Vascular complications should always be remembered and adequately treated in patients with bacterial meningitis. Cervical arterial dissections should be investigated as potential embolic sources of intracranial ischemic lesions.

Adjunctive N-acetyl-L-cysteine in treatment of murine pneumococcal meningitis

Despite antibiotic therapy, acute and long-term complications are still frequent in pneumococcal meningitis. One important trigger of these complications is oxidative stress, and adjunctive antioxidant treatment with N-acetyl-l-cysteine was suggested to be protective in experimental pneumococcal meningitis. However, studies of effects on neurological long-term sequelae are limited. Here, we investigated the impact of adjunctive N-acetyl-l-cysteine on long-term neurological deficits in a mouse model of meningitis. C57BL/6 mice were intracisternally infected with Streptococcus pneumoniae. Eighteen hours after infection, mice were treated with a combination of ceftriaxone and placebo or ceftriaxone and N-acetyl-l-cysteine, respectively. Two weeks after infection, neurologic deficits were assessed using a clinical score, an open field test (explorative activity), a t-maze test (memory function), and auditory brain stem responses (hearing loss). Furthermore, cochlear histomorphological correlates of hearing loss were assessed. Adjunctive N-acetyl-l-cysteine reduced hearing loss after pneumococcal meningitis, but the effect was minor. There was no significant benefit of adjunctive N-acetyl-l-cysteine treatment in regard to other long-term complications of pneumococcal meningitis. Cochlear morphological correlates of meningitis-associated hearing loss were not reduced by adjunctive N-acetyl-l-cysteine. In conclusion, adjunctive therapy with N-acetyl-l-cysteine at a dosage of 300 mg/kg of body weight intraperitoneally for 4 days reduced hearing loss but not other neurologic deficits after pneumococcal meningitis in mice. These results make a clinical therapeutic benefit of N-acetyl-l-cysteine in the treatment of patients with pneumococcal meningitis questionable.

Corticosteroids for acute bacterial meningitis

BACKGROUND

In experimental studies, the outcome of bacterial meningitis has been related to the severity of inflammation in the subarachnoid space. Corticosteroids reduce this inflammatory response.

OBJECTIVES

To examine the effect of adjuvant corticosteroid therapy versus placebo on mortality, hearing loss and neurological sequelae in people of all ages with acute bacterial meningitis.

SEARCH METHODS

We searched CENTRAL 2012, Issue 12, MEDLINE (1966 to January week 2, 2013), EMBASE (1974 to January 2013), Web of Science (2010 to January 2013), CINAHL (2010 to January 2013) and LILACS (2010 to January 2013).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of corticosteroids for acute bacterial meningitis.

DATA COLLECTION AND ANALYSIS

We scored RCTs for methodological quality. We collected outcomes and adverse effects. We performed subgroup analyses for children and adults, causative organisms, low-income versus high-income countries, time of steroid administration and study quality.

MAIN RESULTS

Twenty-five studies involving 4121 participants were included. Corticosteroids were associated with a non-significant reduction in mortality (17.8% versus 19.9%; risk ratio (RR) 0.90, 95% confidence interval (CI) 0.80 to 1.01, P = 0.07). A similar non-significant reduction in mortality was observed in adults receiving corticosteroids (RR 0.74, 95% CI 0.53 to 1.05, P = 0.09). Corticosteroids were associated with lower rates of severe hearing loss (RR 0.67, 95% CI 0.51 to 0.88), any hearing loss (RR 0.74, 95% CI 0.63 to 0.87) and neurological sequelae (RR 0.83, 95% CI 0.69 to 1.00).Subgroup analyses for causative organisms showed that corticosteroids reduced mortality in Streptococcus pneumoniae (S. pneumoniae) meningitis (RR 0.84, 95% CI 0.72 to 0.98), but not in Haemophilus influenzae (H. influenzae) orNeisseria meningitidis (N. meningitidis) meningitis. Corticosteroids reduced severe hearing loss in children with H. influenzae meningitis (RR 0.34, 95% CI 0.20 to 0.59) but not in children with meningitis due to non-Haemophilus species.In high-income countries, corticosteroids reduced severe hearing loss (RR 0.51, 95% CI 0.35 to 0.73), any hearing loss (RR 0.58, 95% CI 0.45 to 0.73) and short-term neurological sequelae (RR 0.64, 95% CI 0.48 to 0.85). There was no beneficial effect of corticosteroid therapy in low-income countries.Subgroup analysis for study quality showed no effect of corticosteroids on severe hearing loss in high-quality studies.Corticosteroid treatment was associated with an increase in recurrent fever (RR 1.27, 95% CI 1.09 to 1.47), but not with other adverse events.

AUTHORS' CONCLUSIONS

Corticosteroids significantly reduced hearing loss and neurological sequelae, but did not reduce overall mortality. Data support the use of corticosteroids in patients with bacterial meningitis in high-income countries. We found no beneficial effect in low-income countries.

Bacterial meningitis in adults after splenectomy and hyposplenic states

OBJECTIVE

To examine the occurrence, disease course, prognosis, and vaccination status of patients with community-acquired bacterial meningitis with a history of splenectomy or functional hyposplenia.

PATIENTS AND METHODS

Patients with bacterial meningitis proven by cerebrospinal fluid culture were prospectively included in a nationwide cohort study between March 1, 2006, and September 1, 2011. Splenectomy or diseases associated with functional hyposplenia were scored for all patients. Vaccination status, clinical features, and outcome of patients with a history of splenectomy or functional hyposplenia were analyzed and compared with patients with normal spleen function.

RESULTS

Twenty-four of 965 patients (2.5%) had an abnormal splenic function: 16 had a history of splenectomy and 8 had functional hyposplenia. All patients had pneumococcal meningitis. Pre-illness vaccination status could be retrieved for 19 of 21 patients (90%), and only 6 patients (32%) were adequately vaccinated against pneumococci. Pneumococcal serotype was known in 21 patients; 52% of pneumococcal isolates had a serotype included in the 23-valent vaccine. Vaccine failure occurred in 3 patients. Splenectomized patients more often presented with signs of septic shock compared with patients with a normal spleen (63% vs 24%; P=.02). Outcome was unfavorable in 14 patients (58%), and 6 patients died (25%).

CONCLUSION

Splenectomy or functional hyposplenia is an uncommon risk factor for bacterial meningitis but results in a high rate of mortality and unfavorable outcome. Most patients were not adequately vaccinated against Streptococcus pneumoniae.

Genetic variation and cerebrospinal fluid levels of mannose binding lectin in pneumococcal meningitis patients

It has been suggested that genetic variants in mannose binding lectin (MBL2) influence susceptibility and outcome of invasive pneumococcal disease. We assessed the influence of genetic variation in MBL2 on susceptibility, outcome and causative serotype of pneumococcal meningitis in a prospective nationwide cohort study including 299 white patients and 216 controls. We assessed functionality of the genetic polymorphisms by measuring levels of MBL, C3a, iC3b, C5a and sC5b-9 in cerebrospinal fluid. We also performed a meta-analysis of studies on MBL2 polymorphisms and susceptibility to invasive pneumococcal disease. The risk of contracting pneumococcal meningitis was substantially increased for white individuals homozygous with the defective MBL2 0/0 genotype (odds ratio [OR] 8.21, 95% confidence interval [CI] 1.05–64.1; p = 0.017). CSF MBL levels were significantly lower in patients with the A/0 and 0/0 genotype compared to homozygotes for the wild-type alleles (A/A; p<0.001). CSF MBL levels were positively correlated with C3a and iC3b levels, indicating complement activation by the lectin pathway. The effect of MBL2 genetic variants on susceptibility remained robust in a meta-analysis including 5 studies with 287 patients (OR 2.33, 99% CI 1.39–3.90). We conclude that MBL2 polymorphisms influence CSF MBL levels and substantially increase the risk of pneumococcal meningitis.

Hearing impairment and its predictors in childhood bacterial meningitis in Angola

Hearing was evaluated in 244 ears of 124 children in Angola by auditory brainstem response audiometry 3 months after bacterial meningitis. Of all ears, 81% recovered without impairment. Of all children, 74% recovered without impairment, 5% had unilateral and 11% bilateral impairment. Seizures before or during hospital stay and disease severity were the best predictors of ≥ 80 dB impairment.

Validation of a Dutch risk score predicting poor outcome in adults with bacterial meningitis in Vietnam and Malawi

We have previously developed and validated a prognostic model to predict the risk for unfavorable outcome in Dutch adults with bacterial meningitis. The aim of the current study was to validate this model in adults with bacterial meningitis from two developing countries, Vietnam and Malawi. Demographic and clinical characteristics of Vietnamese (n = 426), Malawian patients (n = 465) differed substantially from those of Dutch patients (n = 696). The Dutch model underestimated the risk of poor outcome in both Malawi and Vietnam. The discrimination of the original model (c-statistic [c] 0.84; 95% confidence interval 0.81 to 0.86) fell considerably when re-estimated in the Vietnam cohort (c = 0.70) or in the Malawian cohort (c = 0.68). Our validation study shows that new prognostic models have to be developed for these countries in a sufficiently large series of unselected patients.