Clinical presentation and prognostic factors of Streptococcus pneumoniae meningitis according to the focus of infection

Pathogenesis and pathophysiology of pneumococcal meningitis

Pneumococcal meningitis continues to be associated with high rates of mortality and long-term neurological sequelae. The most common route of infection starts by nasopharyngeal colonization by Streptococcus pneumoniae, which must avoid mucosal entrapment and evade the host immune system after local activation. During invasive disease, pneumococcal epithelial adhesion is followed by bloodstream invasion and activation of the complement and coagulation systems. The release of inflammatory mediators facilitates pneumococcal crossing of the blood-brain barrier into the brain, where the bacteria multiply freely and trigger activation of circulating antigen-presenting cells and resident microglial cells. The resulting massive inflammation leads to further neutrophil recruitment and inflammation, resulting in the well-known features of bacterial meningitis, including cerebrospinal fluid pleocytosis, cochlear damage, cerebral edema, hydrocephalus, and cerebrovascular complications. Experimental animal models continue to further our understanding of the pathophysiology of pneumococcal meningitis and provide the platform for the development of new adjuvant treatments and antimicrobial therapy. This review discusses the most recent views on the pathophysiology of pneumococcal meningitis, as well as potential targets for (adjunctive) therapy.

Early symptomatic and late seizures in Kosovar children with bacterial meningitis

INTRODUCTION

Despite the dramatic decrease of mortality rate among children with bacterial meningitis in recent decades, some patients are left with neurologic sequelae. The purpose of this study was to analyze the occurrence of seizures as predictors for meningitis-related deaths or neurological sequelae including late seizures.

METHODS

This study uses a retrospective chart review of 277 children (aged 0-16 years, median 2 years, 162 boys) treated for bacterial meningitis in University Clinical Centre in Prishtina (Kosovo).

RESULTS

Of the 277 children treated for bacterial meningitis, 60 children (22%) manifested seizures prior to admission, 57 children (21%) had seizures after admission, and late seizures were diagnosed in 24 children (9%). The risk for adverse outcome was significantly higher in patients who had seizures prior to admission (52/60) and in patients who manifested seizures later than 24 h (41/41; RR 8.17 and 6.78 respectively, p < 0.0001). All children who manifested late seizures were diagnosed with meningitis-related acute neurologic complications: subdural effusion (18), hydrocephalus (6), intracranial bleeding (1), and subdural empyema (2). Of the 60 children who presented seizures prior to admission, only 11 manifested late seizures.

CONCLUSIONS

Seizures prior to admission were predictors of high risk of adverse outcome in bacterial meningitis in children. The risk of secondary epilepsy (9%) occurred only in children with evident structural neurologic complications during the acute phase of bacterial meningitis.

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

We assessed the incidence of hearing loss and its relationship with clinical characteristics and pneumococcal serotypes in adults surviving pneumococcal meningitis. We analysed hearing loss in 531 adults surviving pneumococcal meningitis included in two prospective nationwide cohort studies performed from April 1998 through to October 2002 and March 2006 through to January 2009. Hearing loss was evaluated on admission and discharge for all patients. Severe hearing loss was assessed by pure tone average on audiology and corrected for age, or by the combination of hearing loss on discharge and a score on the Glasgow Outcome Scale below 5, which could not be explained by other neurological sequelae. A total of 531 episodes of pneumococcal meningitis with non-lethal outcome were included. Predisposing conditions for pneumococcal meningitis were present in the majority of patients (64%), most commonly otitis (36%). Hearing loss was present at discharge in 116 patients (22%) and was classified as mild in 53% and severe in 47%. Hearing loss was related to otitis (odds ratio [OR], 2.58; 95% confidence interval [CI], 1.66-4.02; p < 0.001) and inversely related to serotype 23 F infection (OR, 0.36; 95% CI, 0.13-0.98; p = 0.025), but not with parameters of disease severity or indicators of cerebrospinal fluid inflammation severity. Meningitis due to pneumococcal serotype 3 was associated with the highest rate of hearing loss. Hearing loss frequently complicates pneumococcal meningitis. Risk factors for hearing loss were infection with pneumococcal serotype 23 F and otitis, but not disease severity. Otitis and resulting perilympathic inflammation contribute to meningitis-associated hearing loss.

Prognostic factors related to sequelae in childhood bacterial meningitis: data from a Greek meningitis registry

BACKGROUND

Bacterial meningitis (BM) is a life-threatening disease, often related with serious complications and sequelae. Infants and children who survive bacterial meningitis often suffer neurological and other sequelae.

METHODS

A total of 2,477 patients aged 1 month to 14 years old hospitalized in a Children's Hospital in Greece diagnosed with acute bacterial meningitis were collected through a Meningitis Registry, from 1974 to 2005. Clinical, laboratory and other parameters (sex, age, pathogen, duration of symptoms before and after admission) were evaluated through univariate and multivariate analysis with regard to sequelae. Analysis of acute complications were also studied but not included in the final model.

RESULTS

The rate of acute complications (arthritis and/or subdural effusion) was estimated at 6.8% (152 out of 2,251 patients, 95%CI 5.8-7.9) while the rate of sequelae (severe hearing loss, ventriculitis, hydrocephalus or seizure disorder) among survivors was estimated at 3.3% (73 out of 2,207 patients, 95%CI 2.6-4.2). Risk factors on admission associated with sequelae included seizures, absence of hemorrhagic rash, low CSF glucose, high CSF protein and the etiology of meningitis. A combination of significant prognostic factors including presence of seizures, low CSF glucose, high CSF protein, positive blood culture and absence of petechiae on admission presented an absolute risk of sequelae of 41.7% (95%CI 15.2-72.3).

CONCLUSIONS

A combination of prognostic factors of sequelae in childhood BM may be of value in selecting patients for more intensive therapy and in identifying possible candidates for new treatment strategies.

Clinical features, acute complications, and outcome of Salmonella meningitis in children under one year of age in Taiwan

Background

Salmonella meningitis remains a threat to children below two years of age in both developing and developed countries. However, information on such infections has not been well characterized. We analyzed data related to twelve years of experience in order to clarify the comprehensive features of Salmonella meningitis in our patients, including admission characteristics, acute complications, and long-term outcome.

Methods

The records of patients with spontaneous Salmonella meningitis from 1982 to 1994 were retrospectively reviewed. The long-term outcome was prospectively determined for survivors at school age by the developmental milestones reported by their parents and detailed neurological evaluation along with intelligence, hearing, visual, speech and language assessments.

Results

Of the twenty-four patients, seizures were noted in fifteen (63%) before admission and thirteen (54%) during hospitalization. Acute complications mainly included hydrocephalus (50%), subdural collection (42%), cerebral infarction (33%), ventriculitis (25%), empyema (13%), intracranial abscess (8%), and cranial nerve palsy (8%). Three patients (13%) died during the acute phase of Salmonella meningitis. The twenty-one survivors, on whom we followed up at school age, have sequelae consisting of language disorder (52%), motor disability (48%), intelligence quotient < 80 (43%), epilepsy (33%), sensorineural hearing loss (17%), visual deficits (10%), abducens nerve palsy (5%), microcephaly (5%), and hydrocephalus (5%). Overall, good outcome was noted in six (28.6%) of twenty-one survivors, mild sequelae in three (14.2%), moderate in six (28.6%), and severe in six (28.6%).

Conclusion

Salmonella meningitis in neonates and infants had a wide spectrum of morbidity and acute complications, leading to a complicated hospital course and subsequently a high prevalence of permanent adverse outcome. Thus, early recognition of acute complications of Salmonella meningitis and a follow-up plan for early developmental assessment of survivors are vital.

Streptococcus pneumoniae meningitis in Alberta pre- and postintroduction of the 7-valent pneumococcal conjugate vaccine

OBJECTIVE

To describe the epidemiology, clinical characteristics, microbiology and outcomes of patients of all ages with Streptococcus pneumoniae meningitis two years pre- and postintroduction of a S pneumoniae 7-valent conjugate vaccine program in Alberta in children <2 years of age.

METHODS

Between 2000 and 2004, all cases of invasive pneumococcal disease in Alberta were identified. From this cohort, patients with S pneumoniae meningitis were identified by chart review. Clinical data, laboratory data and in-hospital outcomes were collected.

RESULTS

Of the 1768 cases of invasive pneumococcal disease identified between 2000 and 2004, 110 (6.2%) had S pneumoniae meningitis. The overall incidence was 0.7 per 100,000 persons and remained unchanged over the study period. The rate in children <2 years of age appeared to fall over time, from 10.5 per 100,000 persons in 2000 to five per 100,000 persons in 2004, although there was insufficient evidence of a statistically significant time trend within any age group. Overall, the mean age was 30 years and 47% were male. In-hospital mortality was 20%, ranging from 6% in those ≤2 years of age to 31% for those ≥18 years of age, despite appropriate antimicrobial therapy.

CONCLUSION

The high mortality rate associated with S pneumoniae meningitis suggests that prevention by vaccination is critical. In children <2 years of age, there was a downward trend in the rate of S pneumoniae meningitis after implementation of the S pneumoniae 7-valent conjugate vaccine program, but rates were still high.

Genome-wide identification of Streptococcus pneumoniae genes essential for bacterial replication during experimental meningitis

Meningitis is the most serious of invasive infections caused by the Gram-positive bacterium Streptococcus pneumoniae. Vaccines protect only against a limited number of serotypes, and evolving bacterial resistance to antimicrobials impedes treatment. Further insight into the molecular pathogenesis of invasive pneumococcal disease is required in order to enable the development of new or adjunctive treatments and/or pneumococcal vaccines that are efficient across serotypes. We applied genomic array footprinting (GAF) in the search for S. pneumoniae genes that are essential during experimental meningitis. A total of 6,000 independent TIGR4 marinerT7 transposon mutants distributed over four libraries were injected intracisternally into rabbits, and cerebrospinal fluid (CSF) was collected after 3, 9, and 15 h. Microarray analysis of mutant-specific probes from CSF samples and inocula identified 82 and 11 genes mutants of which had become attenuated or enriched, respectively, during infection. The results point to essential roles for capsular polysaccharides, nutrient uptake, and amino acid biosynthesis in bacterial replication during experimental meningitis. The GAF phenotype of a subset of identified targets was followed up by detailed studies of directed mutants in competitive and noncompetitive infection models of experimental rat meningitis. It appeared that adenylosuccinate synthetase, flavodoxin, and LivJ, the substrate binding protein of a branched-chain amino acid ABC transporter, are relevant as targets for future therapy and prevention of pneumococcal meningitis, since their mutants were attenuated in both models of infection as well as in competitive growth in human cerebrospinal fluid in vitro.

Long-term mortality in patients diagnosed with pneumococcal meningitis: a Danish nationwide cohort study

The objective of the study was to determine the long-term mortality and the causes of death in patients diagnosed with pneumococcal meningitis. The authors performed a nationwide, population-based cohort study including all Danish patients diagnosed with pneumococcal meningitis from 1977 through 2006 and alive 1 year after diagnosis. Data were retrieved from medical databases in Denmark. The absolute and relative risks of all-cause and cause-specific death were analyzed by using Kaplan-Meier survival curves, Poisson regression analysis, Cox regression analysis, and cumulative incidence functions. The authors identified 2,131 pneumococcal meningitis patients and an age- and gender-matched, population-based cohort of 8,524 individuals. Compared with the background population, the pneumococcal meningitis patients had an increased long-term mortality varying from an 8-fold increased mortality in the age category 0-<20 years to a 1.5-fold increased mortality in those aged 60-<80 years. The increased risk of death stemmed from neoplasms, liver diseases, and nervous system diseases. The excess mortality due to neoplasms stemmed mainly from a 5-fold increased risk of death due to hematologic neoplasms. To improve survival in patients surviving the acute phase of pneumococcal meningitis, physicians should meticulously screen this patient population for neurologic sequelae and comorbidity predisposing to the disease.

Impact of bacterial meningitis-associated conditions on pediatric inpatient resource utilization

OBJECTIVE

To define the epidemiology of systemic complications and focal infections associated with bacterial meningitis and quantify how the presence of such complications affects in-hospital healthcare resource utilization.

METHODS

Retrospective cohort study using administrative data from 27 children's hospitals. Children <18 years of age diagnosed with bacterial meningitis from 2001 to 2006 were eligible. The primary exposure of interest was the presence of a bacterial meningitis-associated condition, classified as either systemic complications (eg, sepsis), associated focal infections (eg, pneumonia) or both. The primary outcomes were total in-hospital charges and length of stay (LOS).

RESULTS

A total of 574 of 2319 (25%) of children had a systemic complication or an associated focal infection. Compared with children without complications, in-hospital charges were significantly higher in children with systemic complications (136% increase), associated focal infections (118% increase), and both conditions (351% increase). LOS was also significantly increased in those with systemic complications (by 72%), associated focal infections (by 78%), or both conditions (by 211%). The presence of systemic complications was more common in younger children while the presence of an associated focal infection was more common in older children.

CONCLUSIONS

Children with bacterial meningitis often have additional morbidity due to systemic complications or associated focal infections indicated by increase use of acute in-hospital resource utilization. The apparent increase in in-hospital morbidity related to these conditions should be considered in future evaluations of vaccine efficacy, novel therapeutics, and hospital resource allocation.

Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis

The epidemiology of bacterial meningitis has changed as a result of the widespread use of conjugate vaccines and preventive antimicrobial treatment of pregnant women. Given the significant morbidity and mortality associated with bacterial meningitis, accurate information is necessary regarding the important etiological agents and populations at risk to ascertain public health measures and ensure appropriate management. In this review, we describe the changing epidemiology of bacterial meningitis in the United States and throughout the world by reviewing the global changes in etiological agents followed by specific microorganism data on the impact of the development and widespread use of conjugate vaccines. We provide recommendations for empirical antimicrobial and adjunctive treatments for clinical subgroups and review available laboratory methods in making the etiological diagnosis of bacterial meningitis. Finally, we summarize risk factors, clinical features, and microbiological diagnostics for the specific bacteria causing this disease.

Tracking the transcriptional host response from the acute to the regenerative phase of experimental pneumococcal meningitis

BACKGROUND

Despite the availability of effective antibiotic therapies, pneumococcal meningitis (PM) has a case fatality rate of up to 30% and causes neurological sequelae in up to half of the surviving patients. The underlying brain damage includes apoptosis of neurons in the hippocampus and necrosis in the cortex. Therapeutic options to reduce acute injury and to improve outcome from PM are severely limited.With the aim to develop new therapies a number of pharmacologic interventions have been evaluated. However, the often unpredictable outcome of interventional studies suggests that the current concept of the pathophysiologic events during bacterial meningitis is fragmentary. The aim of this work is to describe the transcriptomic changes underlying the complex mechanisms of the host response to pneumococcal meningitis in a temporal and spatial context using a well characterized infant rat model.

METHODS

Eleven days old nursing Wistar rats were infected by direct intracisternal injection of 2 x 106 cfu/ml of Streptococcus pneumoniae. Animals were sacrificed at 1, 3, 10 and 26 days after infection, the brain harvested and the cortex and hippocampus were sampled. The first two time points represent the acute and sub-acute phase of bacterial meningitis, whereas the latter represent the recovery phase of the disease.

RESULTS

The major events in the regulation of the host response on a transcriptional level occur within the first 3 days after infection. Beyond this time, no differences in global gene expression in infected and control animals were detectable by microarray analysis. Whereas in the acute phase of the disease immunoregulatory processes prevail in the hippocampus and the cortex, we observed a strong activation of neurogenic processes in the hippocampal dentate gyrus, both by gene expression and immunohistology starting as early as 3 days after infection.

CONCLUSIONS

Here we describe the cellular pathways involved in the host response to experimental pneumococcal meningitis in specified disease states and brain regions. With these results we hope to provide the scientific basis for the development of new treatment strategies which take the temporal aspects of the disease into account.

The risk of sequelae due to pneumococcal meningitis in high-income countries: a systematic review and meta-analysis

OBJECTIVES

To determine the risk of various kinds of sequelae in survivors of meningitis due to Streptococcus pneumoniae, as well as the influence of co-factors such as study design, study population and treatment on this risk.

METHODS

MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched from 1 September 1991 to 18 June 2009 for original articles on pneumococcal meningitis sequelae. Prevalence of sequelae was pooled using random effects meta-analysis. Studies were appraised for the influence of referral bias, external validity of study populations, testing procedure and publication bias.

RESULTS

Data were extracted from 63 studies involving 3408 pneumococcal meningitis survivors. The pooled prevalence of any reported sequelae from 48 studies was 31.7% (95% confidence interval 27.2-36.3%) using a random effects model (Cochran-Q = 277, p < 0.01). Differences in studies due to design, study population and treatment were not significant. The pooled prevalence of hearing loss, seizures, hydrocephalus, spasticity/paresis, cranial nerve palsies and visual impairment was 20.9% (17.1-24.7%), 6.5% (3.3-9.7%), 6.8% (3.3-10.2%), 8.7% (6.4-11.0%), 12.2% (5.3-19.1%) and 2.4% (0-5.7%) respectively.

CONCLUSIONS

The burden of sequelae due to pneumococcal meningitis remains high in the reviewed studies.

Fulminant pneumococcal meningitis manifesting as acute abdomen

In January 2007, a 21-year-old woman presented to the emergency department with abdominal pain, fever, nausea, vomiting and diarrhoea for 6 hours. She had no other associated symptoms with unrevealing previous history. On examination she was ill-looking, conscious and oriented, with a temperature of 39.2°C, blood pressure 96/52 mmHg and pulse rate 140 beats per minute, and had clinical evidence of dehydration. Her abdomen was rigid, mainly in the right lower quadrant, with sluggish bowel sounds. The rest of the clinical examination was normal including the neurological examination. The results of blood tests were white blood cell count= 19 × 109/litre (normal range (NR) 4–11× 109/litre) with 91% neutrophils, sodium 138 mmol/litre (NR 135–145 mmol/litre), potassium 3.4 mmol/litre (NR 3.5–5 mmol/litre), serum glucose 7.1 mmol/litre (NR 4–6 mmol/litre). A chest radiograph was normal; the abdominal X-ray showed dilated bowel loops and no free gas under the diaphragm.

The initial differential diagnosis was gastroenteritis vs acute appendicitis. The normal abdominal ultrasound and normal computed tomography (CT) scan made the diagnosis of appendicitis very unlikely. The patient was admitted as a case of gastroenteritis and improved on intravenous hydration, pain control, and intravenous ciprofloxacin 400 mg 12-hourly and metronidazole 500 mg 8-hourly.

Twenty-nine hours after admission she complained of headache, became increasingly lethargic and febrile (39°C), and the abdomen was still rigid. Her level of consciousness deteriorated with Glasgow Coma Scale of 8/15 (eye opening 2/4, verbal response 2/5 and motor response 4/6) and nuchal rigidity was obvious at this stage. Formal neurological exam was not feasible because of the patient's condition, but she was moving all her limbs and had no obvious clinical evidence of lateralizing signs.

Bacterial meningitis was suspected and treated with intravenous dexamethasone 6-hourly, ceftriaxone 2 g 12-hourly and vancomycin 1 g 12-hourly. An hour later, while awaiting a CT scan she developed tonic clonic seizures with fixed dilated pupils and was transferred to the intensive care unit where she was immediately intubated and ventilated. CT of the brain was normal (Figure 1). Lumbar puncture revealed a total cell count of 80 × 109/litre with 52% polymorphs and 48% mononuclear cells, protein concentration 8.3 g/litre (NR 0.1–0.4 g/litre), glucose concentration was <0.03 mmol/litre (NR <20 mg/dl), and Gram staining of CSF showed Gram-positive diplococci. Subsequently, CSF and blood cultures yielded Streptococcus pneumoniae sensitive to penicillin so she was given intravenous penicillin G 4 million units 4-hourly.

Over 2 days she developed septic shock requiring inotropes, and remained in a deep coma. Magnetic resonance imaging of the brain showed diffuse leptomeningeal enhancement and multiple infarctions in both cerebral hemispheres, the brainstem and cerebellum (Figure 2). Unfortunately the patient never regained consciousness and 5 days after presentation she died despite all supportive measures.

Bacteremia causes hippocampal apoptosis in experimental pneumococcal meningitis

Background

Bacteremia and systemic complications both play important roles in brain pathophysiological alterations and the outcome of pneumococcal meningitis. Their individual contributions to the development of brain damage, however, still remain to be defined.

Methods

Using an adult rat pneumococcal meningitis model, the impact of bacteremia accompanying meningitis on the development of hippocampal injury was studied. The study comprised of the three groups: I. Meningitis (n = 11), II. meningitis with attenuated bacteremia resulting from iv injection of serotype-specific pneumococcal antibodies (n = 14), and III. uninfected controls (n = 6).

Results

Pneumococcal meningitis resulted in a significantly higher apoptosis score 0.22 (0.18-0.35) compared to uninfected controls (0.02 (0.00-0.02), Mann Whitney test, P = 0.0003). Also, meningitis with an attenuation of bacteremia by antibody treatment resulted in significantly reduced apoptosis (0.08 (0.02-0.20), P = 0.01) as compared to meningitis.

Conclusions

Our results demonstrate that bacteremia accompanying meningitis plays an important role in the development of hippocampal injury in pneumococcal meningitis.

Diagnostic clinical and laboratory findings in response to predetermining bacterial pathogen: data from the Meningitis Registry

Background

Childhood Meningitis continues to be an important cause of mortality in many countries. The search for rapid diagnosis of acute bacterial meningitis has lead to the further exploration of prognostic factors. This study was scheduled in an attempt to analyze various clinical symptoms as well as rapid laboratory results and provide an algorithm for the prediction of specific bacterial aetiology of childhood bacterial meningitis.

Methodology and Principal Findings

During the 32 year period, 2477 cases of probable bacterial meningitis (BM) were collected from the Meningitis Registry (MR). Analysis was performed on a total of 1331 confirmed bacterial meningitis cases of patients aged 1 month to 14 years. Data was analysed using EPI INFO (version 3.4.3-CDC-Atlanta) and SPSS (version 15.0 - Chicago) software. Statistically significant (p<0.05) variables were included in a conditional backward logistic regression model. A total of 838 (63.0%) attributed to Neisseria meningitidis, 252 (18.9%) to Haemophilus influenzae, 186 (14.0%) to Streptococcus pneumoniae and 55 (4.1%) due to other bacteria. For the diagnosis of Meningococcal Meningitis, the most significant group of diagnostic criteria identified included haemorrhagic rash (OR 22.36), absence of seizures (OR 2.51), headache (OR 1.83) and negative gram stain result (OR 1.55) with a Positive Predictive Value (PPV) of 96.4% (95%CI 87.7–99.6). For the diagnosis of Streptococcus pneumoniae, the most significant group of diagnostic criteria identified included absence of haemorrhagic rash (OR 13.62), positive gram stain (OR 2.10), coma (OR 3.11), seizures (OR 3.81) and peripheral WBC≥15000/µL (OR 2.19) with a PPV of 77.8% (95%CI 40.0–97.2). For the diagnosis of Haemophilus influenzae, the most significant group of diagnostic criteria included, absence of haemorrhagic rash (OR 13.61), age≥1year (OR 2.04), absence of headache (OR 3.01), CSF Glu<40 mg/dL (OR 3.62) and peripheral WBC<15000/µL (OR 1.74) with a PPV of 58.5% (95%CI 42.1–73.7).

Conclusions

The use of clinical and laboratory predictors for the assessment of the causative bacterial pathogen rather than just for predicting outcome of mortality seems to be a useful tool in the clinical management and specific treatment of BM. These findings should be further explored and studied.

Clinical characteristics of Haemophilus influenzae meningitis in Denmark in the post-vaccination era

The introduction of Haemophilus influenzae type b (Hib) vaccine into the Danish childhood vaccination programme in 1993 may have influenced the epidemiology of H. influenzae meningitis (i.e. increasing frequency of other non-vaccine types; presentation in other age groups). Based on nationwide registration, clinical information and laboratory findings were collected from all 65 confirmed cases of H. influenzae meningitis during the period 1994-2005. Twenty-nine patients (45%) were <13 years old [median 15 months (range 0-147)], and 36 patients (55%) were >24 years old [median 62 years (range 25-96)]. Hib accounted for 31% (20/65) of the cases, and significantly more children were infected with Hib compared with adults [53% (16/29) vs. 11% (4/36), respectively, p 0.0003]. Overall, 38% of cases had an otogenic focus and this was thus the most frequent primary focus of infection. Among children infected with Hib, two cases (13%) were identified as true vaccine failures. Six patients (9%) died; one premature infant infected with serotype f and five adults (age 83-96 years) with non-typeable H. influenzae. Hearing loss was reported in 16% of the surviving children and in 10% of the surviving adults. The presence of a lung focus was an independent prognostic factor for an unfavourable outcome (p 0.03). In conclusion, meningitis caused by Hib has been infrequent in Denmark after introduction of the Hib vaccine in the childhood vaccination programme, and no increase in meningitis cases due to non-b type H. influenzae has been observed. Cases with H. influenzae meningitis frequently had an otogenic focus, with low risk of an unfavourable outcome.

[Managing adult patients with acute community-acquired meningitis presumed of bacterial origin]

Early clinical data must lead to suspect bacterial meningitis if fever, the most frequent sign, is present and if it is associated with more or less constant neurological and meningeal signs (consciousness impairment, headache, neck stiffness, focal neurological deficit, seizure, etc.). A skin rash is frequent in case of meningococcal meningitis whereas cranial nerve palsy is more in favor of tuberculous or Listeria meningitis. Presence of otitis, sinusitis, pneumonia, or a recent head trauma strongly suggests a pneumococcal involvement. Tuberculous meningitis is generally characterized by a slow evolution of meningeal signs together with aspecific signs. The main prognostic factors are consciousness impairment, circulatory instability, focal neurological signs, and advanced age. Morbidity and mortality are increased in case of pneumococcal compared to meningococcal meningitis. Cranial tomodensitometry gives further information about intracranial complications of meningitis. In some cases, particularly if focal neurological or intracranial hypertension signs are present, it must be performed before a lumbar puncture. The risk factors of meningitis must be investigated and treated if possible according to the bacterium. The management of patient after hospital discharge depends on evolution after treatment. The presence of neurological sequels imposes a specialized ambulatory follow-up. Neuropsychological sequels (cognitive dysfunction, memory impairment) can also persist for years even in absence of other neurological disorders.

[Antibiotic management of presumptive bacterial meningitis in adults (rational, methods, course, and follow-up)]

The annual incidence of community acquired meningitis ranges between 0.6 and four per 100,000 adults in industrialized countries. The most common causative bacteria are Streptococcus pneumoniae, Neisseria meningitidis, Listeria monocytogenes. The emergence of resistance to antibiotics, especially for S. pneumoniae, could explain the clinical failure of third generation cephalosporins used to treat adults with S. pneumoniae meningitis. The present therapeutic suggestions are more based on the extrapolation of an experimental model than on relevant clinical trials.

High cerebrospinal fluid (CSF) penetration and potent bactericidal activity in CSF of NZ2114, a novel plectasin variant, during experimental pneumococcal meningitis

Plectasin is the first defensin-type antimicrobial peptide isolated from a fungus and has potent activity against gram-positive bacteria. By using an experimental meningitis model, the penetration of plectasin into the cerebrospinal fluid (CSF) of infected and uninfected rabbits and the bactericidal activities in CSF of the plectasin variant NZ2114 and ceftriaxone against a penicillin-resistant Streptococcus pneumoniae strain (NZ2114 and ceftriaxone MICs, 0.25 and 0.5 microg/ml, respectively) were studied. Pharmacokinetic analysis showed that there was a significantly higher level of CSF penetration of NZ2114 through inflamed than through noninflamed meninges (area under the concentration-time curve for CSF/area under the concentration-time curve for serum, 33% and 1.1%, respectively; P = 0.03). The peak concentrations of NZ2114 in purulent CSF were observed approximately 3 h after the infusion of an intravenous bolus of either 20 or 40 mg/kg of body weight and exceeded the MIC >10-fold for a 6-h study period. Treatment with NZ2114 (40 and 20 mg/kg at 0 and 5 h, respectively; n = 11) caused a significantly higher reduction in CSF bacterial concentrations than therapy with ceftriaxone (125 mg/kg at 0 h; n = 7) at 3 h (median changes, 3.7 log(10) CFU/ml [interquartile range, 2.5 to 4.6 log(10) CFU/ml] and 2.1 log(10) CFU/ml [interquartile range, 1.7 to 2.6 log(10) CFU/ml], respectively; P = 0.001), 5 h (median changes, 5.2 log(10) CFU/ml [interquartile range, 3.6 to 6.1 log(10) CFU/ml] and 3.1 log(10) CFU/ml [interquartile range, 2.6 to 3.7 log(10) CFU/ml], respectively; P = 0.01), and 10 h (median changes, 5.6 log(10) CFU/ml [interquartile range, 5.2 to 5.9 log(10) CFU/ml] and 4.2 log(10) CFU/ml [interquartile range, 3.6 to 5.0 log(10) CFU/ml], respectively; P = 0.03) after the start of therapy as well compared to the CSF bacterial concentrations in untreated rabbits with meningitis (n = 7, P < 0.05). Also, significantly more rabbits had sterile CSF at 5 and 10 h when they were treated with NZ2114 than when they were treated with ceftriaxone (67% [six of nine rabbits] and 0% [zero of seven rabbits], respectively, at 5 h and 75% [six of eight rabbits] and 14% [one of seven rabbits], respectively, at 10 h; P < 0.05). Due to its excellent CSF penetration and potent bactericidal activity in CSF, the plectasin variant NZ2114 could be a promising new option for the treatment of CNS infections caused by gram-positive bacteria, including penicillin-resistant pneumococcal meningitis.

Hospital-based study of the prognostic factors in adult patients with acute community-acquired bacterial meningitis in Tokyo, Japan

BACKGROUND

Prognostic factors related to community-acquired bacterial meningitis (BM) in adult patients have been evaluated using multivariate analysis in The Netherlands, where the rate of antibiotic resistance was low. However, an evaluation of these factors in countries with a high rate of antibiotic resistance has not yet been done. Thus, we studied the prognostic factors in adults with community-acquired BM in our hospitals, which are located in Tokyo, Japan, where the rate of antibiotic resistance is high.

METHODS

We selected 71 consecutive adult patients with community-acquired BM in which the pathogens were identified and then classified the patients into two groups based on the Glasgow Outcome Scale: a favorable outcome group (n=48), and an unfavorable outcome group (n=23). Their clinical and laboratory variables were analyzed using single logistic regression analysis followed by multiple logistic regression analysis.

RESULTS

The overall mortality rate was 23%. The rate of antibiotic resistance was 54.9%. The most common resistant bacteria were penicillin-resistant Streptococcus pneumoniae, followed by methicillin-resistant Staphylococcus aureus. The Glasgow Coma Scale score (GCS) at the initiation of antibiotic therapy and a low thrombocyte count were identified as significant unfavorable prognostic factors (GCS: p=0.020, odds ratio=0.528, 95%CI=0.309-0.902; thrombocyte count: p=0.037, odds ratio=0.802, 95%CI=0.652-0.987). The presence of antibiotic-resistant bacteria was not identified as a prognostic factor.

CONCLUSION

Patients with a low GCS at the initiation of antibiotic therapy and low thrombocyte counts had unfavorable outcomes. With appropriate antibiotic administration, the antibiotic-resistant bacteria were not identified as an unfavorable prognostic factor, even in an area with a high rate of antibiotic resistance.

Otogenic pneumococcal meningitis with pneumocephalus

Streptococcus pneumoniae accounts for approximately 50% of bacterial meningitis cases in the United States annually. Since the advent of antibiotics, pneumococcal meningitis as a complication of a primary otogenic focus has been rare in the United States. The widespread use of immunosuppressants and increasing bacterial resistance to commonly prescribed antibiotics may contribute to a higher incidence of complications of otitis media in the future, similar to that of the pre-antibiotic era. We report a case of otogenic pneumococcal meningitis with pneumocephalus in an adult male on chronic immunosuppressant therapy. A 33-year-old man with Crohn's disease and azathioprine use presented to our Emergency Department with progressive headache while taking antibiotics for otitis media. Initial computed tomography scan of the brain revealed pneumocephaly, and cerebrospinal fluid analysis and culture diagnosed pneumococcal meningitis. The patient continued to have fevers while receiving intravenous antibiotics and underwent bilateral myringotomies; his clinical course subsequently improved significantly. Meningitis is a rare complication of Streptococcus pneumoniae infections since the advent of antibiotics; however, it may become more frequent with increasing antibiotic resistance and a growing population of immunocompromised patients. Additionally, pneumocephalus in the setting of meningitis and otitis media should raise the suspicion for mastoiditis (even without overt clinical findings) and early consultation with an otolaryngologist is warranted.

Increased expression of tyrosine phosphatase SHP2 in experimental pneumococcal meningitis: correlation with tumor necrosis factor-alpha and cerebrospinal fluid pleocytosis

Protein tyrosine phosphatase SHP2 plays a crucial role in the development of the central nervous system. To explore the expression and possible role of SHP2 during the course of bacterial meningitis, this article reports a juvenile rat bacterial meningitis model established by direct intracisternal injection of Streptococcus pneumoniae. Expression of SHP2 at both mRNA and protein levels were assessed. White blood cell count and concentration of tumor necrosis factor-alpha (TNF-alpha) in cerebrospinal fluid (CSF) were also measured. In the cortex, bacterial meningitis led to a significant upregulation of mRNA encoding SHP2. SHP2 protein levels and CSF white blood cell count were positively correlated. However, there was no significant correlation between the levels of SHP2 protein and TNF-alpha concentrations in CSF. These findings do not support an essential role of SHP2 in the pathogenesis of experimental pneumoniae meningitis, but it is possible that SHP2 protein expression may be used as a marker of disease activity.

A risk score for unfavorable outcome in adults with bacterial meningitis

OBJECTIVE

To derive and validate a bedside risk score for adverse outcome in adults with bacterial meningitis.

METHODS

We derived a score for the risk for an unfavorable outcome (Glasgow Outcome Scale score 1-4) by performing logistic regression analyses of data from a prospective cohort study (Dutch Meningitis Cohort; N = 696). A key set of independent prognostic variables was selected from 22 potential predictors. A nomogram based on these key variables was constructed to facilitate use in clinical practice. To validate this nomogram, we used data from our randomized controlled trial on adjunctive dexamethasone therapy in adults with bacterial meningitis (European Dexamethasone Study; N = 301).

RESULTS

Unfavorable outcome occurred in 237 of 696 episodes (34%) in the Dutch Meningitis Cohort; 143 patients (21%) died. In the analysis, 6 of 22 variables that are routinely available within 1 hour after admission were robust enough for inclusion in the final risk score: age, heart rate, Glasgow Coma Scale score, cranial nerve palsies, a cerebrospinal fluid leukocyte count less than 1,000 cells/mm3, and gram-positive cocci in cerebrospinal fluid Gram's stain. The concordance index for the risk score was 0.84 (95% confidence interval, 0.80-0.87) in the original cohort and 0.81 (95% confidence interval, 0.74-0.87) in the external validation cohort (European Dexamethasone Study).

INTERPRETATION

This bedside risk score can be used to identify patients with a high risk for unfavorable outcome in adults with bacterial meningitis within 1 hour after the initial presentation.

Cerebral blood flow autoregulation in early experimental S. pneumoniae meningitis

We studied cerebral blood flow (CBF) autoregulation and intracranial pressure (ICP) during normo- and hyperventilation in a rat model of Streptococcus pneumoniae meningitis. Meningitis was induced by intracisternal injection of S. pneumoniae. Mean arterial blood pressure (MAP), ICP, cerebral perfusion pressure (CPP, defined as MAP − ICP), and laser-Doppler CBF were measured in anesthetized infected rats ( n = 30) and saline-inoculated controls ( n = 30). CPP was either incrementally reduced by controlled hemorrhage or increased by intravenous norepinephrine infusion. Twelve hours postinoculation, rats were studied solely during normocapnia, whereas rats studied after 24 h were exposed to either normocapnia or to acute hypocapnia. In infected rats compared with control rats, ICP was unchanged at 12 h but increased at 24 h postinoculation (not significant and P < 0.01, respectively); hypocapnia did not lower ICP compared with normocapnia. Twelve hours postinoculation, CBF autoregulation was lost in all infected rats but preserved in all control rats ( P < 0.01). Twenty-four hours after inoculation, 10% of infected rats had preserved CBF autoregulation during normocapnia compared with 80% of control rats ( P < 0.01). In contrast, 60% of the infected rats and 100% of the control rats showed an intact CBF autoregulation during hypocapnia ( P < 0.05 for the comparison of infected rats at normocapnia vs. hypocapnia). In conclusion, CBF autoregulation is lost both at 12 and at 24 h after intracisternal inoculation of S. pneumoniae in rats. Impairment of CBF autoregulation precedes the increase in ICP, and acute hypocapnia may restore autoregulation without changing the ICP.

Hearing loss and cochlear damage in experimental pneumococcal meningitis, with special reference to the role of neutrophil granulocytes

Hearing loss is a well-known sequelae from meningitis, affecting up to 25% of survivors. However, the principal components of the infectious and inflammatory reaction responsible for the sensorineural hearing loss remain to be identified. The present study aimed to investigate the impact of an augmented neutrophil response on the development of hearing loss and cochlear damage in a model of experimental pneumococcal meningitis in rats. Hearing loss and cochlear damage were assessed by distortion product oto-acoustic emissions (DPOAE), auditory brainstem response (ABR) and histopathology in rats treated with ceftriaxone 28 h after infection. Rats were treated with Granulocyte Colony Stimulating Factor (G-CSF) initiated prior to infection, 28 h after infection or with ceftriaxone only. Rats were followed for 7 days, and assessment of hearing was performed before infection and 24 h and day 8 after infection. Pretreatment with G-CSF increased hearing loss 24 h after infection and on day 8 compared to untreated rats (Mann-Whitney, P = 0.012 and P = 0.013 respectively). The increased sensorineural hearing loss at day 8 was associated with significantly decreased spiral ganglion cell counts (P = 0.0006), increased damage to the organ of Corti (P = 0.007), increased areas of inflammatory infiltrates (P = 0.02) and increased white blood cell (WBC) counts in cerebrospinal fluid on day 8 after infection (P = 0.0084). Initiation of G-CSF 28 h after infection did not significantly affect hearing loss or cochlear pathology compared to controls. In conclusion, the inflammatory host reaction contributes significantly to the development of hearing loss in experimental meningitis.

Influence of the blood bacterial load on the meningeal inflammatory response in Streptococcus pneumoniae meningitis

Background

Despite bacteraemia is present in the majority of patients with pneumococcal, little is known about the influence of the systemic infection on the meningeal inflammatory response.

Methods

To explore the role of systemic infection on the meningeal inflammation, experimental meningitis was induced by intracisternal injection of ~1 × 10⁶ CFU Streptococcus pneumoniae, type 3, and the 26 rabbits were either provided with ~1 × 10⁶ CFU S. pneumoniae intravenously at 0 hour ("bacteraemic" rabbits, n = 9), immunized with paraformaldehyde-killed S. pneumoniae for 5 weeks prior to the experiment ("immunized" rabbits", n = 8), or not treated further ("control" rabbits, n = 9). WBC and bacterial concentrations were determined in CSF and blood every second hour during a 16 hours study period together with CSF IL-8 and protein levels. We also studied CSF and blood WBC levels in 153 pneumococcal meningitis patients with and without presence of bacteraemia.

Results

As designed, blood bacterial concentrations were significantly different among three experimental groups during the 16 hours study period (Kruskal Wallis test, P < 0.05), whereas no differences in CSF bacterial levels were observed (P > 0.05). Blood WBC decreased in bacteraemic rabbits between ~10–16 hours after the bacterial inoculation in contrast to an increase for both the immunized rabbits and controls (P < 0.05). The CSF pleocytosis was attenuated in bacteraemic rabbits as compared to the two other groups between 12–16 hours from time of infection (P < 0.017), despite accelerated CSF IL-8 levels in bacteraemic rabbits.

In patients with pneumococcal meningitis, no significant difference in CSF WBC was observed between patients with or without bacteraemia at admission (n = 103, 1740 cells/μL (123–4032) vs. n = 50, 1961 cells/μL (673–5182), respectively, P = 0.18), but there was a significant correlation between CSF and blood WBC (n = 127, Spearman rho = 0.234, P = 0.008).

Conclusion

Our results suggest that a decrease in peripheral WBC induced by enhanced bacteraemia in pneumococcal meningitis results in an attenuated CSF pleocytosis.

Pneumococcal meningitis in adults: new approaches to management and prevention

Since the virtual eradication of meningitis due to Haemophilus influenzae type B by vaccination in the developed world, pneumococcal meningitis has become the leading cause of bacterial meningitis beyond the neonatal period. Clinical and experimental research has increased our knowledge about the pathophysiology and pathogenesis of the disease over the past decades. Despite the availability of effective antibiotics, supportive care facilities, and recent advances in adjunctive strategies-ie, adjunctive dexamethasone-mortality and morbidity rates associated with pneumococcal meningitis remain unacceptably high. Although preliminary results after the introduction of the pneumococcal conjugate vaccine are promising, the incidence of multidrug-resistant pneumococcal strains is rising worldwide. Here we discuss clinical aspects of pneumococcal meningitis in adults, with focus on pathophysiology, and stress the urgent need for adequate preventive measures and new effective treatments.

Haematogenous Staphylococcus aureus meningitis. A 10-year nationwide study of 96 consecutive cases

Background

Haematogenous Staphylococcus aureus meningitis is rare but associated with high mortality. Knowledge about the disease is still limited. The objective of this study was to evaluate demographic and clinical prognostic features of bacteraemic S. aureus meningitis.

Methods

Nationwide surveillance in Denmark from 1991 to 2000 with clinical and bacteriological data. Risks of death were estimated by Cox proportional hazards regression analysis.

Results

Among 12480 cases of S. aureus bacteraemia/sepsis, we identified 96 cases of non-surgical bacteraemic S. aureus meningitis (0.8%). Incidence rates were 0.24 (95% confidence interval [CI], 0.18 to 0.30)/100 000 population between 1991–1995 and 0.13 (CI, 0.08 to 0.17)/100 000 population between 1996–2000. Mortality was 56%. After adjustment, only co morbidity (hazard ratio [HR], 3.45; CI, 1.15 to 10.30) and critical illness (Pitt score ≥ 4) (HR, 2.14; CI, 1.09 to 4.19) remained independent predictors of mortality.

Conclusion

The incidence, but not mortality of bacteraemic S. aureus meningitis decreased during the study period. Co morbidity and critical illness were independent predictors of a poor outcome.