Update and advances in community acquired bacterial meningitis

High-risk factors associated with refractory childhood bacterial meningitis in Southwest China

BACKGROUND

Refractory bacterial meningitis is acute, develops rapidly, and has higher mortality and morbidity than common bacterial meningitis. This study was undertaken to investigate the high-risk factors related to refractory bacterial meningitis in children with positive pathogens.

METHODS

We retrospectively analyzed the clinical data of 109 patients who had bacterial meningitis. The patients were divided into a refractory group (96 patients) and nonrefractory group (13 patients) based on the classification criteria. Seventeen clinical variables on risk factors were extracted and evaluated by univariate and multivariate logistic regression analyses.

RESULTS

There were 64 males and 45 females. The onset age ranged from 1 month old to 12 years old, and the median age was 181 days old. The pathogenic bacteria included 67 cases of gram-positive (G+) bacteria (61.5%) and 42 cases of gram-negative (G-) bacteria. In patients who were 1 to 3 months old, E. coli was the most common (47.5%), followed by Streptococcus agalactiae and Staphylococcus hemolyticus (10.0%); in patients > 3 months old, S. pneumoniae was the most common (55.1%), followed by E. coli (8.7%). The multivariate analysis indicated that consciousness disorder (odds ratio [OR] = 13.050), peripheral blood C-reactive protein (CRP) ≥ 50 mg/L (OR = 29.436), and the isolate bacteria being gram-positive bacteria (OR = 8.227) were independent risk factors for predicting who would progress to refractory bacterial meningitis in this group.

CONCLUSION

For patients who have pathogenic positive bacterial meningitis along with consciousness disorder, CRP ≥ 50 mg/L, and/or have an isolate bacteria that is a G + bacteria, it is important to be alert to the potential for progression to refractory bacterial meningitis, which demands the physicians' significant attention.

Progress and Challenges in Bacterial Meningitis: A Review

IMPORTANCE

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

OBSERVATIONS

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

CONCLUSIONS AND RELEVANCE

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

Systematic review of efficacy, safety and pharmacokinetics of intravenous and intraventricular vancomycin for central nervous system infections

Objective: The decision of vancomycin dosage for central nervous system (CNS) infections is still a challenge because its bactericidal nature in cerebrospinal fluid (CSF) has not been confirmed by human studies. This study systematically reviewed the literatures on vancomycin in patients with meningitis, ventriculitis, and CNS device-associated infections, to assess efficacy, safety, and pharmacokinetics to better serve as a practical reference. Methods: Medline, Embase, and Cochrane Library were searched using terms vancomycin, Glycopeptides, meningitis, and central nervous system infections. Data were extracted including characteristics of participants, causative organism(s), administration, dosage, etc., The clinical response, microbiological response, adverse events and pharmacokinetic parameters were analyzed. Results: Nineteen articles were included. Indications for vancomycin included meningitis, ventriculitis, and intracranial device infections. No serious adverse effects of intravenous (IV) and intraventricular (IVT) vancomycin have been reported. Dosages of IV and IVT vancomycin ranged from 1000-3000 mg/day and 2-20 mg/day. Duration of IV and IVT vancomycin therapy most commonly ranged from 3-27 days and 2-21 days. Therapeutic drug monitoring was conducted in 14 studies. Vancomycin levels in CSF in patients using IV and IVT vancomycin were varied widely from 0.06 to 22.3 mg/L and 2.5-292.9 mg/L. No clear relationships were found between vancomycin CSF levels and efficacy or toxicity. Conclusion: Using vancomycin to treat CNS infections appears effective and safe based on current evidence. However, the optimal regimens are still unclear. Higher quality clinical trials are required to explore the vancomycin disposition within CNS.

Cerebrospinal fluid analysis: current diagnostic methods in central nervous system infectious diseases

Cerebrospinal fluid (CSF) analysis is an important diagnostic tool for many conditions affecting the central nervous system (CNS), especially CNS infectious diseases. Despite its low specificity, CSF white blood cell counts, CSF protein levels, CSF serum glucose ratio and CSF lactate measurement are useful in differentiating infections caused by distinct groups of pathogens. CSF direct examination and cultures can identify causative organisms and antibiotic sensitivities as well. Adjunctive tests such as latex agglutination, different immunological assays and molecular reactions have great specificities and increasing sensitivities. In this article, some recent diagnostic methods applied to CSF analysis for frequent CNS infections are presented.

Regulation of the p75 neurotrophin receptor attenuates neuroinflammation and stimulates hippocampal neurogenesis in experimental Streptococcus pneumoniae meningitis

Background

Streptococcus pneumoniae meningitis is a destructive central nervous system (CNS) infection with acute and long-term neurological disorders. Previous studies suggest that p75NTR signaling influences cell survival, apoptosis, and proliferation in brain-injured conditions. However, the role of p75NTR signaling in regulating pneumococcal meningitis (PM)-induced neuroinflammation and altered neurogenesis remains largely to be elucidated.

Methods

p75NTR signaling activation in the pathological process of PM was assessed. During acute PM, a small-molecule p75NTR modulator LM11A-31 or vehicle was intranasally administered for 3 days prior to S. pneumoniae exposure. At 24 h post-infection, clinical severity, histopathology, astrocytes/microglia activation, neuronal apoptosis and necrosis, inflammation-related transcription factors and proinflammatory cytokines/mediators were evaluated. Additionally, p75NTR was knocked down by the adenovirus-mediated short-hairpin RNA (shRNA) to ascertain the role of p75NTR in PM. During long-term PM, the intranasal administration of LM11A-31 or vehicle was continued for 7 days after successfully establishing the PM model. Dynamic changes in inflammation and hippocampal neurogenesis were assessed.

Results

Our results revealed that both 24 h (acute) and 7, 14, 28 day (long-term) groups of infected rats showed increased p75NTR expression in the brain. During acute PM, modulation of p75NTR through pretreatment of PM model with LM11A-31 significantly alleviated S. pneumoniae-induced clinical severity, histopathological injury and the activation of astrocytes and microglia. LM11A-31 pretreatment also significantly ameliorated neuronal apoptosis and necrosis. Moreover, we found that blocking p75NTR with LM11A-31 decreased the expression of inflammation-related transcription factors (NF-κBp65, C/EBPβ) and proinflammatory cytokines/mediators (IL-1β, TNF-α, IL-6 and iNOS). Furthermore, p75NTR knockdown induced significant changes in histopathology and inflammation-related transcription factors expression. Importantly, long-term LM11A-31 treatment accelerated the resolution of PM-induced inflammation and significantly improved hippocampal neurogenesis.

Conclusion

Our findings suggest that the p75NTR signaling plays an essential role in the pathogenesis of PM. Targeting p75NTR has beneficial effects on PM rats by alleviating neuroinflammation and promoting hippocampal neurogenesis. Thus, the p75NTR signaling may be a potential therapeutic target to improve the outcome of PM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02294-w.

Deciphering the role of nanoparticles for management of bacterial meningitis: an update on recent studies

Meningitis is an inflammation of the protective membranes called meninges and fluid adjacent the brain and spinal cord. The inflammatory progression expands all through subarachnoid space of the brain and spinal cord and occupies the ventricles. The pathogens like bacteria, fungi, viruses, or parasites are main sources of infection causing meningitis. Bacterial meningitis is a life-threatening health problem that which needs instantaneous apprehension and treatment. Nesseria meningitidis, Streptococcus pneumoniae, and Haemophilus flu are major widespread factors causing bacterial meningitis. The conventional drug delivery approaches encounter difficulty in crossing this blood-brain barrier (BBB) and therefore are insufficient to elicit the desired pharmacological effect as required for treatment of meningitis. Therefore, application of nanoparticle-based drug delivery systems has become imperative for successful dealing with this deadly disease. The nanoparticles have ability to across BBB via four important transport mechanisms, i.e., paracellular transport, transcellular (transcytosis), endocytosis (adsorptive transcytosis), and receptor-mediated transcytosis. In this review, we reminisce distinctive symptoms of meningitis, and provide an overview of various types of bacterial meningitis, with a focus on its epidemiology, pathogenesis, and pathophysiology. This review describes conventional therapeutic approaches for treatment of meningitis and the problems encountered by them while transmitting across tight junctions of BBB. The nanotechnology approaches like functionalized polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carrier, nanoemulsion, liposomes, transferosomes, and carbon nanotubes which have been recently evaluated for treatment or detection of bacterial meningitis have been focused. This review has also briefly summarized the recent patents and clinical status of therapeutic modalities for meningitis.

Nationwide Population-Based Epidemiological Study for Outcomes of Adjunctive Steroid Therapy in Pediatric Patients with Bacterial Meningitis in Taiwan

Although corticosteroids can serve as an effective anti-inflammatory adjuvant therapy, the role of adjunctive steroid therapy in pediatric bacterial meningitis in Taiwan remains under-investigated. Cases of acute bacterial meningitis, aged between 1 month and 20 years, were divided into a steroid group (empirical antibiotics with adjunctive steroid therapy) and a non-steroid group (empirical antibiotics only). Data were identified from the annual hospitalization discharge claims of the National Health Insurance Research Database using the International Classification of Diseases, Ninth Revision codes. Of the 8083 episodes enrolled in this study, 26% (2122/8083) and 74% (5961/8083) were divided into the steroid and non-steroid groups, respectively. The fatality rates were 7.9% in the steroid group and 1.7% in the non-steroid group during hospitalization (p < 0.0001). In the steroid and non-steroid groups, the median length of hospital stay was 13 and 6 days, respectively (p < 0.0001). Medical costs (median (interquartile range)) of hospitalization were 77,941 (26,647–237,540) and 26,653 (14,287–53,421) New Taiwan dollars in the steroid and non-steroid groups, respectively (p < 0.0001). The steroid group had a more fulminant course at baseline, a higher fatality rate, length of hospital stay, and medical cost of hospitalization. Therefore, the beneficial effects of the adjunctive use of corticosteroids in pediatric bacterial meningitis are inconclusive, and additional prospective multicenter investigations are required to clarify this issue.

Adjunctive steroids in adults with encephalitis: a propensity score analysis

OBJECTIVE

Adjuvant steroids have been used for the treatment of encephalitis, although there is limited data regarding its benefit. We described the use and impact of adjunctive steroids on adverse clinical outcomes (ACO) in adults with encephalitis.

METHODS

Retrospective observational study of 230 adults with encephalitis at two tertiary care hospital systems in Houston, Texas, between August 2008 and September 2017. An ACO was assessed at the time of death or discharge and defined as a Glasgow Outcome Scale 1-4. A propensity score analysis was performed.

RESULTS

Out of 230 adult encephalitis patients enrolled, 121 (52.6%) received steroids. Adjunctive steroids were given more frequently to those who had focal neurological deficits (P = 0.01), required mechanical ventilation (MV) (P = 0.01), had intensive care unit admission (P < 0.001), had white matter abnormalities (P = 0.01) or cerebral edema on magnetic resonance imaging of the brain (P = 0.003). An ACO was seen in 135 (58.7%) of patients. The use of adjunctive steroids did not impact ACOs (P = 0.52) on univariate analyses or after propensity score matching. Predictors for an ACO in logistic regression analyses included a Glasgow Coma Score (GCS) < 8, fever, MV, and cerebral edema.

INTERPRETATION

Adjunctive steroids are used more frequently in sicker patients and are not associated with improved clinical outcomes.

SOP: emergency workup in patients with suspected acute bacterial meningitis

Introduction

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

First steps

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

Comments

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

Conclusion

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

The Use of Adjunctive Steroids in Central Nervous Infections

Central nervous system (CNS) infections continue to be associated with significant neurological morbidity and mortality despite various existing therapies. Adjunctive steroid therapy has been employed clinically to reduce inflammation in the treatment of CNS infections across various causative pathogens. Steroid therapy can potentially improve clinical outcomes including reducing mortality rates, provide no significant benefit, or cause worsened outcomes, based on the causative agent of infection. The data on benefits or harms of adjunctive steroid therapy is not consistent in outcome or density through CNS infections, and varies based on the disease diagnosis and pathogen. We summarize the existing literature on the effects of adjunctive steroid therapy on outcome for a number of CNS infections, including bacterial meningitis, herpes simplex virus, West Nile virus, tuberculosis meningitis, cryptococcal meningitis, Angiostrongylus cantonensis, neurocysticercosis, autoimmune encephalitis, toxoplasmosis, and bacterial brain abscess. We describe that while steroid therapy is beneficial and supported in pathogens such as pneumococcal meningitis and tuberculosis, for other diseases, like Listeria monocytogenes and Cryptococcus neoformans they are associated with worse outcomes. We highlight areas of consistent and proven findings and those which need more evidence for supported beneficial clinical use of adjunctive steroid therapy.

HIV Testing in Adults Presenting With Central Nervous System Infections

Background

Universal HIV testing in adults presenting to a health care setting was recommended by the Centers for Disease Control and Prevention (CDC) in 2006, but compliance in central nervous system (CNS) infections is unknown.

Methods

A multicenter study of adults presenting with CNS infections to 18 hospitals in Houston and New Orleans between 2000 and 2015 was done to characterize HIV testing and explore factors associated with a positive HIV test.

Results

A total of 1478 patients with a diagnosis of meningitis or encephalitis were identified; 180 were excluded because of known HIV diagnosis (n = 100) or were <17 years old (n = 80). Out of 1292 patients, 642 (49.7%) had HIV testing, and testing did not differ significantly before or after the CDC recommendations in 2006 (53% vs 48%; P = .068). An HIV test was more commonly done in patients who were non-Caucasian, had fever >38°C, or had seizures on presentation, and of those tested, non-Caucasian patients and those with photophobia were more likely to have a positive HIV test (P < .05). HIV testing also varied by type of CNS infection: community-acquired bacterial meningitis (98/130, 75.4%), encephalitis (174/255, 68.2%), aseptic meningitis (285/619, 46.0%), and health care–associated meningitis (85/288, 29.5%; P < .001).

Conclusions

Even though HIV testing should be done in all adults presenting with a CNS infection, testing remains ~50% and did not improve after the recommendation for universal testing by the CDC in 2006.

Accepting higher morbidity in exchange for sacrificing fewer animals in studies developing novel infection-control strategies

Preventing bacterial infections from becoming the leading cause of death by the year 2050 requires the development of novel, infection-control strategies, building heavily on biomaterials science, including nanotechnology. Pre-clinical (animal) studies are indispensable for this development. Often, animal infection outcomes bear little relation to human clinical outcome. Here, we review conclusions from pathogen-inoculum dose-finding pilot studies for evaluation of novel infection-control strategies in murine models. Pathogen-inoculum doses are generally preferred that produce the largest differences in quantitative infection outcome parameters between a control and an experimental group, without death or termination of animals due to having reached an inhumane end-point during the study. However, animal death may represent a better end-point for evaluation than large differences in outcome parameters or number of days over which infection persists. The clinical relevance of lower pre-clinical outcomes, such as bioluminescence, colony forming units (CFUs) retrieved or more rapid clearance of infection is unknown, as most animals cure infection without intervention, depending on pathogen-species and pathogen-inoculum dose administered. In human clinical practice, patients suffering from infection present to hospital emergency wards, frequently in life-threatening conditions. Animal infection-models should therefore use prevention of death and recurrence of infection as primary efficacy targets to be addressed by novel strategies. To compensate for increased animal morbidity and mortality, animal experiments should solely be conducted for pre-clinical proof of principle and safety. With the advent of sophisticated in vitro models, we advocate limiting use of animal models when exploring pathogenesis or infection mechanisms.