Accuracy of clinical presentation for differentiating bacterial from viral meningitis in adults: a multivariate approach

Diagnostic prediction models for bacterial meningitis in children with a suspected central nervous system infection: a systematic review and prospective validation study

OBJECTIVES

Diagnostic prediction models exist to assess the probability of bacterial meningitis (BM) in paediatric patients with suspected meningitis. To evaluate the diagnostic accuracy of these models in a broad population of children suspected of a central nervous system (CNS) infection, we performed external validation.

METHODS

We performed a systematic literature review in Medline to identify articles on the development, refinement or validation of a prediction model for BM, and validated these models in a prospective cohort of children aged 0-18 years old suspected of a CNS infection.

PRIMARY AND SECONDARY OUTCOME MEASURES

We calculated sensitivity, specificity, predictive values, the area under the receiver operating characteristic curve (AUC) and evaluated calibration of the models for diagnosis of BM.

RESULTS

In total, 23 prediction models were validated in a cohort of 450 patients suspected of a CNS infection included between 2012 and 2015. In 75 patients (17%), the final diagnosis was a CNS infection including 30 with BM (7%). AUCs ranged from 0.69 to 0.94 (median 0.83, interquartile range [IQR] 0.79-0.87) overall, from 0.74 to 0.96 (median 0.89, IQR 0.82-0.92) in children aged ≥28 days and from 0.58 to 0.91 (median 0.79, IQR 0.75-0.82) in neonates.

CONCLUSIONS

Prediction models show good to excellent test characteristics for excluding BM in children and can be of help in the diagnostic workup of paediatric patients with a suspected CNS infection, but cannot replace a thorough history, physical examination and ancillary testing.

A risk score for identifying patients at a low risk of bacterial meningitis amongst adults with cerebrospinal fluid leucocytosis and a negative gram stain result: a derivation and validation study

OBJECTIVES

We aimed to derive and validate a risk score to differentiate patients with bacterial meningitis from those with viral meningitis or encephalitis amongst patients presenting with cerebrospinal fluid (CSF) leucocytosis and a negative Gram staining result.

METHODS

We included adults with bacterial and viral meningitis or encephalitis presenting with CSF leukocyte counts of >10 per mm³ and a negative Gram staining result from cohorts in Houston, Texas (2004-2019), and the Netherlands (2012-2021). Derivation and the first validation were performed in the American patients and further validation in the Dutch patients.

RESULTS

Derivation was performed in 109 American patients with bacterial meningitis (median age, 56 years; interquartile range [IQR], 46-66 years; 46% women) and 194 with viral meningitis or encephalitis (median age, 46 years; IQR, 33-60 years; 53% women). Serum leukocyte counts of >10.0 × 10⁹/L, CSF leukocyte counts of >2000 per mm³, granulocyte counts of >1180 per mm³, protein levels of >2.2 g/L, glucose levels of <1.9 mmol/L and fever on admission were included in the risk score, which was dichotomized into 'low risk' (0 present) and 'high risk' (>0 present). The first validation showed a sensitivity of 100% (95% CI, 96.6-100) and specificity of 34.0% (95% CI, 27.4-41.2). Further validation in 262 Dutch patients with bacterial meningitis (median age, 57 years; IQR 44-70 years; 45% women) and 68 with viral meningitis (median age, 34 years; IQR, 28-45 years; 60% women) showed a sensitivity of 99.6% (95% CI, 97.9-100) and specificity of 41.2% (95% CI, 29.4-53.7).

CONCLUSIONS

Our risk score may be able to rule out bacterial meningitis amongst patients presenting with CSF leucocytosis and a negative Gram staining result. However, it needs prospective testing prior to clinical implementation.

NLRP3 in the Cerebrospinal Fluid as a Potential Biomarker for the Diagnosis and Prognosis of Community-Acquired Bacterial Meningitis in Adults

Objective

To discover the levels of NLR family pyrin domain-containing 3 (NLRP3) in the cerebrospinal fluid (CSF) from adult patients with community-acquired bacterial meningitis (CABM).

Methods

We enrolled 34 patients with CABM, 20 patients with viral meningitis (VM), and 25 patients with non-inflammatory neurological disease. Data on standard clinical parameters, scores, and outcomes were obtained from clinical records, and inflammasome levels in the CSF were measured by an enzyme-linked immunosorbent assay. The area under the receiver operating characteristic curve (AUROC) was used to quantify the diagnostic and prognostic performance of CSF NLRP3 as a biomarker of CABM.

Results

The levels of NLRP3 were elevated in the CSF of patients with CABM, but levels for ASC, caspase-1, or other inflammasomes did not vary significantly. CSF NLRP3 was positively correlated with clinical severity and with the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), lymphocyte count, albumin quotient (Qalb), and immunoglobulin G quotient (QIgG). Patients with unfavorable outcomes had higher levels of NLRP3 in the CSF, which were correlated with several blood indicators, including NLR, PLR, and lymphocyte and monocyte counts.

Conclusions

Our results suggested that the level of CSF NLRP3 could represent the severity of CABM in adults. CSF NLRP3 may be a good biomarker for the diagnosis of CABM and for the discrimination between CABM and VM. It may also be a better biomarker for predicting the prognosis of adult patients with CABM when compared to the NLR or the lymphocyte and monocyte counts.

Point-of-care cerebrospinal fluid Gram stain for the management of acute meningitis in adults: a retrospective observational study

Background

Gram stain of cerebrospinal fluid (CSF) is widely used in the diagnosis of acute meningitis, however, it is often conducted in the laboratory, as only some hospitals have access to point-of-care Gram stain (PCGS). The purpose of this study was to demonstrate the clinical impact and utility of PCGS in diagnosing and treating both bacterial and aseptic meningitis in adults.

Methods

This was a hospital-based, retrospective observational study at a referral center in Okinawa, Japan. We reviewed the records of all patients aged 15 years or older who were admitted to the Division of Infectious Diseases between 1995 and 2015 and finally diagnosed with bacterial (n = 34) or aseptic meningitis (n = 97). For bacterial meningitis, we compared the treatments that were actually selected based on PCGS with simulated treatments that would have been based on the Japanese guidelines. For aseptic meningitis, we compared the rates of antibiotic use between real cases where PCGS was available and real cases where it was not.

Results

PCGS was the most precise predictor for differentiating between bacterial and aseptic meningitis (sensitivity 91.2%, specificity 98.9%), being superior in this regard to medical histories, vital signs and physical examinations, and laboratory data available in the emergency room (ER). In bacterial meningitis, PCGS reduced the frequency of meropenem use (1/34 = 3.0%) compared with simulated cases in which PCGS was not available (19/34 = 55.9%) (p< 0.001). In aseptic meningitis cases, the rate of antibiotic administration was lower when PCGS was used (38/97 = 39.2%) than when it was not (45/74 = 60.8%) (p = 0.006).

Conclusions

PCGS of CSF distinguishes between bacterial and aseptic meningitis more accurately than other predictors available in the ER. Patients with bacterial meningitis are more likely to receive narrower-spectrum antimicrobials when PCGS is used than when it is not. PCGS of CSF thus can potentially suppress the empiric use of antimicrobials for aseptic meningitis.

Systematic review and validation of diagnostic prediction models in patients suspected of meningitis

OBJECTIVES

Diagnostic prediction models have been developed to assess the likelihood of bacterial meningitis (BM) in patients presented with suspected central nervous system (CNS) infection. External validation in patients suspected of meningitis is essential to determine the diagnostic accuracy of these models.

METHODS

We prospectively included patients who underwent a lumbar puncture for suspected CNS infection. After a systematic review of the literature, we applied identified models for BM to our cohort. We calculated sensitivity, specificity, predictive values, area under the curve (AUC) and, if possible, we evaluated the calibration of the models.

RESULTS

From 2012-2015 we included 363 episodes. In 89 (24%) episodes, the patient received a final diagnosis of a CNS infection, of whom 27 had BM. Seventeen prediction models for BM were identified. Sensitivity of these models ranged from 37% to 100%. Specificity of these models ranged from 44% to 99%. The cerebrospinal fluid model of Oostenbrink reached the highest AUC of 0.95 (95% CI 0.91-0.997). Calibration showed over- or underestimation in all models.

CONCLUSION

None of the existing models performed well enough to recommend as routine use in individual patient management. Future research should focus on differences between diagnostic accuracy of the prediction models and physician's therapeutic decisions.

Infectious causes and outcomes in patients presenting with cerebral spinal fluid pleocytosis

To evaluate the infectious etiologies, clinical features, and outcomes of patients with CNS infections at a tertiary care center. Patients that present with a pleocytosis in the cerebral spinal fluid (CSF), defined as a CSF WBC count > 5 cells/mm³, from July 2015 to June 2016 at a tertiary care hospital were analyzed for this report. Data from patients with confirmed (n = 43) and presumed (n = 51) CNS infections were analyzed. CNS infection was the leading known cause of CSF pleocytosis (n = 43, 18% of all patients with a pleocytosis in the CSF), and HSV-2 was identified as the leading causative pathogen (n = 10) followed by varicella zoster virus (n = 5). Fifty-three percent of patients with a pleocytosis in the CSF did not receive a diagnosis. In the patients that did not receive a diagnosis, CNS infection was presumed to be the cause in 51 patients (21% of patients with CSF pleocytosis). The mean time to diagnosis for patients with confirmed CNS infection was 16 days, but time to diagnosis was highly variable depending on the causative pathogen. There was a significant overlap in CSF parameters and peripheral white blood cell counts in patients diagnosed with a viral, bacterial, or fungal infection. Neuroimaging changes were present in only 44% of CNS infections. The overall mortality was 7% for CNS infections, and 17% of patients with a CNS infection had a severe neurologic deficit at presentation while only 3% had a severe deficit at the last neurologic assessment. This study provides new insights into the infectious causes of disease in a cohort of patients with pleocytosis in the CSF. The study provides new insights into the time to diagnosis and outcomes in patients that present with pleocytosis in the CSF.

A New Scoring System for the Differential Diagnosis between Tuberculous Meningitis and Viral Meningitis

BACKGROUND

Tuberculous meningitis (TBM) is associated with high mortality and morbidity despite administering anti-tuberculous chemotherapy to the patients. Differential diagnosis between TBM and viral meningitis (VM) is difficult in some clinical situations.

METHODS

We reviewed and analyzed records of adult patients who were admitted and diagnosed with TBM or VM at a tertiary hospital in Korea, between January 2006 and December 2015. Diagnostic criteria for TBM were categorized into three groups: definite, probable, and possible TBM. The VM group included patients with no evidence of other meningitis who achieved complete recovery with only conservative treatments. Clinical, laboratory and radiological findings, as well as outcomes, were compared between the TBM and VM groups.

RESULTS

Ninety-eight patients were enrolled. Among the study patients, 47 had TBM and 51 had VM. Based on univariate analysis and multivariate logistic regression, sodium < 135 mmol/L in serum (hyponatremia), lactate dehydrogenase > 70 (U/L) in cerebrospinal fluid (CSF), protein > 160 (mg/dL) in CSF, voiding difficulty, and symptoms of cranial nerve palsy were significant predictive factors for TBM in the final model. We constructed a weighted scoring system with predictive factors from multiple regression analyses. Receiver operating characteristic curve analyses and decision tree analyses were plotted to reveal an optimum cutoff point as 4 with this scoring system (range: 0-13).

CONCLUSION

For differential diagnosis between TBM and VM, we created a new weighted scoring system. This scoring system and decision tree analysis are simple and easy to apply in clinical practice to differentiate TBM from VM.

The UK joint specialist societies guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults

Bacterial meningitis and meningococcal sepsis are rare conditions with high case fatality rates. Early recognition and prompt treatment saves lives. In 1999 the British Infection Society produced a consensus statement for the management of immunocompetent adults with meningitis and meningococcal sepsis. Since 1999 there have been many changes. We therefore set out to produce revised guidelines which provide a standardised evidence-based approach to the management of acute community acquired meningitis and meningococcal sepsis in adults. A working party consisting of infectious diseases physicians, neurologists, acute physicians, intensivists, microbiologists, public health experts and patient group representatives was formed. Key questions were identified and the literature reviewed. All recommendations were graded and agreed upon by the working party. The guidelines, which for the first time include viral meningitis, are written in accordance with the AGREE 2 tool and recommendations graded according to the GRADE system. Main changes from the original statement include the indications for pre-hospital antibiotics, timing of the lumbar puncture and the indications for neuroimaging. The list of investigations has been updated and more emphasis is placed on molecular diagnosis. Approaches to both antibiotic and steroid therapy have been revised. Several recommendations have been given regarding the follow-up of patients.

Lipocalin 2 in cerebrospinal fluid as a marker of acute bacterial meningitis

Background

Early differential diagnosis between acute bacterial and viral meningitis is problematic. We aimed to investigate whether the detection of lipocalin 2, a protein of the acute innate immunity response, may be used as a marker for acute bacterial meningitis.

Methods

Transgenic mice expressing the human transferrin were infected by intraperitoneal route and were imaged. Cerebrospinal fluid (CSF) was sampled up to 48hours post- infection to measure lipocalin 2. We also tested a collection of 90 and 44 human CSF with confirmed acute bacterial or acute viral meningitis respectively.

Results

Lipocalin 2 was detected after 5 h in CSF during experimental infection in mice. Lipocalin 2 levels were significantly higher (p < 0.0001) in patients with confirmed acute bacterial meningitis (mean 125 pg/mL, range 106–145 pg/mL) than in patients with acute viral meningitis (mean 2 pg/mL, range 0–6 pg/mL) with a sensitivity of 81%, a specificity of 93%, a positive predictive value of 96% and a negative predictive value of 71% in diagnosing acute bacterial meningitis.

Conclusions

Increased levels of lipocalin 2 in cerebrospinal fluid may discriminate between acute bacterial and viral meningitis in patients with clinical syndrome of meningitis.

Meningitis with a negative cerebrospinal fluid Gram stain in adults: risk classification for an adverse clinical outcome

OBJECTIVE

To derive and validate a risk score for an adverse clinical outcome in adults with meningitis and a negative cerebrospinal fluid (CSF) Gram stain.

PATIENTS AND METHODS

We conducted a retrospective study of 567 adults from Houston, Texas, with meningitis evaluated between January 1, 2005, and January 1, 2010. The patients were divided into derivation (N=292) and validation (N=275) cohorts. An adverse clinical outcome was defined as a Glasgow Outcome Scale score of 4 or less.

RESULTS

Of the 567 patients, 62 (11%) had an adverse clinical outcome. A predictive model was created using 3 baseline variables that were independently associated with an adverse clinical outcome (P<.05): age greater than 60 years, abnormal findings on neurologic examination (altered mental status, focal neurologic deficits, or seizures), and CSF glucose level of less than 2.4975 mmol/L (to convert CSF glucose to mmol/L, multiply by 0.05551). The model classified patients into 2 categories of risk for an adverse clinical outcome--derivation sample: low risk, 0.6% and high risk, 32.8%; P<.001; and validation sample: low risk, 0.5% and high risk, 21.1%; P<.001.

CONCLUSION

Adults with meningitis and a negative CSF Gram stain can be accurately stratified for the risk of an adverse clinical outcome using clinical variables available at presentation.

Performance of thirteen clinical rules to distinguish bacterial and presumed viral meningitis in Vietnamese children

Background and Purpose

Successful outcomes from bacterial meningitis require rapid antibiotic treatment; however, unnecessary treatment of viral meningitis may lead to increased toxicities and expense. Thus, improved diagnostics are required to maximize treatment and minimize side effects and cost. Thirteen clinical decision rules have been reported to identify bacterial from viral meningitis. However, few rules have been tested and compared in a single study, while several rules are yet to be tested by independent researchers or in pediatric populations. Thus, simultaneous test and comparison of these rules are required to enable clinicians to select an optimal diagnostic rule for bacterial meningitis in settings and populations similar to ours.

Methods

A retrospective cross-sectional study was conducted at the Infectious Department of Pediatric Hospital Number 1, Ho Chi Minh City, Vietnam. The performance of the clinical rules was evaluated by area under a receiver operating characteristic curve (ROC-AUC) using the method of DeLong and McNemar test for specificity comparison.

Results

Our study included 129 patients, of whom 80 had bacterial meningitis and 49 had presumed viral meningitis. Spanos's rule had the highest AUC at 0.938 but was not significantly greater than other rules. No rule provided 100% sensitivity with a specificity higher than 50%. Based on our calculation of theoretical sensitivity and specificity, we suggest that a perfect rule requires at least four independent variables that posses both sensitivity and specificity higher than 85–90%.

Conclusions

No clinical decision rules provided an acceptable specificity (>50%) with 100% sensitivity when applying our data set in children. More studies in Vietnam and developing countries are required to develop and/or validate clinical rules and more very good biomarkers are required to develop such a perfect rule.

Application of a prediction rule to discriminate between aseptic and bacterial meningitis in adults

INTRODUCTION

Differentiating between aseptic and bacterial meningitis presents a difficult diagnostic challenge. Accurately ruling out bacterial meningitis may reduce unnecessary hospitalization, patient morbidity, and utilization of resources. This study applies a prediction rule previously developed in the pediatric population to an adult cohort.

METHODS

We performed a retrospective chart review of all patients admitted to an urban community hospital in the United States between 1994 and 2007.

RESULTS

One hundred eleven patients met the inclusion criteria. Twenty-two (20%) had bacterial meningitis and 89 (80%) had aseptic meningitis. The prediction rule generated a negative predictive value of 100% and a sensitivity of 100%, successfully ruling out all patients with aseptic meningitis.

CONCLUSIONS

The prediction rule, previously validated in a pediatric population, was accurate in ruling out bacterial meningitis in an adult cohort. Prospective validation in an adult population is warranted.

High creatinine clearance in critically ill patients with community-acquired acute infectious meningitis

Background

A high dose of anti-infective agents is recommended when treating infectious meningitis. High creatinine clearance (CrCl) may affect the pharmacokinetic / pharmacodynamic relationships of anti-infective drugs eliminated by the kidneys. We recorded the incidence of high CrCl in intensive care unit (ICU) patients admitted with meningitis and assessed the diagnostic accuracy of two common methods used to identify high CrCl.

Methods

Observational study performed in consecutive patients admitted with community-acquired acute infectious meningitis (defined by >7 white blood cells/mm³ in cerebral spinal fluid) between January 2006 and December 2009 to one medical ICU. During the first 7 days following ICU admission, CrCl was measured from 24-hr urine samples (24-hr-UV/P creatinine) and estimated according to Cockcroft-Gault formula and the simplified Modification of Diet in Renal Disease (MDRD) equation. High CrCl was defined as CrCl >140 ml/min/1.73 m² by 24-hr-UV/P creatinine. Diagnostic accuracy was performed with ROC curves analysis.

Results

Thirty two patients were included. High CrCl was present in 8 patients (25%) on ICU admission and in 15 patients (47%) during the first 7 ICU days for a median duration of 3 (1-4) days. For the Cockcroft-Gault formula, the best threshold to predict high CrCl was 101 ml/min/1.73 m² (sensitivity: 0.96, specificity: 0.75, AUC = 0.90 ± 0.03) with a negative likelihood ratio of 0.06. For the simplified MDRD equation, the best threshold to predict high CrCl was 108 ml/min/1.73 m² (sensitivity: 0.91, specificity: 0.80, AUC = 0.88 ± 0.03) with a negative likelihood ratio of 0.11. There was no difference between the estimated methods in the diagnostic accuracy of identifying high CrCl (p = 0.30).

Conclusions

High CrCl is frequently observed in ICU patients admitted with community-acquired acute infectious meningitis. The estimated methods of CrCl could be used as a screening tool to identify high CrCl.

Clinical picture of meningitis in the adult patient and its relationship with age

To analyze the clinical characteristics of acute meningitis and their relationship with age in adult patients presenting to the emergency department. We retrospectively investigated consecutive adult patients admitted with a diagnosis of bacterial or viral meningitis from 2002 to 2006. Data about patient's history, symptoms and signs at presentation, etiology and clinical course were collected. To investigate the relationship of clinical presentation with age, we divided patients in four age quartiles (<30 years, between 30 and 36 years, between 37 and 56 years, >56 years). Among the 202 patients considered in the study (mean age 42.8 ± 18.7 years, range 14-90), 162 (80.2%) patients had viral and 40 (19.8%) bacterial meningitis. Specific signs, such as neck stiffness or Kernig or Brudzinski signs, were more common in the first than in the fourth quartile (73.1 vs. 45.7% P = 0.041). Conversely, altered consciousness expressed as Glasgow Coma Scale (GCS) <15 was more frequent in the fourth (80.4%) than in the first (9.6%) quartile (P < 0.001). The linear regression analysis confirmed a significant decrease of GCS with the increasing of patient's age (r = -0.69, P < 0.001). At multivariate analysis, aging was associated with altered level of consciousness (OR 16.7, P < 0.001) independent of viral or bacterial etiology of the presence of comorbidities and of clinical severity (presence of severe sepsis or septic shock). Meningitis presentation largely differs with aging in adult patients. Level of consciousness is frequently altered in the older patients, when other specific signs become more rare, independent of etiology, comorbidities and clinical severity.

A new diagnostic scoring for discrimination of tuberculous and bacterial meningitis on the basis of clinical and laboratory findings

OBJECTIVES

The aim of this study was to develop a new diagnostic index (DI) on the basis of clinical and laboratory findings including serum C-reactive protein (CRP) for tuberculous meningitis (TM) and bacterial meningitis (BM).

SUBJECTS AND METHODS

During a 7-year period, 96 adult patients with meningitis (30 with TM and 66 with BM) were studied retrospectively. Multivariate logistic regression analysis was performed to investigate the diagnostic value of clinical and laboratory parameters as independent predictors on discrimination of tuberculous from BM patients.

RESULTS

Six features predictive for diagnosis including age, CSF leukocyte count, PML dominance, length of illness, serum CRP level and blood WBC count were used. The DI model developed from these features had very high sensitivity and specificity rates of 100.0 and 95.4%, respectively. The sensitivity and specificity rates were 97.4 and 100%, respectively, in microbiologically proven cases.

CONCLUSION

Our results suggested that this new DI which consists of simple clinical and laboratory parameters had the power to discriminate adult patients with documented tuberculous and BM (excluding Brucella meningitis). It should, however, be tested in prospective studies.

Neurologic infectious disease emergencies

Nearly 70 years after the discovery of penicillin, neurologic infectious diseases (NIDs) remain an important worldwide source of morbidity and mortality. The clinician faced with a potential NID must urgently consider patient demographics, pace of illness and clinical syndrome, and laboratory data. In keeping with the topics of this issue, initial emergency diagnosis and management are emphasized, with appropriate references to relevant literature for subsequent longer-term interventions.

Early diagnosis model for meningitis supports public health decision making

OBJECTIVE

To develop a predictive model for rapid differential diagnosis of meningitis and meningococcal septicaemia to support public health decisions on chemoprophylaxis for contacts.

METHODS

Prospective study of suspected cases of acute meningitis and meningococcal septicaemia admitted to hospitals in the South West, West Midlands and London Regions of England from July 2008 to June 2009. Epidemiological, clinical and laboratory variables on admission were recorded. Logistic regression was used to derive a predictive model.

RESULTS

Of the 719 suspect cases reported, 385 confirmed cases were included in analysis. Peripheral blood polymorphonuclear count of >16 × 10(9)/l, serum C-reactive protein of >100 mg/l and haemorrhagic rash were strongly and independently associated with diagnosis of bacterial meningitis and meningococcal septicaemia. Using a simple scoring system, the presence of any one of these factors gave a probability of >95% in predicting the final diagnosis.

CONCLUSION

We have developed a model using laboratory and clinical factors, but not dependent on availability of CSF, for differentiating acute bacterial from viral meningitis within a few hours of admission to hospital. This scoring system is recommended in public health management of suspected cases of meningitis and meningococcal septicaemia to inform decisions on chemoprophylaxis.

Cerebrospinal fluid viscosity: a novel diagnostic measure for acute meningitis

INTRODUCTION

Early diagnosis of acute meningitis has paramount importance in clinical practice because of mortality and morbidity of the disease. Examination of cerebrospinal fluid (CSF) has critical value for the diagnosis of acute meningitis and discrimination of bacterial and aseptic meningitis. It has been previously reported that plasma viscosity can be used as an inflammatory marker. In this study we aimed to evaluate the role of CSF viscosity as a complementary measure for diagnosis of meningitis in suspected patients.

METHODS

Forty-one consecutive patients who underwent lumbar puncture to rule out meningitis were studied prospectively. Twenty-seven patients were diagnosed with meningitis, of whom 13 patients had aseptic meningitis and 14 patients had bacterial meningitis. Meningitis was ruled out in 14 patients.

RESULTS

CSF protein and CSF viscosity were significantly higher in patients with meningitis compared to nonmeningitis. Receiver operator characteristic (ROC) analysis revealed that CSF viscosity was highly sensitive (100%) and specific (93%); measures for the diagnosis of meningitis in the study population was comparable to those of CSF protein. Additionally, patients with meningitis were also divided into two groups as having bacterial and aseptic meningitis. CSF viscosity also significantly differed between bacterial and aseptic meningitis.

CONCLUSION

The CSF viscosity is a simple and easy method and can be used as an adjunctive measure for the diagnosis of meningitis. With the support of further and larger clinical studies, CSF viscosity may have a role in the discrimination of bacterial versus aseptic meningitis.

Incidence of meningitis secondary to suppurative otitis media in adults

AIM

Meningitis is the commonest intracranial complication of suppurative otitis media, and carries the risk of death and life-changing morbidity. This study aimed to estimate the risk of an adult in the UK developing otogenic meningitis.

METHODS

Adults hospitalised with meningitis in Bristol from 1997 to 2002 were identified retrospectively. Cases confirmed by positive blood culture or cerebrospinal fluid investigation were studied. A case was classified as otogenic if there was coexistent evidence of ear infection.

RESULTS

Eighty-seven cases of meningitis were analysed. The overall mortality rate was 5.7 per cent. Acute and chronic suppurative otitis media accounted for 13 and three cases, respectively. The adult population of Bristol at the midpoint of the study was 635,976.

CONCLUSION

In this study, the age-adjusted incidence of otogenic meningitis was 0.42 per 100,000 per year.

Evaluating the Brighton Collaboration case definitions, aseptic meningitis, encephalitis, myelitis, and acute disseminated encephalomyelitis, by systematic analysis of 255 clinical cases

AIMS

Brighton Collaboration (BC) case definitions are independent from presumed causes or triggers, hence should be applicable in routine clinical settings.

SCOPE

255 cases with discharge diagnoses of aseptic meningitis (ASM; n=164), encephalitis (ENC; n=48), myelitis (MYE; n=8), ADEM (n=10), or bacterial meningitis (BM; n=59; control group) were tested against the BC case definitions ASM, ENC, MYE, and ADEM. Overall rates of agreement between BC criteria and discharge diagnoses were 70%, 78%, 97%, and 97% for ASM, ENC, MYE and ADEM, respectively.

CONCLUSION

BC case definitions are easily applicable in retrospective chart reviews allowing causality assessments with minimal selection bias.

Lumbar puncture and cerebrospinal fluid analysis

Examination of the CSF is the gold standard for the diagnosis of meningitis. There are a number of laboratory tests. in addition to CSF cell count, glucose concentration, Gram's stain, and bacterial culture, that are useful in identifying the organism and differentiating between bacterial and viral meningitis. These laboratory tests can be used in combination with the clinical presentation to determine which patient should be treated for bacterial meningitis while awaiting the result of CSF Gram's stain and bacterial culture.

Identifying low-risk patients for bacterial meningitis in adult patients with acute meningitis

OBJECTIVE

To derive and validate a clinical prediction model with high sensitivity for differentiating aseptic meningitis (AM) patients from bacterial meningitis (BM) patients.

METHODS

We developed the model using the derivation cohort in a community rural hospital in Okinawa and assessed its performance using the validation cohort in a metropolitan urban hospital in Tokyo. There were 66 (39.5%) and 5 (17.9%) adult patients with BM among the derivation (n=167) and the validation cohort (n=28), respectively. Recursive partitioning analysis was used to determine the important classification variables and to develop a sensitive model to safely exclude BM.

RESULTS

The model produced high- and low-risk groups based on the following: 1) Gram stain, 2) CSF neutrophil percent < or =15%, 3) CSF neutrophil count < or =150 cells/mm(3), and, 4) mental status change. Among the derivation cohort, there were 65 patients with BM in the high-risk group (n=76), while only one patient with BM was noted (sensitivity, 99%) in the low-risk group (n=91). Among the validation cohort, there were 5 patients with BM in the high-risk group (n=7), while no patient was classified with BM (sensitivity, 100%) in the low-risk group (n=21).

CONCLUSION

This simple and sensitive model might be useful to safely identify low-risk patients for BM who would not require antibiotic treatment.

Update in the diagnosis and management of central nervous system infections

Central nervous system (CNS) infections presenting to the emergency room include meningitis, encephalitis, brain and spinal epidural abscess, subdural empyema, and ventriculitis. These conditions often require admission to an intensive care unit (ICU) and are complications of ICU patients with neurologic injury, contributing significantly to morbidity and mortality. Reducing morbidity and mortality is critically dependent on rapid diagnosis and, perhaps more importantly, on the timely initiation of appropriate antimicrobial therapy. New insights into the role of inflammation and the immune response in CNS infections have contributed to development of new diagnostic strategies using markers of inflammation, and to the study of agents with focused immunomodulatory activity, which may lead to further adjunctive therapy in human disease.

Emergency department management of meningitis and encephalitis

Bacterial meningitis and viral encephalitis are infectious disease emergencies that can cause significant patient morbidity and mortality. Clinicians use epidemiologic, historical, and physical examination findings to identify patients at risk for these infections, and central nervous system (CNS) imaging and lumbar puncture (LP) may be needed to further evaluate for these diagnoses. The diagnosis of bacterial meningitis can be challenging, as patients often lack some of the characteristic findings of this disease with presentations that overlap with more common disorders seen in the emergency department. This article addresses considerations in clinical evaluation, need for CNS imaging before LP, interpretation of cerebrospinal fluid results, standards for and effects of timely antibiotic administration, and recommendations for specific antimicrobial therapy and corticosteroids.

Advances in the management of central nervous system infections in the ICU

This chapter focuses on early aggressive management of common infections of the central nervous system that require monitoring in an ICU setting. These include meningitis, encephalitis, brain and epidural abscess, subdural empyema and ventriculitis. It emphasizes priorities in evaluation and management due to increasing morbidity and mortality as a result of failure to appreciate non-specific symptoms or administer timely therapy. The emergence of organisms resistant to penicillin and cephalosporins has also further complicated the early management of bacterial meningitis. Current antimicrobial guidelines are provided along with discussion of new diagnostic and therapeutic strategies and controversial aspects of management.

Emergency diagnosis and treatment of adult meningitis

Despite the existence of antibiotic therapies against acute bacterial meningitis, patients with the disease continue to suffer significant morbidity and mortality in both high and low-income countries. Dilemmas exist for emergency medicine and primary-care providers who need to accurately diagnose patients with bacterial meningitis and then rapidly administer antibiotics and adjunctive therapies for this life-threatening disease. Physical examination may not perform well enough to accurately identify patients with meningitis, and traditionally described lumbar puncture results for viral and bacterial disease cannot always predict bacterial meningitis. Results from recent studies have implications for current treatment guidelines for adults with suspected bacterial meningitis, and it is important that physicians who prescribe the initial doses of antibiotics in an emergency setting are aware of guidelines for antibiotics and adjunctive steroids. We present an overview and discussion of key diagnostic and therapeutic decisions in the emergency evaluation and treatment of adults with suspected bacterial meningitis.

Accuracy of the cerebrospinal fluid results to differentiate bacterial from non bacterial meningitis, in case of negative gram-stained smear

OBJECTIVE

The aim of this study was to evaluate the usefulness of various laboratory results for differential diagnosis of bacterial (BM) and nonbacterial meningitis (NBM) with negative initial Gram stain.

DESIGN AND SETTING

A prospective multicenter study was conducted in the emergency departments of 3 teaching hospitals.

PARTICIPANTS AND METHODS

Consecutive adult patients with a diagnosis of meningitis based on compatible clinical features and cerebrospinal fluid (CSF) culture findings with a CSF leukocyte count greater than 5/mm(3) were included in the study. Symptoms, examination findings, data from laboratory results, including CSF results and serum C-reactive protein (CRP) levels, and clinical outcome were assessed.

RESULTS

One hundred fifty-one patients (age, 35 +/- 15 years) with confirmed meningitis were admitted: 133 with NBM and 18 with BM. CRP and procalcitonin (PCT) levels, CSF white cell and absolute neutrophil counts, and CSF glucose/blood glucose and CSF protein levels were significantly higher in the BM group. However, as diagnostic indicators of BM, none of these variables except PCT was more efficient than that of the emergency physician. Values of the area under the receiver operating characteristic curve were 0.59 (95% confidence interval [CI], 0.21-0.82), 0.79 (95% CI, 0.47-0.92), 0.18 (95% CI, 0.0-0.43), 0.70 (95%CI, 0.30-0.89), 0.81 (95% CI, 0.58-0.92), and 0.98 (95% CI, 0.83-1.0) for CSF leukocyte count, percentage of CSF leukocyte, CSF/blood glucose ratio, CSF protein level, serum CRP, and serum PCT (P < .05 vs CRP), respectively.

CONCLUSION

CSF results have a modest role in distinguishing BM from NBM in a negative Gram stain for bacteria. PCT serum levels seem to be an excellent predictor of BM.

Bacterial meningitis and inflammation

PURPOSE OF REVIEW

Bacterial meningitis is a condition in which inflammation plays a role in disease resolution and also contributes to morbidity. Markers of inflammation may be used to aid in establishing diagnoses and prognoses. Medical management aimed at modulating the inflammatory response with broadly active, potent glucocorticosteroids has proved useful as an adjunct to antimicrobial therapy in selected patient populations. Basic immunobiologists, in describing components of the immune response that define its features of specificity, recognition, activation, regulation and tolerance induction have opened the door for the development of agents with focused activity that permit selective immunomodulation. New insights regarding management may result from a better understanding of the role of inflammation in bacterial meningitis.

RECENT FINDINGS

Insights have been gained from recent basic and clinical scientific investigations that examine the components and consequences of inflammation in animal models and patients with bacterial meningitis.

SUMMARY

This issue of Current Opinion in Neurology addresses recent reports that illustrate aspects of the inflammatory responses associated with bacterial meningitis that emphasize the need for early diagnosis, and contribute to prognosis assessment, and reviews the investigations that may predict the next steps in the evolution of clinical management.

Soluble triggering receptor expressed on myeloid cells 1: a biomarker for bacterial meningitis

OBJECTIVE

To evaluate whether soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) in CSF can serve as a biomarker for the presence of bacterial meningitis and outcome in patients with this disease.

DESIGN

Retrospective study of diagnostic accuracy.

SETTING AND PATIENTS

CSF was collected from 92 adults with community-acquired bacterial meningitis who participated in the prospective Dutch Meningitis Cohort Study; 8 patients with viral meningitis and 9 healthy control subjects.

RESULTS

CSF sTREM-1 levels were higher in patients with bacterial meningitis (median 82 pg/ml, range 0-988) than in those with viral meningitis (0 pg/ml, 0-48) and controls (0 pg/ml, 0-36). The diagnostic accuracy of sTREM-1 in discriminating between patients with and without bacterial meningitis, expressed as the area under the receiver operating characteristic curve, was 0.82. At a cutoff level of 20 pg/ml the sensitivity was 0.73 and specificity 0.77. In patients with bacterial meningitis CSF sTREM-1 levels were associated with mortality (survivors, median 73 pg/ml, range 0-449 pg/ml; nonsurvivors, 15 pg/ml, 0-988).

CONCLUSIONS

Measuring sTREM-1 in CSF may be a valuable new additional approach to accurately diagnose bacterial meningitis and identify patients at high risk for adverse outcome. Therefore a prospective study of sTREM-1 as a biomarker in bacterial meningitis is needed.