Cerebrospinal fluid/blood glucose ratio as an indicator for bacterial meningitis

Neonatal Sepsis: Aetiology, Pathophysiology, Diagnostic Advances and Management Strategies

Neonatal sepsis, a bloodstream infection in the first 28 days of life, is a leading cause of morbidity and mortality among infants in both developing and developed countries. Additionally, sepsis is distinguished in neonates by unique pathophysiological and presentational factors relating to its development in immature neonatal immune systems. This review focuses on the current understanding of the mechanics and implications of neonatal sepsis, providing a comprehensive overview of the epidemiology, aetiology, pathophysiology, major risk factors, signs and symptoms and recent consensus on the diagnosis and management of both early-onset and late-onset neonatal sepsis. It also includes a discussion on novel biomarkers and upcoming treatment strategies for the condition as well as the potential of COVID-19 infection to progress to sepsis in infants.

Diagnostic and Monitoring Value of β-2 Transferrin and Transferrin for Intracranial Infection After Neurosurgery

BACKGROUND AND OBJECTIVES

After neurosurgery, intracranial infection is a common complication with high rates of clinical impairment and death. Traditional diagnostic approaches are time-consuming. Early and correct diagnosis improves infection control, treatment success, and survival. Novel markers are used to diagnose and classify post-neurosurgical meningitis (PNM) to overcome the difficulties of diagnosing postoperative intracranial infections and avoid the drawbacks of existing diagnostic measures. The objective was to investigate the diagnostic value of β-2 transferrin (β-2TF) and transferrin (TF) in the cerebrospinal fluid (CSF) for the identification of intracranial infection after neurosurgery.

METHODS

Owing to their symptoms and laboratory results, 168 patients with suspected intracranial infection after neurosurgery were divided into 3 groups: post-neurosurgical bacterial meningitis (PNBM; n = 61), post-neurosurgical aseptic meningitis (PNAM; n = 45), and non-PNM (n = 62). We measured lactate (LA), β-2TF, and TF levels in the CSF.

RESULTS

CSF LA levels were significantly higher in the PNM, PNBM, and PNAM groups compared with the non-PNM group ( P < .05). The CSF β-2TF level in PNM, PNBM, and PNAM were statistically higher than those in non-PNMs ( P < .05). CSF TF levels in the PNBM group were statistically higher than those in the PNAM and non-PNM groups ( P < .05). The PNBM and non-PNM receiver operating curve (ROC) analysis indicates that the cutoff values for the combination (LA, β-2TF, TF) was 0.349, and the area under the curve (AUC) was 0.945 ( P < .0001), with 92.86% sensitivity and 92.98% specificity. The PNAM and non-PNM ROC analysis indicates that the cutoff values for the combination (LA, β-2TF, TF) was 0.346, and the AUC was 0.962 ( P < .0001), with 89.29% sensitivity and 90.24% specificity. The PNM and non-PNM ROC analysis indicates that the cutoff values for the combination (LA, β-2TF, TF) was 0.609, and the AUC was 0.941 ( P < .0001), with 96.36% sensitivity and 82.83% specificity. A Glasgow Coma Scale score ≤8, LA, β-2TF/TF ratio, length of hospital stay, intensive care unit admission, poor surgical wound, and craniotomy were associated with poor outcomes ( P < .05). LA and β-2TF were independent risk factors for intracranial infection.

CONCLUSION

Postoperative cerebral infections can be identified using CSF β-2TF as a particular marker protein. CSF TF helps distinguish PNBM from PNAM. Combining CSF LA with them improves diagnostic speed, sensitivity, and accuracy. LA and β-2TF were independent risk factors for cerebral infection.

Characterization and diagnosis spectrum of patients with cerebrospinal fluid pleocytosis

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Prominent cerebral veins on susceptibility-weighted angiography in acute meningoencephalitis

BACKGROUND AND PURPOSE

We have commonly observed prominent cerebral veins on susceptibility-weighted angiography (SWAN) in acute meningoencephalitis. This study aimed to investigate the clinical significance of these findings.

METHODS

Cerebral veins on SWAN of 98 patients with acute meningoencephalitis diagnosed from February 2016 through October 2020 were classified into three groups according to the degree of venous prominence (mild, 23; moderate, 53; and prominent, 22). Clinical variables and laboratory findings were compared between these groups. The influence of variables on the prediction of prominent cerebral veins was measured by random forest (RF) and gradient boosting machine (GBM).

RESULTS

As cerebral veins became more prominent, cerebrospinal fluid (CSF) glucose level decreased (69.61 ± 29.05 vs. 59.72 ± 22.57 vs. 48.36 ± 20.29 mg/dL, p = .01) and CSF protein level increased (100.73 ± 82.98 vs. 104.73 ± 70.99 vs. 159.12 ± 118.15 mg/dL, p = .03). The etiology of meningoencephalitis, neurological symptoms, and increased intracranial pressure (ICP) signs differed between groups (p < .05). RF and GBM demonstrated that CSF protein level was the variable with the highest power to predict the prominent cerebral vein (mean decrease in node impurity: 4.19, relative influence: 50.66).

CONCLUSION

The presence of prominent cerebral veins on SWAN in acute meningoencephalitis was significantly associated with a low CSF glucose level and a high CSF protein level, as well as ICP. Thus, the visual grade of the cerebral veins on SWAN may be utilized for the management of patients with acute meningoencephalitis.

Comparison between cerebrospinal fluid biomarkers for differential diagnosis of acute meningitis

OBJECTIVES

Given the difficulty in the differential diagnosis of acute bacterial meningitis (BM) and viral meningitis (VM), we aimed to compare the ability of cerebrospinal fluid (CSF) biomarkers, such as lactate, glucose, lactate dehydrogenase (LDH), C-reactive protein (CRP), total white blood cell count, and predominance of neutrophils, as single tests to differentiate microbiologically defined acute BM and VM.

METHODS

CSF samples were divided into three groups: BM (n=17), VM (n=14) (both with the etiological agent identified), and normal control groups (n=26).

RESULTS

All the biomarkers studied were significantly higher in the BM group than in the VM or control groups (p>0.05). CSF lactate showed the best diagnostic clinical performance characteristics: sensitivity (94.12%), specificity (100%), positive and negative predictive value (100 and 97.56%, respectively), positive and negative likelihood ratio (38.59 and 0.06, respectively), accuracy (98.25%), and AUC (0.97). CSF CRP is excellent for screening BM and VM, as its best feature is its specificity (100%). CSF LDH is not recommended for screening or case-finding. LDH levels were higher in Gram-negative diplococcus than in Gram-positive diplococcus. Other biomarkers were not different between Gram-positive and negative bacteria. The highest level of agreement between the CSF biomarkers was between CSF lactate and CRP [kappa coefficient, 0.91 (0.79; 1.00)].

CONCLUSIONS

All markers showed significant differences between the studied groups and were increased in acute BM. CSF lactate is better than the other biomarkers studied for screening acute BM due to its high specificity.

Measuring blood glucose before or after lumbar puncture

Background

The ratio of cerebrospinal fluid (CSF) to peripheral blood glucose at the same period is an important index for diagnosing and monitoring the efficacy of central nervous system infection, especially bacterial meningitis. Some guidelines refer that blood glucose measurement should be carried out before lumbar puncture. The main reason is to avoid possible effect of stress response induced by lumbar puncture on the level of blood glucose. However, there is no consensus on whether it should be followed in actual clinical work, since up to now no research work having been published on whether lumbar puncture will induce the changes on blood glucose. Our study aimed to investigate the changes of peripheral blood glucose before and after lumbar puncture.

Methods

In order to clarify the influence of timing of peripheral blood glucose measurement at the same period of lumbar puncture, a prospective study was conducted including children with an age range from 2 months to 12 years old in the neurology department of a medical center. For those children who need lumbar puncture due to their illness, their blood glucose was measured within 5 min before and after lumbar puncture, respectively. The blood glucose level and the ratio of CSF to blood glucose before and after lumbar puncture were compared. Meanwhile, the patients were divided into different groups according to the factors of sex, age and sedation or not for further comparison. All statistical analyses of the data were performed using SPSS version 26.0 for Windows.

Results

In total, 101 children who needed lumbar puncture during hospitalization from January 1, 2021, to October 1, 2021, were recruited with 65 male and 36 female respectively. There was no significant difference on the level of blood glucose, CSF to blood glucose ratio before and after lumbar puncture among the children (p > 0.05). No differences were observed within different groups (sex, age, sedation or not) either.

Conclusion

It is unnecessary to emphasize blood glucose measurement should be carried out before lumbar puncture, especially for pediatric patients. From the perspective of facilitating smoother cerebrospinal fluid puncture in children, blood glucose measurement after lumbar puncture might be a better choice.

High risk and low prevalence diseases: Adult bacterial meningitis

INTRODUCTION

Acute bacterial meningitis in adults is a rare but serious condition that carries a high rate of morbidity.

OBJECTIVE

This review highlights pearls and pitfalls of acute bacterial meningitis in adults, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Meningitis encompasses a broad spectrum of disease involving inflammation of the meninges and subarachnoid space. It classically presents with fever, nuchal rigidity, and altered mental status, but this triad is not present in all cases. Up to 95% of patients will have at least two of the following four cardinal symptoms: fever, nuchal rigidity, altered mental status, and headache. The most common bacterial etiologies are S. pneumoniae and N. meningitidis. Cerebrospinal fluid testing obtained by lumbar puncture remains the gold standard in diagnosis. Head computed tomography prior to lumbar puncture may not be necessary in most patients. Empiric treatment consists of vancomycin, ceftriaxone, and dexamethasone. Elevated intracranial pressure should be managed using established neurocritical care strategies.

CONCLUSION

A better understanding of the pearls and pitfalls of acute bacterial meningitis can assist emergency clinicians in pursuing its timely diagnosis and management.

Cerebrospinal fluid glucose is not altered in patients with dementia

BACKGROUND

Studies have shown that the pathological changes of many dementia disorders begin several years before clinical onset. A connection between some of these pathophysiological changes and brain hypometabolism, seen in dementia disorders, is well established. Glucose is transported from the blood into the interstitial space, and the decreased demand for glucose by the degenerating brain tissue may thereby mirror increased levels of cerebrospinal fluid (CSF) glucose. In this study, the levels of CSF and plasma glucose and the CSF/plasma glucose ratio were investigated in a large cohort from a mixed memory clinic population in order to evaluate its diagnostic potential.

METHOD

CSF and plasma samples were taken from 446 patients (Alzheimer's Disease (AD) (n = 320), vascular dementia (VaD) (n = 64), frontotemporal dementia (FTD) (n = 27) and dementia with Lewy bodies (DLB) (n = 35)), and 130 healthy controls (HC) (healthy subjects (HS) (n = 34), non-demented HS (n = 96)).

RESULTS

No significant differences were found for CSF and plasma glucose or the CSF/plasma glucose ratio between patients with dementia disorders and HC. In addition, no significant differences were observed between the different dementia etiologies.

CONCLUSION

CSF and plasma glucose were not useful to differentiate between HC and patients with various dementia disorders.

Correlation between cerebrospinal fluid abnormalities before ventriculoperitoneal shunt and postoperative intracranial infection in adult patients with hydrocephalus: A clinical study

Objective

To identify the relationship between preoperative cerebrospinal fluid (CSF) leukocyte, chloride, glucose, aspartate aminotransferase, lactate dehydrogenase, adenosine deaminase, lactic acid and protein levels and ventriculoperitoneal shunt infection.

Methods

Records of 671 consecutive adult patients who underwent ventriculoperitoneal shunt surgery for the treatment of hydrocephalus at Zhujiang Hospital affiliated with Southern Medical University from January 2011 to March 2022 were reviewed. The patients were divided into infection and non-infection groups based on the presence of postoperative infection. For all patients, we analyzed age; sex; primary disease; preoperative CSF leukocyte, chloride, glucose, aspartate aminotransferase, lactate dehydrogenase, adenosine deaminase, lactic acid and protein levels; postoperative temperature; and postoperative infection.

Results

A total of 397 patients were included, 28 (7.05%) of whom had an infection within 6 months of the operation and the remaining had no infection. There was no significant difference in age, sex, primary disease, leukocyte, chloride ion, aspartate aminotransferase, lactate dehydrogenase, adenosine deaminase and protein levels in CSF between infection group and non-infection group (p > 0.05). The postoperative infection rate of patients with CSF glucose < 2.8 mmol/L (x ² = 11.650, p = 0.001) and CSF lactic acid >2.8 mmol/L (x ² = 12.455, p < 0.001) was higher than that of patients with CSF glucose level ≥2.8 mmol/L and CSF lactic acid level in the range of (1-2.8) mmol/L, respectively, with statistical difference. Compared with the non-infection group, the level of CSF glucose (t = 4.113, p < 0.001) was significantly lower, and the level of CSF lactic acid (t = 6.651, p < 0.001) was significantly higher in the infection group. Multivariate logistic regression analysis showed that preoperative cerebrospinal fluid glucose < 2.8 mmol/L (OR = 3.911, 95% CI: 1.653~9.253, p = 0.002) and cerebrospinal fluid lactate >2.8 mmol/L (OR = 4.712, 95% CI: 1.892~11.734, p = 0.001) are risk factors for infection after ventriculoperitoneal shunt. ROC analysis revealed that the area under the curve (AUC) for CSF glucose and lactic acid level were 0.602 (95% CI: 0.492-0.713) and 0.818 (95% CI: 0.738-0.898), respectively. The infection group had higher rates of fever and body temperature on postoperative day 3-7 (p < 0.05).

Conclusions

For adult hydrocephalus patients without clinical manifestations of intracranial infection but only with simple abnormality of cerebrospinal fluid, when the content of glucose in cerebrospinal fluid is < 2.8 mmol/L, and the content of lactic acid is >2.8 mmol/L, it is recommended to perform ventriculoperitoneal shunt after further improvement of cerebrospinal fluid indicators, otherwise, hasty operation will increase the postoperative infection rate. The postoperative fever rate of ventriculoperitoneal shunt surgery is high and the body temperature drops rapidly. If there is still fever after day 3 after surgery, whether there is intracranial infection should be considered.

Navigating the ventricles: Novel insights into the pathogenesis of hydrocephalus

Congenital hydrocephalus occurs in one in 500-1000 babies born in the United States and acquired hydrocephalus may occur as the consequence of stroke, intraventricular and subarachnoid hemorrhage, traumatic brain injuries, brain tumors, craniectomy or may be idiopathic, as in the case of normal pressure hydrocephalus. Irrespective of its prevalence and significant impact on quality of life, neurosurgeons still rely on invasive cerebrospinal fluid shunt systems for the treatment of hydrocephalus that are exceptionally prone to failure and/or infection. Further understanding of this process at a molecular level, therefore, may have profound implications for improving treatment and quality of life for millions of individuals worldwide. The purpose of this article is to review the current research landscape on hydrocephalus with a focus on recent advances in our understanding of cerebrospinal fluid pathways from an evolutionary, genetics and molecular perspective.

Infectious Meningitis and Encephalitis

Infectious meningitis and encephalitis are associated with significant morbidity and mortality worldwide. Acute bacterial meningitis is rapidly fatal and early recognition and institution of therapy are imperative. Viral meningitis is typically a benign self-limited illness. Chronic meningitis (defined as presenting with >4 weeks of symptoms) is most often caused by tuberculosis and fungal infection. Because the diagnostic testing for tuberculous meningitis is insensitive and cultures often take weeks to grow, therapy is often initiated empirically when the diagnosis is suspected. Human simplex virus encephalitis is the most common cause of encephalitis and requires prompt treatment with intravenous acyclovir.

Ability of Procalcitonin and C-Reactive Protein for Discriminating between Bacterial and Enteroviral Meningitis in Children Using Decision Tree

Bacterial meningitis (BM) is a public health burden in developing countries, including Central Asia. This disease is characterized by a high mortality rate and serious neurological complications. Delay with the start of adequate therapy is associated with an increase in mortality for patients with acute bacterial meningitis. Cerebrospinal fluid culture, as a gold standard in bacterial meningitis diagnosis, is time-consuming with modest sensitivity, and this is unsuitable for timely decision-making. It has been shown that bacterial meningitis differentiation from viral meningitis could be done through different parameters such as clinical signs and symptoms, laboratory values, such as PCR, including blood and cerebrospinal fluid (CSF) analysis. In this study, we proposed the method for distinguishing the bacterial form of meningitis from enteroviral one. The method is based on the machine learning process deriving making decision rules. The proposed fast-and-frugal trees (FFTree) decision tree approach showed an ability to determine procalcitonin and C-reactive protein (CRP) with cut-off values for distinguishing between bacterial and enteroviral meningitis (EVM) in children. Such a method demonstrated 100% sensitivity, 96% specificity, and 98% accuracy in the differentiation of all cases of bacterial meningitis in this study. These findings and proposed method may be useful for clinicians to facilitate the decision-making process and optimize the diagnostics of meningitis.

Microwave Planar Resonant Solutions for Glucose Concentration Sensing: A Systematic Review

The measurement of glucose concentration finds interesting potential applications in both industry and biomedical contexts. Among the proposed solutions, the use of microwave planar resonant sensors has led to remarkable scientific activity during the last years. These sensors rely on the changes in the dielectric properties of the medium due to variations in the glucose concentration. These devices show electrical responses dependent on the surrounding dielectric properties, and therefore the changes in their response can be related to variations in the glucose content. This work shows an up-to-date review of this sensing approach after more than one decade of research and development. The attempts involved are sorted by the sensing parameter, and the computation of a common relative sensitivity to glucose is proposed as general comparison tool. The manuscript also discusses the key points of each sensor category and the possible future lines and challenges of the sensing approach.

Leukocyte Esterase and Glucose Reagent Test Can Rule in and Rule out Septic Arthritis

BACKGROUND/AIM

Septic arthritis (SA) requires rapid diagnosis and therapy to avoid joint damage. This study evaluated the diagnostic accuracy of leukocyte esterase (LE) and glucose (GLC) strip tests for diagnosing SA.

PATIENTS AND METHODS

Synovial fluids from 455 patients with atraumatic joint effusions were assessed prospectively over a 5-year period with LE and glucose strip tests. Results were compared to modified Newman criteria for diagnosing joint infections. Synovial fluid cultures, crystal, blood and synovial cell analyses were also performed.

RESULTS

Forty-one patients had SA and 252 non-SA. A positive LE reading combined with negative glucose reading could detect SA with 100% specificity, 85% sensitivity, 100% positive predictive value (PPV) and 98% negative predictive value (NPV). Positive synovial LE reading alone detected SA with 82% specificity, 95% sensitivity, 47% PPV, and 99% NPV.

CONCLUSION

Combined LE and glucose strip tests represent a low-cost tool for rapidly diagnosing or ruling out SA.

Host Diagnostic Biomarkers of Infection in the ICU: Where Are We and Where Are We Going?

Purpose of Review

Early identification of infection in the critically ill patient and initiation of appropriate treatment is key to reducing morbidity and mortality. On the other hand, the indiscriminate use of antimicrobials leads to harms, many of which may be exaggerated in the critically ill population. The current method of diagnosing infection in the intensive care unit relies heavily on clinical gestalt; however, this approach is plagued by biases. Therefore, a reliable, independent biomarker holds promise in the accurate determination of infection. We discuss currently used host biomarkers used in the intensive care unit and review new and emerging approaches to biomarker discovery.

Recent Findings

White cell count (including total white cell count, left shift, and the neutrophil-leucocyte ratio), C-reactive protein, and procalcitonin are the most common host diagnostic biomarkers for sepsis used in current clinical practice. However, their utility in the initial diagnosis of infection, and their role in the subsequent decision to commence treatment, remains limited. Novel approaches to biomarker discovery that are currently being investigated include combination biomarkers, host 'sepsis signatures' based on differential gene expression, site-specific biomarkers, biomechanical assays, and incorporation of new and pre-existing host biomarkers into machine learning algorithms.

Summary

To date, no single reliable independent biomarker of infection exists. Whilst new approaches to biomarker discovery hold promise, their clinical utility may be limited if previous mistakes that have afflicted sepsis biomarker research continue to be repeated.

Diagnostic yield of capillary compared to venous glucose in the diagnosis of hypoglycorrhachia in children: A prospective, observational study

INTRODUCTION

The ratio of cerebrospinal fluid (CSF) glucose and blood glucose is of major relevance, conducting to the diagnosis of hypoglycorrhachia, which is a sign of neuroinfection, as well as a number of neurological diseases of genetic or neoplastic etiology. Glucose in capillary sample (glucometry) is a low cost, readily available technique, as compared to venous glucose. This study aims to compare glucometry to venous glucose in the diagnosis of hypoglycorrhachia in pediatric population.

METHODS

Prospective cross-sectional study based on data obtained from lumbar punctures in the period from February 2017 to January 2019 in a specialized pediatric institution in Colombia.

RESULTS

97 patients were analyzed, aged 1 month to 17 years old, mean 7.67 years, 52 (53.61%) were female. 26 (26.8%) were diagnosed with hypoglycorrhachia. Pearson correlation coefficient for absolute venous and capillary glucose was 0.54, and 0.55 for the ratios of CSF glucose/venous glucose and CSF glucose/glucometry, which support a linear correlation between the variables in both, absolute values and ratios. Intraclass correlation coefficient was calculated for both, the venous glucose and glucometry ratios, which was 0.52, revealing a moderate agreement among the tests. Sensitivity and specificity of CSF glucose/glucometry, as compared to gold standard are 73.1% and 60.6% respectively; whereas predictive positive value (PPV) and negative predictive value (NPV), were 40.4% and 86.0%.

CONCLUSION

Glucometry cannot replace the glucose in venous sample in the diagnosis of hypoglycorrhachia in children.

Next generation rapid diagnostic tests for meningitis diagnosis

Rapid diagnostic tests (RDTs) are increasingly recognized as valuable, transformative tools for the diagnosis of infectious diseases. Although there are a variety of meningitis RDTs currently available, certain product features restrict their use to specific levels of care and settings. For this reason, the development of meningitis RDTs for use at all levels of care, including those in low-resource settings, was included in the "Defeating Meningitis by 2030" roadmap. Here we address the limitations of available meningitis RDTs and present test options and specifications to consider when developing the next generation of meningitis RDTs.

A Biomimetic Plasmonic Nanoreactor for Reliable Metabolite Detection

Reliable monitoring of metabolites in biofluids is critical for diagnosis, treatment, and long-term management of various diseases. Although widely used, existing enzymatic metabolite assays face challenges in clinical practice primarily due to the susceptibility of enzyme activity to external conditions and the low sensitivity of sensing strategies. Inspired by the micro/nanoscale confined catalytic environment in living cells, the coencapsulation of oxidoreductase and metal nanoparticles within the nanopores of macroporous silica foams to fabricate all-in-one bio-nanoreactors is reported herein for use in surface-enhanced Raman scattering (SERS)-based metabolic assays. The enhancement of catalytical activity and stability of enzyme against high temperatures, long-time storage or proteolytic agents are demonstrated. The nanoreactors recognize and catalyze oxidation of the metabolite, and provide ratiometric SERS response in the presence of the enzymatic by-product H2O2, enabling sensitive metabolite quantification in a "sample in and answer out" manner. The nanoreactor makes any oxidoreductase-responsible metabolite a candidate for quantitative SERS sensing, as shown for glucose and lactate. Glucose levels of patients with bacterial infection are accurately analyzed with only 20 µL of cerebrospinal fluids, indicating the potential application of the nanoreactor in vitro clinical testing.

Acute Spinal Cord Injury: Monitoring Lumbar Cerebrospinal Fluid Provides Limited Information about the Injury Site

In some centers, monitoring lumbar cerebrospinal fluid (CSF) is used to guide management of patients with acute traumatic spinal cord injuries (TSCI) and draining lumbar CSF to improve spinal cord perfusion. Here, we investigate whether the lumbar CSF provides accurate information about the injury site and the effect of draining lumbar CSF on injury site perfusion. In 13 TSCI patients, we simultaneously monitored lumbar CSF pressure (CSFP) and intraspinal pressure (ISP) from the injury site. Using CSFP or ISP, we computed spinal cord perfusion pressure (SCPP), vascular pressure reactivity index (sPRx) and optimum SCPP (SCPP_opt). We also assessed the effect on ISP of draining 10 mL CSF. Metabolites at the injury site were compared with metabolites in the lumbar CSF. We found that ISP was pulsatile, but CSFP had low pulse pressure and was non-pulsatile 21% of the time. There was weak or no correlation between CSFP versus ISP (R = -0.11), SCPP_(csf) versus SCPP_(ISP) (R = 0.39), and sPRx_(csf) versus sPRx_(ISP) (R = 0.45). CSF drainage caused no significant change in ISP in 7/12 patients and a significant drop of <5 mm Hg in 4/12 patients and of ∼8 mm Hg in 1/12 patients. Metabolite concentrations in the CSF versus the injury site did not correlate for lactate (R = 0.00), pyruvate (R = -0.12) or lactate-to-pyruvate ratio (R = -0.05) with weak correlations noted for glucose (R = 0.31), glutamate (R = 0.61), and glycerol (R = 0.56). We conclude that, after a severe TSCI, monitoring from the lumbar CSF provides only limited information about the injury site and that lumbar CSF drainage does not effectively reduce ISP in most patients.

Epidemiological profile of meningitis in Iran before pentavalent vaccine introduction

BACKGROUND

No reliable and comprehensive study has been published on the incidence and epidemiological profile of meningitis in Iran from 2008 to 2014, before pneumococcal conjugate vaccine (PCV) and pentavalent vaccine (DTPw-Hep B-Hib (PRP-T) vaccine (pentavac) (adsorbed)) introduction. The present study aimed to portray the epidemiological profile of meningitis in Iran from 2008 to 2014.

METHODS

Data on meningitis cases aged from 1 day to 110 years were extracted from national notifiable diseases surveillance system from March 2008 to December 2014 in Iran. A total number of 48,006 cases of suspected meningitis were identified and 1468 cases of which met the criteria for diagnosis-confirmed meningitis. Of 1468 cases, 1352 patients were included in the study.

RESULTS

The great number of cases reported from urban areas. Moreover, males were more predominant than females (58.51% vs. 33.81%) in total. The estimated annual incidence rate of meningitis varied from 0.28/100000 in 2008 to 0.09/100000 in 2014. Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis were the most leading pathogens causing bacterial meningitis, accounted for 266(23.44%), 145(12.78%), 95(8.37%) of cases, respectively. Each of the three bacterial species showed a descending trend. The majority of infected subjects are children under five years.

CONCLUSIONS

Unlike the decreasing trend of meningitis and high percentage of cultures with negative results, according to World Health Organization recommendation PCV introduction into routine immunization is evident. Implementing an enhanced surveillance system to provide high quality data on epidemiological profile of meningitis in Iran is necessary.

Inflammatory Markers in Serum and Cerebrospinal Fluid for Early Detection of External Ventricular Drain-associated Ventriculitis in Patients With Subarachnoid Hemorrhage

BACKGROUND

External ventricular drain (EVD)-associated ventriculitis is a serious complication. Early diagnosis can be difficult particularly in critically ill patients with aneurysmal subarachnoid hemorrhage (aSAH). We examined the diagnostic potential of standard serum and cerebrospinal fluid (CSF) biomarkers to differentiate between EVD-associated infections and aseptic courses in patients with aSAH.

MATERIALS AND METHODS

We retrospectively evaluated the levels of inflammatory markers in serum (white blood cell count, percentage of neutrophils [sN%], and procalcitonin) and CSF (total leukocyte count [CSFTLC], CSFglucose, CSF/serumglucose ratio, CSF total protein [CSFTP]) of 63 consecutive patients with aSAH. Receiver operating characteristic curves and the area-under-the-curve (AUC) were calculated to detect the diagnostic potential, optimized threshold, sensitivity (SE), specificity (SP), + likelihood ratio (LR), and -LR of each biomarker.

RESULTS

Of all patients, 17 (27%) developed an EVD-associated ventriculitis within a mean of 7.8±2.3 days after implantation. sN% had a very good diagnostic potential (AUC=0.900, SE=70.0%, SP=100%), followed by the CSFTLC with good diagnostic potential (AUC=0.841, SE=75.0%, SP=88.5%), and the CSFTP with moderate diagnostic potential (AUC=0.772, SE=73.3%, SP=76.0%). sN% higher than 70% and a CSFTLC higher than 635/µL were highly associated with the diagnosis of ventriculitis (+LR=∞ and 6.5), sN%<70% or a CSFTLC<635 made a diagnosis of ventriculitis unlikely (-LR=0.3 and 0.28).

CONCLUSIONS

Routine determination of N% and CSFTLC are useful to distinguish ventriculitis from aseptic courses in the acute phase after aSAH and regardless of the bacteriological test result.

Competition for nutrients and its role in controlling immune responses

Changes in cellular metabolism are associated with the activation of diverse immune subsets. These changes are fuelled by nutrients including glucose, amino acids and fatty acids, and are closely linked to immune cell fate and function. An emerging concept is that nutrients are not equally available to all immune cells, suggesting that the regulation of nutrient utility through competitive uptake and use is important for controlling immune responses. This review considers immune microenvironments where nutrients become limiting, the signalling alterations caused by insufficient nutrients, and the importance of nutrient availability in the regulation of immune responses.

Immune cells adapt distinct metabolic strategies to accommodate specific functions associated with cell types or differentiation stages. Here in this review the authors discuss the nutrients, sensors, and mediators of such a metabolic adaption in nutrient-limiting immune microenvironments such as tumors or infections.

Meningitis in adults: diagnosis and management

Bacterial meningitis is a medical emergency. All clinicians who provide acute medical care require a sound understanding of the priorities of managing a patient with suspected meningitis during the first hour. These include obtaining blood cultures, performing lumbar puncture and initiating appropriate therapy, while avoiding harmful delays such as those that result from not administering treatment until neuroimaging has been performed. Despite the increasing availability of newer diagnostic techniques, the interpretation of cerebrospinal fluid parameters remains a vital skill for clinicians. International and local guidelines differ with regard to initial empirical therapy of bacterial meningitis in adults; the North American guideline recommends ceftriaxone and vancomycin for all patients, while the Australian, UK and European guidelines recommend that vancomycin only be added for patients who are more likely to have pneumococcal meningitis or who have a higher likelihood of being infected with a strain of Streptococcus pneumoniae with reduced susceptibility to ceftriaxone. Patients with risk factors for Listeria meningitis also require an anti-Listeria agent, such as benzylpenicillin, to be added to this treatment regimen. Dexamethasone should be a routine component of empirical therapy due to its proven role in reducing morbidity and mortality from pneumococcal meningitis.

Rapid detection of bacterial meningitis using a point-of-care glucometer

BACKGROUND

In case of acute bacterial meningitis, a decision on the need for intensive care admission should be made within the first hour. The aim of this study was to assess the ability of a point-of-care glucometer to determine abnormal cerebrospinal fluid (CSF) glucose concentration at the bedside that contributes toward bacterial meningitis diagnosis.

METHODS

We carried out a prospective study and simultaneously measured the glucose concentrations in CSF and blood using a central laboratory and a point-of-care glucometer. We compared CSF/blood glucose ratios obtained at the bedside with a glucometer versus those obtained by the central laboratory. We determined the performance characteristics of the CSF/blood glucose ratio provided by a glucometer to detect bacterial infection in the CSF immediately after CSF sampling.

RESULTS

We screened 201 CSF collection procedures during the study period and included 172 samples for analysis. Acute bacterial meningitis was diagnosed in 17/172 (9.9%) of CSF samples. The median turnaround time for a point-of-care glucometer analysis was 5 (interquartile range 2-10) min versus 112 (interquartile range 86-154) min for the central laboratory (P<0.0001). The optimal cut-off of the CSF/blood glucose ratio calculated from a bedside glucometer was 0.46, with a sensitivity of 94.1% (95% confidence interval: 71.3-99.9%), a specificity of 91% (95% confidence interval: 85.3-95%), and a positive likelihood ratio of 10.

CONCLUSION

A glucometer accurately detects an abnormal CSF/blood glucose ratio immediately after the lumbar puncture. This cheap point-of-care method has the potential to speed up the diagnostic process of patients with bacterial meningitis.

Cerebrospinal fluid pharmacokinetics of ceftaroline in neurosurgical patients with an external ventricular drain

BACKGROUND

Owing to its antibacterial properties, ceftaroline could be attractive for prevention or treatment of bacterial post-neurosurgical meningitis/ventriculitis. However, few data are available concerning its meningeal concentrations.

OBJECTIVES

To investigate ceftaroline CSF pharmacokinetics in ICU patients with an external ventricular drain (EVD).

METHODS

Patients received a single 600 mg dose of ceftaroline as a 1 h intravenous infusion. Blood and CSF samples were collected before and 0.5, 1, 3, 6, 12 and 24 h after the end of the infusion. Concentrations were assayed in plasma and CSF by LC-MS/MS. A two-step compartmental pharmacokinetic analysis was conducted. Ceftaroline plasma data were first analysed, and thereafter plasma parameters estimated and corrected for protein binding of 20% were fixed to fit unbound CSF concentrations. In the final model, parameters for both plasma and CSF data were simultaneously estimated.

RESULTS

Nine patients with an EVD were included. The Cmax was 18.29 ± 3.33 mg/L in plasma (total concentrations) and at 0.22 ± 0.17 mg/L in CSF (unbound concentration). The model-estimated CSF input/CSF output clearance ratio was 9.4%, attesting to extensive efflux transport at the blood-CSF barrier.

CONCLUSIONS

Ceftaroline CSF concentrations are too low to ensure prophylactic protection against most pathogens with MICs between 1 and 2 mg/L, owing to its limited central distribution.

Cerebrospinal Fluid Lactate as an Indicator for Post-neurosurgical Bacterial Meningitis

Objective

To evaluate the interest of cerebrospinal fluid (CSF) lactate assay for the diagnosis of post-neurosurgical bacterial meningitis (PBM).

Methods

We conducted at our neurosurgical resuscitation unit a prospective study of patients who underwent elective or emergency craniotomy. Lumbar puncture was performed in all patients who had clinical suspicion of PBM for CSF culture and cytological and chemical analysis (glucose, protein, lactate). The diagnosis of PBM is made according to the criteria proposed by the Center for Disease Control and Prevention (CDC). Receiver Operating Characteristic (ROC) was used to determine the diagnostic accuracy of CSF lactate.

Results

72 patients were studied and only 32 of them had the clinical and biological criteria of the diagnosis of PBM. Median CSF lactate was 6.18 mmol/L for PBM vs 2.63 mmol/L for no PBM (p < 0.001). CSF lactate may predict the presence PBM, with a AUC of 0.98 and NPV of 99.1. The analysis of Youden's index also confirms the good diagnostic power of CSF lactate with a value of 83 at a cut-off value of 4 mmol/L and a sensitivity of 92.3% and specificity of 91.6%.

Conclusion

Our study shows that the CSF lactate as an indicator for PBM. It is a fast and simple test that can help the clinician to optimize the management of PBM and decrease premature cessation of antibiotics.

How to cite this article

Lotfi R, Ines B, et al. Cerebrospinal Fluid Lactate as an Indicator for Post-neurosurgical Bacterial Meningitis. Indian J Crit Care Med 2019;23(3):127-130.

Cytokine profiles in cerebrospinal fluid of patients with meningitis at a tertiary general hospital in China

BACKGROUND

There has been a great deal of evidence indicating that cytokines participate in meningeal inflammation. Different cytokine profiles may be presented in central nervous system (CNS) infection due to different pathogens. We have attempted to investigate cytokine profiles in cerebrospinal fluid (CSF) of patients with CNS infection.

METHODS

Forty-three patients with CNS infection including tuberculous meningitis, purulent meningitis and cryptococcal meningitis were enrolled and 11 patients with normal CSF were enrolled as control group. The concentrations of Th1-, Th2- and Th17-type cytokines in CSF were detected using multiplex cytokine assay. Furthermore, the correlation between CSF cytokines and CSF parameters in CNS infection was analyzed.

RESULTS

The CSF levels of IL-1β, IL-4, IL-6, IL-10, IL-17, IL-23, IL-33, IFN-γ, TNF-α and sCD40L among the patients with CNS infection were all higher than control group (all P < 0.05). A remarkable elevation of CSF IL-6 in the patients with CNS infection was observed with the least overlap of the CSF concentrations compared to controls. Moreover, CSF IL-6 levels were strongly negatively correlated with CSF glucose and the CSF/blood glucose ratio (r = -0.4375, P = 0.0042; r = -0.4991, P = 0.0009).

CONCLUSIONS

The excessive activation of immune response characterized by elevated levels of CSF Th1-, Th2- and Th17-type cytokines has been observed during CNS infection. Furthermore, we observed negative correlations between CSF IL-6 levels and CSF glucose and CSF/blood glucose ratio in CNS infection. And we suggested that combined CSF IL-6 levels with CSF glucose may serve as a novel biomarker pool for the differential of CNS infection.

Assessment of acute headache in adults - what the general physician needs to know

Headache is common. Up to 5% of attendances to emergency departments and acute medical units are due to headache. Headache is classified as either primary (eg migraine, cluster headache) or secondary to another cause (eg meningitis, subarachnoid haemorrhage). Even in the acute setting the majority of cases are due to primary causes. The role of the attending physician is to take a comprehensive history to diagnose and treat benign headache syndromes while ruling out sinister aetiologies. This brief article summarises the approach to assessment of headache presenting in acute and emergency care.

Does This Adult Patient With Jolt Accentuation of Headache Have Acute Meningitis?

OBJECTIVE

In order to identify appropriate candidates with suspected meningitis for lumbar puncture (LP), study designs and diagnostic values of jolt accentuation of headache (JA) were reviewed.

BACKGROUND

Acute meningitis is a life-threatening disease that requires LP for accurate diagnosis. JA was reported the most sensitive indicator of cerebrospinal fluid pleocytosis; however, subsequent studies have failed to confirm this claim.

METHODS

We reviewed articles concerning JA, published prior to December 2017, using MEDLINE and Japanese medical databases. Seven original articles based on independent cohorts were eligible for inclusion and articles citing these 7 were thoroughly searched (11 in total). Additionally, all medical records of our previously reported cohort were reviewed again to explore how the patients' background influenced diagnostic values of JA.

RESULTS

We hypothesized that an oversimplified dichotomy of JA findings, pleocytosis, and meningitis created a misconception that JA is a universal indicator of meningitis. We clarify the difference between them and present altered mental status (AMS) as a key to decrease the sensitivity of JA. Notably, the sensitivity and specificity of JA were relatively low in unselected groups, while they tended to be high in the selected sub-groups with acute onset of headache and fever, without AMS or neurological deficits. Unselected populations included etiologies of pleocytosis other than acute meningitis, which might weaken the association between JA and pleocytosis.

CONCLUSION

JA is not a universal, stand-alone, indicator of meningitis in febrile patients with headache. Therefore, we propose a stepwise approach for patients with suspected acute meningitis. AMS or neurological deficits suggest an intracranial pathology, which may necessitate a lumbar puncture. JA seems a useful tool for distinguishing acute aseptic meningitis from upper respiratory infection when used in the selected cohort of febrile patients (≥37°C) with recent-onset headache (within 2 weeks before presentation) and normal mental status. This approach and diagnostic values of JA should be further investigated by prospective studies using operationally sorted candidates.

The combination of cerebrospinal fluid procalcitonin, lactate, interleukin-8 and interleukin-10 concentrations for the diagnosis of postneurosurgical bacterial meningitis: A prospective study

Background

The differential diagnosis between postneurosurgical bacterial meningitis and aseptic meningitis remains challenging both for the clinician and the laboratory. Combinations of markers, as opposed to single ones, may improve diagnosis and thereby survival.

Methods

This prospective cohort study included patients with suspected bacterial meningitis after neurosurgery. The patients were divided into two groups according to the diagnostic criteria of meningitis involving a postneurosurgical bacterial meningitis group and a postneurosurgical aseptic meningitis group. Four biomarkers, including cerebrospinal fluid procalcitonin, lactate, interleukin-8 and interleukin-10 were assayed separately, and three algorithms were constructed using a linear combination. The area under the receiver operating characteristic curve was used to compare their performances.

Results

A cohort of 112 patients was enrolled in our study. Forty-three patients were diagnosed with postneurosurgical bacterial meningitis, and the cerebrospinal fluid values of their biomarkers were higher in patients with postneurosurgical bacterial meningitis than with postneurosurgical aseptic meningitis. The area under the receiver operating characteristic curves for the detection of postneurosurgical bacterial meningitis were 0.803 (95% confidence interval [CI], 0.724–0.883) for procalcitonin; 0.936 (95% CI, 0.895–0.977) for lactate; 0.771 (95% CI, 0.683–0.860) for interleukin-8; 0.860 (95% CI, 0.797–0.929) for interleukin-10; 0.937 (95% CI, 0.897–0.977) for the composite two-marker test; 0.945 (95% CI, 0.908–0.982) for the composite three-marker test and 0.954 (95% CI, 0.922–0.989) for the composite of all tests. The area under the receiver operating characteristic curves of the combination tests were greater than those of the single markers.

Conclusions

Combining information from several markers improved the diagnostic accuracy in detecting postneurosurgical bacterial meningitis.

Dissemination of the ST-103 clonal complex serogroup C meningococci in Salvador, Brazil

Invasive meningococcal disease (IMD) is a major public health problem worldwide. An epidemic of serogroup C (NmC) IMD occurred in 2010 in the city of Salvador. In this study, we describe the antigenic and genetic characterization of meningococcal isolates collected from meningitis cases in Salvador from 2001 to 2012. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed for the analysis of IMD isolates. A total of 733 cases were identified, and the serogroup was determined for 391 (53.0%) of these. Most cases were caused by NmC (53%) or B (47%). The most prevalent strains were B:4,7:P1.19,15 (32.9%; 129/391) and C:23:P1.14-6 (28.6%; 112/391). Based on PFGE/MLST analysis, 71.3% (77/108 PFGE-tested isolates) clustered as two clones of sequence type ST-3779 and ST-3780, both belonging to the ST-103 clonal complex. ST-3779 has been detected in Salvador since 1996 and together with ST-3780 became predominant after 2005. There was a predominance of C:23:P1.14-6, ST-3779/3780 in Salvador during the period of 2007-2012, establishing a major clonal lineage, which remained in the community for a long time; this has serious implications for public health, particularly in terms of prevention and control strategies of IMD.

Comparative Diagnostic Utility of IS6110 PCR Assay in CSF and Peripheral Blood Samples of Tuberculous Meningitis Patients: A Pilot Study from Central India

INTRODUCTION

Tuberculous Meningitis (TBM) is the most severe form of Central Nervous System Tuberculosis (CNS-TB) and constitutes about 6% of all Extrapulmonary TB (EPTB) cases. Most guidelines for the diagnosis and management of TBM agree on the use of simple Cerebrospinal Fluid (CSF) analysis using molecular tools like Polymerase Chain Reaction (PCR). However, the sensitivity of PCR varies while using a CSF sample. In the present study, we have compared the diagnostic utility of PCR assay in both peripheral blood and CSF sample collected from TBM cases.

AIM

To evaluate the application of the peripheral blood PCR assay as an alternate tool for TBM diagnosis compared to conventional CSF-PCR based system.

MATERIALS AND METHODS

A total of 50 TBM patients were prospectively recruited from in patient department wards of Central India Institute of Medical Sciences (CIIMS) between January 2014 - Feburary 2015. Mycobacterium tuberculosis (MTB) specific IS6110 PCR and BactT liquid culture were performed in 20 of recruited cases classified as Stage 1, 2 and 3 based on British Medical Research Council (BMRC) contemporary clinical criteria for the severity of TBM. Clinical characteristics were summarised in terms of percentages for categorical variables, i.e., age groups, gender, signs and symptoms. All statistical analysis was carried out using MedCalc software version 11.6.

RESULTS

Overall IS6110 PCR positivity in CSF was around 80% (16/20), which was higher than culture (29.3%) and peripheral blood (39%). Out of 8 positive cases, stage wise positivity of peripheral blood PCR assay in three TBM stages was 0% (stage1) 50% (stage 2) and 67% (Stage 3) respectively. Positivity of peripheral blood PCR was significantly more (86%) in patients with CSF culture/ IS6110 PCR positive for MTB infection with sensitivity and specificity of 50 and 100% respectively. Increased positivity rates of peripheral blood PCR was observed with decreased CSF/Blood sugar ratio in stage 3 cases, suggesting enhanced probability of mycobacterial blood dissemination in cases of TBM severity.

CONCLUSION

Our results suggest that although the molecular diagnosis of TBM infection in CSF remains the method of choice, peripheral blood based PCR can be used as a good alternative to CSF in case of TBM severity where the repeated CSF collection may be needed. However, study demands further validation in large cohorts to justify the present hypothesis.

Host Biomarkers for Distinguishing Bacterial from Non-Bacterial Causes of Acute Febrile Illness: A Comprehensive Review

Background

In resource limited settings acute febrile illnesses are often treated empirically due to a lack of reliable, rapid point-of-care diagnostics. This contributes to the indiscriminate use of antimicrobial drugs and poor treatment outcomes. The aim of this comprehensive review was to summarize the diagnostic performance of host biomarkers capable of differentiating bacterial from non-bacterial infections to guide the use of antibiotics.

Methods

Online databases of published literature were searched from January 2010 through April 2015. English language studies that evaluated the performance of one or more host biomarker in differentiating bacterial from non-bacterial infection in patients were included. Key information extracted included author information, study methods, population, pathogens, clinical information, and biomarker performance data. Study quality was assessed using a combination of validated criteria from the QUADAS and Lijmer checklists. Biomarkers were categorized as hematologic factors, inflammatory molecules, cytokines, cell surface or metabolic markers, other host biomarkers, host transcripts, clinical biometrics, and combinations of markers.

Findings

Of the 193 citations identified, 59 studies that evaluated over 112 host biomarkers were selected. Most studies involved patient populations from high-income countries, while 19% involved populations from low- and middle-income countries. The most frequently evaluated host biomarkers were C-reactive protein (61%), white blood cell count (44%) and procalcitonin (34%). Study quality scores ranged from 23.1% to 92.3%. There were 9 high performance host biomarkers or combinations, with sensitivity and specificity of ≥85% or either sensitivity or specificity was reported to be 100%. Five host biomarkers were considered weak markers as they lacked statistically significant performance in discriminating between bacterial and non-bacterial infections.

Discussion

This manuscript provides a summary of host biomarkers to differentiate bacterial from non-bacterial infections in patients with acute febrile illness. Findings provide a basis for prioritizing efforts for further research, assay development and eventual commercialization of rapid point-of-care tests to guide use of antimicrobials. This review also highlights gaps in current knowledge that should be addressed to further improve management of febrile patients.

Laboratory-based clinical audit as a tool for continual improvement: an example from CSF chemistry turnaround time audit in a South-African teaching hospital

INTRODUCTION

Timeliness of laboratory results is crucial to patient care and outcome. Monitoring turnaround times (TAT), especially for emergency tests, is important to measure the effectiveness and efficiency of laboratory services. Laboratory-based clinical audits reveal opportunities for improving quality. Our aim was to identify the most critical steps causing a high TAT for cerebrospinal fluid (CSF) chemistry analysis in our laboratory.

MATERIALS AND METHODS

A 6-month retrospective audit was performed. The duration of each operational phase across the laboratory work flow was examined. A process-mapping audit trail of 60 randomly selected requests with a high TAT was conducted and reasons for high TAT were tested for significance.

RESULTS

A total of 1505 CSF chemistry requests were analysed. Transport of samples to the laboratory was primarily responsible for the high average TAT (median TAT = 170 minutes). Labelling accounted for most delays within the laboratory (median TAT = 71 minutes) with most delays occurring after regular work hours (P < 0.05). CSF chemistry requests without the appropriate number of CSF sample tubes were significantly associated with delays in movement of samples from the labelling area to the technologist's work station (caused by a preference for microbiological testing prior to CSF chemistry).

CONCLUSION

A laboratory-based clinical audit identified sample transportation, work shift periods and use of inappropriate CSF sample tubes as drivers of high TAT for CSF chemistry in our laboratory. The results of this audit will be used to change pre-analytical practices in our laboratory with the aim of improving TAT and customer satisfaction.

Usefulness of blood and cerebrospinal fluid laboratory testing to predict bacterial meningitis in the emergency department

INTRODUCTION

The classic clinical presentation of bacterial meningitis (BM) is observed in less than half of the cases in adults, and symptoms are less specific in children, the elderly or immunocompromised, and other chronic patients. The usual signs and symptoms do not provide optimal sensitivity and specificity for distinguishing possible BM from viral meningitis (VM), which may lead to a delay in the appropriate antimicrobial therapy. Society therefore stands to benefit from the development of effective, objective, and rapid tools able to predict and identify patients with BM. These tools include laboratory tests for blood and cerebrospinal fluid (CSF). The aim of this review is to summarise recently published scientific evidence in order to clarify existing controversies and compare the usefulness and diagnostic ability of the different parameters used to predict BM.

DEVELOPMENT

Systematic search of the main bibliographic databases and platforms to identify articles published between January 2000 and January 2016. We selected 59 articles that meet the objectives of this review.

CONCLUSIONS

CSF lactate, proportion of polymorphonuclear leukocytes, and CSF glucose, as well as serum procalcitonin (PCT), are the independent factors most predictive of bacterial aetiology. The model that combines serum PCT and CSF lactate achieves the highest predictive power for BM, with a sensitivity and specificity exceeding 99%. We should consider BM when CSF lactate >33 md/dL and/or PCT>0.25ng/mL.

Escherichia coli K1 Modulates Peroxisome Proliferator-Activated Receptor γ and Glucose Transporter 1 at the Blood-Brain Barrier in Neonatal Meningitis

Escherichia coli K1 meningitis continues to be a major threat to neonatal health. Previous studies demonstrated that outer membrane protein A (OmpA) of E. coli K1 interacts with endothelial cell glycoprotein 96 (Ecgp96) in the blood-brain barrier to enter the central nervous system. Here we show that the interaction between OmpA and Ecgp96 downregulates peroxisome proliferator-activated receptor γ (PPAR-γ) and glucose transporter 1 (GLUT-1) levels in human brain microvascular endothelial cells, causing disruption of barrier integrity and inhibition of glucose uptake. The suppression of PPAR-γ and GLUT-1 by the bacteria in the brain microvessels of newborn mice causes extensive pathophysiology owing to interleukin 6 production. Pretreatment with partial or selective PPAR-γ agonists ameliorate the pathological outcomes of infection by suppressing interleukin 6 production in the brain. Thus, inhibition of PPAR-γ and GLUT-1 by E. coli K1 is a novel pathogenic mechanism in meningitis, and pharmacological upregulation of PPAR-γ and GLUT-1 levels may provide novel therapeutic avenues.

Metabolic regulation of immune responses: therapeutic opportunities

Immune cell metabolism is dynamically regulated in parallel with the substantial changes in cellular function that accompany immune cell activation. While these changes in metabolism are important for facilitating the increased energetic and biosynthetic demands of activated cells, immune cell metabolism also has direct roles in controlling the functions of immune cells and shaping the immune response. A theme is emerging wherein nutrients, metabolic enzymes, and metabolites can act as an extension of the established immune signal transduction pathways, thereby adding an extra layer of complexity to the regulation of immunity. This Review will outline the metabolic configurations adopted by different immune cell subsets, describe the emerging roles for metabolic enzymes and metabolites in the control of immune cell function, and discuss the therapeutic implications of this emerging immune regulatory axis.

Clinical decision rules for acute bacterial meningitis: current insights

Acute community-acquired bacterial meningitis (BM) requires rapid diagnosis so that suitable treatment can be instituted within 60 minutes of admitting the patient. The cornerstone of diagnostic examination is lumbar puncture, which enables microbiological analysis and determination of the cerebrospinal fluid (CSF) cytochemical characteristics. However, microbiological testing is not sufficiently sensitive to rule out this diagnosis. With regard to the analysis of standard CSF cytochemical characteristics (polymorphonuclear count, CSF glucose and protein concentration, and CSF:serum glucose), this is often misleading. Indeed, the relatively imprecise nature of the cutoff values for these BM diagnosis markers can make their interpretation difficult. However, there are two markers that appear to be more efficient than the standard ones: CSF lactate and serum procalcitonin levels. Scores and predictive models are also available; however, they only define a clinical probability, and in addition, their use calls for prior validation on the population in which they are used. In this article, we review current methods of BM diagnosis.

Rapid exclusion of bacterial arthritis using a glucometer

Bacterial arthritis is a medical emergency. However, prompt diagnosis and differentiation from non-infectious diseases are challenging. As bacterial metabolism leads to glucose reduction, measurement of synovial fluid glucose seems to be a promising diagnostic approach. The purpose of this study was to determine whether synovial fluid glucose levels could be accurately measured by using a glucometer and to evaluate its diagnostic accuracy in diagnosing bacterial arthritis compared to currently available markers. In a prospective diagnostic study, 102 consecutive patients with atraumatic joint effusion were included. Synovial fluid glucose concentrations were determined using both glucometer and automated analyzer respectively. Synovial fluid culture, crystal analysis, and synovial cell analysis were performed. Blood samples were taken for blood cultures, analyses of serum infection markers, and serum glucose. There was a high correlation between synovial fluid glucose measured by the glucometer and the automated analyzer (r ² = 0.92). According to the receiver operating characteristic curve, a threshold of 1.4 mmol/l had a sensitivity of 100 % (95 % CI 78.2-100 %), a specificity of 92.0 % (95 % CI 84.1-96.7 %), a positive predictive value of 68.2 % (95 % CI 45.1-86.1 %), and a negative predictive value of 100 % (95 % CI 95.5-100 %). These results suggest that synovial fluid glucose concentrations could be reliably measured using a glucometer. Due to its simplicity, this test has the potential to be an adjunct in the diagnostic cascade of bacterial arthritis.

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.