Cerebrospinal fluid procalcitonin as a biomarker of bacterial meningitis in neonates

Granulocytes in cerebrospinal fluid of adults suspected of a central nervous system infection: a prospective study of diagnostic accuracy

PURPOSE

Cerebrospinal fluid (CSF) granulocytes are associated with bacterial meningitis, but information on its diagnostic value is limited and primarily based on retrospective studies. Therefore, we assessed the diagnostic accuracy of CSF granulocytes.

METHODS

We analyzed CSF granulocytes (index test) from all consecutive patients in two prospective cohort studies in the Netherlands. Both studies included patients ≥ 16 years, suspected of a central nervous system (CNS) infection, who underwent a diagnostic lumbar puncture. All episodes with elevated CSF leukocytes (≥ 5 cells per mm3) were selected and categorized by clinical diagnosis (reference standard).

RESULTS

Of 1261 episodes, 625 (50%) had elevated CSF leukocytes and 541 (87%) were included. 117 of 541 (22%) were diagnosed with bacterial meningitis, 144 (27%) with viral meningoencephalitis, 49 (9%) with other CNS infections, 76 (14%) with CNS autoimmune disorders, 93 (17%) with other neurological diseases and 62 (11%) with systemic diseases. The area under the curve to discriminate bacterial meningitis from other diagnoses was 0.97 (95% confidence interval [CI] 0.95-0.98) for CSF granulocyte count and 0.93 (95% CI 0.91-0.96) for CSF granulocyte percentage. CSF granulocyte predominance occurred in all diagnostic categories. A cutoff at 50% CSF granulocytes gave a sensitivity of 94% (95% CI 90-98), specificity of 80% (95% CI 76-84), negative predictive value of 98% (95% CI 97-99) and positive predictive value of 57% (95% CI 52-62).

CONCLUSION

CSF granulocytes have a high diagnostic accuracy for bacterial meningitis in patients suspected of a CNS infection. CSF granulocyte predominance occurred in all diagnostic categories, limiting its value in clinical practice.

Distinguishing community-acquired bacterial and viral meningitis: Microbes and biomarkers

Diagnostic tools to differentiate between community-acquired bacterial and viral meningitis are essential to target the potentially lifesaving antibiotic treatment to those at greatest risk and concurrently spare patients with viral meningitis from the disadvantages of antibiotics. In addition, excluding bacterial meningitis and thus decreasing antibiotic consumption would be important to help reduce antimicrobial resistance and healthcare expenses. The available diagnostic laboratory tests for differentiating bacterial and viral meningitis can be divided microbiological pathogen-focussed methods and biomarkers of the host response. Bacterial culture-independent microbiological methods, such as highly multiplexed nucleic acid amplification tests, are rapidly making their way into the clinical practice. At the same time, more conventional host protein biomarkers, such as procalcitonin and C-reactive protein, are supplemented by newer proteomic and transcriptomic signatures. This review aims to summarise the current state and the recent advances in diagnostic methods to differentiate bacterial from viral meningitis.

Diagnostic Accuracy of Procalcitonin in Bacterial Infections of the CNS: An Updated Systematic Review, Meta-Analysis, and Meta-Regression

OBJECTIVES

To evaluate diagnostic accuracy of serum and cerebrospinal fluid (CSF) procalcitonin for diagnosing CNS bacterial infections.

DATA SOURCES

We searched MEDLINE, Cochrane Central Register of Controlled Trials, and International Web of Science databases from January 1, 2016, to September 30, 2022.

STUDY SELECTION

Randomized controlled trials and observational studies, either prospective or retrospective, focusing on procalcitonin as a biomarker for CNS infections.

DATA EXTRACTION

We screened and extracted studies independently and in duplicate. We assessed risk of bias using the revised Quality Assessment for Studies of Diagnostic Accuracy tool. Data for diagnostic sensitivity and specificity were pooled using the bivariate or hierarchical model, as appropriate.

DATA SYNTHESIS

Of 5,347 citations identified, 23 studies were included. Overall, CSF procalcitonin showed slightly higher pooled sensitivity, specificity, and positive likelihood ratio compared with serum procalcitonin. In adults, pooled sensitivity of CSF procalcitonin was 0.89 (95% CI, 0.71-0.96), specificity 0.81 (95% CI, 0.66-0.91); pooled sensitivity of serum procalcitonin was 0.82 (95% CI, 0.58-0.94), specificity 0.77 (95% CI, 0.60-0.89). In children, pooled sensitivity of CSF procalcitonin was 0.96 (95% CI, 0.88-0.99), specificity 0.91 (95% CI, 0.72-0.97); pooled sensitivity of serum procalcitonin was 0.90 (95% CI, 0.75-0.97), specificity 0.83 (95% CI, 0.67-0.92). In post-neurosurgical patients, pooled sensitivity of CSF procalcitonin was 0.82 (95% CI, 0.53-0.95), specificity 0.81 (95% CI, 0.63-0.91); pooled sensitivity of serum procalcitonin was 0.65 (95% CI, 0.33-0.88), specificity 0.61 (95% CI, 0.41-0.78). Logistic regression revealed between-study heterogeneity higher for serum than CSF procalcitonin. For the latter, threshold variability was found as source of heterogeneity.

CONCLUSIONS

In children and critical post-neurosurgical patients, CSF procalcitonin gains superior sensitivity and specificity compared with serum procalcitonin. Overall, CSF procalcitonin appears to have a higher pooled positive likelihood ratio compared with serum procalcitonin.

High-throughput sequencing unravels the cell heterogeneity of cerebrospinal fluid in the bacterial meningitis of children

Bacterial meningitis (BM) is a common life-threatening infection in children that occurs in the central nervous system (CNS). The cytologic examination of cerebrospinal fluid (CSF) is a key parameter in the diagnosis of BM, but the heterogeneity of cells in the CSF has not been elucidated, which limits the current understanding of BM neuroinflammation. In this study, CSF samples were collected from a number of BM patients who were in different stages of disease progression. Single-cell RNA-sequencing (scRNA-seq), with additional bulk transcriptome sequencing, was conducted to decipher the characteristics of CSF cells in BM progression. A total of 18 immune cell clusters in CSF were identified, including two neutrophils, two monocytes, one macrophage, four myeloid dendritic cells, five T cells, one natural killer cell, one B cell, one plasmacytoid dendritic cell, and one plasma cell subtype. Their population profiles and dynamics in the initial onset, remission, and recovery stages during BM progression were also characterized, which showed decreased proportions of myeloid cells and increased proportions of lymphoid cells with disease progression. One novel neutrophil subtype, FFAR2+TNFAIP6+ neutrophils, and one novel monocyte subtype, THBS1+IL1B+ monocytes, were discovered, and their quantity changes positively correlated with the intensity of the inflammatory response in the CSF during BM. In addition, the CSF of BM patients with unsatisfactory therapeutic responses presented with different cell heterogeneity compared to the CSF of BM patients with satisfactory therapeutic responses, and their CSF featured altered intercellular communications and increased proportions of type II myeloid dendritic cells and plasmacytoid dendritic cells. Moreover, the bulk transcriptome profiles of autologous CSF cells and peripheral blood leukocytes of BM patients showed that the immune cells in these two physiological compartments exhibited distinct immune responses under different onset conditions. In particular, the CSF cells showed a high expression of macrophage characteristic genes and a low expression of platelet characteristic genes compared with peripheral blood leukocytes. Our study conducted an in-depth exploration of the characteristics of CSF cells in BM progression, which provided novel insights into immune cell engagement in acute CNS infection.

Cerebrospinal fluid and plasma procalcitonin for the diagnosis of neonatal bacterial meningitis

AIM

There is a paucity of data on cerebrospinal fluid (CSF) procalcitonin (PCT) to diagnose neonatal meningitis. We evaluated CSF PCT to diagnose bacterial meningitis among neonates with suspected sepsis.

METHODS

Neonates undergoing lumbar puncture (LP) as part of sepsis workup were included.

INDEX TESTS

CSF PCT, plasma PCT, CSF:plasma PCT ratio and CSF cytochemistry. Reference Standards: 'Definite meningitis' defined by positive CSF culture and/or gram stain and/or broad-based primer 16S rDNA polymerase chain reaction. 'Definite or probable' meningitis is defined as definite meningitis or abnormal cytochemistry.

RESULTS

Of 216 eligible neonates, 18 had 'definite meningitis' and 37 'definite or probable meningitis'. Median (Q₁ , Q₃ ) CSF PCT level was significantly higher in 'definite meningitis' compared to 'no definite meningitis' (0.429 (0.123, 1.300) vs. 0.181 (0.119, 0.286) ng/mL respectively, P = 0.028). Likewise, it was significantly higher in 'definite or probable meningitis' compared to no meningitis (0.245 (0.136, 0.675) vs. 0.170 (0.116, 0.28), P = 0.01). The area under the receiver operator characteristics curve of CSF PCT level for definite meningitis was 0.656 and for 'definite or probable meningitis' 0.635. Paired comparisons of area under the receiver operator characteristics curve of CSF PCT with the other index tests showed no significant differences. Based on a priori cut-off of 0.2 ng/mL, CSF PCT level had a sensitivity (95% confidence interval) of 67% (50, 80), specificity 58% (54, 61), LR⁺ 1.6 (1.1, 2.0) and LR^- 0.6 (0.3, 0.9).

CONCLUSIONS

Higher values of CSF PCT are associated with neonatal bacterial meningitis. However, the diagnostic performance of CSF PCT is modest and not significantly different from standard tests.

Validation of host cerebrospinal fluid protein biomarkers for early diagnosis of tuberculous meningitis in children: a replication and new biosignature discovery study

The diagnosis of tuberculous meningitis (TBM) in children is often delayed due to diagnostic difficulties. New tools are urgently needed to improve the diagnosis of the disease in this vulnerable group. The present study aimed to validate the accuracy of recently identified host cerebrospinal (CSF) biomarkers as candidates for the diagnosis of TBM in children. We collected CSF samples from 87 children aged 3 months to 13 years, that were consecutively admitted at a tertiary hospital in Cape Town, South Africa, on suspicion of having TBM. We evaluated the concentrations of 67 selected host protein biomarkers using a multiplex platform. Previously identified 3-marker (VEGF-A + IFN-γ + MPO) and 4-marker (IFN-γ + MPO + ICAM-1 + IL-8) signatures diagnosed TBM with AUCs of 0.89 (95% CI, 0.81-0.97) and 0.87 (95% CI, 0.79-0.95) respectively; sensitivities of 80.6% (95% CI, 62.5-92.5%) and 81.6% (95% CI, 65.7-92.3%), and specificities of 86.8% (71.9-95.6%) and 83.7% (70.4-92.7%) respectively. Furthermore, a new combination between the analytes (CC4b + CC4 + procalcitonin + CCL1) showed promise, with an AUC of 0.98 (95% CI, 0.94-1.00). We have shown that the accuracies of previously identified candidate CSF biomarkers for childhood TBM was reproducible. Our findings augur well for the future development of a simple bedside test for the rapid diagnosis of TBM in children.

Diagnostic Utility of Cerebrospinal Fluid Procalcitonin in Neonatal Meningitis

We aimed to study the diagnostic utility of cerebrospinal fluid (CSF) procalcitonin (PCT) in neonates with meningitis. All the neonates with sepsis who qualified for lumbar puncture were prospectively evaluated. The neonates were classified into Meningitis and No meningitis group based on predefined criteria. CSF PCT was estimated in these neonates along with cytological and biochemical parameters. A total of 113 neonates were included in the study with 29 in the meningitis group and 84 in the no meningitis group. The median PCT levels were higher in babies with meningitis as compared to those without meningitis [0.194 (0.034-0.534) in meningitis group vs. 0.012 (0.012-0.012) ng/ml in no meningitis group, p < 0.001]. The area under curve for CSF PCT was 0.867 (0.77-0.95) and at a cut-off level of 0.120 ng/ml CSF PCT had a sensitivity of 83%, specificity of 84% and positive and negative predictive likelihood ratios of 5.35 and 0.20, respectively for the diagnosis of meningitis. CSF PCT has a good diagnostic accuracy similar to other parameters in the diagnosis of neonatal meningitis and can be considered as an additional diagnostic marker particularly when CSF culture is negative and cytochemical analysis is inconclusive.

Utility of Cerebrospinal Fluid and Serum Procalcitonin for the Diagnosis of Neonatal Meningitis

OBJECTIVE

Positive CSF culture is the gold standard for the diagnosis of meningitis but it carries poor sensitivity. CSF procalcitonin (PCT) is shown to have some utility for the diagnosis of meningitis though there are limited studies in neonatal age group. We planned this study to compare CSF, serum, and CSF to serum PCT levels in neonates with confirmed, probable, and nonmeningitis groups to determine its optimal cut-off in CSF and serum for diagnosing meningitis.

STUDY DESIGN

Sixty-seven neonates who qualified for lumbar puncture were enrolled in the study. Neonates were categorized into confirmed meningitis, i.e., CSF cytochemistry and culture positive (N = 17), probable meningitis, i.e., CSF cytochemistry positive but culture negative (N = 25) and nonmeningitis, i.e., both cytochemistry and culture negative (N = 25). CSF and serum samples were stored at -80°C for PCT assay.

RESULTS

Significant difference was seen in mean of CSF PCT in neonates with confirmed (0.31 ng/mL), probable (0.22 ng/mL), and nonmeningitis (0.11 ng/mL) groups. Similarly, significant difference was observed in serum PCT levels also, though the ratio of serum to CSF PCT was comparable. At cut-off of 0.2 ng/mL, CSF PCT had sensitivity of 95.2% and specificity of 96% in the diagnosis of meningitis.

CONCLUSION

CSF PCT is more specific marker for the diagnosis of neonatal meningitis as compared with serum PCT and CSF to serum PCT ratio.

KEY POINTS

· CSF procalcitonin is a better marker than serum procalcitonin for diagnosing neonatal meningitis.. · It is better than serum procalcitonin and CSF to serum procalcitonin ratio.. · At cut-off of >0.2 ng/mL CSF procalcitonin can diagnose neonatal meningitis with 96% specificity..

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.

An improved clinical prediction rule for identifying neonatal bacterial meningitis: a multicenter cohort study

BACKGROUND

To refine the bacterial meningitis (BM) score by improving its predictability of neonatal BM.

METHODS

A multicenter, ambispective cohort study was conducted in China, comprising 9 hospitals (retrospective cohort: January 2001 to December 2017; prospective cohort: January 2018 to August 2019). Of 3,504 eligible full-term neonates, 475 neonates with cerebrospinal fluid (CSF) pleocytosis were included. Based on the receiver operating characteristic (ROC) curve and logistic regression analyses, the BM score was refined by changing the thresholds of CSF protein level and the CSF absolute neutrophil count (ANC), and removing some variables (the peripheral blood ANC and a history of seizure before or at the time of presentation).

RESULTS

Of 475 neonates, 94 (19.8%) had BM. Based on the refined BM score, neonates with none of the following high-risk predictors were classified as being at very low risk for BM: CSF protein level ≥1,650 mg/L, CSF ANC ≥84×10⁶ cells/L, and positive CSF Gram stain result. The refined score showed 100% sensitivity in identifying BM and much higher specificity compared to that for the BM score (70.9% vs. 19.4%).

CONCLUSIONS

The refined BM score effectively identifies neonatal BM, and further studies are required to confirm our findings in prospective studies.

Value of lipocalin 2 as a potential biomarker for bacterial meningitis

OBJECTIVES

Central nervous system (CNS) infections are common causes of morbidity and mortality worldwide. We aimed to discover protein biomarkers that could rapidly and accurately identify the likely cause of the infections, essential for clinical management and improving outcome.

METHODS

We applied liquid chromatography tandem mass spectrometry on 45 cerebrospinal fluid (CSF) samples from a cohort of adults with and without CNS infections to discover potential diagnostic biomarkers. We then validated the diagnostic performance of a selected biomarker candidate in an independent cohort of 364 consecutively treated adults with CNS infections admitted to a referral hospital in Vietnam.

RESULTS

In the discovery cohort, we identified lipocalin 2 (LCN2) as a potential biomarker of bacterial meningitis (BM) other than tuberculous meningitis. The analysis of the validation cohort showed that LCN2 could discriminate BM from other CNS infections (including tuberculous meningitis, cryptococcal meningitis and virus/antibody-mediated encephalitis), with sensitivity of 0.88 (95% confident interval (CI), 0.77-0.94), specificity of 0.91 (95% CI, 0.88-0.94) and diagnostic odds ratio of 73.8 (95% CI, 31.8-171.4). LCN2 outperformed other CSF markers (leukocytes, glucose, protein and lactate) commonly used in routine care worldwide. The combination of LCN2, CSF leukocytes, glucose, protein and lactate resulted in the highest diagnostic performance for BM (area under the receiver operating characteristics curve, 0.96; 95% CI, 0.93-0.99). Data are available via ProteomeXchange with identifier PXD020510.

CONCLUSIONS

LCN2 is a sensitive and specific biomarker for discriminating BM from a broad spectrum of other CNS infections. A prospective study is needed to assess the diagnostic utility of LCN2 in the diagnosis and management of CNS infections.

The Diagnostic Dilemma of Traumatic Lumbar Puncture: Current Standing of Cerebrospinal Fluid Leukocyte Corrections and Our Experience With Cerebrospinal Fluid Biomarkers

OBJECTIVE

To assess the diagnostic efficiency of cerebrospinal fluid markers of procalcitonin, lactate, and cerebrospinal fluid/serum lactate ratio for detecting bacterial meningitis during traumatic lumbar puncture, and to compare these markers with routinely used uncorrected and corrected leukocyte measurements.

METHODS

Infants aged ≤90 days with traumatic lumbar puncture were prospectively studied. The diagnostic characteristics of cerebrospinal fluid assays of uncorrected and corrected leukocyte count, procalcitonin, lactate, and lactate ratio were described and compared.

RESULTS

Considering the area under the curve (95% CI) analysis and standard cutoff values, the lactate-ratio (0.985 [0.964-0.989] at cutoff 1.2) had the best test indexes for identifying meningitis, followed by lactate (0.964 [0.945-0.984] at cutoff 2.2 mmol/L) and procalcitonin (0.939 [0.891-0.986] at cutoff 0.33 ng/mL) measurement, whereas the corrected total leukocyte count assay (0.906 [0.850-0.962] at cutoff 350 cells/mm³) had diagnostic properties moderately superior to uncorrected total leukocyte count measurement (0.870 [0.798-0.943] at cutoff 430 cells/mm³).

CONCLUSION

Cerebrospinal fluid levels of procalcitonin, lactate, and lactate-ratio are reliable markers to diagnose bacterial meningitis in blood-contaminated cerebrospinal fluid.