Diagnostic Accuracy of Procalcitonin in Bacterial Meningitis Versus Nonbacterial Meningitis: A Systematic Review and Meta-Analysis

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.

Factors influencing procalcitonin in the cerebrospinal fluid of patients after neurosurgery and its diagnostic value for intracranial infection

OBJECTIVE

This study aimed to investigate the factors influencing Procalcitonin (PCT) in the cerebrospinal fluid (CSF) of patients with high fever and suspected intracranial infection after neurosurgery and its clinical application value.

METHODS

Between February 2021 and August 2022, CSF and serum samples were collected via lumbar puncture from patients with high fever and suspected intracranial infection in the Intensive Care Unit(ICU) of our hospital. Multivariate logistic regression analysis was performed to analyze the factors influencing elevated PCT in CSF. The diagnostic efficacy of each index was assessed using receiver operating characteristic (ROC) curves.

RESULTS

A total of 183 CSF samples were collected, of which 148 had increased PCT levels, including 73 cases of intracranial infection and 75 cases in the case‒control group. Multivariate logistic regression analysis showed that intracranial infection [OR = 0.117, 95% CI: 0.025-0.559; p < 0.01] and hemorrhagic CSF [OR = 0.162, 95% CI: 0.029-0.916; p < 0.04] were factors influencing CSF PCT, while trauma [OR = 3.43, 95% CI: 0.76-15.45; p < 0.12], epileptic seizure [OR = 0.00, 95% CI: 0.00; p < 0], age [OR = 1.02, 95% CI: 0.98-1.52; p < 0.32] and Glasgow Coma Scale (GCS) score [OR = 1.03, 95% CI: 0.78-1.32; p < 0.83] did not influence CSF PCT. The CSF PCT and serum PCT levels in the intracranial infection group and the case‒control group were 0.13 (0.11, 0.25) ng/ml and 0.14 (0.07, 0.25) ng/ml and 0.14 (0.08,0.32) ng/ml and 0.23 (0.13,0.48)ng/ml, respectively, with no statistically significant difference. The median values of CSF lactate in the intracranial infection group and the case‒control group were 6.45 (4.475, 8.325) mmol/l and 3.2 (2.02, 4.200) mmol/l, respectively, with a statistically significant difference between the groups.The areas under the ROC curve of CSF PCT, serum PCT,CSF lactate, CSF PCT combined with lactate were 0.59, 0.63, 0.82,and 0.83,respectively.

CONCLUSION

Intracranial infection and hemorrhagic CSF are influencing factors for elevated CSF PCT following neurosurgery. It should be noted that the diagnostic value of intracranial infection by CSF PCT elevated alone is limited, but the combination it with other indicators can help improve diagnostic efficacy.

Diagnostic value of soluble biomarkers for parapneumonic pleural effusion

Parapneumonic pleural effusion (PPE) is a common complication in patients with pneumonia. Timely and accurate diagnosis of PPE is of great value for its management. Measurement of biomarkers in circulating and pleural fluid have the advantages of easy accessibility, short turn-around time, objectiveness and low cost and thus have utility for PPE diagnosis and stratification. To date, many biomarkers have been reported to be of value for the management of PPE. Here, we review the values of pleural fluid and circulating biomarkers for the diagnosis and stratification PPE. The biomarkers discussed are C-reactive protein, procalcitonin, presepsin, soluble triggering receptor expressed on myeloid cells 1, lipopolysaccharide-binding protein, inflammatory markers, serum amyloid A, soluble urokinase plasminogen activator receptor, matrix metalloproteinases, pentraxin-3 and cell-free DNA. We found that none of the available biomarkers has adequate performance for diagnosing and stratifying PPE. Therefore, further work is needed to identify and validate novel biomarkers, and their combinations, for the management of PPE.

Progress and Challenges in Bacterial Meningitis: A Review

IMPORTANCE

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

OBSERVATIONS

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

CONCLUSIONS AND RELEVANCE

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

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.

Extra-pulmonary applications of procalcitonin: an updated literature review

INTRODUCTION

: Procalcitonin (PCT) is a biomarker with established performance in the differentiation between bacterial and viral infections, predominantly in pulmonary infections, as well as the diagnosis and prognosis of bacterial sepsis. However, the role of PCT in extra-pulmonary infections is not well described.

AREAS COVERED

: We reviewed the role of PCT in commonly experienced extra-pulmonary infections including meningitis, diabetic foot infection, prosthetic joint infection, osteomyelitis, and skin and soft tissue infection. PubMed and Medline online libraries were searched, from 2013 till 2022, for relevant articles.

EXPERT OPINION

: For meningitis, PCT could distinguish bacterial from viral meningitis. PCT distinguished septic arthritis from different types of arthritis but had variable performance in discriminating septic arthritis from crystal arthropathy. For periprosthetic joint infections, results were inconclusive. PCT had a potential role in diagnosis of more complex infections such as osteomyelitis and diabetic foot infections, but further studies are needed for a definitive cutoff. In skin and soft tissue infections, PCT performance was more variable requiring further investigation to define cutoff for the discrimination of cellulitis from necrotizing fasciitis. We find that PCT performed best for meningitis and helps in the reduction of unnecessary antibiotic treatment, but has variable outcomes with other extra-pulmonary infections.

Heparin-Binding Protein (HBP), Neutrophil Gelatinase-Associated Lipocalin (NGAL) and S100 Calcium-Binding Protein B (S100B) Can Confirm Bacterial Meningitis and Inform Adequate Antibiotic Treatment

The empirical administration of antibiotics for suspected bacterial meningitis denotes a poor bacterial stewardship. In this context, the use of biomarkers can distinguish between bacterial and viral infections before deciding treatment. Our study assesses how levels of heparin-binding protein (HBP), neutrophil gelatinase-associated lipocalin (NGAL), S100 calcium-binding protein B (S100B), and neuron-specific enolase (NSE) in cerebrospinal fluid (CSF) and in blood can promptly confirm bacterial etiology and the need for antibiotic treatment. The CSF and blood levels of HBP, NGAL, S100B, and NSE of 81 patients with meningitis were measured and analyzed comparatively. Statistical sensitivity, specificity, and positive and negative predictive values were evaluated. CSF levels of HBP and NGAL and the blood level of S100B in the bacterial meningitis group were significantly higher (p < 0.05). The area under curve (AUC) for predicting bacterial meningitis was excellent for the CSF level of HBP (0.808 with 93.54% sensitivity and 80.64% specificity), good for the CSF level of NGAL (0.685 with 75.00% sensitivity and 65.62% specificity), and good for the blood level of S100B (0.652 with 65.90% sensitivity and 57.14% specificity). CSF levels of HBP and NGAL, as well as the blood level of S100B, could help discriminate between bacterial and viral meningitis before considering antibiotic treatment.

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.

Use of infection biomarkers in the emergency department

The use of infection biomarkers in the emergency department is discussed in terms of their possible contributions to diagnostic-prognostic uncertainties, appropriate antibiotic treatments, and triage and follow-up planning. Procalcitonin (PCT), C-reactive protein (CRP), proadrenomedullin (proADM), and presepsin are among the most discussed infection biomarkers for use in the emergency department. Due to the variable sensitivity results and cutoff values, there are insufficient data to recommend the widespread use of CRP and procalcitonin (PCT) for the diagnosis and prognosis of infection in the emergency department. However, these biomarkers can be used for appropriate antibiotic use in selected infection groups, such as community-acquired pneumonia, especially to reduce unnecessary antibiotic prescribing. With its prognostic superiority over other biomarkers and its contribution to prognostic score systems in community-acquired pneumonia (CAP), proADM can be used to predict hospitalization, preferably within the scope of clinical studies. Although presepsin has been shown to have some advantages over other biomarkers to rule out sepsis, there are insufficient data for its clinical use in the emergency department.

Procalcitonin for antimicrobial stewardship among cancer patients admitted with COVID-19

Background

Procalcitonin (PCT) has been used to guide antibiotic therapy in bacterial infections. We aimed to determine the role of PCT in decreasing the duration of empiric antibiotic therapy among cancer patients admitted with COVID-19.

Methods

This retrospective study included cancer patients admitted to our institution for COVID-19 between March 1, 2020, and June 28, 2021, with a PCT test done within 72 hr after admission. Patients were divided into two groups: PCT <0.25 ng/ml and PCT ≥0.25 ng/ml. We assessed pertinent cultures, antibacterial use, and duration of empiric antibacterial therapy.

Results

The study included 530 patients (median age, 62 years [range, 13-91]). All the patients had ≥1 culture test within 7 days following admission. Patients with PCT <0.25 ng/ml were less likely to have a positive culture than were those with PCT ≥0.25 ng/ml (6% [20/358] vs. 17% [30/172]; p<0.0001). PCT <0.25 ng/ml had a high negative predictive value for bacteremia and 30 day mortality. Patients with PCT <0.25 ng/ml were less likely to receive intravenous (IV) antibiotics for >72 hr than were patients with PCT ≥0.25 ng/ml (45% [162/358] vs. 69% [119/172]; p<0.0001). Among patients with PCT <0.25 ng/ml and negative cultures, 30 day mortality was similar between those who received IV antibiotics for ≥72 hr and those who received IV antibiotics for shorter durations (2% [2/111] vs. 3% [5/176], p=0.71).

Conclusions

Among cancer patients with COVID-19, PCT level <0.25 ng/ml is associated with lower likelihood of bacterial co-infection and greater likelihood of a shorter antibiotic course. In patients with PCT level <0.25 ng/ml and negative cultures, an antibiotic course of >72 hr may not be necessary. PCT could be useful in enhancing antimicrobial stewardship in cancer patients with COVID-19.

Funding

This research was supported by the National Institutes of Health/National Cancer Institute under award number P30CA016672, which supports MD Anderson Cancer Center's Clinical Trials Office.

Procalcitonin measurement in West Nile virus neuroinvasive disease: A first case series

West Nile virus neuroinvasive disease (WNV-NID) is challenging to diagnose. Procalcitonin (PCT) is a useful diagnostic test to identify bacterial infections. We present four cases of WNV-NID with serum PCT measurements.

METHODS

Daily (days 1-7) serum PCT (bioMérieux) was examined for critically ill patients with sepsis enrolled in a provincial sepsis study. Patients with identified WNV-NID are descriptively analyzed in this case series. PCT values of ≥0.5 ng/mL were suggestive of bacterial infection.

RESULTS

Four patients with WNV-NID were identified. Those with viral infections alone had consistently low PCT values ranging from 0.09 ng/mL to 0.34 ng/mL. Those with documented bacterial co-infections had initially elevated PCT levels that decreased by more than 50% with antimicrobial therapy.

CONCLUSION

These cases are the first to report serial PCT measurements in confirmed cases of WNV-NID and support a low serum PCT in WNV-NID.

SOP: emergency workup in patients with suspected acute bacterial meningitis

Introduction

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

First steps

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

Comments

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

Conclusion

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

Derivation of a metabolic signature associated with bacterial meningitis in infants

BACKGROUND

Diagnosis of bacterial meningitis (BM) is challenging in newborn infants. Presently, biomarkers of BM have limited diagnostic accuracy. Analysis of cerebrospinal fluid (CSF) metabolites may be a useful diagnostic tool in BM.

METHODS

In a nested case-control study, we examined >400 metabolites in CSF of uninfected infants and infants with culture-confirmed BM using gas and liquid chromatography mass spectrometry. Preterm and full-term infants in a Level III or IV Neonatal Intensive Care Unit were prospectively enrolled when evaluated for serious bacterial infection.

RESULTS

Over 200 CSF metabolites significantly differed in uninfected infants and infants with BM. Using machine learning, we found that as few as 6 metabolites distinguished infants with BM from uninfected infants in this pilot cohort. Further analysis demonstrated three metabolites associated with Group B Streptococcal meningitis.

CONCLUSIONS

We report the first comprehensive metabolic analysis of CSF in infants with BM. In our pilot cohort, we derived a metabolic signature that predicted the presence or absence of BM, irrespective of gestational age, postnatal age, sex, race and ethnicity, presence of neurosurgical hardware, white blood cell count in CSF, and red blood cell contamination in CSF. Metabolic analysis may aid diagnosis of BM and facilitate clinical decision-making in infants.

IMPACT

In a pilot cohort, metabolites in cerebrospinal fluid distinguished infants with bacterial meningitis from uninfected infants.We report the first comprehensive metabolic analysis of cerebrospinal fluid in infants with bacterial meningitis.Our findings may be used to improve diagnosis of bacterial meningitis and to offer mechanistic insights into the pathophysiology of bacterial meningitis in infants.

Validation of the Bacterial Meningitis Score in adults consulting at an emergency department: a retrospective multicentric study

OBJECTIVE

The Bacterial Meningitis Score (BMS) is recommended by pediatric academic societies to rule out the diagnosis of bacterial meningitis. The aim of this study was to evaluate the performance of the BMS to identify adults at no risk for bacterial meningitis.

METHODS

We conducted a multicentric retrospective study including adults who consulted the emergency department (ED) for meningitis [cerebrospinal fluid (CSF) white blood cells ≥5/mm with a ratio of white blood cells/red blood cells <1:900) during a 4-year period. The BMS variables were: CSF positive Gram stain, CSF absolute neutrophil count ≥1000 cells/μL, CSF protein ≥80 mg/dL, peripheral blood absolute neutrophil count ≥10 000 cells/μL, and seizures. Bacterial meningitis was defined for patients who had a lumbar puncture with CSF pleocytosis and positive bacterial analysis of CSF. The primary endpoint was the sensitivity of the BMS to rule out bacterial meningitis in adults. The secondary outcome was to assess the rate of patients for whom antibiotics could have been avoided using the BMS and the diagnostic performance of procalcitonin in patients with a BMS ≥1.

RESULTS

Of 930 patients with meningitis, 626 were included in the analysis, and 27 (4.3%) were diagnosed with bacterial meningitis. A total of 384/626 (61.3%) patients had a BMS = 0, and none presented bacterial meningitis. BMS sensitivity was 100% [95% confidence interval (CI), 87.2-100%], and its negative predictive values were 100% (95% CI, 98.8-100%).

CONCLUSION

Among patients with a diagnosis of meningitis in ED, a BMS of 0 may safely rule out bacterial meningitis.

A 2020 review on the role of procalcitonin in different clinical settings: an update conducted with the tools of the Evidence Based Laboratory Medicine

Biomarkers to guide antibiotic treatment decisions have been proposed as an effective way to enhancing a more appropriate use of antibiotics. As a biomarker, procalcitonin (PCT) has been found to have good specificity to distinguish bacterial from non-bacterial inflammations. Decisions regarding antibiotic use in an individual patient are complex and should be based on the pre-test probability for bacterial infection, the severity of presentation and the results of PCT serum concentration. In the context of a high pre-test probability for bacterial infections and/or a high-risk patient with sepsis, monitoring of PCT over time helps to track the resolution of infection and decisions regarding early stop of antibiotic treatment. As outlined by the Evidence Based Laboratory Medicine (EBLM), not only the pre-test probability but also the positive likelihood ratio influence the performance of a test do be really diagnostic. This aspect should be taken into account in the interpretation of the results of clinical trials evaluating the performance of PCT in guiding antibiotic therapy.

Higher Procalcitonin Level in Cerebrospinal Fluid than in Serum Is a Feasible Indicator for Diagnosis of Intracranial Infection

Objective: To explore the value of the difference in procalcitonin (PCT) levels in serum and cerebrospinal fluid (CSF) for diagnosing intracranial infection in post-neurosurgical patients. Methods: Patients who were treated at our hospital after craniotomy from January 2015 to January 2019 were enrolled in this study. Twenty patients eventually diagnosed with intracranial infection were included in a study group and 22 patients with no intracranial infection were included in a control group. A t-test was used to compare the differences between serum and CSF PCT levels of PCT, and the diagnostic value of PCT was evaluated by receiver operating characteristic (ROC) curve analysis. Results: The serum PCT levels in the study and control groups were 0. 10 ± 0. 03 ng/mL and 0. 09 ± 0. 03 ng/mL, respectively, and they were not substantially different between the groups. The CSF PCT level in the study group was substantially higher than that in the control group, with values of 0. 13 ± 0. 03 ng/mL and 0. 07 ± 0. 02 ng/mL, respectively. The CSF/serum PCT ratio in the study group was substantially higher than that in the control group, with values of 1. 31 ± 0. 19 and 0. 79 ± 0. 23, respectively. The areas under the ROC curve for serum PCT, CSF PCT and the CSF/serum PCT ratio were 0. 56, 0. 92, and 0. 95, respectively, resulting in a substantial difference among the three groups. Conclusion: CSF PCT may be a valuable marker for diagnosing intracranial infection in patients after neurosurgery; in particular, the specificity of CSF PCT is higher if the CSF PCT level is higher than the serum PCT level.

Procalcitonin in respiratory disease: use as a biomarker for diagnosis and guiding antibiotic therapy

Procalcitonin (PCT) is a peptide measurable in serum which becomes elevated in response to bacterial infection. Multiple trials have explored the safety and efficacy of using PCT as a biomarker to guide decisions about starting or stopping antibiotic therapy in a wide variety of situations, and PCT assays have recently been approved by the Federal Drug Administration (FDA) in the US for use in both sepsis and respiratory tract infections. While there have been a number of promising results particularly in acute respiratory tract infections and intensive care unit settings, problems including adherence to protocol, cost of the assay and improved antimicrobial stewardship more generally, have limited more widespread adoption.

This educational article summarises the evidence for the use of procalcitonin as a biomarker of bacterial infection across the spectrum of respiratory disease and reviews how the use of procalcitonin-guided antibiotic therapy is reflected in current major international guidelines.

Procalcitonin has been widely investigated as a biomarker of bacterial infection to aid diagnosis and decisions to start or stop antibiotics in a range of conditions, including in diseases of the lower respiratory tracthttp://bit.ly/2ZgDwNO

Biomarkers of Sepsis and Bloodstream Infections: The Role of Procalcitonin and Proadrenomedullin With Emphasis in Patients With Cancer

Sepsis and bloodstream infections remain a leading cause of death in immunocompromised patients with cancer. The management of these serious infections consist of empiric use of antimicrobial agents which are often overused. Procalcitonin and proadrenomedullin are biomarkers that have been extensively evaluated in the general populations but with little emphasis in the population immunocompromised patients with cancer, where they may have promising roles in the management of febrile patients. In this review, we summarize the available evidence of the potential role of these available biomarkers in guiding antimicrobial therapy to optimize the use of resources in the general patient population. Special emphasis is given to the role of these 2 biomarkers in the immunocompromised and critically ill patients with cancer, highlighting the distinctive utility of each.

Procalcitonin: Between evidence and critical issues

Sepsis is a life-threatening organ dysfunction caused by a dysregulated response of the host to infection. It represents one of the major health care problems worldwide. Unfortunately, the diagnosis of sepsis is challenging for many reasons, including a lack of a sufficiently sensitive and specific diagnostic test. When procalcitonin (PCT) was discovered, it was thought that it could become the best test for identifying patients with sepsis. From the evidence sources in the available literature, it is now clear that the power of PCT in differentiating infectious from non-infectious forms of systemic inflammatory response syndrome in adults, and in stratifying morbidity and mortality risk, is limited. Nevertheless, PCT determination can be a useful tool for diagnosing late-onset neonatal sepsis, bacterial meningitis and other forms of organ-related bacterial infections and, above all, it can be used for guiding antibiotic stewardship in critical patients. The real impact of this application of PCT testing, however, still needs to be clearly defined. Laboratories should offer unrestricted PCT testing only to intensive care units (as an aid in decision for continuing or stopping antibiotics) and pediatric wards. For all other clinical wards, the laboratory should guide PCT requests and give them support towards the most appropriate approach to testing.

Comparison of the novel ARCHITECT procalcitonin assay with established procalcitonin assay systems

Aims

This study assessed the performance of a new fully automated immunoassay, ARCHITECT B.R.A.H.M.S procalcitonin (PCT), comparing the results with other commercial assays on routine clinical specimens.

Methods

At nine sites from eight countries, precision analysis was carried out on controls by ANOVA. Threshold and linearity were verified according to standard procedures. Comparison of ARCHITECT B.R.A.H.M.S PCT with the Cobas^®, LIAISON^®, VIDAS^® and Kryptor^® PCT assays was evaluated using Passing-Bablok and Deming regression analyses.

Results

The within-laboratory standard deviation and %CV across all sites ranged from 0.005 to 0.008 and 2.7 to 4.1; 0.040 to 0.212 and 2.1 to 11.7; 1.628 to 4.191 and 2.5–6.3 for the three control levels, respectively. The mean slope (linearity analysis) across all sites ranged from 0.85 to 1.03, with a mean y-intercept ranging from –6.15 to + 1.71 and a correlation coefficient ranging from 0.94 to 1.00. The LoB, LoD, and LoQ claims were verified. Deming regression analysis of 1116 plasma or serum samples with PCT results detected across a dynamic assay range of 0.02–100 μg/l using the ARCHITECT B.R.A.H.M.S PCT assay yielded results of r = 0.989 vs. Roche Cobas^®, r = 0.986 vs Kryptor^® B.R.A.H.M.S, r = 0.987 vs BioMèrieux VIDAS^® and r = 0.972 vs. Diasorin LIAISON^®, respectively. Concordance at cut-offs of 0.25 μg/l and 0.50 μg/l were 96.9% and 98.1% with Roche Cobas^®, 95.4% and 96.1% with B.R.A.H.M.S Kryptor^®, 93.8% and 98.4% with BioMèrieux VIDAS^®, and 92.7% and 93.9% with Diasorin LIAISON^®.

Conclusions

Compared with other assays, ARCHITECT B.R.A.H.M.S PCT offers excellent precision and low-end sensitivity.

The Role of Procalcitonin in the Diagnosis of Meningitis: A Literature Review

OBJECTIVE

To review the current published literature on the use of procalcitonin as a diagnostic and prognostic marker in adult patients with meningitis.

METHODS

We conducted a PubMed search to identify all relevant publications regarding the diagnostic and prognostic value of serum procalcitonin in patients with a known or suspected central nervous system infection. We also reviewed the bibliographies of all identified manuscripts in an attempt to identify additional relevant references.

RESULTS

A significant body of evidence suggests that serum procalcitonin has a promising role and can be a useful biomarker in the assessment of patients with meningitis.

CONCLUSIONS

Our literature review suggests that data on the role of Cerebrospinal Fluid (CSF) procalcitonin are limited, whereas serum procalcitonin (S⁻PCT) is probably a useful tool in the evaluation of patients with a known or suspected central nervous system infection and can help distinguish between bacterial and viral meningitis.

Role of Procalcitonin in the Management of Infected Patients in the Intensive Care Unit

The combination of molecular pathogen diagnostics and the biomarker procalcitonin (PCT) are changing the use of antimicrobials in patients admitted to critical care units with severe community-acquired pneumonia, possible septic shock, or other clinical syndromes. An elevated serum PCT level is good supportive evidence of a bacterial pneumonia, whereas a low serum PCT level virtually eliminates an etiologic role for bacteria even if the culture for a potential bacterial pathogen is positive. Serum PCT levels can be increased in any shocklike state; a low PCT level eliminates invasive bacterial infection as an etiology in more than 90% of patients.

Five-Year Multicenter Study of Clinical Tests of Neonatal Purulent Meningitis

This study aimed to provide more data support for early diagnosis and treatment of neonatal purulent meningitis through retrospective analysis of its clinical diagnosis and treatment, pathogen distribution, and drug resistance in 5 third-class A hospitals in Southwest and Northwest China from January 2011 to December 2015. It was found that both the positive rates of blood and cerebrospinal fluid culture were low, and Escherichia coli should be the main pathogenic bacteria. Drug-resistant strains with varying degrees to the third generation of cephalosporin antibiotics have appeared currently.

Expression of MMP-2 and TIMP-1 in cerebrospinal fluid and the correlation with dynamic changes of serum PCT in neonatal purulent meningitis

Matrix metalloproteinase 2 (MMP-2) and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels in cerebrospinal fluid of pediatric patients with neonatal purulent meningitis were observed to analyze changes in serum procalcitonin (PCT) and the correlation among the three factors (MMP-2, TIMP-1 and PCT). Sixty pediatric patients with neonatal purulent meningitis from April 2015 to December 2016 were enrolled as the purulent meningitis group and 60 pediatric patients with viral encephalitis treated during the same period were enrolled as the viral encephalitis group. Additionally, 60 healthy newborns who underwent physical examinations in our hospital during the same period were enrolled as the control group. The levels of MMP-2 were 136.73±25.42 ng/ml in the purulent meningitis group, 45.32±6.57 ng/ml in the viral encephalitis group and 1.32±0.51 ng/ml in the control group and the differences between the three groups were statistically significant (F=15.052, p<0.05). The levels of TIMP-1 in cerebrospinal fluid were 374.55±36.04 ng/ml in the purulent meningitis group, 176.61±21.06 ng/ml in the viral encephalitis group and 7.72±2.44 ng/ml in the control group. The serum levels of PCT were 14.56±2.21 ng/ml in the purulent meningitis group, 9.04±1.17 ng/ml in the viral encephalitis group and 0.38±0.14 ng/ml in the control group. The level of MMP-2 in cerebrospinal fluid of pediatric patients in the purulent meningitis group was positively correlated with the level of serum PCT (r=0.582, p<0.05); the level of TIMP-1 in cerebrospinal fluid of pediatric patients in the viral encephalitis group was positively correlated with the level of serum PCT (r=0.635, p<0.05). In conclusion, MMP-2 and TIMP-1 were positively correlated with the levels of serum PCT, suggesting that MMP-2, TIMP-1 and PCT were involved in the occurrence and development of neonatal purulent meningitis.

Elevations of novel cytokines in bacterial meningitis in infants

Background

Bacterial meningitis is challenging to diagnose in infants, especially in the common setting of antibiotic pre-treatment, which diminishes yield of cerebrospinal fluid (CSF) cultures. Prior studies of diagnostic markers have not demonstrated sufficient accuracy. Interleukin-23 (IL-23), interleukin-18 (IL-18) and soluble receptor for advanced glycation end products (sRAGE) possess biologic plausibility, and may be useful as diagnostic markers in bacterial meningitis.

Methods

In a prospective cohort study, we measured IL-23, IL-18 and sRAGE levels in CSF. We compared differences between infected and non-infected infants, and conducted receiver operating characteristic (ROC) analyses to identify individual markers and combinations of markers with the best diagnostic accuracy.

Results

189 infants <6 months, including 8 with bacterial meningitis, 30 without meningitis, and 151 with indeterminate diagnosis (due to antibiotic pretreatment) were included. CSF IL-23, IL-18 and sRAGE levels were significantly elevated in infants with culture proven meningitis. Among individual markers, IL-23 possessed the greatest accuracy for diagnosis of bacterial meningitis (area under the curve (AUC) 0.9698). The combination of all three markers had an AUC of 1.

Conclusions

IL-23, alone and in combination with IL-18 and sRAGE, identified bacterial meningitis with excellent accuracy. Following validation, these markers could aid clinicians in diagnosis of bacterial meningitis and decision-making regarding prolongation of antibiotic therapy.

Pleocytosis is not fully responsible for low CSF glucose in meningitis

Objective

The mechanism of hypoglycorrhachia-low CSF glucose-in meningitis remains unknown. We sought to evaluate the relative contribution of CSF inflammation vs microorganisms (bacteria and fungi) in lowering CSF glucose levels.

Methods

We retrospectively categorized CSF profiles into microbial and aseptic meningitis and analyzed CSF leukocyte count, glucose, and protein concentrations. We assessed the relationship between these markers using multivariate and stratified linear regression analysis for initial and repeated CSF sampling. We also calculated the receiver operating characteristics of CSF glucose and CSF-to-serum glucose ratios to presumptively diagnose microbial meningitis.

Results

We found that increasing levels of CSF inflammation were associated with decreased CSF glucose levels in the microbial but not aseptic category. Moreover, elevated CSF protein levels correlated more strongly than the leukocyte count with low CSF glucose levels on initial (R² = 36%, p < 0.001) and repeated CSF sampling (R² = 46%, p < 0.001). Hypoglycorrhachia (<40 mg/dL) was observed in 50.1% of microbial cases, but only 9.6% of aseptic cases, most of which were neurosarcoidosis. Absolute CSF glucose and CSF-to-serum glucose ratios had similar low sensitivity and moderate-to-high specificity in diagnosing microbial meningitis at thresholds commonly used.

Conclusions

The main driver of hypoglycorrhachia appears to be a combination of microbial meningitis with moderate to high degrees of CSF inflammation and proteins, suggesting that the presence of microorganisms capable of catabolizing glucose is a determinant of hypoglycorrhachia in meningitis. A major notable exception is neurosarcoidosis. Low CSF glucose and CSF-to-serum glucose ratios are useful markers for the diagnosis of microbial meningitis.

Development and Validation of an Ultrasensitive Procalcitonin Sandwich Immunoassay

Procalcitonin (PCT) is well established as a highly specific biomarker for the detection of bacterial infections and sepsis. However, the currently available diagnostic tests are not able to detect very low or very early increases of PCT or even baseline levels in healthy individuals or patients with non-bacterial infections. In order to be able to detect these very low concentrations of PCT, a sandwich immunoassay was developed using high sensitivity Single Molecule Array technology (Simoa). The assay was thoroughly validated and applied to analyze human cerebrospinal fluid (CSF) and serum samples from patients with bacterial or viral meningitis as well as CSF, serum, and K2 EDTA plasma from healthy control subjects. A 50-fold increase in sensitivity compared to the current gold standard assays was achieved, which was sensitive enough for the detection of baseline PCT levels. Both serum and CSF showed significantly elevated PCT levels in patients with bacterial meningitis compared to patients with viral meningitis and the healthy control group. Procalcitonin concentration levels for patients with viral meningitis and the control group could be measured, but were not significantly different. The determination of PCT in the low pg·mL⁻¹ range could help to improve the monitoring of bacterial infectious diseases, as PCT level changes could be detected earlier.

Diagnostic Accuracy of Cerebrospinal Fluid Procalcitonin in Bacterial Meningitis Patients with Empiric Antibiotic Pretreatment

Accurate diagnosis of bacterial meningitis (BM) relies on cerebrospinal fluid (CSF) Gram staining and bacterial culture, which often present high false-negative rates because of antibiotic abuse. Thus, a novel and reliable diagnostic biomarker is required. Procalcitonin (PCT) has been well demonstrated to be specifically produced from peripheral tissues by bacterial infection, which makes it a potential diagnostic biomarker candidate. Here, we performed a prospective clinical study comprising a total of 143 patients to investigate the diagnostic value of CSF PCT, serum PCT, and other conventional biomarkers for BM. Patients were assigned to the BM (n = 49), tuberculous meningitis (TBM) (n = 25), viral meningitis/encephalitis (VM/E) (n = 34), autoimmune encephalitis (AIE) (n = 15), or noninflammatory nervous system diseases (NINSD) group (n = 20). Empirical antibiotic pretreatment was not an exclusion criterion. Our results show that the CSF PCT level was significantly (P < 0.01) higher in patients with BM (median, 0.22 ng/ml; range, 0.13 to 0.54 ng/ml) than in those with TBM (median, 0.12 ng/ml; range, 0.07 to 0.16 ng/ml), VM/E (median, 0.09 ng/ml; range, 0.07 to 0.11 ng/ml), AIE (median, 0.06 ng/ml; range, 0.05 to 0.10 ng/ml), or NINSD (median, 0.07 ng/ml; range, 0.06 to 0.08 ng/ml). Among the assessed biomarkers, CSF PCT exhibited the largest area under the receiver operating characteristic curve (0.881; 95% confidence interval, 0.810 to 0.932; cutoff value, 0.15 ng/ml; sensitivity, 69.39%; specificity, 91.49%). Our study sheds light upon the diagnostic dilemma of BM due to antibiotic abuse. (This study has been registered at ClinicalTrials.gov under registration no. NCT02278016.).

Procalcitonin-guided diagnosis and antibiotic stewardship revisited

Several controlled clinical studies have evaluated the potential of the infection biomarker procalcitonin (PCT) to improve the diagnostic work-up of patients with bacterial infections and its influence on decisions regarding antibiotic therapy. Most research has focused on lower respiratory tract infections and critically ill sepsis patients. A clinical utility for PCT has also been found for patients with urinary tract infections, postoperative infections, meningitis, and patients with acute heart failure with possible superinfection (i.e., pneumonia). In these indications, PCT levels measured on hospital admission were found to substantially reduce the initiation of antibiotic treatment in low-risk situations (i.e., bronchitis, chronic obstructive pulmonary disease exacerbation). For more severe infections (i.e., pneumonia, sepsis), antibiotic stewardship by monitoring of PCT kinetics resulted in shorter antibiotic treatment durations with early cessation of therapy. Importantly, these strategies appear to be safe without increasing the risk for mortality, recurrent infections, or treatment failures. PCT kinetics also proved to have prognostic value correlating with disease severity (i.e., pancreatitis, abdominal infection) and resolution of illness (i.e., sepsis). Although promising findings have been published in these different types of infections, there are a number of limitations regarding PCT, including suboptimal sensitivity and/or specificity, which makes a careful interpretation of PCT in the clinical context mandatory. This narrative review aims to update clinicians on the strengths and limitations of PCT for patient management, focusing on research conducted within the last 4 years.