Corrected white blood cell count, cell index, and validation of a clinical model for the diagnosis of health care-associated ventriculitis and meningitis in adults with intracranial hemorrhage

Utility of cell index in the diagnosis of healthcare-associated ventriculitis and meningitis: an analytical cross-sectional study

BACKGROUND

The diagnosis of healthcare-associated ventriculitis and meningitis (HCAVM) can be complex because multiple factors confound the interpretation of cerebrospinal fluid (CSF) tests. The cell index (CI) may help in the diagnosis of HCAVM. It does not incur additional medical cost and it avoids delays from the turnaround time of CSF cultures. It is derived by calculating the ratio of CSF white blood cell (WBC) and red blood cell (RBC) divided by the ratio of peripheral WBC and RBC. This study aimed to evaluate the diagnostic utility of this parameter.

METHODS

An analytic, observational, cross-sectional study was conducted at the University of the Philippines - Philippine General Hospital. All admitted pediatric and adult patients from 2015 to 2022 who underwent external ventricular drain (EVD) insertion for hydrocephalus secondary to intracranial hemorrhage (ICH), acute ischemic stroke, intracranial neoplasms, traumatic brain injury, or congenital hydrocephalus were screened. Records of patients fulfilling the inclusion criteria were then reviewed.

RESULTS

A total of 363 patients underwent EVD insertion from 2015 to 2022. Of these, 161 were included in the study. Two-thirds (66.5%) were adults ≥ 19 years old whereas the remaining were pediatric patients 1 to < 19 years old. There were no patients < 12 months old as they fulfilled at least one exclusion criteria. Forty-nine of them were later confirmed to have HCAVM based on the CDC/NHSN criteria. A CI cut-off of ≥ 1.21 gave a maximum sensitivity of 30.6% and specificity of 86.4%. Receiver operating characteristic area under the curve (AUC-ROC) analysis was 0.585. Subgroup analysis by age showed sensitivity of 52.9% in the pediatric age group and 3.13% in adults. Subgroup analysis by neurologic indication showed sensitivity of 27.6% for ICH and 35.0% for neoplasms. Subsequent AUC-ROC analyses, however, showed that CI failed to adequately diagnose HCAVM in these subgroups.

CONCLUSIONS

In our population of neurologic patients who underwent EVD insertion, the cell index is not a reliable parameter in the diagnosis of HCAVM.

Combined Lactate Glucose Ratio as a Novel Marker for Rapid Diagnosis of Cerebrospinal Fluid Bacterial Infection in Neurosurgical Patients: Diagnostic Accuracy Study and Benchtop Analyzer Correlation

OBJECTIVE

This study aimed to assess the diagnostic accuracy of a novel marker, the combined lactate glucose ratio (CLGR), in identifying cerebrospinal fluid (CSF) bacterial infection (CBI) in neurosurgical patients. Additionally, it seeks to establish cutoff values for CLGR and evaluate the reliability of measurement using blood gas analyzer (BGA).

METHODS

CSF samples were collected from 2 neurosurgical centers in Kuala Lumpur, Malaysia, between January 2022 and October 2023. Conventional markers and CLGR were quantified using standard laboratory methods, with BGA utilized for measurement when feasible. Samples were categorized into confirmed CBI-positive (CBI+) and CBI-negative (CBI-) groups. Marker performance was compared, and receiver operating characteristic analysis conducted. Pearson correlation assessed the agreement between BGA and laboratory measurements.

RESULTS

Among the 130 CSF samples, 11 were CBI+. Both cerebrospinal fluid lactate (cLac) and CLGR were significantly elevated in the CBI + group (P < 0.001). The area under the curve for cLac and CLGR was 0.990 and 0.994, respectively. Using a cutoff of 6.0 mmol/L, cLac demonstrated sensitivity of 100%, specificity of 93.3%, positive predictive value of 57.9%, negative predictive value of 100%, and diagnostic accuracy of 93.9%. CLGR ≥20.0 showed even higher accuracy: 100.0% sensitivity, 98.6% specificity, 84.6% positive predictive value, 100% negative predictive value, and overall accuracy of 98.5%. Both markers maintained excellent performance in blood-stained CSF. BGA measurements correlated well with laboratory results (r = 0.980 and 0.999, respectively, P < 0.001).

CONCLUSIONS

CLac levels ≥6.0 mmol/L and CLGR ≥20.0 accurately identified CBI in neurosurgical patients, with CLGR exhibiting superior efficacy. The potential for instant BGA measurement suggests promise for point-of-care testing.

Broad Range Eubacterial Polymerase Chain Reaction of Cerebrospinal Fluid Reduces the Time to Exclusion of and Costs Associated with Ventriculostomy-Related Infection in Hemorrhagic Stroke

BACKGROUND

Patients with hemorrhagic stroke and an external ventricular drain in situ are at risk for ventriculostomy-related-infections (VRI). Because of the contamination of the cerebrospinal fluid (CSF) with blood and the high frequency of false negative CSF culture, the diagnosis of VRI remains challenging. This study investigated the introduction of CSF broad range eubacterial polymerase chain reaction (ePCR) and its effect on frequency and duration of antibiotic therapy for VRI, neurocritical care unit (NCCU) length of stay, related costs, and outcome.

METHODS

Between 2020 and 2022, we prospectively included 193 patients admitted to the NCCU of the University Hospital of Zürich with hemorrhagic stroke and an external ventricular drain for more than 48 h. Patient characteristics, serum inflammatory markers, white blood cell count in CSF, use and duration of antibiotic treatment for VRI, microbiological findings (CSF cultures and ePCR tests), and NCCU length of stay were compared in patients with no infection, noncerebral infection, suspected VRI, and confirmed VRI. Data of patients with suspected VRI of this cohort were compared with a retrospective cohort of patients with suspected VRI treated at our NCCU before the introduction of CSF ePCR testing (2013-2019).

RESULTS

Out of 193 patients, 12 (6%) were diagnosed with a confirmed VRI, 66 (34%) with suspected VRI, 90 (47%) with a noncerebral infection, and 25 (13%) had no infection at all. Compared with the retrospective cohort of patients, the use of CSF ePCR resulted in a reduction of patients treated for suspected VRI for the whole duration of 14 days (from 51 to 11%). Furthermore, compared with the retrospective group of patients with suspected VRI (n = 67), after the introduction of CSF ePCR, patients with suspected VRI had shorter antibiotic treatment duration of almost 10 days and, hence, lower related costs with comparable outcome at 3 months.

CONCLUSIONS

The use of CSF ePCR to identify VRI resulted in shorter antibiotic treatment duration without changing the outcome, as compared with a retrospective cohort of patients with suspected VRI.

Ventriculostomy-associated infection (VAI) in patients with acute brain injury-a retrospective study

BACKGROUND

Ventriculostomy-associated infection (VAI) is common after external ventricular drains (EVD) insertion but is difficult to diagnose in patients with acute brain injury. Previously, we proposed a set of criteria for ruling out VAI in traumatic brain injury. This study aimed to validate these criteria. For exploratory purposes, we sought to develop and validate a score for VAI risk assessment in patients with different types of severe acute brain injury.

METHODS

This retrospective cohort study included adults with acute brain injury who received an EVD and in whom CSF samples were taken over a period of 57 months. As standard non-coated bolt-connected EVDs were used. The predictive performance of biomarkers was analyzed as defined previously. A multivariable regression model was performed with five variables.

RESULTS

A total of 683 patients with acute brain injury underwent EVD placement and had 1272 CSF samples; 92 (13.5%) patients were categorized as culture-positive VAI, 130 (19%) as culture-negative VAI, and 461 (67.5%) as no VAI. A low CSF WBC/RBC ratio (< 0.037), high CSF/plasma glucose ratio (> 0.6), and low CSF protein (< 0.5g/L) showed a positive predictive value of 0.09 (95%CI, 0.05-0.13). In the multivariable logistic regression model, days to sample (OR 1.09; 95%CI, 1.03-1.16) and CSF WBC/RBC ratio (OR 34.86; 95%CI, 3.94-683.15) were found to predict VAI.

CONCLUSION

In patients with acute brain injury and an EVD, our proposed combined cut-off for ruling out VAI performed satisfactorily. Days to sample and CSF WBC/RBC ratio were found independent predictors for VAI in the multivariable logistic regression model.

Heparin-binding protein as a marker of ventriculostomy related infection and central nervous system inflammation in neuro-intensive care

OBJECTIVE

Diagnosis of ventriculostomy related infections (VRI) in the neuro-intensive care unit remains challenging and current biomarkers lack adequate precision. The aim of this study was to explore the potential of Heparin-binding protein (HBP) in cerebrospinal fluid (CSF) as a diagnostic biomarker of VRI.

METHODS

All patients treated with an external ventricular drain (EVD) between January 2009 and March 2010 at Skåne university hospital in Lund, Sweden, were consecutively included. CSF samples obtained during routine care were analyzed for HBP. VRI was defined as a positive bacterial microbiology test result on a CSF sample with an erythrocyte-corrected leukocyte count of > 50 × 106/l. HBP levels at VRI diagnosis was compared to peak HBP levels in non-VRI controls.

RESULTS

In total, 394 CSF samples from 103 patients were analyzed for HBP. Seven patients (6.8%) fulfilled VRI criteria. Levels of HBP were significantly higher in VRI subjects (31.7 ng/mL [IQR 26.9-40.7 ng/mL]) compared to non-VRI controls (7.7 ng/mL [IQR 4.1-24.5 ng/mL]) (p = 0.024). The AUC of the receiver operating characteristic (ROC) curve was 0.76 (95% confidence interval [CI], 0.62-0.90). Among non-VRI patients, HBP was highest in patients with acute bacterial meningitis. Patients with subarachnoid hemorrhage displayed higher HBP levels than those with traumatic brain injury or shunt dysfunction.

CONCLUSIONS

HBP levels were higher in VRI subjects and varied between patients and different diagnoses. To validate the clinical usefulness and added value of HBP as a biomarker for VRI, the results need to be confirmed in larger studies with head-to-head comparisons to current biomarkers.

Effect of Spontaneous Subarachnoid Hemorrhage on Cerebrospinal Fluid Indicators

The cerebrospinal fluid (CSF) analysis in ruptured aneurysms can be greatly affected by subarachnoid hemorrhage (SAH), making the diagnosis of intracranial infection more difficult after surgery. This study aimed to identify the reference value range of CSF in the pathological state following spontaneous SAH. A retrospective analysis of demographic and CSF data of all spontaneous SAH patients treated between January 2018 and January 2023 was conducted. A total of 101 valid CSF specimen data were collected for analysis. Our results indicate that in 95% of patients after spontaneous SAH, the leukocyte count in CSF was less than 880 × 10⁶/L. Additionally, the proportion of neutrophils, lymphocytes, and monocytes did not exceed 75%, 75%, and 15%, respectively, in 95% of the population. Furthermore, in 95% of the specimens, the concentration of chloride, glucose, and protein was >115 mmol/L, >2.2 mmol/L, and <2.3 g/L, respectively. Compared to the normal reference values, the CSF indexes after spontaneous SAH showed significant changes, especially in the leukocyte count, chloride concentration, and glucose concentration. Using "white blood cell count < 880/mm³, glucose > 2.2 mmol/L, chloride > 115" as the reference values for SAH pathological status is more meaningful for reference purposes.

Diagnostic Accuracy of Clinical Signs and Biochemical Parameters for External Ventricular Cerebrospinal Fluid Catheter-Associated Infection

Background and Objectives

Few prospective well-designed diagnostic accuracy studies have been performed to study the parameters of infection in patients suspected for external ventricular catheter-associated infection. Our objective was to analyze the diagnostic accuracy of clinical characteristics and biochemical and microbiological parameters in diagnosing external ventricular CSF catheter-associated infection.

Methods

From 2014 to 2017, we performed a single-center cohort study in consecutive patients at the intensive care unit who required an external ventricular CSF catheter in the Hague, the Netherlands. CSF was sampled and analyzed daily. Ventricular catheter-associated infection was defined according to the 2017 Infectious Diseases Society of America's Clinical Practice Guidelines. We compared clinical characteristics and biochemical parameters between patients with and without infection from 3 days before to 3 days after the day the CSF sample was collected that grew bacteria.

Results

A total of 103 patients were included of whom 15 developed a catheter-associated infection (15%). The median day cultures were positive was 3 days after CSF collection (interquartile range [IQR] +2 to +4). On day 0, none of the tests could differentiate between patients with and without infection. The CSF leukocyte count was increased in patients with ventricular catheter-associated infection as compared with patients without on days +2 and +3. The difference was most prominent on day +2 (1,703 × 10⁶/L [IQR 480–6,296] vs 80 × 10⁶/L [IQR 27–251]; p < 0.001; area under the curve [AUC] 0.87 [95% confidence interval (CI) 0.71–1.00]). Sensitivity for the CSF leukocyte count at a cutoff level >1,000 × 10⁶/L was 67% (95% CI 30–93), and specificity was 100% (95% CI 90–100); the positive predictive value was 100%, and the negative predictive value was 92% (95% CI 83–97). The percentage of polymorphonuclear cells (PMNs) was higher in patients with infection on days +1 and +2 (day +2 89% [IQR 78–94] vs 59% [IQR 39–75]; p < 0.01; AUC 0.91 [95% CI 0.81–1.0]).

Discussion

An elevated CSF leukocyte count and increased percentage of PMNs are the strongest indicators for external catheter-associated infections on the days before culture positivity. New CSF markers of drain-associated infection should be studied to enable earlier diagnosis and treatment in patients with an infection and reduce antibiotic treatment in those with no infection.

Classification of Evidence

This study provides Class I evidence that in individuals requiring an external ventricular CSF catheter, an elevated CSF leukocyte count and an increased percentage of PMNs are the strongest indicators of catheter-associated infections in the days before CSF culture positivity.

Diagnostic criteria of CNS infection in patients with external ventricular drainage after traumatic brain injury: a pilot study

BACKGROUND

Ventriculostomy-related infection (VRI) is a common complication in patients with traumatic brain injury (TBI) treated with an external ventricular drain (EVD). The aim of this study was to investigate incidence and characteristics of patients with VRI, and to explore diagnostic criteria to confidently rule out VRI in patients with TBI.

METHODS

This retrospective cohort pilot study included adults with severe TBI who were admitted to the ICU and received an EVD, during a 26-month period. Patients were categorized as having Culture-positive VRI, Culture-negative VRI, or No VRI. Variables that were potentially associated with Culture-positive VRI was analyzed, and predictive values were calculated.

RESULTS

75 of 215 patients with severe TBI (35%) underwent EVD placement; nine of these (12%) were classified as Culture-negative VRI and eight (11%) as Culture-positive VRI. The CSF cell counts that led to VRI treatment were compared with 46 CSF cell counts from No VRI patients. A CSF/plasma glucose ratio below 0.6 had a negative predictive value (NPV) for culture-verified VRI of 0.97 (95% CI: 0.85-1), whereas a combination of three CSF-derived biomarkers within the reference limits (white/red blood cell ratio, CSF/plasma glucose ratio, and protein content) ruled out Culture-positive VRI in this cohort (PPV 0, 95% CI: 0-0.14). C-reactive protein did not reliably predict VRI.

CONCLUSIONS

In this pilot study of patients after severe, a combination of biomarkers within reference limits ruled out VRI (PPV 0, CI: 0-0.14). Hypoglycorrhachia was a sensitive marker of VRI (NPV 0.97, CI: 0.85-1). Systemic signs and markers of infection did not predict VRI.

Current Perspectives on the Diagnosis and Management of Healthcare-Associated Ventriculitis and Meningitis

Ventriculitis or post-neurosurgical meningitis or healthcare-associated ventriculitis and meningitis (VM) is a severe infection that complicates central nervous system operations or is related to the use of neurosurgical devices or drainage catheters. It can further deteriorate patients who have already presented significant neurologic injury and is associated with high morbidity, mortality, and poor functional outcome. VM can be difficult to distinguish from aseptic meningitis, inflammation that follows hemorrhagic strokes and neurosurgical operations. The associated microorganisms can be either skin flora or nosocomial pathogens, most commonly, Gram-negative bacteria. Classical microbiology can fail to isolate the culprit pathogen. Novel cerebrospinal fluid (CSF) biomarkers and molecular microbiology can fill the diagnostic gap and expedite pathogen identification and treatment. The pathogens may demonstrate significant resistant patterns and their antibiotic treatment can be difficult, as many important drug classes, including the beta-lactams and the glycopeptides, hardly penetrate to the CSF, and do not achieve therapeutic levels at the site of the infection. Treatment modifications, such as higher daily dose and prolonged or continuous administration, might increase antibiotic levels in the site of infection and facilitate pathogens clearance. However, in the case of therapeutic failure or infection due to difficult-to-treat bacteria, the direct antibiotic instillation into the CSF, in addition to the intravenous antibiotic delivery, may help in the resolution of infection. However, intraventricular antibiotic therapy may result in aseptic meningitis and seizures, concerning the administration of aminoglycosides, polymyxins, and vancomycin. Meanwhile, bacteria form biofilms on the catheter or the device that should routinely be removed. Novel neurosurgical treatment modalities comprise endoscopic evacuation of debris and irrigation of the ventricles. VM prevention includes perioperative antibiotics, antimicrobial impregnated catheters, and the implementation of standardized protocols, regarding catheter insertion and manipulation.

Central nervous system infections associated with neurologic devices

PURPOSE OF REVIEW

To review recent data on the epidemiology, microbiology, diagnosis, and management of central nervous system (CNS) infections associated with neurologic devices.

RECENT FINDINGS

The increasing use of implanted neurologic devices has led to an increase in associated infections. Cerebrospinal fluid (CSF) inflammation may be present after a neurosurgical procedure, complicating the diagnosis of CNS infection. Newer biomarkers such as CSF lactate and procalcitonin show promise in differentiating infection from other causes of CSF inflammation. Molecular diagnostic tests including next-generation or metagenomic sequencing may be superior to culture in identifying pathogens causing healthcare-associated ventriculitis and meningitis.

SUMMARY

Neurologic device infections are serious, often life-threatening complications. Rapid recognition and initiation of antibiotics are critical in decreasing morbidity. Device removal is usually required for cure.

Healthcare-associated ventriculitis: current and emerging diagnostic and treatment strategies

Introduction: Healthcare-associated ventriculitis and meningitis occur after neurosurgical procedures, is associated with an adverse outcome in the majority of patients and represent a diagnostic challenge to clinicians. As the cerebrospinal fluid (CSF) culture is the cornerstone of diagnosis, obtaining CSF studies prior to starting antibiotic therapy is key.Areas covered: This review will evaluate the incidence, risk factors, clinical presentation, diagnosis, empirical intravenous antibiotic therapy, adjunctive intrathecal therapy, microbiology, prognosis, and prevention of HCAVM. We highlight the challenges and limitations of the currently available diagnostic methods and definitions and explore novel technologies. Our review included the search for published literature until June 2020.Expert opinion: Despite available preventive measures, HCAVM continues to occur and to be independently associated with significant neurological morbidity and mortality in the majority of patients. The cornerstone of the diagnosis of HCAVM is a positive CSF culture but the microbiological yield is reduced to ~50% with prior antimicrobial therapy. Although the CSF profile is not affected by antibiotic therapy it has a fair diagnostic accuracy. Future research efforts should concentrate in identifying novel diagnostic tools such as polymerase chain reaction (PCR) or metagenomic sequencing.

Application of combined cerebrospinal fluid physicochemical parameters to detect intracranial infection in neurosurgery patients

Routine test of cerebrospinal fluid (CSF), such as glucose concentrations, chloride ion, protein and leukocyte, as well as color, turbidity and clot, were important indicators for intracranial infection. However, there were no models to predict the intracranial infection with these parameters. We collected data of 221 cases with CSF positive-culture and 50 cases with CSF negative culture from January 1, 2016 to December 31, 2018 in the First Affiliated Hospital of Nanchang University, China. SPSS17.0 software was used to establish the model by adopting seven described indicators, and P < 0.05 was considered as statistically significant. Meanwhile, 40 cases with positive-culture and 10 cases with negative-culture were selected to verify the sensitivity and specificity of the model. The results showed that each parameter was significant in the model establishment (P < 0.05). To extract the above seven parameters, the interpretation model C was established, and C = 0.952–0.183 × glucose value (mmol/L) - 0.024 × chloride ion value (mmol/L)- 0.000122 × protein value (mg/L) - 0.0000859 × number of leukocytes per microliter (× 10⁶/L) + 1.354 × color number code + 0.236 × turbidity number code + 0.691 × clot number code. In addition, the diagnostic sensitivity and specificity of the model were 85.0 and 100%, respectively. The combining application of seven physicochemical parameters of CSF might be of great value in the diagnosis of intracranial infection for adult patients.

Utility of the Cell Index in Predicting External Ventricular Drain-Related Ventriculo-Meningitis

BACKGROUND/OBJECTIVE

Ventriculo-meningitis (VM) is an important complication of external ventricular drains (EVDs) in neurosurgical patients. Consequences include increased morbidity, mortality, and duration of hospital stay. Early diagnosis of EVD-associated VM allows earlier treatment intervention. The cell index (CI) may provide a simple measure that overcomes the limitations of isolated cerebrospinal fluid (CSF) parameters and other diagnostic tests, allowing earlier prediction of VM.

METHODS

All patients admitted to a tertiary hospital and requiring EVD insertion during 2015 and 2016 were assessed for inclusion in this retrospective case-control study. Patients with a known or suspected intracranial infection were excluded. Of the 186 patients who underwent EVD insertion, 95 patients were included in the final cohort. Data pertaining to patient characteristics and laboratory indices were extracted from health records and the microbiology laboratory database. The CI was calculated as the ratio of temporally related CSF leukocytes/erythrocytes to peripheral blood leukocytes/erythrocytes. Data from patients with microbiologically confirmed VM were analyzed in comparison with those not developing VM during the course of their stay. Categorical and continuous variables with skewed distributions were analyzed by Chi square and Mann-Whitney tests, respectively.

RESULTS

EVD-associated VM developed in 7.4% of patients. The highest CSF CI (within 3 days prior to diagnosis of VM or at any time for those not developing VM) differed significantly between the two groups (16; IQR 10.8-48.5 vs. 3.3; IQR 1.0-12.8, respectively; p = .046). The area under the receiver operating characteristic curve (AUROC) for the highest CI was 0.727 (95% confidence interval [CI] 0.526-0.929; p = .027). A CI of 10.4 provided a sensitivity and specificity of 80.5% and 70.5%, respectively, for the early diagnosis of VM.

CONCLUSIONS

In neurosurgical patients with an EVD, the CSF CI significantly predicted the development of VM.

Healthcare-Associated Infections in the Neurocritical Care Unit

PURPOSE OF REVIEW

This article summarizes updated data and knowledge on healthcare-associated infections in the neurocritical care unit, with a focus on central nervous system infections and systemic infectious complications in patients with acute brain disease. It also reviews the concept of brain injury-induced immune modulation, an underlying mechanism to explain why the neuro-ICU population is particularly susceptible to infections.

RECENT FINDINGS

Healthcare-associated infections in the neuro-ICU are common: up to 40 % of meningitides in the developed world are now healthcare-associated. The number of gram-negative infections is rising. New diagnostic approaches attempt to aid in the diagnosis of healthcare-associated meningitis and ventriculitis. Healthcare-associated infections in the neurocritical care unit remain a challenge for diagnosis, treatment, and prevention. Gaining a better understanding of at-risk patients and development of preventative strategies will be the goal for future investigation.