Indicators of external ventricular drainage-related infections--a retrospective observational study

Performance of routine surveillance diagnostics of external ventricular drain-associated infections in a critical care setting: a retrospective cohort study

INTRODUCTION

External ventricular drains (EVDs) are crucial for treating neurocritically ill patients but are complicated by feared EVD-associated infections (EVDIs) in up to 35% of all inserted drains, contributing significantly to morbidity, mortality and account for a significant proportion of intensive care unit (ICU) antibiotic use. However, the lack of a universal definition for EVDIs leads to inconsistent diagnostic criteria across studies, with a concern of substantial overtreatment with broad-spectrum antibiotics. This study aimed to evaluate if current EVDI surveillance parameters can be optimized to better distinguish true from suspected EVDI.

METHODS

We conducted a retrospective cohort study at the Karolinska University Hospital ICU, including all patients treated with EVDs between 2006 and 2023, excluding patients with primary central nervous system (CNS) infections. EVDI surveillance included biweekly sampling and cultures from cerebrospinal fluid (CSF). Patients were categorized as no infection (NI), suspected infection (SI), or verified infection (VI) based on culture results and treatment status. We employed classification and regression analyses to identify predictors of VI.

RESULTS

Among 1,828 patients with EVDs, 29.8% were initiated on antibiotic treatment due to suspected infection and 4.1% were found to have culture confirmed infections. The main finding is that current accepted diagnostic parameters cannot distinguish aseptic inflammation from true EVDI. In multivariable logistic analysis the best models exhibited low accuracy, with a pseudo- R 2 of only 0.06. CSF lactate was the most important metric in a univariable setting, however with a cut-off of 8.9 mmol/L it showed low discrimintive ability and limited clinical utility.

CONCLUSIONS

In this study we evaluate current accepted EVDI surveillance methods in, to our knowledge, the largest cohort of paired samples to date. We find that current surveillance parameters cannot distinguish aseptic CNS inflammation from true EVDIs in an ICU setting. This contributes to a significant antibiotic overtreatment, with 25% of our entire cohort being unnecessarily initiated on broad-spectrum antibiotics, a number we expect can be generalized. We identify a large clinical problem with consequences on both a individual and population level, and recommend that future research focus on evaluating new techniques, such as fast bedside sequencing methods.

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.

Treatment of wound infections linked to neurosurgical implants

As neurosurgery has advanced technologically, more and more neurosurgical implants are being employed on an aging patient population with several comorbidities. As a result, there is a steady increase in the frequency of infections linked to neurosurgical implants, which causes serious morbidity and mortality as well as abnormalities of the skull and inadequate brain protection. We discuss infections linked to internal and external ventricular and lumbar cerebrospinal fluid drainages, neurostimulators, craniotomies, and cranioplasty in this article. Biofilms, which are challenging to remove, are involved in all implant-associated illnesses. It takes a small quantity of microorganisms to create a biofilm on the implant surface. Skin flora bacteria are implicated in the majority of illnesses. Microorganisms that cause disruptions in wound healing make their way to the implant either during or right after surgery. In about two thirds of patients, implant-associated infections manifest early (within the first month after surgery), whereas the remaining infections present later as a result of low-grade infections or by direct extension from adjacent infections (per continuitatem) to the implants due to soft tissue damage. Except for ventriculo-atrial cerebrospinal fluid shunts, neurosurgical implants are rarely infected by the haematogenous route. This research examines established and clinically validated principles that are applicable to a range of surgical specialties using implants to treat biofilm-associated infections in orthopaedic and trauma cases. Nevertheless, there is little evidence and no evaluation in sizable patient populations to support the success of this extrapolation to neurosurgical patients. An optimal microbiological diagnostic, which includes sonicating removed implants and extending culture incubation times, is necessary for a positive result. Additionally, a strategy combining surgical and antibiotic therapy is needed. Surgical procedures involve a suitable debridement along with implant replacement or exchange, contingent on the biofilm's age and the state of the soft tissue. A protracted biofilm-active therapy is a component of antimicrobial treatment, usually lasting 4-12 weeks. This idea is appealing because it allows implants to be changed or kept in place for a single surgical procedure in a subset of patients. This not only enhances quality of life but also lowers morbidity because each additional neurosurgical procedure increases the risk of secondary complications like intracerebral bleeding or ischemia.

Cerebrospinal fluid white cell count to red cell count ratio as a predictor of ventriculitis in patients with external ventricular drains

INTRODUCTION

External ventricular drain (EVD) associated ventriculitis is a complication of EVD placement associated with significant morbidity and mortality. Gold-standard for EVD associated bacterial ventriculitis diagnosis involves cerebrospinal fluid (CSF) sampling from the EVD with microscopy, culture and sensitivity testing. The ratio of white blood cells to red blood cells has anecdotally been considered a predictive factor in diagnosing EVD associated ventriculitis, however no study has been done demonstrating this.

METHODS

A retrospective cross-sectional study was designed to assess whether the ratio of CSF white blood cells to red blood cells could be used to diagnose EVD associated ventriculitis. Data was collected for all patients undergoing EVD insertion at a major neurosurgical unit in Sydney, Australia. A receiver operator characteristics (ROC) curve was used to determine if this ratio was useful, and Youden's index was calculated to determine the appropriate cut-off point.

RESULTS

This sample of n = 157 consecutive patients a total of 29 patients were diagnosed with ventriculitis. The area under the ROC curve was significant (0.706, P <0.001), and Youden's index demonstrated an appropriate cut-off point was a ratio of 1:106.

DISCUSSION

CSF parameters have long been considered predictive of EVD associated ventriculitis. We demonstrated that using a component of routine testing it is possible to accurately predict a ventriculitis diagnosis. As the ratio is used, it enables discrimination in a raised white blood cell count due to local trauma with interventricular bleeding.

CONCLUSION

CSF white blood cell to red blood cell ratio is an appropriate diagnostic test for ventriculitis.

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.

Risk Factors Promoting External Ventricular Drain Infections in Adult Neurosurgical Patients at the Intensive Care Unit-A Retrospective Study

Objectives: Multiple risk factors have been described to be related to external ventricular drain (EVD) associated infections, with results varying between studies. Former studies were limited by a non-uniform definition of EVD associated infection, thus complicating a comparison between studies. In this regard, we assessed risk factors promoting EVD associated infections and propose a modified practice-oriented definition of EVD associated infections.

Methods: We performed a retrospective, single-center study on patients who were treated with an EVD, at the neurosurgical intensive care unit (ICU) at a tertiary center between 2008 and 2019. Based on microbiological findings and laboratory results, patients were assigned into an infection and a non-infection group. Patient characteristics and potential risk factors were compared between the two groups (p < 0.05). Receiver operating characteristics (ROC) for significant clinical, serum laboratory and cerebrospinal fluid (CSF) parameters were calculated.

Results: In total, 396 patients treated with an EVD were included into the study with a mean age of 54.3 (range: 18–89) years. EVD associated infections were observed in 32 (8.1%) patients. EVD insertion at another hospital (OR 3.86), and an increased CSF sampling frequency of more than every third day (OR 12.91) were detected as major risk factors for an EVD associated infection. The indication for EVD insertion, surgeon's experience, the setting of EVD insertion (ICU vs. operating room) and the operating time did not show any significant differences between the two groups. Furthermore, ROC analysis showed that clinical, serum laboratory and CSF parameters did not provide specific prediction of EVD associated infections (specificity 44.4%). This explains the high overtreatment rate in our cohort with the majority of our patients who received intrathecal vancomycin (63.3%), having either negative microbiological results (n = 12) or were defined as contaminations (n = 7).

Conclusions: Since clinical parameters and blood analyzes are not very predictive to detect EVD associated infections in neurosurgical patients, sequential but not too frequent microbiological and laboratory analysis of CSF are still necessary. Furthermore, we propose a uniform classification for EVD associated infections to allow comparability between studies and to sensitize the treating physician in determining the right treatment.

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.

Factors and measures predicting external CSF drain-associated ventriculitis

Objective

To determine the diagnostic value of clinical factors and biochemical or microbiological measures for diagnosing a drain-associated ventriculitis, we summarized the available evidence.

Methods

We performed a systematic review and meta-analysis of studies of patients with external ventricular CSF drains who developed drain-associated ventriculitis by searching MEDLINE, EMBASE, and CENTRAL electronic database. We reported the occurrence of abnormal test results in patients with and without drain-associated ventriculitis. For continuous variables, we recalculated mean values presented in multiple studies.

Results

We identified 42 articles published between 1984 and 2018 including 3,035 patients with external CSF drains of whom 697 (23%) developed drain-associated bacterial ventriculitis. Indications for drain placement were subarachnoid, intraventricular or cerebral hemorrhage or hemorrhage not further specified (69%), traumatic brain injury (13%), and obstructive hydrocephalus secondary to a brain tumor (10%). Fever was present in 116 of 162 patients with ventriculitis (72%) compared with 80 of 275 (29%) patients without ventriculitis. The CSF cell count was increased for 74 of 80 patients (93%) with bacterial ventriculitis and 30 of 95 patients (32%) without ventriculitis. CSF culture was positive in 125 of 156 episodes classified as ventriculitis (80%), and CSF Gram stain was positive in 44 of 81 patients (54%). In patients with ventriculitis, PCR on ribosomal RNA was positive on 54 of 78 CSF samples (69%).

Conclusion

Clinical factors and biochemical and microbiological measures have limited diagnostic value in differentiating between ventriculitis and sterile inflammation in patients with external CSF drains. Prospective well-designed diagnostic accuracy studies in drain-associated ventriculitis are needed.

Peripheral white blood cell count as a screening tool for ventriculostomy-related infections

One of the most common complications following external ventricular drain (EVD) placement is infection. Routine cultures of cerebrospinal fluid (CSF) are often used to screen for infection, however several days may pass before infection is discovered. In this study, we compared the predictive value of daily recorded vital sign parameters and peripheral white blood count (WBC) in identifying ventriculostomy-related infections. Patients with EVDs who had CSF cultures for microorganisms performed between January 2011 and July 2017 were assigned to either an infected and/or uninfected study group. Clinical parameters were then compared using t-test, chi squared and multiple logistic regression analyses. Patients of any age and gender were included. One hundred seventy uninfected and 10 infected subjects were included in the study. Nine of the 10 infected patients had an elevated WBC (>10.4 × 10³/μL), with a significantly greater WBC (15.9 × 10³/μL) than the uninfected group (10.4 × 10³/μL) (p-value ≤ 0.0001). Using logistic regression, we found no association between patient vital signs and CSF infection except for WBC (p = .003). As a diagnostic marker for CSF infection, the sensitivity and specificity of WBC elevation greater than 15 × 10³/μL was 70% (7/10) and 90.2% (147/163), respectively. This study serves as a 'proof of concept' that WBC could be useful as potential screening tool for early detection of CSF infection post-EVD placement. Future investigation using a large, multicenter prospective study is needed to further assess the applicability of this parameter.

Neutrophil CD64 index in cerebrospinal fluid as a marker of bacterial ventriculitis in children with external ventricular drainage

Background

Bacterial ventriculitis is a common complication in children with temporary external ventricular drains (EVD) and the diagnosis is challenging. The present study compared the diagnostic accuracy of novel cerebrospinal fluid (CSF) marker - CD64 expression on neutrophils measured as neutrophil CD64 index (CD64in) to routine laboratory CSF and blood markers for bacterial ventriculitis in children with EVD.

Methods

We conducted a prospective, observational study, enrolling children with EVD. CD64in in CSF together with CSF markers (leukocyte count, percentage of neutrophils, glucose, and proteins) and blood markers (leukocyte and differential count, C-reactive protein (CRP), and procalcitonin (PCT)) were studied at the time of suspected bacterial ventriculitis. CD64in was measured by flow cytometry. Diagnostic accuracy determined by the area under the receiver–operating characteristic (ROC) curves (AUC) was defined for each marker.

Results

Thirty-three episodes of clinically suspected ventriculitis in twenty-one children were observed during a 26-month period. Episodes were classified into those with microbiologically proven ventriculitis (13 episodes) and into those with microbiologically negative CSF (20 episodes). CD64in and leukocyte count were the only CSF markers that could differentiate between groups with diagnostic accuracy of 0.875 and 0.694, respectively. Among blood markers only CRP and band neutrophils differentiated between groups with diagnostic accuracy of 0.792 and 0.721, respectively.

Conclusions

CD64in in CSF is a promising diagnostic marker of bacterial ventriculitis in children with EVD as it has higher diagnostic accuracy than routine blood and CSF markers for diagnosing bacterial ventriculitis at the time of clinical suspicion.

Modalities and accuracy of diagnosis of external ventricular drainage-related infections: a prospective multicentre observational cohort study

BACKGROUND

Device infection is a major complication of placement external ventricular drains (EVD). Diagnostic features are often masked by underlying disease or cerebrospinal fluid (CSF) contamination by blood. We aim to assess which diagnostic modalities are applied for EVD-related infection (ERI) diagnosis and evaluate their accuracy.

METHODS

This observational prospective study included 187 adult patients with an EVD. Modalities of clinical diagnosis of ERI diagnosed by treating physicians on clinical grounds and blood and CSF analysis (clinically diagnosed ERI (CD-ERI)) were assessed prospectively. Additionally, the diagnostic accuracy of clinical and laboratory parameters for the diagnosis of culture proven ERI (CP-ERI) was evaluated, using data of the study patients and including a retrospective cohort of 39 patients with CP-ERI.

RESULTS

Thirty-one CD-ERIs were diagnosed in the prospective cohort. Most physicians used CSF analysis to establish the diagnosis. ROC analysis revealed an AUC of 0.575 (p = 0.0047) for the number of positive SIRS criteria and AUC of 0.5420 (p = 0.11) for the number of pathological neurological signs for diagnosis of CP-ERI. Diagnostic accuracy of laboratory values was AUC 0.596 (p = 0.0006) for serum white blood cell count (WBCC), AUC 0.550 (p = 0.2489) for serum C-reactive protein, AUC 0.644 (p < 0.0001) for CSF WBCC and AUC 0.690 for CSF WBC/red blood cell count ratio (both p < 0.0001). Neither a temporal trend in potential predictors of CP-ERI nor a correlation between clinical diagnosis and proven CSF infection was found.

CONCLUSIONS

Clinicians base their diagnosis of ERI mostly on CSF analysis and occurrence of fever, leading to over-diagnosis. The accuracy of the clinical diagnosis is low. Commonly used clinical and laboratory diagnostic criteria have a low sensitivity and specificity for ERI.

Polymerase chain reaction based detection of bacterial 16S rRNA gene in the cerebrospinal fluid in the diagnosis of bacterial central nervous system infection in the course of external cerebrospinal fluid drainage. Comparison with standard diagnostics currently used in clinical practice

BACKGROUND AND PURPOSE

External drainage of cerebrospinal fluid (CSF) is a commonly used neurosurgical procedure. Complications of the procedure comprise central nervous system (CNS) bacterial infections, the frequency of which is estimated at around 6-10%. Detection of these infections is ineffective in many cases. The aim of the study was to evaluate the usefulness of a polymerase chain reaction (PCR)-based detection of bacterial 16S rRNA gene (16S rDNA) in the CSF.

MATERIAL AND METHODS

The study group consisted of 50 patients. Clinical signs of CNS infection were monitored and routine laboratory and microbiological tests were performed. The results of standard methods were compared with the bacterial 16S rDNA detection.

RESULTS

Using cultures, CNS infection was diagnosed in 8 patients, colonization of the drainage catheter in 6 patients, and sample contamination in 7 patients. In the group of the remaining 29 patients, no positive CSF culture was obtained and 13 of these patients also had all negative results for 16S rDNA detection. For the remaining 16 patients of this group, CNS infection, colonization of the catheter and sample contamination were diagnosed via PCR alone. Routine biochemical CSF tests and blood inflammatory parameters had a supporting value.

CONCLUSIONS

Routine hospital tests do not provide rapid and efficient detection of the external drainage related bacterial CNS infection. It is justified to use several diagnostic methods simultaneously. The16S rDNA determination in CSF can increase the probability of detection of possible pathogens.