Neutrophil CD64: diagnostic accuracy and prognostic value in patients presenting to the emergency department

Neutrophil CD64-a prognostic marker of sepsis in intensive care unit: a prospective cohort study

Background

Little is known about the prognostic ability of nCD64 in critically ill patients. This study aimed to assess the prognostic values of nCD64 in adult ICU patients with sepsis.

Methods

A prospective cohort study was conducted at the ICU of Cho Ray Hospital in Vietnam between January 2019 to September 2020. All newly admitted 86 septic patients diagnosed based on sepsis-3 criteria were included. An evaluation of nCD64 was performed at admission (T0) and 48 h thereafter (T48). Delta nCD64 (nCD64 T48 - nCD64 T0), %delta nCD64 [(nCD64 T48 - nCD64 T0)/nCD64 T0 x 100%], APACHE II and SOFA scores were calculated and examined. Serum procalcitonin levels and white blood cell counts were documented. Spearman's rank correlation coefficient was used to test the correlation between nCD64 and severity scores. Receiver-operating characteristic (ROC) curve was performed to evaluate the predictive efficacy of the sepsis parameters.

Results

Patients with septic shock had significantly higher nCD64 levels than septic patients [3,568 (2,589; 5,999) vs. 1,514 (1,416;2,542) molecules/cell, p < 0.001]. nCD64 T0 and SOFA scores had a moderately positive linear correlation (R = 0.31, p = 0.004). In the survivor group, nCD64 levels significantly decreased within the first 48 h of admission (p < 0.001), while this trend was not statistically significant in the non-survivor group (p = 0.866). The area under the ROC curve (AUC) value of %delta nCD64 combined with APACHE II score (0.81) was higher than that of any other parameter alone or in combination with each other.

Conclusion

The nCD64 index may serve as a valuable biomarker for predicting the course of sepsis. Monitoring changes in nCD64 during the initial 48 h of admission can aid in predicting the prognosis of septic patients. The use of a combination of the trends of nCD64 index in the first 48 h with APACHE II score would further enhance the predictive accuracy. More studies with longer follow-ups are needed to fully understand the implications of serial trend and kinetics of nCD64 in septic patients.

Prognostic performance of neutrophil CD64 expression in patients with complicated intra-abdominal infections - a prospective study

No study yet analyzed the prognostic abilities of neutrophil CD64 expression (nCD64) in complicated intra-abdominal infections (cIAIs), therefore our aim was to evaluate the possible association between this biomarker and outcome in such patients. This single-center prospective study was conducted in the Department of Surgical Diseases at a University Hospital 'Prof. Dr. Stoyan Kirkovich' Stara Zagora for the period November 2018 - August 2021. We used flow cytometry to measure the percentage of nCD64 preoperatively and on the 3rd postoperative day (POD) in 62 patients with cIAIs and 31 healthy controls. Of the 62 enrolled patients, nine (14.5%) died during hospitalization. The perioperative expression of nCD64 was significantly higher in non-survivors compared to survivors (p = 0.02 before surgery and p = 0.024 after surgery). ROC Curve analysis revealed the good prognostic value of pre- and postoperative nCD64 levels as mortality predictors (AUROC = 0.744 and 0.765, respectively). Preoperatively, the identified sensitivity and specificity for nCD64 cut-off = 94.8% were 66.7% and 84.6%, respectively and on the 3rd POD for nCD64 cut-off = 84.85% we observed a sensitivity of 71.4% and a specificity of 78.8%. Neutrophil CD64 shows good prognostic value in patients with cIAIs both preoperatively and on the 3rd POD.

The Low Expression of Fc-Gamma Receptor III (CD16) and High Expression of Fc-Gamma Receptor I (CD64) on Neutrophil Granulocytes Mark Severe COVID-19 Pneumonia

Hyperinflammation through neutrophil granulocytes contributes to disease severity in COVID-19 pneumonia and promotes acute lung failure. Understanding the mechanisms of the dysregulations within the myeloid cell compartment may help to improve therapies for severe COVID-19 infection. Here, we investigated the immunopathological characteristics of circulating neutrophil granulocytes and monocytes in 16 patients with COVID-19 pneumonia by multiparameter flow cytometry in comparison to 9 patients with pulmonary infiltrates but without COVID-19. We correlated the immunophenotypes with the scores of the severity-of-disease classification system, APACHE-II. We found that the mean fluorescence intensity (MFI) of CD15, which is important for the transendothelial migration, was significantly reduced in the patients with COVID-19 (difference ± SD; 295.70 ± 117.50 MFI; p = 0.02). In addition, the granularity was significantly lower in the neutrophil granulocytes of patients with COVID-19 (difference ± SD; 1.11 ± 0.43 side-scatter ratio; p = 0.02). Moreover, the Fc-gamma receptor III (CD16) and Fc-gamma receptor I (CD64) on the neutrophil granulocytes were expressed discordantly with COVID-19 severity. CD16 correlated as inversely proportional (ρ = (-)0.72; 95% CI (-)0.92-(-)0.23; p = 0.01) and CD64 as proportional (ρ = 0.76; 95% CI 0.31-0.93; p = 0.01) with the APACHE-II scores of the patients. We conclude that the deviant expression of the Fc-gamma receptors might play role in a dysregulated antibody-mediated phagocytosis in severe cases of COVID-19 pneumonia.

Neutrophil CD64 a Diagnostic and Prognostic Marker of Sepsis in Adult Critically Ill Patients: A Brief Review

INTRODUCTION

Sepsis is a life-threatening organ dysfunction with increased incidence of morbidity and mortality. Early diagnosis and prompt therapeutic intervention is the cornerstone of sepsis care. Biomarkers play an important role in sepsis having both diagnostic and prognostic implications. Neutrophil CD64 (nCD64) is a useful candidate biomarker for sepsis. Neutrophil CD64 also known as Fc receptor 1 (FcR1), is a high-affinity receptor present on neutrophils for Fc part of immunoglobulin-G (IgG) heavy chain. Its expression gets strongly upregulated in response to proinflammatory cytokines of infection within 4-6 hours. Neutrophil CD64 integrates function involving both innate and adaptive immune responses. The aim of this review is to present literature about nCD64 as a diagnostic and prognostic marker in patients with sepsis/septic shock.

BACKGROUND

The authors searched articles over 13 years, i.e., from 2006 to 2019. They included articles written in English only and further reviewed the reference list of selected articles to obtain potentially relevant articles. Reviews, letters, commentaries, correspondences, case reports, conference abstracts, expert opinions, editorials, and animal experiments were excluded. Articles involving pediatric patients (≤18 years) were also excluded.

REVIEW RESULTS

Several studies have indicated that nCD64 is a highly sensitive and specific marker for the diagnosis of sepsis. Various combinations of biomarkers have been used with nCD64 for a better diagnostic value. Neutrophil CD64 as a prognostic marker in critically ill patients needs to be explored more. Most of the existing literatures have highlighted its prognostic utility based on single value at enrolment. There are limited literatures on prognostic implications of serial trend and kinetics of nCD64.

CONCLUSION

Neutrophil CD64 is a useful diagnostic and prognostic marker of sepsis in critically ill patients. Additional studies are needed on nCD64 in sepsis based on sepsis-3 criteria. Further trials with large sample size are needed to establish prognostic implications of serial nCD64 trend.

HOW TO CITE THIS ARTICLE

Patnaik R, Azim A, Agarwal V. Neutrophil CD64 a Diagnostic and Prognostic Marker of Sepsis in Adult Critically Ill Patients: A Brief Review. Indian J Crit Care Med 2020;24(12):1242-1250.

Association of the early absolute CD64-expressing neutrophil count and sepsis outcome

To evaluate the early absolute CD64/CD15/CD45 neutrophil count as a marker of prognosis of sepsis outcome the absolute CD64/CD15/CD45 count was measured by flow cytometry in 65 patients with confirmed or suspected Gram-negative sepsis and organ dysfunction. Serum interleukin(IL)-8 and interferon-gamma (IFNγ) were measured by an enzyme immunoassay. An absolute count lower than 2500 cells/mm³ could early discriminate non-survivors with sensitivity 82.9% (OR 3.46, 95%CIs 1.10-10.95, p 0.042). After forward step-wise Cox- regression analysis, it was found that acute coagulopathy, acute renal injury, and an early absolute CD64/CD15/CD45 count lower than 2500/mm³ were independently associated with unfavorable outcome. The OR for death among patients with an absolute CD64/CD15/CD45 neutrophil count greater than 2500/mm³ and circulating IL-8 greater than 95 pg/ml was 0.44; this was significantly increased to 7.44 among patients with an absolute CD64/CD15/CD45 neutrophil count lower than 2500/mm³ (p 0.045 by the Breslow-Day's test; p 0.046 by the Tarone's test). An absolute CD64/CD15/CD45 count below 2500/mm³ can be a useful prognosticator of sepsis outcome and a probable indicator of sepsis immunosuppression.

Correlation of Neutrophil CD64 with Clinical Profile and Outcome of Sepsis Patients during Intensive Care Unit Stay

Introduction:

Neutrophil CD64 (nCD64) has been found to identify sepsis from nonseptic patients. It is also reported to be a predictor of survival and severity of sepsis. The goal of this study was to correlate serial nCD64 with Intensive Care Unit (ICU) outcome and severity of sepsis.

Materials and Methods:

A prospective observational study was conducted in 12-bedded critical care unit of a tertiary care center. Adult patients with sepsis were included in this study. Demographics, illness severity scores, clinical parameters, laboratory data, and 28-day outcome were recorded. Serial nCD64 analysis was done (on days 0, 4, and 8) in consecutive patients.

Results:

Fifty-one consecutive patients were included in the study. Median Acute Physiology and Chronic Health Evaluation II was 16 (12–20) and mean Sequential Organ Failure Assessment was 9 (8–10). Compared to survivors, nonsurvivors had higher nCD64 on day 8 (P = 0.001). nCD64 was higher in the septic shock group compared to sepsis group on days 0 and 8 (P < 0.05). Survivors showed improving trend of nCD64 over time while nonsurvivors did not. This trend was similar in the presence or absence of septic shock. nCD64 count was a good predictor of the septic shock on day 0 (area under the curve [AUC] = 0.747, P = 0.010) and moderate predictor at day 8 (AUC = 0.679, P = 0.028).

Conclusion:

Monitoring serial nCD64 during ICU stay may be helpful in determining the clinical course of septic patients.

The intensive care infection score - a novel marker for the prediction of infection and its severity

Background

The prediction of infection and its severity remains difficult in the critically ill. A novel, simple biomarker derived from five blood-cell derived parameters that characterize the innate immune response in routine blood samples, the intensive care infection score (ICIS), could be helpful in this respect. We therefore compared the predictive value of the ICIS with that of the white blood cell count (WBC), C-reactive protein (CRP) and procalcitonin (PCT) for infection and its severity in critically ill patients.

Methods

We performed a multicenter, cluster-randomized, crossover study in critically ill patients between January 2013 and September 2014. Patients with a suspected infection for which blood cultures were taken by the attending intensivist were included. Blood was taken at the same time for WBC, ICIS, CRP and PCT measurements in the control study periods. Results of imaging and cultures were collected. Patients were divided into groups of increasing likelihood of infection and invasiveness: group 1 without infection or with possible infection irrespective of cultures, group 2 with probable or microbiologically proven local infection without blood stream infection (BSI) and group 3 with BSI irrespective of local infection. Septic shock was assessed.

Results

In total, 301 patients were enrolled. CRP, PCT and ICIS were higher in groups 2 and 3 than group 1. The area under the receiver operating characteristic curve (AUROC) for the prediction of infection was 0.70 for CRP, 0.71 for PCT and 0.73 for ICIS (P < 0.001). For the prediction of septic shock the AUROC was 0.73 for CRP, 0.85 for PCT and 0.76 for ICIS. These AUROC did not differ from each other.

Conclusion

The data suggest that the ICIS is potentially useful for the prediction of infection and its severity in critically ill patients, non-inferiorly to CRP and PCT. In contrast to CRP and PCT, the ICIS can be determined routinely without extra blood sampling and lower costs, yielding results within 15 minutes.

Trial registration

ClinicalTrials.gov identifier: ID NCT01847079. Registered on 24 April 2013.

Could Neutrophil CD64 Expression Be Used as a Diagnostic Parameter of Bacteremia in Patients with Febrile Neutropenia?

OBJECTIVE

The aim of this study is to investigate if neutrophil CD64 expression in febrile neutropenia patients could be used as an early indicator of bacteremia.

MATERIALS AND METHODS

All consecutive patients older than 18 years of age who had developed febrile neutropenia episodes due to hematological malignancies were included in the study. Those patients who had significant growth in their blood cultures constituted the case group, while those who had febrile neutropenia without any growth in their cultures and who did not have any documented infections formed the control group. Blood culture bottles were incubated in the Bact ALERT 3D system (bioMerieux, France), identification and susceptibility testing were performed using an automated broth microdilution method (VITEK 2, bioMerieux), and CD64 expression analysis was performed by the flow cytometry method. C-reactive protein (CRP) was measured by turbidimetric methods (Biosystems, Spain) and erythrocyte sedimentation rate (ESR) was measured by the Wintrobe method.

RESULTS

In total, we prospectively evaluated 31 febrile episodes. The case group consisted of 17 patients while the control group included 14 patients. CD64 was found on neutrophils of the case group patients with a mean count of 8006 molecules/cell and of control group with a mean count of 2786 molecules/cell. CD64 levels of the case group were significantly higher than those of the control group (p=0.005). In the differentiation of the case group from the control group, a 2500 cut-off value for CD64 had significant [AUC=0.792 (0.619-0.965)] predictive value (p=0.001). In the prediction of patients with a 2500 cut-off value for CD64, sensitivity was 94.1%, positive predictive value was 76.2%, specificity was 64.3%, and negative predictive value was 90.0%. CRP levels and ESR values did not differ significantly between the groups (p=0.005).

CONCLUSION

Neutrophil CD64 expression could be a good predictor as an immune parameter with high sensitivity and a negative predictive value for bacteremia in febrile neutropenic patients.

Lipoxin A4 augments host defense in sepsis and reduces Pseudomonas aeruginosa virulence through quorum sensing inhibition

Bacterial infections can quickly turn into sepsis, with its attendant clinical sequelae of inflammation, tissue injury, and organ failure. Paradoxically, sustained inflammation in sepsis may lead to immune suppression, because of which the host is unable to clear the existing infection. Use of agents that suppress the inflammatory response may accelerate host immune suppression, whereas use of traditional antibiotics does not significantly affect inflammation. In this study, we investigated whether lipoxin A4 (LXA4), a specialized, proresolution lipid mediator, could increase neutrophil phagocytic activity as well as reduce bacterial virulence. Using the mouse cecal ligation and puncture (CLP) model of sepsis, the administration of LXA4 (7 μg/kg i.v.) 1 h after surgery increased neutrophil phagocytic ability and Fcγ receptor I (CD64) expression. Ex vivo studies have confirmed that the direct addition of LXA4 to CLP neutrophils increased phagocytic ability but not CD64 expression. LXA4 did not affect neutrophils taken from control mice in which CD64 expression was minimal. Taken together with in vivo data, these results suggest that LXA4 directly augments CD64-mediated neutrophil phagocytic ability but does not directly increase neutrophil CD64 expression. Bacterial communication and virulence is regulated by quorum sensing inducers. In Pseudomonas aeruginosa, virulence is induced with release of various virulence factors, by N-3-oxododecanolyl homoserine lactone binding to the quorum sensing receptor, LasR. We show that LXA4 is an inhibitor of LasR in P. aeruginosa and that it decreases the release of pyocyanin exotoxin. These results suggest that LXA4 has the novel dual properties of increasing host defense and decreasing pathogen virulence by inhibiting quorum sensing.-Wu, B., Capilato, J., Pham, M. P., Walker, J., Spur, B., Rodriguez, A., Perez, L. J., Yin, K. Lipoxin A4 augments host defense in sepsis and reduces Pseudomonas aeruginosa virulence through quorum sensing inhibition.

Prognostic Value and Daily Trend of Interleukin-6, Neutrophil CD64 Expression, C-Reactive Protein and Lipopolysaccharide-Binding Protein in Critically Ill Patients: Reliable Predictors of Outcome or Not?

Background

Severe sepsis and/or trauma complicated by multiple organ dysfunction syndrome are the leading causes of death in critically ill patients. The aim of this prospective single-centre study was to assess the prognostic value and daily trend of interleukin-6 (IL-6), neutrophil CD64 expression, C-reactive protein (CRP) and lipopolysaccharide-binding protein (LBP) regarding outcome in critically ill patients with severe trauma and/or severe sepsis. Outcome measure was hospital mortality.

Methods

One hundred and two critically ill patients admitted to the intensive care unit of a tertiary university hospital were enrolled in this prospective study. Blood samples were collected on admission (day 1), days 2 and 3.

Results

CD64 index was 1.6-fold higher on day 1 and 1.78-fold higher on day 2 in non-survivors (p<0.05). The area under the curve (AUC) for the CD64 index on day 1 for outcome was 0.727. At a cut-off level of 2.80 sensitivity was 75% and specificity was 65%. Patients with CD64 index level on day 1 higher than 2.80 had 2.4-fold higher probability of dying. Odds ratio is 2.40; 95% CI 0.60–9.67.

Conclusions

CD64 index on day 1 is a fairly good predictor of outcome. AUCs for IL-6, CRP and LBP were < 0.55, suggesting these biomarkers failed to predict outcome.

Kinetics of leukocyte CD11b and CD64 expression in severe sepsis and non-infectious critical care patients

BACKGROUND

Leukocyte surface molecules may improve sepsis diagnostics. Our aim was to study whether monocyte and neutrophil CD11b and CD64 expression differs between patients with severe sepsis (including septic shock) and intensive care unit (ICU) controls, and also to investigate the expression kinetics in patient groups.

METHODS

Monocyte and neutrophil CD11b and CD64 expression was analyzed in 27 patients with severe sepsis, 7 off-pump coronary artery bypass (OPCAB) patients, and 8 ICU patients without systemic inflammation in the beginning of the treatment using quantitative flow cytometry. Blood samples were collected within 48 h of the beginning of severe sepsis, at admission to the ICU for non-systemic inflammatory response syndrome patients, and on the day of surgery before the skin incision for OPCAB patients, and on 2 consecutive days for all patients. Ten healthy individuals served as controls.

RESULTS

Monocyte and neutrophil CD11b and neutrophil CD64 expression was higher in severe sepsis patients compared with the other groups (P < 0.05). In severe sepsis, the expression decreased over time (P < 0.05). In OPCAB patients, the monocyte and neutrophil CD64 expression increased after surgery (P < 0.05). Neutrophil CD64 expression had the highest and statistically significant area under curves (AUC) values for identification of severe sepsis during 3 consecutive days, the highest AUC being 0.990 on D0.

CONCLUSION

Neutrophil CD64 as well as neutrophil and monocyte CD11b expressions were highest in severe sepsis compared with non-infectious conditions, and thus analyses of their expression may be promising approach for sepsis diagnosis in ICU population.

Neutrophil CD64 expression as a diagnostic marker for sepsis in adult patients: a meta-analysis

INTRODUCTION

Neutrophil CD64 (nCD64) expression appears to be a promising marker of bacterial infections. The aim of this meta-analysis was to assess the accuracy of nCD64 expression for the diagnosis of sepsis in critically ill adult patients.

METHODS

We systematically searched PubMed, Embase, ISI Web of Knowledge, and the Cochrane Library for literature published between database inception and 19 May 2014, as well as reference lists of identified primary studies. Studies were included if they included assessment of the accuracy of nCD64 expression for sepsis diagnosis in adult patients and provided sufficient information to construct a 2×2 contingency table.

RESULTS

A total of 8 studies comprising 1986 patients fulfilled the inclusion criteria for the final analysis. The pooled sensitivity and specificity were 0.76 (95 % confidence interval [CI], 0.73-0.78) and 0.85 (95 % CI, 0.82-0.87), respectively. The positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio were 8.15 (95 % CI, 3.82-17.36), 0.16 (95 % CI, 0.09-0.30), and 60.41 (95 % CI, 15.87-229.90), respectively. The area under the summary receiver operating characteristic curve of nCD64 expression with Q* value were 0.95 (Q* =0.89).

CONCLUSIONS

On the basis of our meta-analysis, nCD64 expression is a helpful marker for early diagnosis of sepsis in critically ill patients. The results of the test should not be used alone to diagnose sepsis, but instead should be interpreted in combination with medical history, physical examination, and other test results.

Role of CD64 expression on neutrophils in the diagnosis of sepsis and the prediction of mortality in adult critically ill patients

Intensive care unit patients who developed systemic inflammatory response syndrome (SIRS) with proven microbial etiology were assigned to the infectious causes (n = 29), while patients with negative cultures and more probable other etiology were assigned to the noninfectious causes (n = 37). Flow cytometry was used to detect the presence of CD64 on neutrophils. The multivariate analysis revealed that KPC-producing Klebsiella pneumoniae rectal colonization and >1.39 mean fluorescence intensity (MFI) of CD64 expression on neutrophils upon day 1 of SIRS were significantly associated with an infectious SIRS. The overall mortality was 29% (19 patients) and was independently associated with Simplified Acute Physiology Score II >44 points and multiple-organ dysfunction syndrome, while appropriate antibiotic treatment was identified as predictor of good prognosis. MFI of CD64 expression on neutrophils showed high sensitivity, specificity, and accuracy in the diagnosis of sepsis but not for the prediction of survival.

Automated analysis of flow cytometric data for measuring neutrophil CD64 expression using a multi-instrument compatible probability state model

BACKGROUND

Leuko64™ (Trillium Diagnostics) is a flow cytometric assay that measures neutrophil CD64 expression and serves as an in vitro indicator of infection/sepsis or the presence of a systemic acute inflammatory response. Leuko64 assay currently utilizes QuantiCALC, a semiautomated software that employs cluster algorithms to define cell populations. The software reduces subjective gating decisions, resulting in interanalyst variability of <5%. We evaluated a completely automated approach to measuring neutrophil CD64 expression using GemStone™ (Verity Software House) and probability state modeling (PSM).

METHODS

Four hundred and fifty-seven human blood samples were processed using the Leuko64 assay. Samples were analyzed on four different flow cytometer models: BD FACSCanto II, BD FACScan, BC Gallios/Navios, and BC FC500. A probability state model was designed to identify calibration beads and three leukocyte subpopulations based on differences in intensity levels of several parameters. PSM automatically calculates CD64 index values for each cell population using equations programmed into the model. GemStone software uses PSM that requires no operator intervention, thus totally automating data analysis and internal quality control flagging. Expert analysis with the predicate method (QuantiCALC) was performed. Interanalyst precision was evaluated for both methods of data analysis.

RESULTS

PSM with GemStone correlates well with the expert manual analysis, r(2) = 0.99675 for the neutrophil CD64 index values with no intermethod bias detected. The average interanalyst imprecision for the QuantiCALC method was 1.06% (range 0.00-7.94%), which was reduced to 0.00% with the GemStone PSM. The operator-to-operator agreement in GemStone was a perfect correlation, r(2) = 1.000.

CONCLUSION

Automated quantification of CD64 index values produced results that strongly correlate with expert analysis using a standard gate-based data analysis method. PSM successfully evaluated flow cytometric data generated by multiple instruments across multiple lots of the Leuko64 kit in all 457 cases. The probability-based method provides greater objectivity, higher data analysis speed, and allows for greater precision for in vitro diagnostic flow cytometric assays.

Neutrophil CD64 expression as an important diagnostic marker of infection and sepsis in hospital patients

INTRODUCTION

Infection and sepsis are major health problems. Therefore, the need for improved diagnostic indicators, as well as for better therapeutic monitors in the treatment of infection, remains, since the current diagnostic tools have low specificity and passed through minimal changes in the last two decades.

OBJECTIVE

The aim of this study was to establish the correlation of neutrophil CD64 with indicators of infection and sepsis.

METHODS

We established the correlation of the neutrophil CD64 expression with the following variables: complete white blood count, band count, neutrophils, C-reactive protein (CRP), cultures, flags released by automated hematology analyzers and clinical groups. Accordingly clinical groups were divided into two: patients "without clinical or laboratory evidence of infection or inflammatory process" and "clinical or laboratory evidence of a systemic inflammatory response (SIRS) and systemic sepsis" based upon identification of organisms by culture. We analyzed 93 whole blood samples anticoagulated with K3EDTA of patients admitted in the Intensive Care Unit (ICU) of a community hospital.

RESULTS

The expression CD64 was statistically significant with clinical groups, flags, and neutrophils and was not significantly correlated with total count of white blood cells and cultures.

CONCLUSION

Our results indicate that high expression of CD64 is an indicator important in the diagnosis of infection and sepsis.

Biomarkers of sepsis

Sepsis remains a leading cause of death in critically ill patients, despite efforts to improve patient outcome. Thus far, no magic drugs exist for severe sepsis and septic shock. Instead, early diagnosis and prompt initial management such as early goal-directed therapy are key to improve sepsis outcome. For early detection of sepsis, biological markers (biomarkers) can help clinicians to distinguish infection from host response to inflammation. Ideally, biomarkers can be used for risk stratification, diagnosis, monitoring of treatment responses, and outcome prediction. More than 170 biomarkers have been identified as useful for evaluating sepsis, including C-reactive protein, procalcitonin, various cytokines, and cell surface markers. Recently, studies have reported on the usefulness of biomarker-guided antibiotic stewardships. However, the other side of these numerous biomarkers is that no novel single laboratory marker can diagnose, predict, and track the treatment of sepsis. The purpose of this review is to summarize several key biomarkers from recent sepsis studies.

Diagnostic and prognostic markers in sepsis

Sepsis is a common and serious complication in intensive care unit patients. An important factor in optimizing survival rates in septic patients is the ability to start treatment early in the course of disease; there is, therefore, a need for accurate diagnostic tests. In recent years, there has been a move away from the rather vague and nonspecific signs that were previously used to diagnose sepsis towards the possible adjunctive role of biomarkers. Many biomarkers have been proposed and assessed clinically, but none alone is specific enough to definitively determine diagnosis. The future direction of research is most likely a greater focus on the use of panels or combinations of markers with clinical signs. Some biomarkers may also be useful for prognosis and guiding therapy. Here, the authors will review our changing approaches to sepsis diagnosis and discuss some of the markers that seem most relevant at the present time.

Neutrophil CD64 expression as a biomarker in the early diagnosis of bacterial infection: a meta-analysis

BACKGROUND

Neutrophil CD64 expression is widely reported as an efficacious biomarker to differentiate infected patients from other non-infected patients. This meta-analysis was conducted to comprehensively and quantitatively summarize the accuracy of neutrophil CD64 in the early diagnosis of bacterial infection.

METHODS

A systematic review of related studies was conducted, and the sensitivity, specificity, and other data about the accuracy of CD64 expression on neutrophils were pooled using random effects models with 95% confidence intervals (CI) as the effect measurements. Summary receiver operating characteristic (SROC) curves and the Q* value were also calculated in the meta-analysis. Heterogeneity was tested, as well as the publication bias. Potential sources of heterogeneity were explored by assessing whether or not certain covariates significantly influenced the summary diagnostic odds ratio (SDOR).

RESULTS

A total of 26 studies including 3944 patients met the inclusion criteria for the final analysis. The summary estimate was 0.76 (95% CI 0.74-0.78) for sensitivity and 0.85 (95% CI 0.83-0.86) for specificity. The positive likelihood ratio (PLR), negative likelihood ratio (NLR), SDOR, and area under the SROC of neutrophil CD64 expression with Q* value were 6.67 (95% CI 4.67-9.53), 0.24 (95% CI 0.18-0.31), 34.29 (95% CI 19.59-60.01), and 0.92 (Q*=0.85), respectively. The pooled data from the included studies had high heterogeneity and the Egger test suggested a publication bias.

CONCLUSIONS

On the basis of our meta-analysis, neutrophil CD64 expression could be a promising and meaningful biomarker for diagnosing bacterial infection. Nevertheless, more large prospective studies should be carried out before the neutrophil CD64 test is used widely in the clinical setting because of the various cut-off values.