Comparison of neutrophil CD64 expression, manual myeloid immaturity counts, and automated hematology analyzer flags as indicators of infection or sepsis

Point-of-care neutrophil and monocyte surface markers differentiate bacterial from viral infections at the emergency department within 30 min

Rapid discrimination between viral and bacterial infections in a point-of-care setting will improve clinical outcome. Expression of CD64 on neutrophils (neuCD64) increases during bacterial infections, whereas expression of CD169 on classical monocytes (cmCD169) increases during viral infections. The diagnostic value of automated point-of-care neuCD64 and cmCD169 analysis was assessed for detecting bacterial and viral infections at the emergency department. Additionally, their value as input for machine learning models was studied. A prospective observational cohort study in patients suspected of infection was performed at an emergency department. A fully automated point-of-care flow cytometer measured neuCD64, cmCD169, and additional leukocyte surface markers. Flow cytometry data were gated using the FlowSOM algorithm. Bacterial and viral infections were assessed in standardized clinical care. The sole and combined diagnostic value of the markers was investigated. Clustering based on unsupervised machine learning identified unique patient clusters. Eighty-six patients were included. Thirty-five had a bacterial infection, 30 had a viral infection, and 21 had no infection. neuCD64 was increased in bacterial infections (P < 0.001), with an area under the receiver operating characteristic curve (AUROC) of 0.73. cmCD169 was higher in virally infected patients (P < 0.001; AUROC 0.79). Multivariate analyses incorporating additional markers increased the AUROC for bacterial and viral infections to 0.86 and 0.93, respectively. The additional clustering identified 4 distinctive patient clusters based on infection type and outcome. Automated neuCD64 and cmCD169 determination can discriminate between bacterial and viral infections. These markers can be determined within 30 min, allowing fast infection diagnostics in the acute clinical setting.

Flow Cytometry: An Important Diagnostic Tool in Critically Ill Preterm Neonates with Suspected Sepsis

OBJECTIVE

Sepsis is a major cause of neonatal mortality. The gold standard for diagnosis is blood culture which suffers from low sensitivity and huge turn-around time. Flow cytometry has been extensively applied to malignant disorders and is an upcoming tool for diagnosis of nonmalignant disorders due to its rapidity and accuracy in detecting cells, cell products, and their functional states. The aim of this study was to investigate the utility of flow cytometric expression of neutrophil CD64, monocyte human leukocyte antigen (HLA-DR) and CD16 in diagnosis in suspected preterm neonates.

STUDY DESIGN

In total, 100 preterm neonates with clinical signs of sepsis were enrolled in the study. Blood culture, C-reactive protein (CRP) and flow cytometry for nCD64, mHLA-DR, and mCD16 were performed. The neonates were divided into two groups: culture positive and culture negative and CRP and flow cytometric findings compared. ROC analysis was performed to determine the best cut-off for nCD64, mHLA-DR, and mCD16 values along with estimation of sensitivity, specificity, and predictive values. Probability of <0.05 was taken as significant.

RESULTS

Out of the 100 enrolled neonates, 34 (34%) were culture positive. CRP was not found to be significantly different in the two groups. Expression of nCD64 (p = 0.03) was significantly upregulated in the blood culture positive cases with a cut-off mean fluorescence intensity (MFI) value = 4.72 and sensitivity of 92% and specificity of 52%. Expression of mCD16 (p = 0.02) was also upregulated in the blood culture positive cases with a cut-off MFI value = 4.9, with sensitivity of 41%, specificity of 83%.

CONCLUSION

The study concluded that nCD64 and mCD16 can be potential biomarkers for early diagnosis of neonatal sepsis with a high sensitivity and specificity.

KEY POINTS

· Neutrophil CD64 significantly upregulated in septic neonates.. · Monocyte CD16 significantly upregulated in septic neonates.. · C-reactive protein values were not significantly different in septic versus nonseptic neonates..

The lymphatic system as a potential mechanism of spread of melioidosis following ingestion of Burkholderia pseudomallei

Burkholderia pseudomallei is the causative agent of melioidosis, which is a Gram negative, facultative intracellular bacterium. Disease is prevalent in SE Asia and in northern Australia, as well as in other tropical and subtropical regions. Recently, there is an increasing awareness of the importance of bacterial ingestion as a potential route of infection, particularly in cases of unexplained origin of the disease. The marmoset is a New World Monkey (NWM) species that is being developed as an alternative NHP model to complement the more traditionally used Old World Monkeys (OWM). Models have been developed for the traditional routes of disease acquisition, subcutaneous and inhalational. This manuscript details the development and characterisation of an ingestion model of melioidosis. Dose-ranging study assessed the lethality of B. pseudomallei and disease progression was assessed by euthanizing animals at predetermined time points, 12, 36, 48 and 54 hours post-challenge. Challenge doses of greater than 6.2 x 106 cfu resulted in an acute, lethal, febrile disease. Following challenge the lung was the first organ, outside of the gastrointestinal tract, to become colonised. Enteritis (duodenitis, ileitis and/or jejunitis) was observed in sections of the small intestine from animals that succumbed to disease. However, the most severe pathological features were observed in the mesenteric lymph nodes from these animals. These findings are consistent with lymphatic draining as route of dissemination.

Expression, Role, and Regulation of Neutrophil Fcγ Receptors

Neutrophils are best known for their critical role in host defense, for which they utilize multiple innate immune mechanisms, including microbe-associated pattern recognition, phagocytosis, production of reactive oxygen species, and the release of potent proteases, mediators, antimicrobials, and neutrophil extracellular traps. Beyond their well-established contribution to innate immunity, neutrophils were more recently reported to interact with various other cell types, including cells from the adaptive immune system, thereby enabling neutrophils to tune the overall immune response of the host. Neutrophils express different receptors for IgG antibodies (Fcγ receptors), which facilitate the engulfment of IgG-opsonized microbes and trigger cell activation upon cross-linking of several receptors. Indeed, FcγRs (via IgG antibodies) confer neutrophils with a key feature of the adaptive immunity: an antigen-specific cell response. This review summarizes the expression and function of FcγRs on human neutrophils in health and disease and how they are affected by polymorphisms in the FCGR loci. Additionally, we will discuss the role of neutrophils in providing help to marginal zone B cells for the production of antibodies, which in turn may trigger neutrophil effector functions when engaging FcγRs.

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 Diagnostic Accuracy of Serum Procalcitonin for Bacteremia in Critically Ill Children

BACKGROUND

Bacterial sepsis is frequently encountered in children admitted to the Pediatric Intensive Care Unit (PICU) and requires early recognition and treatment. Procalcitonin (PCT) is a serum biomarker with a high sensitivity to predict bacteremia in critically-ill adults. This study sought to evaluate the diagnostic accuracy of PCT for bacteremia in febrile children in the PICU.

METHODS

This retrospective observational study used data from children admitted to the PICU from October 2010 to October 2012. Patients up to 21 years of age were included if they had an abnormal temperature, serum PCT and blood culture assayed, and were not receiving empiric antibiotics at the time.

RESULTS

There were 202 PCT values that met inclusion criteria. The prevalence of positive blood cultures was 13.2% (27 total positive blood cultures). The area under the curve (AUC) for PCT was 0.79 (95% CI, 0.70-0.89), the AUC for lactate was 0.76 (95% CI, 0.65-0.87), and the AUC for C-reactive protein was 0.68 (95% CI, 0.57-0.80). The optimal threshold of PCT for accuracy was determined to be 2 ng/mL (sensitivity = 69.2%, specificity = 74.4%, positive predictive value = 28.6%, negative predictive value = 94.2%). The combination of an abnormal lactate (> 2.0mmol/L) increased the specificity of PCT for diagnosing bacteremia.

CONCLUSIONS

PCT has a good diagnostic accuracy to rule-out bacteremia in critically-ill, febrile children. The combination of PCT and an abnormal lactate value increases the specificity and may improve the ability to diagnose bacteremia.

Diagnosing sepsis - The role of laboratory medicine

Sepsis is the host response to microbial pathogens resulting in significant morbidity and mortality. An accurate and timely diagnosis of sepsis allows prompt and appropriate treatment. This review discusses laboratory testing for sepsis because differentiating systemic inflammation from infection is challenging. Procalcitonin (PCT) is currently an FDA approved test to aid in the diagnosis of sepsis but with questionable efficacy. However, studies support the use of PCT for antibiotic de-escalation. Serial lactate measurements have been recommended for monitoring treatment efficacy as part of sepsis bundles. The 2016 sepsis consensus definitions include lactate concentrations >2mmol/L (>18mg/dL) as part of the definition of septic shock. Also included in the 2016 definitions are measuring bilirubin and creatinine to determine progression of organ failure indicating worse prognosis. Hematologic parameters, including a simple white blood cell count and differential, are frequently part of the initial sepsis diagnostic protocols. Several new biomarkers have been proposed to diagnose sepsis or to predict mortality, but they currently lack sufficient sensitivity and specificity to be considered as stand-alone testing. If sepsis is suspected, new technologies and microbiologic assays allow rapid and specific identification of pathogens. In 2016 there is no single laboratory test that accurately diagnoses sepsis.

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.

Neutrophil CD64 as a diagnostic marker of sepsis: impact on neonatal care

OBJECTIVE

The aim of this study is to determine the validity and reliability of neutrophil CD64 in identifying infected infants and to evaluate the impact of this marker on clinical care.

STUDY DESIGN

Neutrophil CD64 index was incorporated in 371 infection evaluations in 234 infants (ages 1-293 days) from 2005 to 2009 and the impact of this change on clinical care was evaluated.

RESULTS

The sensitivity of the neutrophil CD64 assay was 87% in identifying 31 episodes of culture positive sepsis and 83% in identifying 12 infants with ventilator-associated pneumonia. There was no difference in the mean number of antibiotic days in infants with a normal CD64 versus those with a normal complete blood count (CBC) (p = 0.89), but twofold more infants were identified as "not infected" by CD64 than by CBC.

CONCLUSION

CD64 had a high sensitivity for identifying infected infants while also decreasing the number of infants that were exposed to unnecessary antibiotic use.

Biomarkers for sepsis: a review with special attention to India

Sepsis is a serious infection and still a common cause of morbidity and mortality in resource-limited settings such as India. Even when microbiologic diagnostics are available, bacteremia is only identified in a proportion of patients who present with sepsis and bloodstream infections. Biomarkers have been used in a variety of disease processes and can help aid in diagnosing bacterial infections. There have been numerous biomarkers investigated to aid with diagnosis and prognostication in sepsis with the majority suffering from lack of sensitivity or specificity. Procalcitonin has been heralded as the biomarker that holds the most promise for bloodstream infections. Data are emerging in India, and in this review, we focus on the current data of biomarkers in sepsis with particular attention to how biomarkers could be used to augment diagnosis and treatment in India.

Delta mean neutrophil volume (ΔMNV) is comparable to procalcitonin for predicting postsurgical bacterial infection

BACKGROUND

The Coulter LH750 (Beckman Coulter, Brea, CA) analyzer can determine intrinsic biophysical properties of white blood cell (WBC), known as cell population data. Previous studies have shown that mean neutrophil volume (MNV) was significantly increased in postsurgical patients with bacterial infection. To further validate its potential clinical usefulness, we investigate the changes in MNV before and after surgery, called ΔMNV. We also compare the ΔMNV with procalcitonin (PCT) and C-reactive protein (CRP) in terms of diagnostic sensitivity and specificity for postsurgical bacterial infection.

METHODS

Blood samples from 300 healthy controls, 219 cardiac surgical patients without postsurgical infection, and 31 cardiac surgical patients complicated with postsurgical bacterial infection were studied.

RESULTS

There are no statistically significant differences for WBC count and neutrophil percentage prior to or after surgery between postsurgical noninfected and infected patients. However, the ΔMNV is significantly increased in postsurgical infected patients when compared with noninfected patients (P < 0.05). The receiver-operating characteristics analysis reveals the ΔMNV and PCT have largest areas under curves (0.92, 0.93 on the second day and 0.94, 0.99 on the third day postsurgery, respectively) compared to other parameters.

CONCLUSION

ΔMNV shows comparable sensitivity and specificity to PCT and superior sensitivity and specificity to WBC or CRP for predicting postsurgical bacterial infection. The potential clinical application of this parameter merits further exploration in a larger prospective study.

Novel parameters of extended complete blood cell count under fluorescence flow cytometry in patients with sepsis

BACKGROUND

We first describe a patient who developed urosepsis from an ordinary urinary tract infection. In this case, the new hematological parameters of immature leukocytes, that is, the high-fluorescence lymphocyte cell (HFLC) and immature granulocyte (IG) counts peaked early, whereas the established infection parameters, that is, C-reactive protein (CRP) and total white blood cell count showed less dynamic regarding infection and therapy.

METHODS

To investigate this phenomenon in greater detail, the novel parameters HFLC and IG counts are investigated retrospectively in a cohort of 38 patients who were admitted to the anesthesia intensive care unit. Three groups of patients have been analyzed and compared: patients without signs of infection, patients with limited infections, and patients with sepsis. Data were collected with a Sysmex XE-5000 hematological analyzer.

RESULTS

In patients (n = 22) without any signs of infection, both values are very low. In patients with limited local infections (n = 10), moderate elevations of the IG and HFLC counts are seen. In patients with sepsis (n = 6), the IG and HFLC counts are significantly higher.

CONCLUSION

The total IG count seems to be useful for distinguishing a septic patient from a nonseptic (P < 0.004). Hematological parameters have the advantage of being measured easily during routine blood cell analysis.

Which biomarkers reveal neonatal sepsis?

We address the identification of optimal biomarkers for the rapid diagnosis of neonatal sepsis. We employ both canonical correlation analysis (CCA) and sparse support vector machine (SSVM) classifiers to select the best subset of biomarkers from a large hematological data set collected from infants with suspected sepsis from Yale-New Haven Hospital's Neonatal Intensive Care Unit (NICU). CCA is used to select sets of biomarkers of increasing size that are most highly correlated with infection. The effectiveness of these biomarkers is then validated by constructing a sparse support vector machine diagnostic classifier. We find that the following set of five biomarkers capture the essential diagnostic information (in order of importance): Bands, Platelets, neutrophil CD64, White Blood Cells, and Segs. Further, the diagnostic performance of the optimal set of biomarkers is significantly higher than that of isolated individual biomarkers. These results suggest an enhanced sepsis scoring system for neonatal sepsis that includes these five biomarkers. We demonstrate the robustness of our analysis by comparing CCA with the Forward Selection method and SSVM with LASSO Logistic Regression.

Polymorphic mononuclear neutrophils CD64 index for diagnosis of sepsis in postoperative surgical patients and critically ill patients

BACKGROUND

Surface neutrophil CD64 expression is upregulated in patients with bacterial infection. As it was suggested that the CD64 index could be used to detect sepsis in hospitalized patients, we questioned whether the CD64 index could discriminate between septic patients and postoperative surgical patients, defined as systemic inflammatory response syndrome (SIRS), both admitted at the intensive care unit (ICU). Furthermore, we wondered whether the CD64 index was an improved diagnostic compared to standard assays used at the laboratory. For this, outclinic (OC) patients were included as controls.

METHODS

The Leuko64™ assay was used to determine the CD64 index in residual EDTA blood samples from selected septic patients (n=25), SIRS patients (n=19), and OC patients (n=24). Additionally, WBC count, neutrophilic and eosinophilic granulocyte count, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were measured simultaneously.

RESULTS

The CD64 index was higher in septic patients compared to both the SIRS and OC group (p<0.0001). In addition, the WBC count, neutrophil count, ESR and CRP were also higher in septic patients than the OC group (p<0.0001). However, only the WBC count, eosinopenia, and ESR were comparable between the SIRS and the sepsis group and proved to be discriminative to the OC group (p<0.05). The CD64 index demonstrated higher sensitivity and specificity than CRP, WBC count, neutrophilic and eosinophilic granulocyte count, and ESR.

CONCLUSIONS

A high CD64 index was found in septic intensive care patients, while a low CD64 index was observed in OC and SIRS patients, demonstrating that the CD64 index can be used for routine diagnostics in the ICU setting.

New approaches to sepsis: molecular diagnostics and biomarkers

Sepsis is among the most common causes of death in hospitals. It arises from the host response to infection. Currently, diagnosis relies on nonspecific physiological criteria and culture-based pathogen detection. This results in diagnostic uncertainty, therapeutic delays, the mis- and overuse of antibiotics, and the failure to identify patients who might benefit from immunomodulatory therapies. There is a need for new sepsis biomarkers that can aid in therapeutic decision making and add information about screening, diagnosis, risk stratification, and monitoring of the response to therapy. The host response involves hundreds of mediators and single molecules, many of which have been proposed as biomarkers. It is, however, unlikely that one single biomarker is able to satisfy all the needs and expectations for sepsis research and management. Among biomarkers that are measurable by assays approved for clinical use, procalcitonin (PCT) has shown some usefulness as an infection marker and for antibiotic stewardship. Other possible new approaches consist of molecular strategies to improve pathogen detection and molecular diagnostics and prognostics based on transcriptomic, proteomic, or metabolic profiling. Novel approaches to sepsis promise to transform sepsis from a physiologic syndrome into a group of distinct biochemical disorders and help in the development of better diagnostic tools and effective adjunctive sepsis therapies.

Diagnostic accuracy of HMGB-1, sTREM-1, and CD64 as markers of sepsis in patients recently admitted to the emergency department

OBJECTIVES

The objectives were to evaluate the diagnostic accuracy for sepsis in an emergency department (ED) population of the cluster of differentiation-64 (CD64) glycoprotein expression on the surface of neutrophils (nCD64), serum levels of soluble triggering receptor expressed on myeloid cells-1 (s-TREM-1), and high-mobility group box-1 protein (HMGB-1).

METHODS

Patients with any of the following as admission diagnosis were enrolled: 1) suspected infection, 2) fever, 3) delirium, or 4) acute hypotension of unexplained origin within 24 hours of ED presentation. Levels of nCD64, HMGB-1, and s-TREM-1 were measured within the first 24 hours of the first ED evaluation. Baseline clinical data, Sepsis-related Organ Failure Assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACHE II) score, daily clinical and microbiologic information, and 28-day mortality rate were collected. Because there is not a definitive criterion standard for sepsis, the authors used expert consensus based on clinical, microbiologic, laboratory, and radiologic data collected for each patient during the first 7 days of hospitalization. This expert consensus defined the primary outcome of sepsis, and the primary data analysis was based in the comparison of sepsis versus nonsepsis patients. The cut points to define sensitivity and specificity values, as well as positive and negative likelihood ratios (LRs) for the markers related to sepsis diagnosis, were determined using receiver operative characteristics (ROC) curves. The patients in this study were a prespecified nested subsample population of a larger study.

RESULTS

Of 631 patients included in the study, 66% (95% confidence interval [CI] = 62% to 67%, n = 416) had sepsis according with the expert consensus diagnosis. Among these sepsis patients, SOFA score defined 67% (95% CI = 62% to 71%, n = 277) in severe sepsis and 1% (95% CI = 0.3% to 3%, n = 6) in septic shock. The sensitivities for sepsis diagnosis were CD64, 65.8% (95% CI = 61.1% to 70.3%); HMGB-1, 57.5% (95% CI = 52.7% to 62.3%); and s-TREM-1, 60% (95% CI = 55.2% to 64.7%). The specificities were CD64, 64.6% (95% CI = 57.8% to 70.8%), HMGB-1, 57.8% (95% CI = 51.1% to 64.3%), and s-TREM-1, 59.2% (95% CI = 52.5% to 65.6%). The positive LR (LR+) for CD64 was 1.85 (95% CI = 1.52 to 2.26) and the negative LR (LR-) was 0.52 (95% CI = 0.44 to 0.62]; for HMGB-1 the LR+ was 1.36 (95% CI = 1.14 to 1.63) and LR- was 0.73 (95% CI = 0.62 to 0.86); and for s-TREM-1 the LR+ was 1.47 (95% CI = 1.22 to 1.76) and the LR- was 0.67 (95% CI = 0.57 to 0.79).

CONCLUSIONS

In this cohort of patients suspected of having any infection in the ED, the accuracy of nCD64, s-TREM-1, and HMGB-1 was not significantly sensitive or specific for diagnosis of sepsis.

Neutrophil CD64 expression in inflammatory autoimmune diseases: its value in distinguishing infection from disease flare

The purpose of this research was to clarify the significance of neutrophil CD64 expression in discrimination between infection and disease flare in patients with inflammatory autoimmune diseases. The study included 63 subjects, 20 healthy controls and 43 patients with inflammatory autoimmune diseases (24 with rheumatoid arthritis & 19 with systemic lupus erythematosus). The FC gamma receptor I (CD64 expression) on neutrophils was measured using flow cytometry. The intensity of CD64 expression on neutrophils was significantly elevated in patients with infections; 49.0 (13-205), and active autoimmune disease; 36.15 (12-133) compared to healthy controls; 5.35 (2.6-14) or patients with inactive disease; 7.5 (3.3-18). In the infectious disease group, expression of CD64 was significantly higher than in the active inflammatory disease group, while there was no significant difference between the group of patients with inactive inflammatory disease and healthy controls (P > 0.05). The sensitivity of CD64 bearing neutrophil intensity for detection of infection (using a cut off value of ≥43.5) was 94.4% and specificity was 88.9%. Neutrophil CD64 expression has a good sensitivity and specificity in differentiating infection from disease flare in patients with inflammatory autoimmune diseases. This assay could facilitate early and accurate diagnosis and greatly aid timely institution of appropriate treatment.

Increased CD64 expression on polymorphonuclear neutrophils indicates infectious complications following solid organ transplantation

The aim of this study was to evaluate the diagnostic value of monitoring CD64 antigen upregulation on polymorphonuclear neutrophils (PMN) for the identification of infectious complications in the postoperative course of solid organ transplanted patients. Twenty-five kidney, 13 liver, and four pancreas-kidney transplanted patients were included. Beginning with preoperative values up to postoperative values after 3 months for each patient, the PMN CD64 Index, HLA-DR on monocytes, NKp44+ NK and NK/T cells, CXCR3+ NK cells, CXCR3+ T helper cells, CXCR3+ NK/T cells, and CD4/CD8 ratio were measured by flow cytometry. Subsequently they were correlated with confirmed postoperative complications. Measuring the PMN CD64 Index reached a sensitivity of 89% and a specificity of 65% in the detection of infectious complications. Concerning this matter, it was a significantly better marker than all other included parameters except CXCR3+ NK/T cells. In contrast, according to our results the PMN CD64 Index has no diagnostic relevance in detection of rejections. The combination of included parameters showed no improved diagnostic value. Due to its high sensitivity and specificity for infectious complications CD64 on PMN could be proven a very good indicator in evaluating suspected infectious complications in the postoperative course of transplanted patients.

Flow cytometry developments and perspectives in clinical studies: examples in ICU patients

Septic syndromes represent a major, although largely under-recognized, healthcare problem worldwide accounting for thousands of deaths every year. Although flow cytometry (FCM) remains a relatively confidential diagnostic tool, it is useful at every step of intensive care unit (ICU) patients' management. This review will focus on biomarkers measurable by FCM on a routine standardized basis and usable for the diagnosis of sepsis and for prediction of adverse outcome, occurrence of secondary nosocomial infections or guidance of putative immunotherapy relative to innate and adaptive immune dysfunctions in ICU patients. Regarding early diagnosis of infection, neutrophil CD64 has been shown to be a highly sensitive and specific marker for systemic infection and sepsis in adults, neonates, and children. A diminished monocyte HLA-DR expression is a reliable marker for the development of monocyte anergy, secondary nosocomial infection, and death in critically ill patients. Finally, the measurement of an increased CD4(+)CD25(+)CD127(low) regulatory T cell percentage may represent a reliable marker for the diagnosis of lymphocyte dysfunctions in these patients. These stainings can be performed using lyse-no-wash methods and results are available within 1 h. Ideally, these biomarkers should be part of a panel helping to define ICU patients' immune status. In the specific clinical context of ICU patients' monitoring, the increasing potential of FCM is further illustrated by the use of the biomarkers listed above as stratification tools in preliminary clinical studies. The next critical step is to use these standardized FCM protocols in large multicentric clinical trials testing individualized immunotherapy. Importantly, many other markers of immune dysfunction are currently under development that could further enable the administration of targeted individualized therapy in ICU patients.

Neutrophil CD64 expression as marker of bacterial infection: a systematic review and meta-analysis

OBJECTIVE

We performed a systematic review and meta-analysis of studies to evaluate the diagnostic accuracy of expression of CD64 on polymorphonuclear neutrophils (PMN) as a marker for bacterial infection.

METHODS

The analysis included studies of patients from all age groups that prospectively evaluated CD64 expression on PMNs for the diagnosis of bacterial infection. We evaluated the methodological quality of the studies according to the 25-item criteria developed by the Standards for Reporting of Diagnostic Accuracy (STARD) committee. We calculated a summary receiver operating characteristic (SROC) curve across studies included in the meta-analysis.

RESULTS

The methodological quality score of the 13 included studies ranged from 9 to 16 points (maximum score was 25 points). The pooled sensitivity and specificity for CD64 expression on PMNs were 79% (95% CI: 70-86%) and 91% (95% CI: 85-95%), respectively. The area under curve (AUC) was 0.94.

CONCLUSIONS

On the basis of this meta-analysis, CD64 expression on PMNs could be a useful diagnostic cell-based parameter of bacterial infections. However, published studies about this topic showed a low methodological quality.

Neutrophil and monocyte CD64 indexes, lipopolysaccharide-binding protein, procalcitonin and C-reactive protein in sepsis of critically ill neonates and children

OBJECTIVE

To compare the diagnostic accuracy of neutrophil and monocyte CD64 indexes (CD64in and CD64im) for sepsis in critically ill neonates and children with that of lipopolysaccharide-binding protein (LBP), procalcitonin (PCT) and C-reactive protein (CRP).

DESIGN AND SETTING

Prospective, observational study in a level III multidisciplinary neonatal and pediatric intensive care unit (ICU).

PATIENTS

Forty-six neonates and 36 children with systemic inflammatory response syndrome (SIRS) and suspected infection, classified into two groups: those with bacterial sepsis (microbiologically proven or clinical sepsis) and those without bacterial sepsis (infection not supported by subsequent clinical course, laboratory data and microbiological tests).

INTERVENTIONS AND MEASUREMENTS

Flow cytometric CD64in and CD64im, serum LBP, PCT and CRP measurement on 2 consecutive days from admission to the ICU.

RESULTS

There were 17 cases of bacterial sepsis in neonates and 24 cases of bacterial sepsis in children. All neonates and the majority of children were mechanically ventilated, and more than two-thirds of neonates with sepsis and one-third of children with sepsis needed inotropic/vasopressor drugs. The highest diagnostic accuracy for sepsis on the 1st day of suspected sepsis was achieved by LBP in neonates (0.86) and by CD64in in children (0.88) and 24 h later by CD64in in neonates (0.96) and children (0.98).

CONCLUSIONS

Neutrophil CD64 index (CD64in) is the best individual marker for bacterial sepsis in children, while in neonates the highest diagnostic accuracy at the time of suspected sepsis was achieved by LBP and 24 h later by CD64in.

CD64 index provides simple and predictive testing for detection and monitoring of sepsis and bacterial infection in hospital patients

The rapid diagnosis and management of bacterial infection are heavily dependent upon clinical assessment. Blood culture may take up to 2 days for results and may be suspect. Surface neutrophil CD64 expression has been shown to be upregulated in cases of bacterial infection. Recently, a standardized kit for the CD64 index was used in neonatal intensive care units, showing high sensitivity and specificity for bacterial infections. Our study was designed to confirm and extend these results to adult hospital patients and to determine the impact of this testing on a clinical laboratory's finances and staffing. CD64 indices were performed with peripheral blood drawn in tandem with blood cultures from 109 patients over a 2-month period. We found that a CD64 index of <or=1.19 was predictive of "no growth" blood culture results. An index of >1.19 was predictive of an ultimate clinical and/or culture diagnosis of infection with a sensitivity and specificity of 94.6% and 88.7%, respectively. Positive and negative predictive values were 89.8% and 94%, respectively. The CD64 index was easily performed using our flow cytometer and staff, producing minimal alteration in clinical workflow. A 7-day-a-week testing schedule will result in some additional expense but will be more than offset by the expected cost savings. The CD64 index is a useful and inexpensive test for improving the diagnosis and management of hospital patients with bacterial infection. It can be readily performed by clinical laboratories and could result in considerable savings for the institution.

Prognostic value of phagocytic activity of neutrophils and monocytes in sepsis. Correlation to CD64 and CD14 antigen expression

The role of the phagocytic function of monocytes and neutrophils in sepsis has been poorly investigated. The present study evaluated the impact of the phagocytic activity of neutrophils and monocytes on the outcome of patients with severe sepsis. Thirty-one patients and 30 healthy individuals were enrolled in the study. The phagocytic activity of monocytes and neutrophils was evaluated during 24 h after admission and the results were correlated to the expression of CD64 on neutrophils and monocytes, CD14 antigen on monocytes, the Simplified Acute Physiology Score II and the patients' survival. A reduced phagocytic activity of neutrophils during the first 24 h after admission was a negative predictor for survival. Increased expression of CD64 antigen on polymorphonuclear cells (PMNs) and monocytes was favourably correlated to the patients' survival. In multivariate analysis the phagocytic activity of PMNs was the only independent predictor factor for survival. Patients with PMN phagocytic activity <37% had lower expression of CD64 on monocytes and PMNs and worse outcome, while those with phagocytic activity >37% had higher expression of CD64 on monocytes and PMNs and better outcome. Reduced phagocytic activity of neutrophils may represent a state of neutrophil inactivation similar to that previously described for monocytes during the compensatory anti-inflammatory response.

Neutrophil and monocyte CD64 and CD163 expression in critically ill neonates and children with sepsis: comparison of fluorescence intensities and calculated indexes

Objective. To evaluate the expression of CD64 and CD163 on neutrophils and monocytes in SIRS with/without sepsis and to compare the diagnostic accuracy of CD64 and CD163 molecules expression determined as (1) mean fluorescence intensities (MFI) of CD64 and CD163; and (2) the ratio (index) of linearized MFI to the fluorescence signal of standardized beads. Patients and methods. Fifty-six critically ill neonates and children with systemic inflammatory response syndrome (SIRS) and suspected sepsis, classified into two groups: SIRS with sepsis (n = 29) and SIRS without sepsis (n = 27). Results. CD64 and CD163 MFI measured on neutrophils and monocytes were elevated in patients with SIRS with sepsis. Diagnostic accuracy of indexes was equal to diagnostic accuracy of MFI for CD64 on neutrophils (0.833 versus 0.854 for day 0 and 0.975 versus 0.983 for day 1) and monocytes (0.811 versus 0.865 for day 0 and 0.825 versus 0.858 for day 1), and CD163 on neutrophils (0.595 versus 0.655 for day 0 and 0.677 versus 0.750 for day 1), but not for CD163 on monocytes. Conclusion. CD64 MFI, CD163 MFI, CD64 indexes for neutrophils and monocytes, and CD163 index for neutrophils can all be used for discrimination of SIRS and sepsis in critically ill neonates and children. CD64 index for neutrophils, however, is superior to all other markers.

Use of plasma C-reactive protein, procalcitonin, neutrophils, macrophage migration inhibitory factor, soluble urokinase-type plasminogen activator receptor, and soluble triggering receptor expressed on myeloid cells-1 in combination to diagnose infections: a prospective study

Introduction

Accurate and timely diagnosis of community-acquired bacterial infections in patients with systemic inflammation remains challenging both for clinician and laboratory. Combinations of markers, as opposed to single ones, may improve diagnosis and thereby survival. We therefore compared the diagnostic characteristics of novel and routinely used biomarkers of sepsis alone and in combination.

Methods

This prospective cohort study included patients with systemic inflammatory response syndrome who were suspected of having community-acquired infections. It was conducted in a medical emergency department and department of infectious diseases at a university hospital. A multiplex immunoassay measuring soluble urokinase-type plasminogen activator (suPAR) and soluble triggering receptor expressed on myeloid cells (sTREM)-1 and macrophage migration inhibitory factor (MIF) was used in parallel with standard measurements of C-reactive protein (CRP), procalcitonin (PCT), and neutrophils. Two composite markers were constructed – one including a linear combination of the three best performing markers and another including all six – and the area under the receiver operating characteristic curve (AUC) was used to compare their performance and those of the individual markers.

Results

A total of 151 patients were eligible for analysis. Of these, 96 had bacterial infections. The AUCs for detection of a bacterial cause of inflammation were 0.50 (95% confidence interval [CI] 0.40 to 0.60) for suPAR, 0.61 (95% CI 0.52 to 0.71) for sTREM-1, 0.63 (95% CI 0.53 to 0.72) for MIF, 0.72 (95% CI 0.63 to 0.79) for PCT, 0.74 (95% CI 0.66 to 0.81) for neutrophil count, 0.81 (95% CI 0.73 to 0.86) for CRP, 0.84 (95% CI 0.71 to 0.91) for the composite three-marker test, and 0.88 (95% CI 0.81 to 0.92) for the composite six-marker test. The AUC of the six-marker test was significantly greater than that of the single markers.

Conclusion

Combining information from several markers improves diagnostic accuracy in detecting bacterial versus nonbacterial causes of inflammation. Measurements of suPAR, sTREM-1 and MIF had limited value as single markers, whereas PCT and CRP exhibited acceptable diagnostic characteristics.

Trial registration

NCT 00389337

Circulating and airway neutrophils in cystic fibrosis display different TLR expression and responsiveness to interleukin-10

We compared blood neutrophils (PMNs) collected from healthy subjects with PMNs derived from either blood or airways collected from the same cystic fibrosis (CF) patients. When compared to healthy blood PMNs, CF blood PMNs expressed enhanced level of CD64, a marker of neutrophil activation, and lower level of Toll-like receptor-2 (TLR2). CF airway PMNs expressed enhanced level of TLR4. Interleukin-8 (IL-8) production by CF blood PMNs could be enhanced upon addition of lipopolysaccharide or peptidoglycan, and this production was inhibited by recombinant human IL-10. In contrast, CF airway PMNs released spontaneously high level of IL-8 that was neither further enhanced by microbial activators nor inhibited by recombinant human IL-10. The levels of IL-10 receptors were similar in all types of neutrophils. These data further demonstrate that circulating PMNs from CF patients display a distinct pattern of surface markers, including TLRs, as compared to PMNs from healthy donors, and that airways PMNs from CF patients are primed and resistant to anti-inflammatory signals delivered by IL-10.

Selective expansion of the CD14(+)/CD16(bright) subpopulation of circulating monocytes in patients with hemophagocytic syndrome

Overproduction of proinflammatory cytokines is characteristic of hemophagocytic syndrome (HPS), a highly lethal inflammatory disease. Peripheral blood monocytes include two distinct subpopulations according to surface antigen expression: a major type, CD14(+)/CD16(-) (classical monocytes), and a minor type, CD14(+)/CD16(bright) (proinflammatory monocytes). Among peripheral blood monocytes from HPS patients, CD14(+)/CD16(bright) cells were increased, together with lipopolysaccharide-induced production of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6. By three-color immunofluorescence, CD14(+)/CD16(bright) monocytes exhibited more intense human leukocytic antigen DR than CD14(+)/CD16(-) monocytes, consistent with greater maturity. Serum IL-6, TNF-alpha, and IL-8 were increased in HPS patients. A sensitive inflammatory marker, neutrophil CD64 expression, also was significantly elevated in HPS patients. In conclusion, expansion of proinflammatory monocytes and increased expression of neutrophil CD64 appeared to be important in the pathophysiology of HPS. Expansion of CD14(+)/CD16(bright) monocytes and neutrophil CD64 expression could serve as indicators of the inflammatory state in HPS.

Neutrophil VCS Parameters Are Superior Indicators for Acute Infection

A reliable and cost-effective laboratory method for diagnosing early bacterial infection is needed. The purpose of this study is to compare the sensitivity and specificity of the mean neutrophil volume (MNV) and neutrophil volume distribution width (NDW) parameters with manual band counts, as well as absolute neutrophil count (ANC) and Creactive protein (CRP). We analyzed the clinical history and laboratory data from 242 adult patients with subsequent randomization into 3 groups: patients with no apparent clinical evidence of infection (group 1), localized infection (group 2), and severe infection (group 3). Total white blood cell counts, percentage of neutrophils, ANC, band counts, MNV, and NDW were progressively elevated from group 1 to group 3. There were good correlations between MNV and ANC (P < .05) or band counts (P < .001). Similarly, the NDW correlated well with ANC (P < .001) and band counts (P < .05). Statistical analyses further confirmed that the MNV and NDW were better parameters, with larger areas under the curve than those of CRP, band count, and ANC. The neutrophil VCS parameters, MNV and NDW, have superior sensitivity and specificity compared to manual band count, ANC, and CRP. MNV and NDW are useful indicators in diagnosing acute infectious processes.

Neutrophil CD64 is an improved indicator of infection or sepsis in emergency department patients

CONTEXT

Sepsis, affecting millions of individuals annually with an associated high mortality rate, is among the top 10 causes of death. In addition, improvements in diagnostic tests for detecting and monitoring sepsis and infection have been limited in the last 25 years. Neutrophil CD64 expression has been proposed as an improved diagnostic test for the evaluation of infection and sepsis.

OBJECTIVE

To evaluate the diagnostic performance of a quantitative flow cytometric assay for leukocyte CD64 expression in comparison with the standard tests for infection/sepsis in an ambulatory care setting.

DESIGN

Prospective analysis of 100 blood samples from patients from an emergency department setting in a 965-bed tertiary care suburban community hospital was performed for neutrophil CD64 expression, C-reactive protein, erythrocyte sedimentation rate, and complete blood count. The laboratory findings were compared with a clinical score for the likelihood of infection/sepsis, which was obtained by a blinded retrospective chart review.

RESULTS

The diagnostic performance, as gauged by the clinical score, varied with neutrophil CD64 (sensitivity 87.9%, specificity 71.2%, efficiency 76.8%) and outperformed C-reactive protein (sensitivity 88.2%, specificity 59.4%, efficiency 69.4%), absolute neutrophil count (sensitivity 60.0%, specificity 50.8%, efficiency 53.8%), myeloid left shift (sensitivity 68.2%, specificity 76.3%, efficiency 73.3%), and sedimentation rate (sensitivity 50.0%, specificity 65.5%, efficiency 61.0%).

CONCLUSION

Neutrophil CD64 expression quantitation provides improved diagnostic detection of infection/sepsis compared with the standard diagnostic tests used in current medical practice.