Utility of immune response-derived biomarkers in the differential diagnosis of inflammatory disorders

Osteoprotegerin in infection-induced acute inflammatory states in children

Background and aims

Osteoprotegerin (OPG) is a tumor necrosis factor receptor superfamily member which increases in chronic inflammation and is associated with altered bone turnover and cardiovascular complications. In this study, we investigated whether OPG increases during acute inflammatory states induced by infections in children and correlated its levels with other biomarkers.

Materials and methods

This is a prospective study that included 59 patients with documented bacterial infections, 20 with viral infections and 20 healthy controls. OPG, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and white blood cells (WBC) were measured.

Results

OPG serum levels were significantly increased during inflammation induced by a bacterial infection, compared to viral infection and controls (4.17 pmol/l (2.40-12.12) vs 3.2 (1.66-5.33) and 3 pmol/l (2.13-4.76), respectively, p < 0.001). In addition, OPG correlated well with CRP (rho = 0.428, p = 0.0011), ESR (rho = 0.3, p = 0.026), and WBC (rho = 0.266, p = 0.05) only in the group with bacterial infection. The sensitivity of CRP in detecting a bacterial infection was superior to OPG (67.3% vs 38.3%).

Conclusion

This study provides proof of concept that OPG increases differentially in bacterial infections, although with a lower sensitivity than CRP. Further studies are needed to define the role of OPG during the inflammatory states of infection in pediatric infections.

CD64 plays a key role in diabetic wound healing

Introduction

Wound healing poses a clinical challenge in diabetes mellitus (DM) due to compromised host immunity. CD64, an IgG-binding Fcgr1 receptor, acts as a pro-inflammatory mediator. While its presence has been identified in various inflammatory diseases, its specific role in wound healing, especially in DM, remains unclear.

Objectives

We aimed to investigate the involvement of CD64 in diabetic wound healing using a DM animal model with CD64 KO mice.

Methods

First, we compared CD64 expression in chronic skin ulcers from human DM and non-DM skin. Then, we monitored wound healing in a DM mouse model over 10 days, with or without CD64 KO, using macroscopic and microscopic observations, as well as immunohistochemistry.

Results

CD64 expression was significantly upregulated (1.25-fold) in chronic ulcerative skin from DM patients compared to non-DM individuals. Clinical observations were consistent with animal model findings, showing a significant delay in wound healing, particularly by day 7, in CD64 KO mice compared to WT mice. Additionally, infiltrating CD163+ M2 macrophages in the wounds of DM mice decreased significantly compared to non-DM mice over time. Delayed wound healing in DM CD64 KO mice correlated with the presence of inflammatory mediators.

Conclusion

CD64 seems to play a crucial role in wound healing, especially in DM conditions, where it is associated with CD163+ M2 macrophage infiltration. These data suggest that CD64 relies on host immunity during the wound healing process. Such data may provide useful information for both basic scientists and clinicians to deal with diabetic chronic wound healing.

Neutrophil CD64 index as a good biomarker for early diagnosis of bacterial infection in pregnant women during the flu season

Background

Pregnant women are at high risk of developing febrile illness during the flu season. Early identification of a viral or bacterial infection is crucial in the management of febrile pregnant patients. Neutrophil CD64 (nCD64) has been shown to have more important diagnostic value in sepsis than traditional inflammatory indicators.

Methods

The pregnant women enrolled were divided into three groups according to disease: influenza A infection, bacterial infection and healthy controls. Peripheral blood CD64, leukocyte, C-reactive protein (CRP), procalcitonin (PCT) and human Th1/Th2-related cytokines levels were routinely measured. The correlation between and diagnostic value of the nCD64 index and other biomarkers were evaluated using Spearman's correlation test and receiver operating characteristic (ROC) curve analysis.

Results

Pregnant women with bacterial infection had significantly elevated levels of leukocytes (8.4 vs. 5.95, 109/L; P = 0.004), CRP (89.70 vs. 50.05 mg/mL; P = 0.031), PCT (0.13 vs. 0.04 ng/mL; P = 0.010) and TNF-α (0.46 vs. 0.38 pg/mL; P = 0.012) and an elevated nCD64 index (12.16 vs. 0.81; P < 0.001) compared with those with influenza A infection. The area under the receiver operating characteristic (AUROC) curve of the nCD64 index to discriminate bacterial infection among pregnant women (AUROC = 0.9183, P < 0.0001) was the largest. The sensitivity and specificity of the nCD64 index at an optimal cut-off value of 3.16 were 84% and 100%, respectively, with a negative predictive value (NPV) of 94%.

Conclusions

Our study demonstrates the clinical value of the nCD64 index in distinguishing between bacterial infection and influenza A in pregnant women.

Neutrophil CD64 index as a superior indicator for diagnosing, monitoring bacterial infection, and evaluating antibiotic therapy: a case control study

BACKGROUND

Neutrophil CD64 (nCD64) index has been widely studied as an indication of bacteria-infected diseases, but the exact usage of nCD64 index in monitoring infections remains debated. So this study aims to investigate the functionality of nCD64 index in tracking infections' progression and evaluating antibiotic therapy.

METHODS

160 participants (36 healthy controls, 34 culture-negative patients, 56 respiratory tract infected patients, and 34 bloodstream infected patients) were recruited and divided into groups. Data on nCD64 index, T lymphocyte subsets, and conventional indicators, including white blood cell count, neutrophil to lymphocyte ratio, procalcitonin, and C-reactive protein, were tested and compared.

RESULTS

Bacteria-infected patients had significantly higher nCD64 indexes (p < 0.05), especially patients with both bloodstream and respiratory tract infections. The nCD64 index could identify infected patients from culture-negative patients or controls, which conventional indicators cannot achieve. We followed up with 24 infected patients and found that their nCD64 indexes were promptly down-regulated after effective antibiotic therapy (3.16 ± 3.01 vs. 1.20 ± 1.47, p < 0.001).

CONCLUSION

The nCD64 index is a sensitive indicator for clinical diagnosis of bacterial infection, especially in monitoring infection and evaluating antibiotics' efficacy. Therefore, nCD64 has the potential to improve diagnostic accuracy and provide rapid feedback on monitoring disease progression in infected patients.

Optimizing antibiotic therapies to reduce the risk of bacterial resistance

The incidence of infections caused by bacteria that are resistant to antibiotics is constantly increasing. In Europe alone, it has been estimated that each year about 33'000 deaths are attributable to such infections. One important driver of antimicrobial resistance is the use and abuse of antibiotics in human medicine. Inappropriate prescribing of antibiotics is still very frequent: up to 50% of all antimicrobials prescribed in humans might be unnecessary and several studies show that at least 50% of antibiotic treatments are inadequate, depending on the setting. Possible strategies to optimize antibiotic use in everyday clinical practice and to reduce the risk of inducing bacterial resistance include: the implementation of rapid microbiological diagnostics for identification and antimicrobial susceptibility testing, the use of inflammation markers to guide initiation and duration of therapies, the reduction of standard durations of antibiotic courses, the individualization of antibiotic therapies and dosing considering pharmacokinetics/pharmacodynamics targets, and avoiding antibiotic classes carrying a higher risk for induction of bacterial resistance. Importantly, measures to improve antibiotic prescribing and antibiotic stewardship programs should focus on facilitating clinical reasoning and improving prescribing environment in order to remove any barriers to good prescribing.

Unraveling the Nature of Antibiotics: Is It a Cure or a New Hurdle to the Patient Treatment?

Antimicrobial resistance is an increasing problem worldwide that has been exacerbated by antibiotic misuse worldwide. Growing antibiotic resistance can be attributed to as well as leads to severe infections, complications, prolonged hospital admissions, and higher mortality. One of the most important goals of administering antimicrobials is to avoid establishing antibiotic resistance during therapy. This can be done by drastically lowering worldwide antimicrobial usage, both in present and future. While current management methods to legislate antimicrobials and educate the healthcare community on the challenges are beneficial, they do not solve the problem of attaining an overall reduction in antimicrobial usage in humans. Application of rapid microbiological diagnostics for identification and antimicrobial susceptibility testing, use of inflammation markers to guide initiation and duration of therapies, reduction of standard antibiotic course durations, individualization of antibiotic treatments, and dosing considering pharmacokinetics are all possible strategies to optimize antibiotic use in everyday clinical practice and reduce the risk of inducing bacterial resistance. Furthermore, to remove any impediments to proper prescribing, strategies to improve antibiotic prescribing and antibiotic stewardship programs should enable clinical reasoning and enhance the prescribing environment. In addition, the well-established association between antimicrobial usage and resistance should motivate efforts to develop antimicrobial treatment regimens that facilitate the evolution of resistance. This review discusses the role of antibiotics, their current application in human medicine, and how the resistance has evolved to the existing antibiotics based on the existing literature.

Rapid detection of bacterial infection using a novel single-tube, four-colour flow cytometric method: Comparison with PCT and CRP

BACKGROUND

A key factor behind the unnecessary use of antibiotics is the lack of rapid and accurate diagnostic tests. In this study, we developed a novel and fast flow cytometric single-tube method to detect bacterial infections within 30 minutes.

METHODS

Quantitative flow cytometric four-colour analysis of host biomarkers CD35, CD64, CD329, and MHC class I expression on neutrophils and lymphocytes was performed on samples taken from 841 febrile patients with suspected infection. Obtained data was incorporated into the four-colour bacterial infection (FCBI)-index, using the developed bacterial infection algorithm.

FINDINGS

In distinguishing between microbiologically confirmed bacterial (n = 193) and viral (n = 291) infections, the FCBI-index method was superior to serum C-reactive protein (CRP) and procalcitonin (PCT). In 269 confirmed viral respiratory tract infections, 43% (95% CI: 37-49%) of the patients had an increased FCBI-index, suggesting probable bacterial coinfection.

INTERPRETATION

The proposed FCBI-index test might be a potent additional tool when assessing appropriateness of empiric antibiotic treatment.

FUNDING

This study has been financially supported by Turku University Hospital (Turku, Finland) and The Finnish Medical Foundation.

Diagnostic, Prognostic, Predictive, and Monitoring Role of Neutrophil CD11b and Monocyte CD14 in Neonatal Sepsis

Background

Sepsis is a critical medical condition that requires additional diagnostic considerations. Recently, focus has shifted to the diagnosis of sepsis using new markers to overcome the limitations of traditional laboratory diagnostic modalities. Neutrophil CD11b (nCD11b) and monocyteCD14 (mCD14) cell surface antigens have been shown to be useful in such diagnostic consideration.

Aim

To investigate the diagnostic, monitoring, prognostic, and predictive roles of nCD11b and mCD14 as sepsis biomarkers in comparison to each other and to traditional laboratory sepsis parameters in order to select the best fit for routine daily use in neonatal intensive care units (NICUs).

Subject

The study included 188 neonates from Ain Shams University Hospitals' NICUs, who were divided into two groups: the control group (n = 100) and the sepsis group (n = 88). Highly sensitive CRP (hs-CRP), complete blood count (CBC), blood culture, and nCD11b and mCD14 evaluations were all part of the laboratory sepsis evaluation (done by flow cytometry technology). Positive blood culture results (BACT/ALERT system) confirmed the sepsis diagnosis. Twenty-four enrolled sepsis neonates were subjected to follow-up assessments, and they were divided into two groups based on clinical improvement: improved sepsis and sepsis without improvement. In order to predict performance evaluation, the subjected neonates were reclassified according to their outcome into survivors' and nonsurvivors' group.

Results

Sepsis patients had a significant increase in mCD14 MFI values when compared to controls. With sensitivity 75.4 percent, specificity 71.9 percent, efficacy 73.3 percent, and AUC 0.703, mCD14 MFI at cutoff 9.36 could distinguish the presence of septicemia. Significant increases in both mCD14 MFI and nCD11b MFI (P = 0.001) were observed in the severe sepsis/septic shock group compared to the nonsevere sepsis group. The combined measurement of CD14 MFI at cutoff 9.97 and CD14 percent at cutoff 44.7 percent yielded the best predictive performance.

Conclusion

Sepsis patients had a significant increase in mCD14 MFI comparable to the controls. mCD14 MFI demonstrated better diagnostic, prognostic, and predictive results than nCD11b. hs-CRP outperformed mCD14 and nCD11b in terms of diagnostic efficacy and AUC. In the monitoring of sepsis patients, both mCD14 and nCD11b produced unsatisfactory results. Currently, the routine use of mCD14 or nCD11b as sepsis biomarkers in neonatal ICUs is not justified.

A two-transcript biomarker of host classifier genes for discrimination of bacterial from viral infection in acute febrile illness: a multicentre discovery and validation study

BACKGROUND

Acute febrile illness is one of the main reasons for outpatient hospital visits worldwide. However, differential diagnosis between bacterial and viral causes is challenging and misdiagnosis can result in antimicrobial overuse and hinder prompt treatment. We aimed to build and validate a diagnostic model to discriminate bacterial from viral infection in acute febrile illness by evaluating the expression of potential classifier host genes.

METHODS

In this multicentre discovery and validation study, we included patients aged 14-85 years with acute febrile illness (fever for ≤14 days, axillary temperature of ≥38°C, and confirmed bacterial infection, viral infection, or non-infectious inflammatory disease), and healthy control participants (no significant medical history and no fever within the past 90 days) from four hospitals in Shandong province, China. Patients from the first hospital were divided into the screening, discovery, and internal validation groups, and patients from the three other hospitals comprised the external validation group. We measured expression of candidate genes in peripheral blood by RT-PCR, and patients for whom a successful RT-PCT result was recorded were included in the next-step analysis. For patients from the first hospital, those enrolled during the early phase of the study were assigned to the screening group, which was used to identify the optimal transcripts (IFI44L and PI3) for discrimination between bacterial and viral infections by screening four candidate genes (FAM89A, IFI44L, PI3, and ITGB2) by RT-PCR. The remaining patients were then randomly assigned (1:1) to discovery and internal validation groups by time of admission and blood drawing via the equidistant random sampling method. A logistic regression model integrating the mRNA levels of IFI44L and PI3 was built by use of the discovery group, and the diagnostic performance of the model was evaluated in the internal and external validation groups using area under the receiver operating curve (AUC), sensitivity, and specificity.

FINDINGS

Between March 1, 2018, and Aug 31, 2019, we assessed 1658 individuals for inclusion in the study. After exclusion of ineligible participants, 458 participants were enrolled (178 patients with acute febrile illness caused by bacterial infection, 212 with acute febrile illness caused by viral infection, 38 with non-infectious inflammatory diseases, and 30 healthy controls). The 390 patients with bacterial or viral infections were assigned to one of four groups: screening (n=64, 33 with bacterial infections and 31 with viral infections), discovery (n=124, 55 with bacterial infections and 69 with viral infections), internal validation (n=124, 55 with bacterial infections and 69 with viral infections), and external validation (n=78, 35 with bacterial infections and 43 with viral infections). Of the four candidate host genes (FAM89A, IFI44L, PI3, and ITGB2), IFI44L and PI3 showed the most discriminative expression pattern and were used to build the logistic regression model. We established the optimal cutoff of the bacterial infection likelihood score to be 0·547598. With the diagnostic result from the gold standard tests (culture and PCR) as the reference, the two-transcript classifier model had an AUC of 0·969 (95% CI 0·937-1·000), sensitivity of 0·891 (0·782-0·949), and specificity of 0·971 (0·900-0·992) to discriminate bacterial and viral infections in the internal validation group. The model showed similar results in the external validation group (AUC 0·986, 95% CI 0·968-1·000; sensitivity 0·857, 0·706-0·937; and specificity 0·954, 0·845-0·987).

INTERPRETATION

IFI44L and PI3 transcripts, measured by RT-PCR, are robust classifiers to discriminate bacterial from viral infection in acute febrile illness. This two-transcript biomarker has the potential to be transformed into a commercial panel and applied universally.

FUNDING

None.

An Aptamer Linked Immobilized Sorbent Assay (ALISA) to Detect Circulatory IFN-α, an Inflammatory Protein among Tuberculosis Patients

Dysregulation of IFN-α is the basis for pathogenesis of autoimmune as well as infectious diseases. Identifying inflammatory signatures in peripheral blood of patients is an approach for monitoring active infection. Hence, estimation of type I IFNs as an inflammatory biomarker to scrutinize disease status after treatment is useful. Accordingly, an Aptamer Linked Immobilized Sorbent Assay (ALISA) for the detection of IFN-α in serum samples was developed. Sixteen aptamers were screened for their ability to bind IFN-α. Aptamer IFNα-3 exhibited specificity for IFN-α with no cross-reactivity with interferons β and γ and human serum albumin. The disassociation constant (K_d) was determined to be 3.96 ± 0.36 nM, and the limit of detection was ∼2 ng. The characterized IFNα-3 aptamer was used in ALISA to screen tuberculosis (TB) patients' sera. An elevated IFN-α level in sera derived from untreated TB patients (median = 0.31), compared to nontuberculous household contacts (median = 0.13) and healthy volunteers (median = 0.12), and further a decline in IFN-α level among treated patients (median = 0.13) were seen. The ALISA assay facilitates direct estimation of inflammatory protein(s) in circulation unlike mRNA estimation by real time PCR. Designing of aptamers similar to the IFNα-3 aptamer provides a novel approach to assess other inflammatory protein(s) in patients before, during, and after completion of treatment and would denote clinical improvement in successfully treated patients.

Differential expression of CD64 in patients with Mycobacterium tuberculosis infection: A potential biomarker for clinical diagnosis and prognosis

To evaluate the clinical utility of neutrophil (n)CD64 index to diagnose pulmonary tuberculosis (PTB) and extrapulmonary TB (ePTB) and to predict the outcome of Mycobacterium tuberculosis infection. We recruited 189 patients with active TB and 140 controls and measured the differential expression of nCD64 index using flow cytometry. The receiver operating characteristics (ROC) curve analysis was performed to estimate the diagnostic performance of the nCD64 index and T‐SPOT.TB assay for the diagnosis of TB. Furthermore, we analysed whether the nCD64 index in patients with TB was correlated with inflammatory indicators. Finally, we assessed the prognosis of patients by following the dynamic changes of the nCD64 index once a week. The nCD64 index was significantly higher in active TB group (PTB and ePTB), than in the anti‐TB and healthy controls (HC) groups. The sensitivity and specificity of nCD64 index for the differential diagnosis of PTB and pneumonia (PN) patients were 68.33% and 77.55%, respectively. The sensitivity and specificity of nCD64 index for the diagnosis of tuberculous meningitis (TBM) were 53.85% and 100%, respectively. Furthermore, there was a weak correlation between the nCD64 index and inflammatory indicators. More importantly, with the improvement in patient condition, the nCD64 index started to decline in the first week of anti‐TB therapy and significantly decreased at 4 weeks after treatment. Our study demonstrated that the CD64 assay is a rapid, non‐invasive and stable method for clinical application, and the nCD64 index can serve as a potential biomarker for the diagnosis and prognosis of TB.

The Utility of Neutrophil CD64 and Presepsin as Diagnostic, Prognostic, and Monitoring Biomarkers in Neonatal Sepsis

Background

Neonatal septicemia is a critical medical situation; current conventional laboratory methods still have many limitations and diagnostic obstacles. For this purpose, last decades have witnessed a challenge between the battery of sepsis biomarkers including many leukocyte surface antigens, not only for early diagnostic purposes but also for better follow-up and good management of sepsis patients.

Aim

To evaluate the diagnostic, prognostic, and monitoring performance of both neutrophil CD64 (nCD64) and presepsin as sepsis biomarkers compared to each other and to the conventional laboratory sepsis parameters aiming to decide which is the best fitting for routine daily use in neonatal intensive care units (NICUs).

Methods

235 neonates were enrolled from three Egyptian neonatal ICUs, during the period from November 2015 till March 2018; they were classified into two main groups: the control group (n = 102) and the sepsis group (n = 133). Laboratory sepsis evaluation included highly sensitive CRP (hs-CRP), CBC, in addition to nCD64 (flow cytometry technique), and presepsin measurement (CLEIA technique combined with Magtration® technology); the diagnosis was confirmed thereafter by positive blood culture results (BacT/Alert system). Sixty-two of the enrolled sepsis neonates were subjected to follow-up assessment; they were reclassified according to their clinical improvement at the second time assessment into (group 1: sepsis group without improvement) (n = 20) and (group 2: improved sepsis group) (n = 42).

Results

Significant increase in nCD64 and presepsin values was found in sepsis groups compared to the controls. At cutoff 41.6%, nCD64% could discriminate the presence of septicemia with sensitivity 94.7%, specificity 93.6 %, and AUC 0.925, while presepsin at cutoff 686 pg/ml achieves sensitivity 82.7%, specificity 95.5%, and AUC 0.887, respectively. Significant increase in nCD64 (P < 0.001) and hs-CRP (P=0.018) values was observed in severe sepsis/septic shock patients compared to nonsevere sepsis patients. Delta change percentage (dC%) between initial and follow-up evaluations for both improved and nonimproved sepsis patients was dC Z value −5.904 for nCD64% followed by dC Z value −4.494 for presepsin.

Conclusion

nCD64 and presepsin are valuable early diagnostic and monitoring sepsis biomarkers; the highest sensitivity could be achieved by a univariant sepsis marker in this study was recorded by the nCD64% biomarker, while the highest specificity was documented by presepsin. Combined measurement of both achieves the highest diagnostic performance in sepsis neonates. Either of CD64 or presepsin combined with hs-CRP associated with better performance than any of them alone. nCD64 carries an additional promising role in reflecting sepsis prognosis.

The plasma level of mCRP is linked to cardiovascular disease in antineutrophil cytoplasmic antibody-associated vasculitis

Background

C-reactive protein (CRP) has two natural isomers: C-reactive protein pentamer (pCRP) and C-reactive protein monomer (mCRP). The levels of CRP are significantly elevated in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). mCRP not only activates the endothelial cells, platelets, leukocytes, and complements, but also has a proinflammatory structural subtype that can localize and deposit in inflammatory tissues. Thus, it regulates a variety of clinical diseases, such as ischemia/reperfusion (I/R) injury, Alzheimer’s disease, age-related macular degeneration, and cardiovascular disease. We hypothesized that plasma mCRP levels are related to cardiovascular disease in AAV.

Methods

In this cross-sectional study, 37 patients with AAV were assessed. Brain natriuretic peptide (BNP) and mCRP in plasma were assessed by enzyme-linked immunosorbent assay (ELISA). The acute ST-segment elevation myocardial infarction (STEMI) was diagnosed by coronary angiography, and the Gensini score calculated. Echocardiography evaluated the ejection fraction (EF%), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and left ventricular mass index (LVMI). Estimated glomerular filtration rate (eGFR) was calculated based on serum creatinine, age, and gender.

Results

The plasma level of mCRP in AAV was significantly higher than that in healthy volunteers (P < 0.001). Then, mCRP and CRP levels were compared with and without STEMI complications in AAV. The plasma level of mCRP was higher, but that of CRP was lower in STEMI. The plasma level of mCRP was correlated with Birmingham vasculitis activity score (BVAS), eGFR, BNP, EF%, LVEDV, LVESV, LVMI, and STEMI complications’ Gensini score in AAV; however, CRP did not correlate with BNP, EF%, LVEDV, LVESV, LVMI, and Gensini score.

Conclusions

The plasma level of mCRP was related to cardiovascular diseases in AAV patients.

Using the kinetics of C-reactive protein response to improve the differential diagnosis between acute bacterial and viral infections

PURPOSE

Differential diagnosis between acute viral and bacterial infection is an emerging common challenge for a physician in the emergency department. Serum C-reactive protein (CRP) is used to support diagnosis of bacterial infection, but in patients admitted with low CRP, its ability to discriminate between viral and bacterial infections is limited. We aimed to use two consecutive CRP measurements in order to improve differential diagnosis between bacterial and viral infection.

METHODS

A single-center retrospective cohort (n = 1629) study of adult patients admitted to the emergency department with a subsequent microbiological confirmation of either viral or bacterial infection. Trend of CRP was defined as the absolute difference between the first two measurements of CRP divided by the time between them, and we investigated the ability of this parameter to differentiate between viral and bacterial infection.

RESULTS

In patients with relatively low initial CRP concentration (< 60 mg/L, n = 634 patients), where the uncertainty regarding the type of infection is the highest, the trend improved diagnosis accuracy (AUC 0.83 compared to 0.57 for the first CRP measurement). Trend values above 3.47 mg/L/h discriminated bacterial from viral infection with 93.8% specificity and 50% sensitivity.

CONCLUSIONS

The proposed approach for using the kinetics of CRP in patients whose first CRP measurement is low can assist in differential diagnosis between acute bacterial and viral infection.

Diagnosis and Monitoring of Acute Infections with Emphasis on the Novel Biomarker Human Neutrophil Lipocalin

Background

Acute infections affect all of us at least once or twice a year. Sometimes the infection prompts a visit to our doctor, and the question asked by the patient and the doctor is whether the infection should be treated with antibiotics or not. This is an important question because unnecessary prescription of antibiotics adds to the increasing problem of antibiotics resistance. Objective means to determine whether the infection is caused by bacteria or virus, therefore, are necessary tools for the doctor.

Content

White blood cell counts, C-reactive protein, and other acute-phase reactants in blood are important tools and are commonly used, but unfortunately lack in sensitivity and specificity. In this review we describe some novel biomarkers with increased clinical performance in this regard. The superior biomarker is human neutrophil lipocalin (HNL), a protein released from activated blood neutrophils. HNL may be measured in serum, plasma, or in whole blood after activation with a neutrophil activator. The diagnostic accuracy in the distinction between bacterial and viral acute infections was shown to be in the range of 90%–95% when measured in serum or activated whole blood.

Summary

A point-of-care assay for the measurement of HNL in whole blood is currently being developed, which will allow the diagnosis of acute infections within 5–10 min. For certain indications, HNL measurement may be complemented by 1 or 2 other biomarkers, which may increase the diagnostic discrimination between bacterial and viral infections even further.

CD35 and CD64 of Neutrophils Can Differentiate Between Bacterial and Viral Infections in Children by Simultaneous Quantitative Analysis

BACKGROUND The aim of this study was to determine the relationship between the expression of CD35 and CD64 from white blood cells (neutrophil, monocytes, and lymphocytes) and acute infectious diseases in children. MATERIAL AND METHODS The blood samples were collected from 104 children with infections (42 viral infections and 62 bacterial infections). Blood samples were stained with CD45-PC5, CD35-FITC, and CD64-PE, and the fluorescence intensities were measured by flow cytometer, and then the ratio of CD35 to CD64 was calculated. RESULTS The ratio of CD64/CD35 on neutrophils (NCD35/NCD64) was significantly different between the bacterial group, the virus group, and the healthy control group. According to receiver operating characteristic (ROC) analysis, a cutoff value of 7.256 (sensitivity: 90.0%, specificity: 93.7%) was determined for the NCD35/NCD64 ratio. CONCLUSIONS This study shows that NCD35/NCD64 is helpful in the differential diagnosis of acute viral infection and bacterial infection in children.

Utility of leucocyte antigens in distinguishing between bacterial and viral infection in children

Introduction

Accurate diagnosis of bacterial and viral infection is very difficult. Unfortunately, there is still no quick and discriminative diagnostic test that would help clinicians in establishing the diagnosis and taking a decision on treatment. The aim of the study was to compare the expression of antigens on phagocytes, which are involved in the first defence line during bacterial and viral infections in children, as a potential tool to distinguish the etiology of the infection.

Material and methods

The expression of CD35, CD32, CD88, and MHC class I on phagocytes in 49 blood samples from children with high fever and suspected infection as well as 19 healthy children (control group) was assessed by flow cytometry. Thirty-three children were diagnosed with bacterial and 16 with viral infection. Expression of antigens was analysed on a FACSCanto II flow cytometer according to mean fluorescence intensity (MFI) and antibody binding cites (ABC).

Results

Significant differences were observed for the following: CD32, CD35, CD88, and MHCI on granulocytes; CD32, CD35, CD88 on monocytes; and MHC-I ratio between groups were observed. The obtained results did not allow us to establish valuable score points for distinguishing between bacterial and viral infections. Classification and a regression tree using CD88 expression on granulocytes and CRP was developed. It enabled us to differentiate between the origin of infection with sensitivity and specificity of more than 90%.

Conclusions

Utility of use of wide range antigens’ expression on phagocytes for distinguishing between bacterial and viral infection in children has limited value. More adequate seems to be use of CD88 expression on granulocytes linked with CRP value.

Examining the utility of the CD64 index compared with other conventional indices for early diagnosis of neonatal infection

As specific clinical manifestations and detection tools for early neonatal infections are lacking, early detection and treatment are ongoing challenges. The present study aimed to investigate the role and clinical significance of the CD64 index in comparison with conventional examination indices (WBC, PCT and CRP) for the early diagnosis of neonatal infection. Of 74 in-patient newborns, non-sepsis (non-specific infection but free of sepsis), sepsis and control [newborns with ABO hemolytic disease of the newborn (ABOHDN) but without infection] groups involved 32, 16 and 26 cases, respectively. Peripheral blood WBC, PCT, CRP and CD64 indices were acquired for all groups. The sepsis group showed significantly higher WBC, PCT and CRP levels than the control group. Compared with the non-sepsis group, the sepsis group demonstrated significant increases in PCT but not in WBC or CRP. Compared with the control group, the non-sepsis and sepsis groups had higher CD64 indices. Combined, compared with the WBC, PCT and CRP indices, the CD64 index is unique in its capacity to diagnose neonatal infections early. The CD64 index combined with other conventional indices may lay a basis for the future early diagnosis and effective treatment of neonatal infections.

A host-protein signature is superior to other biomarkers for differentiating between bacterial and viral disease in patients with respiratory infection and fever without source: a prospective observational study

Bacterial and viral infections often present with similar symptoms. Etiologic misdiagnosis can alter the trajectory of patient care, including antibiotic overuse. A host-protein signature comprising tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), interferon gamma-induced protein-10 (IP-10), and C-reactive protein (CRP) was validated recently for differentiating bacterial from viral disease. However, a focused head-to-head comparison of its diagnostic performance against other biomarker candidates for this indication was lacking in patients with respiratory infection and fever without source. We compared the signature to other biomarkers and prediction rules using specimens collected prospectively at two secondary medical centers from children and adults. Inclusion criteria included fever > 37.5 °C, symptom duration ≤ 12 days, and presentation with respiratory infection or fever without source. Comparator method was based on expert panel adjudication. Signature and biomarker cutoffs and prediction rules were predefined. Of 493 potentially eligible patients, 314 were assigned unanimous expert panel diagnosis and also had sufficient specimen volume. The resulting cohort comprised 175 (56%) viral and 139 (44%) bacterial infections. Signature sensitivity 93.5% (95% CI 89.1–97.9%), specificity 94.3% (95% CI 90.7–98.0%), or both were significantly higher (all p values < 0.01) than for CRP, procalcitonin, interleukin-6, human neutrophil lipocalin, white blood cell count, absolute neutrophil count, and prediction rules. Signature identified as viral 50/57 viral patients prescribed antibiotics, suggesting potential to reduce antibiotic overuse by 88%. The host-protein signature demonstrated superior diagnostic performance in differentiating viral from bacterial respiratory infections and fever without source. Future utility studies are warranted to validate potential to reduce antibiotic overuse.

Detection of sepsis in patient blood samples using CD64 expression in a microfluidic cell separation device

A microfluidic affinity separation device was developed for the detection of sepsis in critical care patients.

Validation of a Novel Assay to Distinguish Bacterial and Viral Infections

BACKGROUND

Reliably distinguishing bacterial from viral infections is often challenging, leading to antibiotic misuse. A novel assay that integrates measurements of blood-borne host-proteins (tumor necrosis factor-related apoptosis-inducing ligand, interferon γ-induced protein-10, and C-reactive protein [CRP]) was developed to assist in differentiation between bacterial and viral disease.

METHODS

We performed double-blind, multicenter assay evaluation using serum remnants collected at 5 pediatric emergency departments and 2 wards from children ≥3 months to ≤18 years without (n = 68) and with (n = 529) suspicion of acute infection. Infectious cohort inclusion criteria were fever ≥38°C and symptom duration ≤7 days. The reference standard diagnosis was based on predetermined criteria plus adjudication by experts blinded to assay results. Assay performers were blinded to the reference standard. Assay cutoffs were predefined.

RESULTS

Of 529 potentially eligible patients with suspected acute infection, 100 did not fulfill infectious inclusion criteria and 68 had insufficient serum. The resulting cohort included 361 patients, with 239 viral, 68 bacterial, and 54 indeterminate reference standard diagnoses. The assay distinguished between bacterial and viral patients with 93.8% sensitivity (95% confidence interval: 87.8%-99.8%) and 89.8% specificity (85.6%-94.0%); 11.7% had an equivocal assay outcome. The assay outperformed CRP (cutoff 40 mg/L; sensitivity 88.2% [80.4%-96.1%], specificity 73.2% [67.6%-78.9%]) and procalcitonin testing (cutoff 0.5 ng/mL; sensitivity 63.1% [51.0%-75.1%], specificity 82.3% [77.1%-87.5%]).

CONCLUSIONS

Double-blinded evaluation confirmed high assay performance in febrile children. Assay was significantly more accurate than CRP, procalcitonin, and routine laboratory parameters. Additional studies are warranted to support its potential to improve antimicrobial treatment decisions.

[Value of combined determination of neutrophil CD64 and procalcitonin in early diagnosis of neonatal bacterial infection]

OBJECTIVE

To investigate the value of combined determination of neutrophil CD64 and procalcitonin (PCT) in the early diagnosis of neonatal bacterial infection.

METHODS

According to discharge diagnosis, 37 neonates with bacterial infection were divided into sepsis (n=15) and ordinary infection (non-sepsis) groups (n=22). Twenty-one neonates without infection who were hospitalized during the same period of time were enrolled as the control group. Venous blood samples were collected immediately after admission. Flow cytometry was used to measure the serum level of neutrophil CD64. Chemiluminescence and immune transmission turbidimetry were used to measure the serum levels of PCT and CRP respectively.

RESULTS

The sepsis group had higher serum levels of neutrophil CD64, PCT, and CRP than the control group (P<0.01), the ordinary infection group had a higher serum level of neutrophil CD64 than the control group (P<0.01), and the sepsis group had higher serum levels of PCT and CRP than the ordinary infection group (P<0.01). The areas under the ROC curve (AUC) of neutrophil CD64, PCT, and CRP in diagnosing bacterial infection were 0.818, 0.818, and 0.704 respectively, and the AUC of combined neutrophil CD64 and PCT was 0.926. A combination of neutrophil CD64 and PCT had a sensitivity of 97.29% and an accuracy of 89.65% in the early diagnosis of neonatal bacterial infection.The sensitivity and accuracy were higher than those of a combination of CRP and neutrophil CD64 or PCT as well as neutrophil CD64, PCT, or CRP alone for the early diagnosis of neonatal bacterial infection.

CONCLUSIONS

The combined determination of neutrophil CD64 and PCT can improve the sensitivity and accuracy in the diagnosis of neonatal bacterial infection, which helps with early identification of bacterial infection.

["Choosing wisely" in infectious diseases : Overuse of antibiotics - too few vaccinations]

The "choosing wisely" recommendations of the German Society of Internal Medicine (DGIM) and its specialist societies address diagnostic and therapeutic procedures, which are of particular medical importance but applied too often or too rarely in clinical practice. The aim is to further improve treatment of patients. Important topics of overuse and insufficient treatment related to the diagnostics, therapy, prevention and exclusion of infectious diseases could be identified. These topics not only play an important role in the discipline of infectious diseases but are also relevant for other internal medical disciplines. These topics related to infectious diseases have also been integrated into the recommendations of the German Society of Gastroenterology, Digestive and Metabolic Diseases as well as the German Societies for Internal Intensive Care and Emergency Medicine, for Pneumology, for Nephrology and for Rheumatology. The pivotal issues of the recommendations are the inappropriate use of antibiotics and insufficient vaccination rates.

Novel tools for primary immunodeficiency diagnosis: making a case for deep profiling

PURPOSE OF REVIEW

This review gives an overview of the systems-immunology single-cell proteomic and transcriptomic approaches that can be applied to study primary immunodeficiency. It also introduces recent advances in multiparameter tissue imaging, which allows extensive immune phenotyping in disease-affected tissue.

RECENT FINDINGS

Mass cytometry is a variation of flow cytometry that uses rare earth metal isotopes instead of fluorophores as tags bound to antibodies, allowing simultaneous measurement of over 40 parameters per single-cell. Mass cytomety enables comprehensive single-cell immunophenotyping and functional assessments, capturing the complexity of the immune system, and the molecularly heterogeneous consequences of primary immunodeficiency defects. Protein epitopes and transcripts can be simultaneously detected allowing immunophenotype and gene expression evaluation in mixed cell populations. Multiplexed epitope imaging has the potential to provide extensive phenotypic characterization at the subcellular level, in the context of 3D tissue microenvironment.

SUMMARY

Mass cytometry and multiplexed epitope imaging can complement genetic methods in diagnosis and study of the pathogenesis of primary immunodeficiencies. The ability to understand the effect of a specific defect across multiple immune cell types and pathways, and in affected tissues, may provide new insight into tissue-specific disease pathogenesis and evaluate effects of therapeutic interventions.

The "Choosing Wisely" initiative in infectious diseases

OBJECTIVE

"Choosing Wisely" is a growing international campaign aiming at practice changes to improve patient health and safety by both, conduct of essential and avoidance of unnecessary diagnostic, preventive and therapeutic procedures. The goal is to create an easily recognizable and distributable list ("Choosing Wisely items") that addresses common over- and underuse in the management of infectious diseases.

METHODS

The German Society of Infectious Diseases (DGI) participates in the campaign "Klug Entscheiden" by the German Society of Internal Medicine. Committee members of the (DGI) listed potential 'Choosing Wisely items'. Topics were subjected to systematic evidence review and top ten items were selected for appropriateness. Five positive and negative recommendations were approved via individual member vote.

RESULTS

The final recommendations are: (1) Imperatively start antimicrobial treatment and remove the focus in Staphylococcus aureus bloodstream infection. (2) Critically ill patients with signs of infection need early appropriate antibiotic therapy. (3) Annual influenza vaccination should be given to individuals with age >60 years, patients with specific co-morbidities and to contact persons who may spread influenza to others. (4) All children should receive measles vaccine. (5) Prefer oral formulations of highly bioavailable antimicrobials whenever possible. (6) Avoid prescribing antibiotics for uncomplicated upper respiratory tract infections. (7) Do not treat asymptomatic bacteriuria with antibiotics. (8) Do not treat Candida detected in respiratory or gastrointestinal tract specimens. (9) Do not prolong prophylactic administration of antibiotics in patients after they have left the operating room. (10) Do not treat an elevated C-reactive protein (CRP) or procalcitonin with antibiotics for patients without signs of infection.

CONCLUSIONS

Physicians will reduce potential harm to patients and increase the value of health care when implementing these recommendations.