Value of serum procalcitonin, neopterin, and C-reactive protein in differentiating bacterial from viral etiologies in patients presenting with lower respiratory tract infections

Photonic sensor to detect rapid changes in CRP levels

One of the most important biomarkers used to determine inflammation is C-reactive protein (CRP). Its level, when it is within the range that does not define inflammation, informs about the risk of cardiovascular events. If the norm is exceeded and inflammation is detected in the body, CRP level can increase 1000 times within a few hours. The type of infection can also be determined based on the level of elevated CRP. All this makes CRP a very important element of diagnostics. A sensor based on low coherence interference is presented. Preliminary studies have shown that its sensitivity is 5.65 μg/L and the measurement time is short, <10 min. The entire system is built of commercially available components, which allow production cost minimalization. In addition, the user-friendly operation allows it to be operated by unqualified people. Due to these features, our solution is a promising alternative to commercially used enzyme-linked immunosorbent assay, which needs trained personnel to perform time-consuming measurement procedures.

Differentiating between bacterial and viral infections by estimated CRP velocity

PURPOSE

Differentiating between acute viral and bacterial infection is challenging due to the similarity in symptom presentation. Blood tests can assist in the diagnosis, but they reflect the immediate status and fail to consider the dynamics of an inflammatory response with time since symptom onset. We applied estimated C-reactive protein (CRP) velocity (eCRPv), as derived from the admission CRP level divided by time from symptom onset, in order to better distinguish between viral and bacterial infections.

METHODS

This cross-sectional study included patients admitted to the emergency department with a confirmed viral (n = 83) or bacterial (n = 181) infection. eCRPv was defined as the ratio between the absolute CRP level upon admission to time from symptom onset (in hours). Absolute CRP and eCRPv values were compared between the 3 groups.

RESULTS

Bacterial patients presented with higher CRP levels (133 mg/L) upon admission compared to viral patients (23.31 mg/L) (P < 0.001). Their median value of eCRPv velocity was 4 times higher compared to the viral patients (1.1 mg/L/h compared 0.25 mg/L/h, P < 0.001). Moreover, in intermediate values of CRP (100-150 mg/L) upon admission, in which the differential diagnosis is controversial, high eCRPv is indicative of bacterial infection, eCRPv >4 mg/L/h represents only bacterial patients.

CONCLUSIONS

During an acute febrile illness, the eCRPv value can be used for rapid differentiation between bacterial and viral infection, especially in patients with high CRP values. This capability can potentially expedite the provision of appropriate therapeutic management. Further research and validation may open new applications of the kinetics of inflammation for rapid diagnosis of an infectious vs. a viral source of fever.

Elevated neopterin in tuberculosis and co-infection with HIV and the effect of treatment: A systematic review, meta-analysis, and meta-regression

BACKGROUND

Neopterin (NEO) is a marker of immune stimulation. Increased NEO levels have been associated with autoimmune diseases, infections, and malignancies. Studies of NEO alterations in tuberculosis (TB) with or without HIV co-infection show inconsistent results. Moreover, challenges exist regarding TB diagnosis in people with HIV.

METHODS

We did a systematic review and meta-analysis of studies comparing urinary, pleural, and blood NEO levels between patients with TB or HIV-TB co-infection as the case group and subjects without TB and HIV or subjects with HIV without TB as the control group, respectively.

RESULTS

Blood NEO levels in patients with active TB were higher than healthy controls, with a large effect size of 1.99. Patients with TB had higher blood NEO levels before anti-tuberculosis therapy (ATT) than after ATT for months or when treatment ended with moderate effect sizes (1.13-1.46). meta-analysis of studies of patients with HIV-TB co-infection yielded similar results, with higher blood NEO levels in patients than controls that remained significant in subgroups of studies on pulmonary TB (PTB) patients and serum NEO and higher blood NEO levels in patients before than after ATT.

CONCLUSION

Meta-analyses reveal alteration in NEO levels in different specimens, e.g., blood, urine, and pleural fluid, in patients with TB with or HIV-TB co-infection compared to the control groups. Future studies need to investigate the utility of NEO as a diagnostic/prognostic biomarker for TB. Also, cellular and molecular mechanisms linking NEO and TB remain to be addressed.

C-Reactive protein and SOFA scale: A simple score as early predictor of critical care requirement in patients with COVID-19 pneumonia in Spain

OBJECTIVE

To identify potential markers at admission predicting the need for critical care in patients with COVID-19 pneumonia.

MATERIAL AND METHODS

An approved, observational, retrospective study was conducted between March 15 to April 15, 2020. 150 adult patients aged less than 75 with Charlson comorbidity index ≤6 diagnosed with COVID-19 pneumonia were included. Seventy-five patients were randomly selected from those admitted to the critical care units (critical care group [CG]) and seventy-five hospitalized patients who did not require critical care (non-critical care group [nCG]) represent the control group. One additional cohort of hospitalized patients with COVID-19 were used to validate the score.

MEASUREMENTS AND MAIN RESULTS

Multivariable regression showed increasing odds of in-hospital critical care associated with increased C-reactive protein (CRP) (odds ratio 1.052 [1.009-1.101]; P = 0.0043) and higher Sequential Organ Failure Assessment (SOFA) score (1.968 [1.389-2.590]; P < 0.0001), both at the time of hospital admission. The AUC-ROC for the combined model was 0.83 (0.76-0.90) (vs AUC-ROC SOFA P < 0.05). The AUC-ROC for the validation cohort was 0.89 (0.82-0.95) (P > 0.05 vs AUC-ROC development).

CONCLUSION

Patients COVID-19 presenting at admission SOFA score ≥ 2 combined with CRP ≥ 9.1 mg/mL could be at high risk to require critical care.

Effects of atorvastatin doses on serum level of procalcitonin and predictors for major adverse cardiovascular events in patients with acute myocardial infarction: a pilot study and post hoc analysis

BACKGROUND

Inflammation plays an important role in acute myocardial infarction (AMI). Procalcitonin levels rise in response to proinflammatory stimuli. This study aimed to investigate the effects of different doses of atorvastatin on the serum inflammatory profiles, especially procalcitonin and major adverse cardiovascular events (MACEs) in patients with AMI during hospitalization.

METHODS

The patients who were admitted to the Coronary Care Unit of The Third Medical Center of PLA General Hospital (Beijing, China) between January 2015 and December 2015 with a diagnosis of AMI were enrolled, and randomized to atorvastatin 20 mg/day postoperatively (20-mg group), 40 mg/day postoperatively (40-mg group) and 80 mg preoperatively+40 mg/day postoperatively (80/40-mg group). Serum procalcitonin and high-sensitivity C-reactive protein (hs-CRP) were evaluated before and at 1 and 3 days after percutaneous coronary intervention (PCI).

RESULTS

A total of 112 patients with AMI (23 women and 89 men) were prospectively eligible for the study. There were no significant differences in most clinical data among the three groups. The 80/40-mg group showed significantly reduced serum procalcitonin levels at 1 and 3 days after PCI (P < 0.001) and reduced hs-CRP levels at 3 days P = 0.001) compared with 20-mg and 40-mg groups. Serum procalcitonin (OR, 4.593; 95% CI, 1.476-8.387; P = 0.005), hs-CRP (OR, 1.149; 95% CI, 1.012-1.338; P = 0.018), highly sensitive cardiac troponin T (OR, 1.255; 95% CI, 1.004-1.569, P = 0.009) and Gensini score (OR, 1.022; 95% CI, 1.045-1.062; P = 0.013) were independently associated with MACEs during hospitalization.

CONCLUSION

The use of atorvastatin 80 mg before and 40 mg/day after PCI in patients with AMI can effectively reduce serum inflammatory factors. procalcitonin and hs-CRP were independently associated with in-hospital MACEs.

The effect of C-reactive protein on chest X-ray interpretation: A decision-making experiment among pediatricians

INTRODUCTION

Clinical decision-making is complex and requires the integration of multiple sources of information. Physicians tend to over-rely on objective measures, despite the lack of supportive evidence in many cases. We sought to test if pediatricians over-rely on C-reactive protein (CRP) results when managing a child with suspected pneumonia.

METHODS

A nationwide decision-making experiment was conducted among 337 pediatricians in Israel. Each participant was presented with two detailed vignettes of a child with suspected pneumonia, each with a chest X-ray (CXR) taken from a real-life case of viral pneumonia. Participants were randomly assigned to one of three groups: Controls-where no lab tests were provided, and two intervention groups where the vignettes also noted a high or a low CRP value, in varying orders. Between-participant and within-participant analyses were conducted to study the effect of CRP on CXR interpretation. The three groups were presented with identical medical history, vital signs, findings on physical examination, blood count, and CXR.

RESULTS

Three-hundred and one pediatricians (89.3% of those approached) completed the study. Pediatricians were 60%-90% more likely to diagnose viral pneumonia as bacterial when presented with high CRP levels versus low CRP levels, despite the identical clinical data and CXR (62% vs. 39% and 58% vs. 31% of physicians; p = .002). Accordingly, they were 60%-90% more likely to prescribe antibiotics in these cases (86% vs. 53% and 78% vs. 41% of physicians; p < .001).

CONCLUSIONS

CRP by itself may modify the way in which pediatricians interpret a CXR, leading to the overprescription of antibiotics.

C-Reactive protein and SOFA scale: A simple score as early predictor of critical care requirement in patients with COVID-19 pneumonia in Spain

OBJECTIVE

To identify potential markers at admission predicting the need for critical care in patients with COVID-19 pneumonia.

MATERIAL AND METHODS

An approved, observational, retrospective study was conducted between March 15 to April 15, 2020. 150 adult patients aged less than 75 with Charlson comorbidity index ≤6 diagnosed with COVID-19 pneumonia were included. Seventy-five patients were randomly selected from those admitted to the critical care units (critical care group [CG]) and seventy-five hospitalized patients who did not require critical care (non-critical care group [nCG]) represent the control group. One additional cohort of hospitalized patients with COVID-19 were used to validate the score.

MEASUREMENTS AND MAIN RESULTS

Multivariable regression showed increasing odds of in-hospital critical care associated with increased C-reactive protein (CRP) (odds ratio 1.052 [1.009-1.101]; P=.0043) and higher Sequential Organ Failure Assessment (SOFA) score (1.968 [1.389-2.590]; P<.0001), both at the time of hospital admission. The AUC-ROC for the combined model was 0.83 (0.76-0.90) (vs AUC-ROC SOFA P<.05). The AUC-ROC for the validation cohort was 0.89 (0.82-0.95) (P>0.05 vs AUC-ROC development).

CONCLUSION

Patients COVID-19 presenting at admission SOFA score ≥2 combined with CRP ≥9,1mg/mL could be at high risk to require critical care.

The potential role of neopterin in Covid-19: a new perspective

Neopterin (NPT) is a member of pteridines group, synthesized by macrophages when stimulated by interferon gamma (INF-γ). NPT is regarded as a macrophage stimulation indicator, marker of cellular immune activation and T helper 1 (Th1) type 1 immune response. Here, we aimed to provide a view point on the NPT features and role in Covid-19. Serum NPT level is regarded as an independent prognostic factor for Covid-19 severity, with levels starting to increase from the 3rd day of SARS-CoV-2 infection, being associated with severe dyspnea, longer hospitalization period and complications. Also, early raise of NPT reflects monocytes/macrophages activation before antibody immune response, despite the NPT level may also remain high in Covid-19 patients or at the end of incubation period before the onset of clinical symptoms. On the other hand, NPT attenuates the activity of macrophage foam cells and is linked to endothelial inflammation through inhibition of adhesion molecules and monocytes migration. However, NPT also exerts anti-inflammatory and antioxidant effects by suppressing NF-κB signaling and NLRP3 inflammasomes. NPT can be viewed as a protective compensatory mechanism to counterpoise hyper-inflammation, oxidative stress, and associated organ damage.

Differential Markers of Bacterial and Viral Infections in Children for Point-of-Care Testing

Children suffering from infectious diseases, both bacterial and viral, are often treated with empirical antibiotics. Keeping in mind both the menace of microorganisms and antibiotic toxicity, it is imperative to develop point-of-care testing (POCT) to discriminate bacterial from viral infections, and to define indications for antibiotic treatment. This article reviews potential protein biomarkers and host-derived gene expression signatures for differentiating between bacterial and viral infections in children, and focuses on emerging multiplex POCT devices for the simultaneous detection of sets of protein biomarkers or streamlined gene expression signatures that may provide rapid and cost-effective pathogen-discriminating tools.

Bacteria and viruses activate or inhibit different signaling pathways in the cells they infect, and further give rise to different host transcriptional signatures as well as to unique protein biomarkers.

Many of the newly evaluated protein biomarkers, especially in combination, have better discriminative value for distinguishing between bacterial and viral infections than the biomarkers that are currently used for examining infections in children.

The transcriptomes of children undergo remarkable changes when they are infected by different types of bacteria and viruses. Approaches based on host-derived DNA/RNA signatures can accurately discriminate bacterial from viral infections.

Emerging multiplex POCT techniques allow simultaneous testing of protein- or gene-based biomarkers in an outpatient setting.

The prognostic role of neopterin in COVID-19 patients

In Coronavirus disease-2019 (COVID-19) cases, hyper inflammation is associated with the severity of the disease. High levels of circulating cytokines were reported in severe COVID-19 patients. Neopterin produced by macrophages on stimulation with interferon-gamma, which is an important cytokine in the antiviral immune response, hence it can be used to predict the severity of disease in COVID-19 cases. In this study, it was aimed to determine the prognostic value of the neopterin for the prediction of severe disease in patients with COVID-19. This single-center, prospective study was conducted in hospitalized COVID-19 patients and healthy volunteers. Severe and mild COVID-19 cases were compared in terms of clinical and laboratory findings as well as serum neopterin levels on hospital admission. To assess the prognostic utility of neopterin between the severe and mild COVID-19 groups, a receiver-operating characteristic (ROC) curve was generated, and the area under the curve (AUC) was calculated. The median serum neopterin level was four times higher in COVID-19 patients than the healthy controls (46 vs. 12 nmol/L; p < .001). The AUC value of serum neopterin was 0.914 (95% confidence interval, 0.85-0.97). The sensitivity and specificity of serum neopterin for the cut-off value of 90 nmol/L to identify severe COVID-19 cases were 100% and 76%, respectively. Serum neopterin levels on hospitalization were significantly higher in severe COVID-19 disease than mild COVID-19 patients. Neopterin levels can be used as an early prognostic biomarker for COVID-19 on admission.

Severe respiratory viral infection induces procalcitonin in the absence of bacterial pneumonia

INTRODUCTION

Procalcitonin expression is thought to be stimulated by bacteria and suppressed by viruses via interferon signalling. Consequently, during respiratory viral illness, clinicians often interpret elevated procalcitonin as evidence of bacterial coinfection, prompting antibiotic administration. We sought to evaluate the validity of this practice and the underlying assumption that viral infection inhibits procalcitonin synthesis.

METHODS

We conducted a retrospective cohort study of patients hospitalised with pure viral infection (n=2075) versus bacterial coinfection (n=179). The ability of procalcitonin to distinguish these groups was assessed. In addition, procalcitonin and interferon gene expression were evaluated in murine and cellular models of influenza infection.

RESULTS

Patients with bacterial coinfection had higher procalcitonin than those with pure viral infection, but also more severe disease and higher mortality (p<0.001). After matching for severity, the specificity of procalcitonin for bacterial coinfection dropped substantially, from 72% to 61%. In fact, receiver operating characteristic curve analysis showed that procalcitonin was a better indicator of multiple indices of severity (eg, organ failures and mortality) than of coinfection. Accordingly, patients with severe viral infection had elevated procalcitonin. In murine and cellular models of influenza infection, procalcitonin was also elevated despite bacteriologic sterility and correlated with markers of severity. Interferon signalling did not abrogate procalcitonin synthesis.

DISCUSSION

These studies reveal that procalcitonin rises during pure viral infection in proportion to disease severity and is not suppressed by interferon signalling, in contrast to prior models of procalcitonin regulation. Applied clinically, our data suggest that procalcitonin represents a better indicator of disease severity than bacterial coinfection during viral respiratory infection.

Adherence to Treatment Guideline Improves Patient Outcomes in a Prospective Cohort of Adults Hospitalized for Community-Acquired Pneumonia

Background

Understanding local epidemiology and etiologies of community-acquired pneumonia in hospitalized patients is crucial for determining the appropriateness of treatment guidelines. We aim to determine the etiologies, severity, and outcomes in adults hospitalized for community-acquired pneumonia and to study the impact of empirical antibiotic therapy on patient outcomes.

Methods

We performed a prospective observational cohort study involving adults hospitalized for community-acquired pneumonia in Hong Kong. Sputum, nasopharyngeal aspirate, blood, and urine were collected for bacterial culture, molecular tests for detection of viruses and atypical pathogens, and antigen tests. Multivariable logistic regression model and Cox proportional hazard models were performed to determine independent factors associated with prolonged hospitalization and mortality.

Results

From February 2017 to July 2018, 258 patients were enrolled. The median age was 73 (interquartile range, 61-80) years, 66% were male, 57% had underlying chronic illnesses, 13% had CURB-65 score ≥3, and 10% had higher 1-year mortality. Pathogens were identified in 45% of patients; 20% had viral, 15% had bacterial, and 9% had polymicrobial pneumonia. Streptococcus pneumoniae (12%), influenza virus (12%), and Mycoplasma pneumoniae (1.2%) were the most common bacterial, viral, and atypical pathogens, respectively. Nonadherence to local empirical antibiotic treatment guidelines (primarily recommending beta-lactam and doxycycline) was observed in 25% and was independently associated with prolonged hospitalization (≥7 days) and higher mortality, after adjustment for age, underlying chronic illness, and disease severity.

Conclusions

Adherence to treatment guidelines was associated with shorter hospitalization and improved survival. We provided evidence for the use of doxycycline for coverage of atypical pathogens in nonsevere pneumonia.

Calprotectin, a new biomarker for diagnosis of acute respiratory infections

Respiratory tract infections require early diagnosis and adequate treatment. With the antibiotic overuse and increment in antibiotic resistance there is an increased need to accurately distinguish between bacterial and viral infections. We investigated the diagnostic performance of calprotectin in respiratory tract infections and compared it with the performance of heparin binding protein (HBP) and procalcitonin (PCT). Biomarkers were analyzed in patients with viral respiratory infections and patients with bacterial pneumonia, mycoplasma pneumonia and streptococcal tonsillitis (n = 135). Results were compared with values obtained from 144 healthy controls. All biomarkers were elevated in bacterial and viral infections compared to healthy controls. Calprotectin was significantly increased in patients with bacterial infections; bacterial pneumonia, mycoplasma pneumonia and streptococcal tonsillitis compared with viral infections. PCT was significantly elevated in patients with bacterial pneumonia compared to viral infections but not in streptococcal tonsillitis or mycoplasma caused infections. HBP was not able to distinguish between bacterial and viral causes of infections. The overall clinical performance of calprotectin in the distinction between bacterial and viral respiratory infections, including mycoplasma was greater than performance of PCT and HBP. Rapid determination of calprotectin may improve the management of respiratory tract infections and allow more precise diagnosis and selective use of antibiotics.

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.

Host-response biomarkers for the diagnosis of bacterial respiratory tract infections

Appropriate antibiotic treatment for respiratory tract infections (RTIs) necessitates rapid and accurate diagnosis of microbial etiology, which remains challenging despite recent innovations. Several host response-based biomarkers due to infection have been suggested to allow discrimination of bacterial and non-bacterial microbial RTI etiology. This review provides an overview of clinical studies that investigated the diagnostic performance of host-response proteomic biomarkers to identify RTI microbial etiology. Procalcitonin and C-reactive protein have been studied most extensively; whereof procalcitonin has demonstrated the strongest diagnostic performance compared to other biomarkers. Proadrenomedullin, soluble triggering receptor expressed on myeloid cells-1, neopterin and pentraxin-3 need more studies to confirm their diagnostic value. For syndecan-4 and lipocalin-2 currently insufficient evidence exists. Common limitations in several of the studies were the relatively small scale setting, heterogeneous patient population and the absence of statistical power calculation.

Assessment of neopterin and indoleamine 2,3-dioxygenase activity in patients with seasonal influenza: A pilot study

BACKGROUND

Seasonal influenza is an important cause of morbidity and mortality worldwide. Immune activation after stimulation with interferon-gamma leads to increased production of neopterin but also results in increased tryptophan catabolism through indoleamine 2,3-dioxygenase (IDO). Our pilot study determined neopterin serum levels and IDO activity in patients with influenza infection and investigated whether neopterin is linked to clinical outcome parameters (mortality ≤30 days, acute cardiac events (ACE) length of hospitalization, ICU admission).

METHODS

Neopterin concentrations were analyzed in serum samples of 40 patients with a confirmed diagnosis of influenza infection and in-hospital treatment for >24 hours. Data were compared to values of 100 healthy blood donors and 48 age-matched pneumonia patients. In a subgroup of 14 patients, tryptophan and kynurenine concentrations, as well as kynurenine-to-tryptophan ratio, were analyzed.

RESULTS

In all influenza patients, neopterin concentrations were increased and significantly higher compared to those determined in patients with pneumonia and healthy controls. Positive correlations between the duration of hospitalization and neopterin were found. Significantly higher levels of kynurenine, kynurenine-to-tryptophan ratio, and lower levels of tryptophan were seen in influenza patients compared to healthy controls.

CONCLUSIONS

Neopterin seems to be related to the course of the disease and could be a valuable biomarker to identify patients at an elevated risk of a worsened outcome; however, further prospective validation studies are needed to support the here presented preliminary results.

HNL (Human Neutrophil Lipocalin) and a multimarker approach to the distinction between bacterial and viral infections

OBJECTIVES

The distinction between bacterial and viral causes of acute infections is a major clinical challenge. In this report we investigate the diagnostic performance in this regard of nine candidate biomarkers together with HNL (Human Neutrophil Lipocalin).

METHODS

Blood was obtained from patients with symptoms of infectious (n = 581). HNL was measured in whole blood (B-HNL) after pre-activation with the neutrophil activator fMLP or in plasma (P-HNL). Azurocidin also known as heparin-binding protein (HBP), Calprotectin, PMN-CD64, CRP (C-reactive protein), IP-10 (Interferon γ-induced Protein 10 kDa), PCT (Procalcitonin), TK1 (Thymidine kinase 1), TRAIL (TNF-related apoptosis-inducing ligand) were measured in plasma/serum. Area under the ROC (receiver operating characteristics) curve (AuROC) was used for the evaluation of the clinical performance of the biomarkers.

RESULTS

Side-by-side comparisons of the ten biomarkers showed large difference in the AuROC with B-HNL being the superior biomarker (0.91, 95% CI 0.86-0.95) and with the other nine biomarkers varying from AuROC of 0.63-0.79. The combination of B-HNL with IP-10 and/or TRAIL increased the diagnostic performance further to AuROCs of 0.94-0.97. The AuROCs of the combination of CRP with IP-10 and/or TRAIL were significantly lower than combinations with B-HNL 0.87 (95% CI 0.83-0.91).

CONCLUSION

The diagnostic performance of whole blood activated HNL was superior in the distinction between bacterial or viral infections. The addition of IP-10 and/or TRAIL to the diagnostic algorithm increased the performance of B-HNL further. The rapid analysis of HNL, reflecting bacterial infections, together with biomarkers reflecting viral infections may be the ideal combination of diagnostic biomarkers of acute infections.

Interferon-γ Mediated Pathways And Mitogen Stimulated Proliferation During And After An Acute Infection

Background: Interferon-γ (IFN- γ) regulates the degradation of tryptophan to kynurenine via induction of indoleamine- 2,3-dioxygenase (IDO). Local tryptophan depletion and accumulation of toxic metabolites might impair the proliferative capacity of lymphocytes. The aim of this study was to assess the actual status of immune system activation of patients with bacterial infection in the acute phase and during convalescence in vivo and in vitro. Parameters of systemic immune system activation were evaluated for associations with proliferative responsiveness of immune cells, and compared with healthy controls. Methods: 24 patients with various acute bacterial infections were included in the group of acutely ill patients. Sixteen patients participated in a follow-up examination after convalescence. The control group consisted of 6 healthy people. To assess the status of immune system activation in vivo, inflammation parameters C-reactive protein and differential blood counts were determined. Neopterin concentrations were measured by enzyme-linked immunosorbent assay (ELISA). Tryptophan and kynurenine measurements were performed with high pressure liquid chromatography (HPLC). Peripheral blood mononuclear cells (PBMCs) were isolated from the patients’ blood and stimulated with concanavalin A (Con A), phytohemagglutinin (PHA) and pokeweed mitogen (PWM) in vitro proliferation rates were evaluated by ³H-thymidine incorporation and neopterin production and tryptophan degradation were determined in supernatants of mitogen stimulated PBMCs. Results: Patients with acute bacterial infections showed reduced tryptophan and elevated neopterin concentrations, which did not normalize after convalescence period. Higher plasma neopterin values and increased IDO-activity were associated with reduced proliferative responses in vitro after stimulation with PHA. Associations were observed during acute infection as well as convalescence. Conclusions: Results of this study show that increased immune system activation in vivo is associated with impaired proliferative responsiveness of immune cells in vitro in acute bacterial infections as well as during convalescence.

Association of C-Reactive Protein With Bacterial and Respiratory Syncytial Virus-Associated Pneumonia Among Children Aged <5 Years in the PERCH Study

Background.

Lack of a gold standard for identifying bacterial and viral etiologies of pneumonia has limited evaluation of C-reactive protein (CRP) for identifying bacterial pneumonia. We evaluated the sensitivity and specificity of CRP for identifying bacterial vs respiratory syncytial virus (RSV) pneumonia in the Pneumonia Etiology Research for Child Health (PERCH) multicenter case-control study.

Methods.

We measured serum CRP levels in cases with World Health Organization-defined severe or very severe pneumonia and a subset of community controls. We evaluated the sensitivity and specificity of elevated CRP for "confirmed" bacterial pneumonia (positive blood culture or positive lung aspirate or pleural fluid culture or polymerase chain reaction [PCR]) compared to "RSV pneumonia" (nasopharyngeal/oropharyngeal or induced sputum PCR-positive without confirmed/suspected bacterial pneumonia). Receiver operating characteristic (ROC) curves were constructed to assess the performance of elevated CRP in distinguishing these cases.

Results.

Among 601 human immunodeficiency virus (HIV)-negative tested controls, 3% had CRP ≥40 mg/L. Among 119 HIV-negative cases with confirmed bacterial pneumonia, 77% had CRP ≥40 mg/L compared with 17% of 556 RSV pneumonia cases. The ROC analysis produced an area under the curve of 0.87, indicating very good discrimination; a cut-point of 37.1 mg/L best discriminated confirmed bacterial pneumonia (sensitivity 77%) from RSV pneumonia (specificity 82%). CRP ≥100 mg/L substantially improved specificity over CRP ≥40 mg/L, though at a loss to sensitivity.

Conclusions.

Elevated CRP was positively associated with confirmed bacterial pneumonia and negatively associated with RSV pneumonia in PERCH. CRP may be useful for distinguishing bacterial from RSV-associated pneumonia, although its role in discriminating against other respiratory viral-associated pneumonia needs further study.

Sustained increase in angiopoietin-2, heparin-binding protein, and procalcitonin is associated with severe sepsis

PURPOSE

The identification of infection at its early stage in vulnerable patients is challenging. This study aimed to investigate potential biomarkers to distinguish patients progressing to severe sepsis from those with uncomplicated sepsis.

MATERIALS AND METHODS

Serum samples were collected from sepsis patients admitted to the emergency department. The mRNA and protein levels of angiopoietin-2 (Ang-2), interleukin-10 (IL-10), heparin-binding protein (HBP), procalcitonin (PCT), adrenomedullin (ADM), and interleukin-6 (IL-6) were evaluated.

RESULTS

Compared to those of healthy individuals (n = 47), mRNA levels of ANG2, IL10, HBP, PCT, and ADM were increased in patients who eventually developed sepsis. ANG2 was the only gene whose expression was significantly increased in patients developing severe sepsis than in those with uncomplicated sepsis. Serum levels of Ang-2, IL-10, HBP, PCT, and IL-6 were also increased in sepsis patients, but only Ang-2, HBP, and PCT were elevated in the serum of patients developing severe septic shock than in those with uncomplicated sepsis. Serum levels of Ang-2, HBP, and PCT were closely associated with the sequential organ failure assessment (SOFA) score of the patients.

CONCLUSIONS

These findings indicated that sustained elevation of Ang-2, HBP, and PCT were associated with severe infection in critically ill patients.

Human Neutrophil Lipocalin in Activated Whole Blood Is a Specific and Rapid Diagnostic Biomarker of Bacterial Infections in the Respiratory Tract

The distinction between bacterial and viral causes of infections of the respiratory tract is a major but important clinical challenge. We investigated the diagnostic performance of human neutrophil lipocalin (HNL) in respiratory tract infections compared to those of C-reactive protein (CRP) and procalcitonin (PCT). Patients were recruited from the emergency department and from a primary care unit (n = 162). The clinical diagnosis with regard to bacterial or viral cause of infection was complemented with objective microbiological/serological testing. HNL was measured in whole blood after preactivation with the neutrophil activator formyl-methionine-leucine-phenylalanine (fMLP) (B-HNL), and CRP and PCT were measured in plasma. Head-to-head comparisons of the three biomarkers showed that B-HNL was a superior diagnostic means to distinguish between causes of infections, with areas under the concentration-time curve (AUCs) of receiver operating characteristic (ROC) analysis for HNL of 0.91 (95% confidence interval [CI], 0.83 to 0.96) and 0.92 (95% CI, 0.82 to 0.97) for all respiratory infections and for upper respiratory infections, respectively, compared to 0.72 (95% CI, 0.63 to 0.80) and 0.68 (95% CI, 0.56 to 0.79) for CRP, respectively (P = 0.001). In relation to major clinical symptoms of respiratory tract infections (cough, sore throat, stuffy nose, and signs of sinusitis), AUCs varied between 0.88 and 0.93 in those patients with likely etiology (i.e., etiology is likely determined) of infection, compared to 0.63 and 0.71 for CRP, respectively, and nonsignificant AUCs for PCT. The diagnostic performance of B-HNL is superior to that of plasma CRP (P-CRP) and plasma PCT (P-PCT) in respiratory tract infections, and the activity specifically reflects bacterial challenge in the body. The rapid and accurate analysis of HNL by point-of-care technologies should be a major advancement in the diagnosis and management of respiratory infections with respect to antibiotic treatment.

Diagnostic and Prognostic Value of Inflammatory Parameters Including Neopterin in the Setting of Pneumonia, COPD, and Acute Exacerbations

Acute exacerbations and community-acquired pneumonia (CAP) are severe complications in patients with chronic obstructive pulmonary disease (COPD). In this study, we analyzed inflammatory parameters in serum including C-reactive protein (CRP), procalcitonin (PCT), and serum neopterin (NPT) to determine their potential to differentiate between patients with CAP+COPD and with acute exacerbations of COPD (AECOPD) without pneumonia. 102 (39 women and 63 men) patients were included in this retrospective study, of whom 48 presented with CAP without underlying COPD, 20 with CAP+COPD and 34 with AECOPD. CRP, PCT, and blood counts were determined by routine automated tests, and NPT concentrations were determined by ELISA. The ratios of CRP to NPT levels were calculated. Upon patient admission, CRP, PCT, and NPT levels were significantly higher in patients with CAP compared to those in AECOPD patients. CRP/NPT ratio was lower in AECOPD compared to CAP (+/-COPD) patients. Positive correlations were found between duration of hospitalization and CRP levels and the CRP/NPT ratio at study entry. Patients who were readmitted within 30 days tended to have higher NPT levels at initial presentation. Patients under ongoing corticosteroid treatment presented with lower inflammatory parameters. The CRP/NPT-ratio was suited well to discriminate between AECOPD and CAP on the basis of COPD, a CRP/NPT cutoff of 0.346 provided a sensitivity of 65% and a specificity of 79%. The combinatory use of inflammatory patterns might help to differentiate patients with AECOPD from those with CAP on the basis of COPD.

Enabling robust quantitative readout in an equipment-free model of device development

A critical constraint in the design of appropriate medical devices for the lowest-resource settings is the lack of access to maintenance or repair on instrumentation. There are numerous point-of-care applications for which quantitative readout would have clinical utility. Thus, a challenge to the device developer is to enable quantitative device readout in an equipment-free model that is appropriate for use in even the lowest-resource settings. Paper microfluidics has great potential for enabling equipment-free devices that are low-cost, operable by minimally-trained users, and provide quantitative readout. The focus of this critical review is to describe the work, starting several decades ago and continuing to the present, to enable assays with quantitative readout in a fully-disposable device.

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

Differentiating between inflammatory disorders is difficult, but important for a rational use of antimicrobial agents. Biomarkers reflecting the host immune response may offer an attractive strategy to predict the etiology of an inflammatory process and can thus be of help in decision making. We performed a review of the literature to evaluate the diagnostic value of inflammatory biomarkers in adult patients admitted to the hospital with suspected systemic acute infections. Elevated procalcitonin (PCT) concentrations indicate a bacterial infection in febrile patients with an auto-immune disease, rather than a disease flare. CD64 expression on neutrophils can discriminate between non-infectious systemic inflammation and sepsis, and limited evidence suggests the same for decoy receptor 3. PCT is useful for both diagnosing bacterial infection complicating influenza and guiding antibiotic treatment in lower respiratory tract infections in general. In undifferentiated illnesses, increased CD35 expression on neutrophils distinguishes bacterial from viral infections. Compared to bacterial infections, invasive fungal infections are characterized by low concentrations of PCT. No biomarker predicting a specific infecting agent could be identified.

Human Neutrophil Lipocalin as a Superior Diagnostic Means To Distinguish between Acute Bacterial and Viral Infections

The distinction between causes of acute infections is a major clinical challenge. Current biomarkers, however, are not sufficiently accurate. Human neutrophil lipocalin (HNL) concentrations in serum or whole blood activated by formyl-methionine-leucine-phenylalanine (fMLP) were shown to distinguish acute infections of bacterial or viral cause with high accuracy. The aim was therefore to compare the clinical performance of HNL with currently used biomarkers. Seven hundred twenty-five subjects (144 healthy controls and 581 patients with signs and symptoms of acute infections) were included in the study. C-reactive protein (CRP), the expression of CD64 on neutrophils, procalcitonin (PCT), and blood neutrophil counts were measured by established techniques, and HNL concentrations were measured in whole-blood samples after activation with fMLP. All tested biomarkers were elevated in bacterial as opposed to viral infections (P < 0.001). CRP, PCT, and CD64 expression in neutrophils was elevated in viral infections compared to healthy controls (P < 0.001). In the distinction between healthy controls and patients with bacterial infections, the areas under the receiver operating characteristic (ROC) curves were >0.85 for all biomarkers, whereas for the distinction between bacterial and viral infections, only HNL concentration in fMLP-activated whole blood showed an area under the ROC curve (AUROC) of >0.90 and superior clinical performance. The clinical performance of HNL in fMLP-activated whole blood was superior to current biomarkers and similar to previous results of HNL in serum. The procedure can be adopted for point-of-care testing with response times of <15 min.

Human neutrophil lipocalin in fMLP-activated whole blood as a diagnostic means to distinguish between acute bacterial and viral infections

The distinction between causes of acute infections is a major clinical challenge. Current biomarkers, however, are not sufficiently accurate. Human neutrophil lipocalin (HNL) in serum distinguishes acute infections with high accuracy, but in the emergency setting the assay time should be <15-20min, which excludes the use of serum samples. The aim was therefore to develop a novel rapid assay principle and test its clinical performance.

METHODS

Serum and neutrophils obtained from 84 infected and 20 healthy subjects were used in the experimental study. 725 subjects (144 healthy controls and 581 patients with signs and symptoms of acute infections) were included in the clinical study. HNL was measured in EDTA-plasma by ELISA or in heparinized whole blood after fMLP activation by a prototype point-of-care assay.

RESULTS

Increased release of HNL from neutrophils after activation with fMLP was seen already after 5 min incubation. The release of HNL from purified neutrophils after 15 min incubation with fMLP was significantly correlated to the HNL concentrations in serum obtained from the same patient (r = 0.74, p < 0.001). In the distinction between healthy controls and patients with bacterial infections, the areas under the ROC-curves were 0.95 (95% CI 0.91-0.97) and 0.88 (95% CI 0.84-0.91) for HNL in fMLP-activated whole blood and EDTA-plasma, respectively, (p < 0.001) and in the distinction between bacterial and viral infections 0.91 (95% CI 0.86-0.95) and 0.76 (95% CI 0.70-0.81), respectively (p < 0.001).

CONCLUSION

The clinical performance of HNL in fMLP-activated whole blood was superior to HNL in EDTA-plasma and similar to HNL in serum. The procedure can be adopted for point-of-care testing with response times of <15 min.

A prospective study of the immune system activation biomarker neopterin and colorectal cancer risk

BACKGROUND

Neopterin may be relevant for colorectal cancer (CRC) development, as a biomarker of cellular immune activity exerting pleiotropic effects on cellular ageing, oxidative stress, and inflammation. So far, the association between prediagnostic neopterin and colon and rectal cancer risk has not been evaluated in human populations.

METHODS

A nested case-control study was conducted within the European Prospective Investigation into Cancer and Nutrition cohort using data on plasma concentrations of total neopterin (T-N, sum of neopterin and 7,8-dihydroneopterin) in 830 incident CRC case patients (561 colon and 269 rectal) matched within risk sets to 830 control participants. A subsequent replication study used data from the Hordaland Health Study, where 173 CRC case patients have been diagnosed among 6594 healthy participants over 12 years of follow-up.

RESULTS

After multivariable adjustment for a priori chosen CRC risk factors, a "U-shaped" association of T-N with CRC was revealed. Compared with the second quintile of the T-N distribution, the relative risks for the first, third, fourth, and fifth quintiles were 2.37 (95% CI = 1.66 to 3.39), 1.24 (95% CI = 0.87 to 1.77), 1.55 (95% CI = 1.08 to 2.22), and 2.31 (95% CI = 1.63 to 3.27), respectively. Replication of these associations within the Hordaland Health Study yielded similar results. No differences have been observed when the associations were explored by colon and rectal cancer site (two-sided P difference = .87) and after excluding case patients diagnosed within the first four follow-up years.

CONCLUSIONS

These novel findings provide evidence of the role of both suppressed and activated cell-mediated immunity as reflected by prediagnostic T-N concentrations in the development of CRC.

Combined use of biomarkers for distinguishing between bacterial and viral etiologies in pediatric lower respiratory tract infections

BACKGROUND

In clinical practice it is often troublesome to discriminate bacterial etiologies from viral etiologies in pediatric lower respiratory tract infections (LRTIs). The aim of this study was to develop an accurate analytic method to improve diagnostic determination for bacterial and viral etiologies in pediatric LRTIs.

METHODS

A total of 45 children with confirmed bacterial LRTIs and 51 children with viral LRTIs were finally included after assessment of the children visiting the emergency department with a suspected infection and identification of pathogens. C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), CD35, and CD64 were assessed and then the areas under receiver operating characteristic (ROC) curves (AUC) of PCT, IL-6, CD35, and CD64 in combination with CRP were compared to the AUC of CRP alone in all subjects.

RESULTS

The levels of CRP, PCT, IL-6, CD45, and CD64 observed in children with bacterial LRTIs were statistically higher than for viral infections. The AUC of CRP combined with CD53 (0.963, 95% confidence interval (CI) 0.921-1.002) or CD64 (0.952, 95% CI 0.907-0.998) or CD35/CD64 (0.971, 95% CI 0.932-1.004) increased compared with that of the single biomarker.

CONCLUSIONS

The combined analysis improved diagnostic accuracy in children with bacterial and viral LRTIs.

Sustained elevation of resistin, NGAL and IL-8 are associated with severe sepsis/septic shock in the emergency department

OBJECTIVE

To identify biomarkers which distinguish severe sepsis/septic shock from uncomplicated sepsis in the Emergency Department (ED).

METHODS

Patients with sepsis underwent serial blood sampling, including arrival in the ED and up to three subsequent time points over the first 24 hours. Messenger RNA (mRNA) levels of 13 genes representing arms of the innate immune response, organ dysfunction or shock were measured in peripheral blood leucocytes using quantitative PCR, and compared with healthy controls. Serum protein concentrations of targets differentially expressed between uncomplicated sepsis and severe sepsis/septic shock were then measured at each time point and compared between the two patient groups.

RESULTS

Of 27 participants (median age 66 years, (IQR 35, 78)), 10 had uncomplicated sepsis and 17 had sepsis with organ failure (14 septic shock; 3 had other sepsis-related organ failures). At the time of first sample collection in the ED, gene expression of Interleukin (IL)-10 and Neutrophil Gelatinase Associated Lipocalin (NGAL) were significantly higher in severe sepsis than uncomplicated sepsis. Expression did not significantly change over time for any target gene. Serum concentrations of IL-6, IL-8, IL-10, NGAL and Resistin were significantly higher in severe sepsis than uncomplicated sepsis at the time of first sample collection in the ED, but only IL-8, NGAL and Resistin were consistently higher in severe sepsis compared to uncomplicated sepsis at all time points up to 24 h after presentation.

CONCLUSIONS

These mediators, produced by both damaged tissues and circulating leukocytes, may have important roles in the development of severe sepsis. Further work will determine whether they have any value, in addition to clinical risk parameters, for the early identification of patients that will subsequently deteriorate and/or have a higher risk of death.

Expression of CD64 on neutrophils can be used to predict the severity of bloodstream infection before broad range 16S rRNA PCR

The aging population and increased incidence of severe bacterial infection can lead to sepsis. Interest to early identification of endangered patients and identification of pathogen do not always confirm the infection. To use biomarkers can help in early identification of infection and opportunity to start therapy timeously. All biomarkers were defined in 33 out of 96 patients. Thirty-two (97 %) patients had bacterial infection and 1 (3 %) patient had systemic inflammatory response syndrome (SIRS) without infection. PCR confirmed the infection in 27 cases and blood cultures in 8. Area under curve (AUC) for CD64 was 1.00, meanwhile other biomarkers showed 2-fold smaller AUC for positive infection. CD64 index was associated with bacterial infection (p<0.001) and could be used to confirm assessment of SIRS severity (p=0.037). As regards to our results, limited to only 33 patients, CD64 index served as a good parameter to predict bacterial infection and determine severity. The use of broad range 16S ribosomal RNA (rRNA) PCR proved to be an excellent tool to confirm bloodstream infection. The CD64 index had the highest AUC, which exceeded all the others, and could be used to predict the outcome of broad range 16S rRNA PCR from whole blood. However, C-reactive protein (CRP), procalcitonin (PCT) and sCD14 are much easier and faster to measure, but the values could be elevated in other clinical assessments.

Microfluidic platforms for biomarker analysis

Biomarkers have been described as characteristics, most often molecular, that provide information about biological states, whether normal, pathological, or therapeutically modified. They hold great potential to assist diagnosis and prognosis, monitor disease, and assess therapeutic effectiveness. While a few biomarkers are routinely utilised clinically, these only reflect a very small percentage of all biomarkers discovered. Numerous factors contribute to the slow uptake of these new biomarkers, with challenges faced throughout the biomarker development pipeline. Microfluidics offers two important opportunities to the field of biomarkers: firstly, it can address some of these developmental obstacles, and secondly, it can provide the precise and complex platform required to bridge the gap between biomarker research and the biomarker-based analytical device market. Indeed, adoption of microfluidics has provided a new avenue for advancement, promoting clinical utilisation of both biomarkers and their analytical platforms. This review will discuss biomarkers and outline microfluidic platforms developed for biomarker analysis.

Non-invasive biomarkers in exacerbations of obstructive lung disease

BACKGROUND AND OBJECTIVE

Current methods of diagnosing exacerbations of asthma and chronic obstructive pulmonary disease (COPD) shed little light on their aetiology or pathophysiology. This study aimed to define the inflammatory biomarker profile of subjects with obstructive lung disease and to compare these with control subjects also with respiratory infections, using exhaled breath condensate (EBC) and induced sputum biomarker analysis.

METHODS

EBC, induced sputum and C-reactive protein were collected from subjects with exacerbations of asthma (n = 28), exacerbations of COPD (n = 29) and otherwise healthy controls with symptoms of respiratory tract infection (n = 28). Subjects were tested again after recovery. EBC and induced sputum were analysed for protein, hydrogen peroxide, interferon gamma inducible protein-10 (IP-10), neopterin, interleukin (IL)-6, IL-8, leukotriene B4 and tumour necrosis factor (TNF)-α. Sputum cell counts and EBC pH were also analysed.

RESULTS

EBC pH was significantly lower in exacerbation compared with recovery (5.54 0.07 vs 6.04 ± 0.08; P < 0.001). The novel markers IP-10 and neopterin were significantly increased in induced sputum supernatant (pooled groups pre and post exacerbation: IP-10: 188.6 ± 102.1 vs 5.40 ± 1.28 pg/mL, P = 0.006; neopterin: 15.81 ± 2.50 vs 5.38 ± 0.45 nmol/L, P < 0.0001), as was TNF-α (137.8 ± 49.64 vs 71.56 ± 45.03 pg/mL, P = 0.018). Few other biomarkers proved significantly different in exacerbation, although C-reactive protein was raised.

CONCLUSIONS

Non-invasive biomarker assessment may provide useful information in exacerbation of obstructive lung diseases, particularly sputum IP-10 and neopterin and EBC pH.

Four assay designs and on-chip calibration: gadgets for a sepsis protein array

A protein microarray for the early stage diagnosis of sepsis that allows the simultaneous detection of C-reactive protein (CRP) (2-200 μg/mL), procalcitonin (PCT) (0.2-50 ng/mL), and interleukin 6 (IL-6) (2-2000 pg/mL) has been developed. To enable the parallel detection of the differently abundant analytes, the low binding affinity between CRP and phosphocholine is exploited in a "low-sensitive" sandwich assay for CRP. The calibration is integrated directly on the chip resulting in a "one patient-one array" format, to provide a user-friendly and rapid diagnostic tool. Four different assay designs are introduced: (I) the classical assay that works with biotin-streptavidin chemistry, (II) the rapid assay that is performed in a single detection step, and two ultrasensitive assay designs accomplished either by (III) an enzymatic or (IV) an antibody mediated amplification resulting in high density labeling. The assay designs were evaluated by the repetitive measurement of low, medium, and high concentration levels of commercially available certified control sera. The precision was similar across all assay designs (coefficient of variation (CV), CVintra: 8-14%; CVinter: 18-34%), while the sensitivity (limits of detection (LODs)) increased by 1 order of magnitude for the ultrasensitive assays (III, IV) and the accuracy was analyte dependent but best for the classical (I) and the antibody amplified (IV) assays.

Cost-effectiveness of point-of-care C-reactive protein testing to inform antibiotic prescribing decisions

BACKGROUND

Point-of-care C-reactive protein (POCCRP) is a biomarker of inflammation that offers clinicians a rapid POC test to guide antibiotic prescribing decisions for acute cough and lower respiratory tract infections (LRTI). However, evidence that POCCRP is cost-effective is limited, particularly outside experimental settings.

AIM

To assess the cost-effectiveness of POCCRP as a diagnostic tool for acute cough and LRTI from the perspective of the health service.

DESIGN AND SETTING

Observational study of the presentation, management, and outcomes of patients with acute cough and LRTI in primary care settings in Norway and Sweden.

METHOD

Using hierarchical regression, data were analysed in terms of the effect on antibiotic use, cost, and patient outcomes (symptom severity after 7 and 14 days, time to recovery, and EQ-5D), while controlling for patient characteristics (self-reported symptom severity, comorbidities, and health-related quality of life) at first attendance.

RESULTS

POCCRP testing is associated with non-significant positive reductions in antibiotic prescribing (P = 0.078) and increased cost (P = 0.092). Despite the uncertainty, POCCRP testing is also associated with a cost per quality-adjusted life year (QALY) gain of €9391. At a willingness-to-pay threshold of €30,000 per QALY gained, there is a 70% probability of CRP being cost-effective.

CONCLUSION

POCCRP testing is likely to provide a cost-effective diagnostic intervention both in terms of reducing antibiotic prescribing and in terms of QALYs gained.

Neopterin in Diagnosis and Monitoring of Infectious Diseases

Neopterin is produced by activated monocytes, macrophages, and dendritic cells upon stimulation by interferon gamma produced by T-lymphocytes. Quantification of neopterin in body fluids has been achieved by standard high-performance liquid chromatography, radioimmunoassays, and enzyme-linked immunosorbent assays. Neopterin levels predict HIV-related mortality more efficiently than clinical manifestations. Successful highly active antiretroviral therapy is associated with a decrease in neopterin levels. Elevated neopterin levels were associated with hepatitis by hepatitis A, B, and C viruses. Serum neopterin levels were found to be a predictor of response to treatment of chronic HCV infection with pegylated interferon combined with ribavirin. Neopterin levels of patients with pulmonary tuberculosis were found to be higher in patients with more extensive radiological changes. Elimination of blood donors with elevated neopterin levels to reduce risk of transmission of infections with known and unknown viral pathogens has been undertaken. Neopterin measurement is hereby more cost effective but less sensitive than screening using polymerase chain reaction based assays. In conclusion neopterin is a nonspecific marker of activated T-helper cell 1 dominated immune response. It may be a useful marker for monitoring of infectious disease activity during treatment and for more accurate estimation of extent of disease and prognosis.

Simultaneous determination of three potential cancer biomarkers in rat urine by synchronous fluorescence spectroscopy

A rapid, simple, sensitive and accurate method for the simultaneous determination of three potential cancer biomarkers [tryptophan (TRP), isoxanthopterin (ISO) and xanthopterin (XAN)] in rat urine with synchronous fluorescence spectroscopy has been developed. In order to eliminate the interference in urine samples, the synchronous fluorescence spectra were obtained with Δλ=70 nm in a KH2PO4-NaOH buffer solution (pH=8.0). The detected wavelengths of quantitative analysis were set at 275 nm for TRP, 325 nm for ISO and 400 nm for XAN, respectively. Under the optimized conditions, the limits of the detection of the three compounds were 2.73 ng/mL, 0.52 ng/mL and 0.94 ng/mL, respectively. The recoveries were in the range of 80.5-98.0%, with the coefficient of variation between 0.62% and 2.48%. The proposed method has been applied to the simultaneous determination of TRP, ISO and XAN in rat urines of bladder cancer group and control group. The determination results showed that the average level of TRP, ISO and XAN had different change trends with the growth of the tumor. The three analytes could be used as potential biomarkers for noninvasive diagnosis of different stage of bladder cancer. However, more data are needed to support this hypothesis.

[Diagnostic and prognostic power of biomarkers to improve the management of community acquired pneumonia in the emergency department]

OBJECTIVES

To analyse the usefulness and performance of several biomarkers [C-reactive protein (CRP), mid-regional pro-adrenomedullin (MR-proADM), procalcitonin (PCT)] and lactate in predicting short- and medium-term mortality compared with the prognostic severity scales (PSS) usually employed for community-acquired pneumonia (CAP) and in assessing the aetiological suspicion of infection by Streptococcus pneumoniae and bacteraemia.

METHODS

Observational, prospective and analytical study was conducted on patients who were diagnosed with CAP in our emergency department (ED). The data collected included socio-demographic and comorbidity variables, Charlson index, priority level according to the Spanish Triage System (STS), stage in the Pneumonia Severity Index (PSI) and in the CURB-65 (confusion, urea, respiratory rate, blood pressure and age ≥65years), criteria of severe CAP, microbiological studies, and biomarkers determinations. The patients were followed-up for 180days to calculate the prognostic power and the diagnostic performance for bacteraemia and aetiology.

RESULTS

A total of 127patients were finally enrolled in the study. The 30-day mortality was 10.3% (13), and 22.6% (28) at 180 days. Blood cultures were positive in 29 patients (23%) and S.pneumoniae was identified as the responsible pathogen in 28 cases (22.2%). The area under the ROC curve (AUC-ROC) for lactate and MR-proADM to predict 30-day mortality was 0.898 (95%CI: 0.824-0.973; P<.0001) and 0.892 (95%CI: 0.811-0.974; P<.0001), respectively, and for MR-proADM at 180 days it was 0.921 (95%CI: 0.874-0.968; P<.0001). The AUC-ROC for PCT to predict bacteraemia was 0.952 (95%CI: 0.898-1.000; P<.0001) and, considering a cut-off value ≥0.95ng/ml, the negative predictive value (NPV) and the likelihood ratio (LR+) were 97.8% and 9.03, respectively. Using a PCT cut-off value >0.85ng/ml, the NPV and the LR+ were 96.6% and 5.89%, respectively, to predict a S.pneumoniae infection.

CONCLUSIONS

MR-proADM and lactate showed a similar or even better performance for 30-day intra-hospital mortality than PSI, CURB-65, STS and CAP severity criteria in patients diagnosed with CAP (P>.05). Furthermore, the MR-proADM capacity to predict 180-day mortality was higher than PSS and the rest of biomarkers (P>.05), and its AUC-ROC increased if it was used in combination with PSI, CURB65 and STS. The determination of PCT has a remarkable diagnostic performance to rule out bacteraemia and to orientate the aetiology towards a S.pneumoniae infection.

Non-culture-based methods to diagnose bloodstream infection: Does it work?

Bloodstream infections are a major cause of morbidity and mortality worldwide. Molecular methods for the detection of pathogens in blood have been developed. The clinical utility of these methods and their integration into the clinical workflow is discussed.

Improved management of community-acquired pneumonia in the emergency department

OBJECTIVES

To determine the impact of implementing clinical practice guidelines (CPGs) in the treatment of community-acquired pneumonia (CAP) in the emergency department (ED) by analyzing case management decisions (admission or discharge, appropriateness and timeliness of antibiotic therapy, complementary tests) and the consequent results (clinical stabilization time, length of hospital stay, re-admission to ED and mortality).

METHODS

A prospective, observational, descriptive, comparative study carried out from 1st January 2008 to 1st August 2009 in two phases: before and after the implementation of the "Management of CAP in ED" SEMES-SEPAR (Spanish Society of Emergency Medicine - Spanish Society of Pneumology and Thoracic Surgery) clinical practice guidelines from 2008. Two hundred adult patients treated in the ED with a diagnosis of CAP were included in the study, both in the pre-intervention and post-intervention groups.

RESULTS

The application of the guidelines increased the administration of early and appropriate antibiotic therapy (P<.001) and shortened both the total antibiotic therapy (P<.001) and the intravenous antibiotic therapy (P=.042) times. Time to clinical stabilization (P=.027), length of hospital stay (1.14 days, P=.01), intra-hospital mortality (P=.004) and total 30-day mortality (P=.044) were all reduced. Assessment with the Pneumonia Severity Index (PSI) and biomarkers aided in appropriate decision-making concerning admission/discharge (P<.001).

CONCLUSIONS

The implementation of the SEMES-SEPAR 2008 guidelines, along with the use of PSI and biomarkers, significantly improved the entire treatment process of CAP. This benefitted both patients and the system by reducing mortality and improving the results of other patient management factors.

Combination of biomarkers for the discrimination between bacterial and viral lower respiratory tract infections

OBJECTIVES

To investigate whether additional determinations of plasma lipopolysaccharide binding protein (LBP), procalcitonin (PCT), interleukin-6 (IL-6), IL-18, or soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) to C-reactive protein (CRP) improve the discrimination between bacterial and viral lower respiratory tract infections (LRTI).

METHODS

Out of 342 patients visiting the emergency department because of a suspected infection and ≥2 clinical signs of sepsis, 56 patients with proven bacterial (n = 39) or viral (n = 17) LRTI were included. The area under the ROC curves (AUC) of the five possible combinations of CRP with one other biomarker were compared with the AUC of CRP alone. Next, the same analysis was performed in the group of patients with a CRP concentration with <95% specificity for bacterial LRTI.

RESULTS

While CRP, PCT, IL-6, sTREM-1, and LBP concentrations were significantly different between patients with bacterial or viral LRTI, the AUC of CRP (0.82, 95% CI 0.70-0.93) did not increase after combination analyses. After exclusion of patients with a CRP >150 mg/l, biomarker panel analyses did not improve diagnostic accuracy of CRP either.

CONCLUSIONS

Combining CRP with LBP, PCT, IL-6, IL-18, or sTREM-1 does not improve differentiation between patients with a bacterial or viral LRTI compared with CRP alone.

Usefulness of consecutive biomarkers measurement in the management of community-acquired pneumonia

The aim of this study was to investigate whether procalcitonin (PCT), neopterin, C-reactive protein (CRP), and mid regional pro-atrial natriuretic peptide (MR-proANP) levels at admission and during the clinical course can be useful for the management of patients with pneumonia. The study population consisted of 75 patients with clinical and radiological diagnosis of pneumonia. Serum samples were collected at admission and during hospitalization. Complications were defined as intensive care unit (ICU) admission or death. The levels of PCT were significantly higher in pneumonia of definite bacterial origin in comparison to probable bacterial or unknown origin. The PCT levels were higher in pneumococcal pneumonia. The PCT and MR-proANP levels increased significantly according to the Pneumonia Severity Index (PSI). All biomarkers levels are higher in patients developing complications and who were dying. The serial levels of MR-proANP remain significantly elevated in patients developing complications and in patients classified in PSI and CURB-65 risk groups. In patients not developing complications, there is a significant decrease in the PCT levels. PCT can be useful for identifying pneumonia etiology. PCT and MR-proANP levels correlate with pneumonia severity rules. PCT and MR-proANP serial measurements can be useful for predicting short-term prognosis. Systemic biomarkers can provide additional information regarding clinical evolution, because these are dynamic and can be measured daily.

Protein chip for the parallel quantification of high and low abundant biomarkers for sepsis

We present herein a protein chip for diagnosis of sepsis that combines both a sandwich and a binding inhibition format in order to quantify high (CRP) and low abundant proteins (cytokines, PCT, neopterin) in parallel. Using the combined assay format the lowest detectable concentrations for CRP, IL-6, IL-8, IL-10, TNFα, PCT, and neopterin are 3 mg/L, 15 ng/L, 26 ng/L, 65 ng/L, 40 ng/L, 78 ng/L, and 0.46 μg/L. Four different combined assay formats are tested, using separate or joint incubation steps of analytes and detection antibodies. Yet, low limit of detection (LOD) and short processing time are contradictory: while the combined assay performed in a multistep protocol is extremely sensitive (e.g., the LOD for IL-6 is 15 ng/L), but more time-consuming (4 h), the all-in-one protocol takes only 2.5 h, but suffers from lower sensitivity compared with the multistep protocol (e.g., the LOD for IL-6 is up to 40 times enhanced). Reproducibility is good in both cases (CV 5-20%).

Value of procalcitonin, C-reactive protein, and neopterin in exacerbations of chronic obstructive pulmonary disease

Objective:

The identification of biological markers in order to assess different aspects of COPD is an area of growing interest. The objective of this study was to investigate whether levels of procalcitonin (PCT), C-reactive protein (CRP), and neopterin in COPD patients could be useful in identifying the etiological origin of the exacerbation and assessing its prognosis.

Methods:

We included 318 consecutive COPD patients: 46 in a stable phase, 217 undergoing an exacerbation, and 55 with pneumonia. A serum sample was collected from each patient at the time of being included in the study. A second sample was also collected 1 month later from 23 patients in the exacerbation group. We compared the characteristics, biomarker levels, microbiological findings, and prognosis in each patient group. PCT and CRP were measured using an immunofluorescence assay. Neopterin levels were measured using a competitive immunoassay.

Results:

PCT and CRP showed significant differences among the three patient groups, being higher in patients with pneumonia, followed by patients with exacerbation (P < 0.0001). For the 23 patients with paired samples, PCT and CRP levels decreased 1 month after the exacerbation episode, while neopterin increased. Neopterin showed significantly lower levels in exacerbations with isolation of pathogenic bacteria, but no differences were found for PCT and CRP. No significant differences were found when comparing biomarker levels according to the Gram result: PCT (P = 0.191), CRP (P = 0.080), and neopterin (P = 0.109). However, median values of PCT and CRP were high for Streptococcus pneumoniae, Staphylococcus aureus, and enterobacteria. All biomarkers were higher in patients who died within 1 month after the sample collection than in patients who died later on.

Conclusions:

According to our results, biomarker levels vary depending on the clinical status. However, the identification of the etiology of infectious exacerbation by means of circulating biomarkers is encouraging, but its main disadvantage is the absence of a microbiological gold standard, to definitively demonstrate their value. High biomarker levels during an exacerbation episode correlate with the short-term prognosis, and therefore their measurement can be useful for COPD management.