Discrimination of sepsis and systemic inflammatory response syndrome by determination of circulating plasma concentrations of procalcitonin, protein complement 3a, and interleukin-6

Circulating complement (C3 and C4) for differentiation of SIRS from sepsis

The systemic inflammatory response of the body to invading microorganisms, called sepsis, leads to profound activation of the complement (C3 and C4) system. The present study was conducted to compare the use of serum C3 and C4 levels with C-reactive protein (CRP) and thrombocyte and leukocyte counts in differentiating patients with systemic inflammatory response syndrome (SIRS) from those with sepsis. Over a 6-mo period, all patients with SIRS or sepsis who stayed in the intensive care unit for >24 h were enrolled in the study. At admission, each patient's clinical status was recorded, and blood was taken for laboratory analysis (complete blood count, CRP, C3, and C4). A total of 58 patients with SIRS and 41 patients with sepsis were admitted to the study. The mean+/-SD thrombocyte count was found to be significantly lower in septic patients (179,975+/-95,615) than in those with SIRS (243,165+/-123,706) (P=.005); no difference in plasma concentrations of CRP and levels of C3 and C4 was noted between groups. The thrombocyte count was determined to be the most reliable parameter for differentiating between SIRS and sepsis (highest area under the curve=0.656).

Markers for sepsis diagnosis: what is useful?

Timely diagnosis of the different severities of septic inflammation is potentially lifesaving because therapies that have been shown to lower mortality should be initiated early. Sepsis and severe sepsis are accompanied by clinical and laboratory signs of systemic inflammation but patients with inflammation caused by noninfectious causes may present with similar signs and symptoms. It is important to identify markers for an early diagnosis of sepsis and organ dysfunction. This article presents currently interesting sepsis biomarkers. Other novel markers and their potential role are discussed.

[Role of plasma procalcitonin determination in the postoperative follow-up of cephalic pancreatoduodenectomy]

BACKGROUND

Procalcitonin (PCT) is widely accepted as an early marker of the severity of sepsis and its prognosis. This study was designed to evaluate the utility of PCT in the early diagnosis of immediate postoperative complications (infectious and non-infectious) following cephalic pancreatoduodenectomy (PD).

PATIENTS AND METHOD

Thirty-one patients who underwent elective PD were prospectively analyzed. The patients were divided into two groups according to the presence or absence of postoperative complications. Plasma PCT concentrations were determined by an immunochromatographic method. The correlation between PCT concentrations and the presence of complications, as well as the existence of statistically significant differences in PCT concentrations between the 2 groups of patients, were analyzed. The value of plasma PCT concentrations in predicting complications compared with that of other biochemical variables (C-reactive protein, lactic acid, base excess) and clinical parameters (systemic inflammatory response syndrome) was analyzed.

RESULTS

Significant differences in PCT concentrations were found between the two groups. An inverse correlation between marker levels and patient outcome was observed. The variables that best predicted the development of complications were PCT concentrations and axillary temperature.

CONCLUSIONS

Plasma PCT should be taken into account as a useful marker for postoperative clinical course in the follow-up of PD and for the early detection of non-infectious complications.

The role of complement in danger sensing and transmission

Self-non-self discrimination has long been considered the main function of the immune system. Increasing evidence supports the view of the immune system as a network of complex danger sensors and transmitters in which self-non-self discrimination is only one facet. To meet the challenge of danger sensing, the immune system carries a large stock of germline-encoded, highly conserved molecules that can recognize microbial as well as modified host structures. Among those are the Toll-like receptors (TLR), which comprise a dozen membrane-bound pattern-recognition receptors that directly link danger recognition to danger transmission through activation of several distinct cellular signaling pathways. Here, I discuss the function and biology of a complex, evolutionary ancient system, the complement system, which has long been considered critical to host defense. In contrast to TLRs, the complement system senses danger by a panel of soluble molecules that can directly bind to specific complement receptors and/or initiate a complex cascade of proteolytic events that lead to the generation of soluble complement fragments able to bind to another, distinct set of specific complement receptors. As I will outline in this review, complement- mediated danger sensing and the complex transition of this information into distinct cellular activation profiles is critical for tissue homeostasis under steady-state conditions and in response to infection and cell injury. Furthermore, I will discuss recent findings that support a concept of intense cross-talk between the complement system and TLRs, which defines the quality and the magnitude of immune responses in vivo.

Procalcitonin as a diagnostic test for sepsis in critically ill adults and after surgery or trauma: a systematic review and meta-analysis

OBJECTIVE

To quantify the accuracy of serum procalcitonin as a diagnostic test for sepsis, severe sepsis, or septic shock in adults in intensive care units or after surgery or trauma, alone and compared with C-reactive protein. To draw and compare the summary receiver operating characteristics curves for procalcitonin and C-reactive protein from the literature.

DATA SOURCE

MEDLINE (keywords: procalcitonin, intensive care, sepsis, postoperative sepsis, trauma); screening of the literature.

STUDY SELECTION

Meta-analysis of all 49 published studies in medical, surgical, or polyvalent intensive care units or postoperative wards. Children, medical patients, and immunocompromised patients were excluded.

DATA EXTRACTION

Thirty-three studies fulfilled inclusion criteria (3,943 patients, 1,828 males, 922 females; mean age: 56.1 yrs; 1,825 patients with sepsis, severe sepsis, or septic shock; 1,545 with only systemic inflammatory response syndrome); eight studies could not be analyzed statistically. Global mortality rate was 29.3%.

DATA SYNTHESIS

Global odds ratios for diagnosis of infection complicated by systemic inflammation were 15.7 for the 25 studies (2,966 patients) using procalcitonin (95% confidence interval, 9.1-27.1) and 5.4 for the 15 studies (1,322 patients) using C-reactive protein (95% confidence interval, 3.2-9.2). The summary receiver operating characteristics curve for procalcitonin was better than for C-reactive protein. In the 15 studies using both markers, the Q* value (intersection of summary receiver operating characteristics curve with the diagonal line where sensitivity equals specificity) was significantly higher for procalcitonin than for C-reactive protein (0.78 vs. 0.71, p = .02), the former test showing better accuracy.

CONCLUSIONS

Procalcitonin represents a good biological diagnostic marker for sepsis, severe sepsis, or septic shock, difficult diagnoses in critically ill patients. Procalcitonin is superior to C-reactive protein. Procalcitonin should be included in diagnostic guidelines for sepsis and in clinical practice in intensive care units.

Post-operative neutrophil-lymphocyte ratio predicts complications following colorectal surgery

INTRODUCTION

The neutrophil-lymphocyte ratio (NLR) correlates with serial organ dysfunction scores in colorectal surgical patients in critical care units. We hypothesised that the NLR on the first day after an elective colorectal resection would identify patients at increased risk of subsequent complications.

METHODS

With Ethics Committee approval, 100 patients were recruited to a prospective cohort study. Pre-operative test results and the full blood count on the first post-operative day were noted for all patients. The development of any pre-defined post-operative complications was recorded.

RESULTS

Elective colorectal resection was associated with an increase in mean NLR from 3.5 to 11.6 (p<0.001). Thirty patients developed at least one predefined complication. Patients with an NLR > or =9.3 on the first post-operative day had a significantly greater risk of complications (likelihood ratio 2.12; 95% confidence interval 1.366-3.253). Twenty-two patients had a white cell count > or =11 on the first post-operative day but this was not associated with a significantly increased risk of complications (likelihood ratio 1.94; 95% confidence interval 0.94-3.9).

CONCLUSION

NLR > or =9.3 on the first post-operative day is associated with an increased risk of complications. This simple derivation of routinely available data helps to identify patients at high-risk of complications, allowing targeted preventive measures.

Biomarkers of sepsis: clinically useful?

PURPOSE OF REVIEW

The purpose of this review is to indicate recent developments in biomarkers of sepsis and to evaluate their impact on clinical use. According to the 'surviving sepsis campaign,' diagnosis of sepsis and infection is urgent; early and specific treatment is most effective to reduce complications and to decrease mortality.

RECENT FINDINGS

A variety of biomarkers of sepsis is presently available. The diagnostic spectrum of the various markers, however, is different. Some primarily indicate severity of inflammation (e.g. interleukin-6), others respond to infection, but do not indicate the host response well (endotoxin, lipoprotein binding protein, triggering receptor on myeloid cells). There are new markers with limited clinical experience, for example triggering receptor on myeloid cells or mid-pro atrial natriuretic peptide (Seristra, Brahms AG, Hennigsdorf, Germany). Procalcitonin is a well-established biomarker of sepsis that fulfills several criteria of clinical needs: it responds both to infection and severity of inflammation and thus has an impact on therapy. Recent studies indicate that antibiotic treatment can also be guided by procalcitonin. Further indications, including diagnosis of invasive bacterial infections and diagnosis of sepsis in neonates and children have been reported recently.

SUMMARY

Recent data and cumulative analyses indicate that biomarkers of sepsis improve diagnosis of sepsis. However, only a few markers have impact on therapy and fulfill the clinical requirements. Procalcitonin is a well-established marker, indicating infection, sepsis, and progression to the more severe stages of the disease. Today, this biomarker should be in the diagnostic portfolio of an intensive care unit or emergency ward.

Quantitative analysis of procalcitonin after pediatric cardiothoracic surgery

Procalcitonin appears to be an early and sensitive marker of bacterial infection in a variety of clinical settings. The use of levels of procalcitonin to predict infection in children undergoing cardiac surgery, however, may be complicated by the systemic inflammatory response that normally accompanies cardiopulmonary bypass. The aim of our study was to estimate peri-operative concentrations of procalcitonin in non-infected children undergoing cardiac surgery. Samples of serum for assay of procalcitonin were obtained in 53 patients at baseline, 24, 48, and 72 hours following cardiac surgery. Concentrations were assessed using an immunoluminetric technique. Median concentrations were lowest at baseline at less than 0.5 nanograms per millilitre, increased at 24 hours to 1.8 nanograms per millilitre, maximized at 48 hours at 2.1 nanograms per millilitre, and decreased at 72 hours to 1.3 nanograms per millilitre, but did not return to baseline levels. Ratios of concentrations between 24, 48 and 72 hours after surgery as compared to baseline were 6.15, with 95 percent confidence intervals between 4.60 and 8.23, 6.49, with 95 percent confidence intervals from 4.55 to 9.27, and 4.26, with 95 percent confidence intervals between 2.78 and 6.51, respectively, with a p value less than 0.001. In 8 patients, who had no evidence of infection, concentrations during the period from 24 to 72 hours were well above the median for the group. We conclude that concentrations of procalcitonin in the serum increase significantly in children following cardiac surgery, with a peak at 48 hours, and do not return to baseline within 72 hours of surgery. A proportion of patients, in the absence of infection, had exaggerated elevations post-operatively.

Evaluation of a newly identified soluble CD14 subtype as a marker for sepsis

CD14, a high-affinity receptor for lipopolysaccharide (LPS), is a glycoprotein expressed on the surface membranes of monocytes/macrophages. We have identified a previously unknown form of soluble CD14, named soluble CD14 subtype (sCD14-ST), that is increased in patients with sepsis. To measure sCD14-ST concentrations in plasma, we prepared anti-sCD14-ST antibodies and developed an enzyme immunoassay (EIA) for this soluble form of CD14. With this assay, quantitative measurements are available within 4 h, and we compared the levels of sCD14-ST in plasma from normal subjects (healthy controls), patients with systemic inflammatory response syndrome (SIRS), and sepsis patients. The level of sCD14-ST in subjects with sepsis was much higher than the levels in subjects with SIRS and the healthy controls. Additionally, when a subject's sCD14-ST level was used as a diagnostic marker for sepsis, the area under the receiver operating characteristic (ROC) curve was 0.817, thereby demonstrating that elevated sCD14-ST levels were a better marker for sepsis than the other molecular markers we tested. sCD14-ST levels also correlated with procalcitonin (PCT) levels and with sequential organ failure assessment (SOFA) scores. Finally, changes in sCD14-ST concentration correlated with the severity of sepsis. Taken together, these results indicate that sCD14-ST is a useful marker for the rapid diagnosis of sepsis and for monitoring the severity of the disease.

Monitoring therapeutic interventions in critically ill septic patients

Sepsis is the leading cause of admission to intensive care units in the United States. Although the treatment of sepsis is complex and multimodal, nutrition support plays an important role in the management of these patients. The diagnosis of sepsis, disease category, and severity of illness and the change in sepsis severity and organ function over time affect the delivery of nutrition support. This paper reviews the diagnostic criteria of sepsis, the use of "sepsis biomarkers," and regional and global markers of organ function in sepsis and quantitative measures of illness severity and organ dysfunction.

Early and innovative interventions for severe sepsis and septic shock: taking advantage of a window of opportunity

The pathogenic, diagnostic and therapeutic landscape of sepsis is no longer confined to the intensive care unit: many patients from other portals of entry to care, both outside and within the hospital, progress to severe disease. Approaches that have led to improved outcomes with other diseases (e.g., acute myocardial infarction, stroke and trauma) can now be similarly applied to sepsis. Improved understanding of the pathogenesis of severe sepsis and septic shock has led to the development of new therapies that place importance on early identification and aggressive management. This review emphasizes approaches to the early recognition, diagnosis and therapeutic management of sepsis, giving the clinician the most contemporary and practical approaches with which to treat these patients.

Mannan-binding lectin and procalcitonin measurement for prediction of postoperative infection

Introduction

Postoperative infection is a major cause of morbidity and mortality. We investigated two serum markers for their ability to identify patients at risk for postoperative infection. Mannan-binding lectin (MBL) is a central molecule of the innate immune system and MBL deficiency is known to predispose to infection. Procalcitonin (PCT) is a sensitive marker for bacterial infection.

Methods

We investigated 162 patients undergoing elective surgery for cancer of the gastrointestinal tract. Patients were classified as having no complications (group A), having infection for unknown reason (group B) or having sepsis after events like aspiration or anastomotic leakage (group C). Analysis was done pre- and postoperatively for serum levels of MBL, PCT and C-reactive-protein. DNA was preoperatively sampled and stored and later analysed for genetic polymorphisms of MBL.

Results

The preoperative serum levels of MBL were significantly lower in group B patients than in group A patients (1332 ± 466 ng/ml versus 2523 ± 181 ng/ml). PCT measured on day one post-surgery was significantly higher in group B patients than in group A (3.33 ± 1.08 ng/ml versus 1.38 ± 0.17 ng/ml). Patients with an aberrant MBL genotype had a significantly higher risk of postoperative infections than wild-type carriers (p < 0.05).

Conclusion

Preoperative MBL and early postoperative PCT measurement may help identify patients at risk for postoperative infection.

Clinical laboratory differentiation of infectious versus non-infectious systemic inflammatory response syndrome

OBJECTIVE

To evaluate the accuracy of C-reactive protein (CRP), procalcitonin (PCT), neopterin, and endotoxin in the differential diagnosis of sepsis and non-infectious systemic inflammatory response syndrome (SIRS).

METHODS

A Medline database and references from identified articles were used to perform a literature search relating to the differential diagnosis of sepsis versus non-infectious SIRS.

RESULTS

CRP, PCT, and neopterin are released both in sepsis and in non-infectious inflammatory disease. CRP and PCT are equally effective, although not perfect, in differentiating between sepsis and non-infectious SIRS. However, CRP and PCT have different kinetics and profiles. The kinetics of CRP is slower than that of PCT, and CRP levels may not further increase during more severe stages of sepsis. On the contrary, PCT rises in proportion to the severity of sepsis and reaches its highest levels in septic shock. PCT tends to be higher in nonsurvivor than in survivor. Therefore, PCT demonstrated a closer correlation with the severity of sepsis and outcome than CRP. Unlike CRP and PCT, neopterin is increased in viral infection as well as bacterial infection, and neopterin is also a useful indicator of sepsis. Endotoxemia was detected in no more than half of patients with Gram-negative bacteremia, and Gram-negative bacteremia was detected in half of patients with endotoxemia.

CONCLUSIONS

The diagnostic capacity of PCT is superior to that of CRP due to the close correlation between PCT levels and the severity of sepsis and outcome. Neopterin is very useful in the diagnosis of viral infection. The endotoxin assay in combination with CRP, PCT, or neopterin may help as a diagnostic marker for Gram-negative bacterial infection.

C-reactive protein as a marker of infection in critically ill patients

A prospective, observational study was conducted in a medico-surgical intensive care unit to assess the value of C-reactive protein (CRP), temperature and white cell count (WCC) measurements for the diagnosis of infection in critically ill patients. CRP, temperature and WCC were monitored daily in 76 infected and 36 non-infected patients. Multiple receiver-operating characteristics (ROC) curves were used to compare each parameter for infection diagnosis. The area under the curve (AUC) of CRP was significantly higher than that of temperature (0.93 and 0.75, respectively; p < 0.001). A CRP concentration of >8.7 mg/dL and a temperature of >38.2 degrees C were associated with infection, with a sensitivity of 93.4% and 54.8%, and a specificity of 86.1% and 88.9%, respectively. The ROC curve of WCC showed a poor diagnostic performance. The combination of CRP and temperature increased the specificity for infection diagnosis to 100%. In the subgroup of patients with ventilator-associated pneumonia (n = 48), CRP measurements were more reliable than temperature (AUC 0.92 and 0.78, respectively; p 0.006). The CRP levels in infected patients with sepsis, severe sepsis and septic shock were 15.2 +/- 8.2, 20.3 +/- 10.9 and 23.3 +/- 8.7 mg/dL, respectively (p 0.044). It was concluded that CRP was a better marker of infection than temperature. However, the combination of CRP and temperature measurements further increased the specificity for infection diagnosis, even in the subgroup of patients with VAP.

Interleukin-6, interleukin-8, and a rapid and sensitive assay for calcitonin precursors for the determination of bacterial sepsis in febrile neutropenic children

OBJECTIVE

Children with cancer often develop febrile illnesses after cytotoxic chemotherapy. Determining which children have serious bacterial infections in this vulnerable period would be valuable. We evaluated the ability of a rapid and sensitive assay for the concentration of calcitonin precursors (CTpr) as a sensitive diagnostic marker for bacterial sepsis in febrile, neutropenic children and determined the utility of measuring cytokines to improve the predictive value of this approach.

DESIGN

Prospective cohort study.

SETTING

Academic children's hospital.

PATIENTS

Fifty-six children (aged 5 months to 17 yrs) with a known malignancy who presented with fever and neutropenia.

INTERVENTIONS

Serial blood samples were obtained (admission, 24 hrs, and 48 hrs), and concentrations of CTpr, interleukin-6, and interleukin-8 were determined. Demographic and laboratory data from the patients were collected from the medical record.

MEASUREMENTS AND MAIN RESULTS

Sixteen (29%) of the children met the criteria for bacterial sepsis. Plasma levels of CTpr and interleukin-8, but not interleukin-6, were increased at all time points in children with sepsis compared with those without sepsis. CTpr at 24 and 48 hrs after admission were reliable markers for sepsis (area under the curve = 0.92 and 0.908, respectively). Logistic regression using CTpr at 24 hrs in addition to interleukin-8 at 48 hrs produced the best-fit models associated with sepsis. Using cutoff values of CTpr >500 pg/mL and interleukin-8 >20 pg/mL produced a screening test for sepsis with 94% sensitivity and 90% specificity.

CONCLUSIONS

Our data show the utility of a rapid and sensitive assay for CTpr combined with interleukin-8 as a highly sensitive and specific diagnostic marker of bacterial sepsis in febrile, neutropenic children. The use of these markers as a clinical tool may allow for better prognostication for clinicians and may eventually lead to more targeted therapies for this heterogeneous population.

Plasma concentration of procalcitonin and systemic inflammatory response syndrome after colorectal surgery

BACKGROUND

To study whether plasma concentrations of procalcitonin (PCT), interleukin-6 (IL-6), complement 3a (C3a), C-reactive protein and white blood cell count (WBC) correlate with the presence of systemic inflammatory response syndrome (SIRS) during the early post-operative period after major colorectal surgery.

METHODS

Prospective, observational study during the first 24 h post-operatively. The setting for the study was the operating theatre and the recovery unit at the university hospital. Fifty consecutive patients, operated on electively with major resection of the large bowel or rectum. PCT levels increased significantly to the maximum level 18 h postoperatively. PCT levels were significantly higher in the SIRS group in comparison to the non-SIRS group of patients 6 and 12 h after surgery (P < 0.05). The IL-6 levels were increased directly after the surgery and then decreased gradually in both study groups. Twenty-four hours after the surgery, C3a levels decreased and then returned to normal levels. Twenty-four hours post-operatively, patients with SIRS had a higher plasma concentration of C3a compared with patients without SIRS (P < 0.05). CRP and WBC increased during the study period in both groups (P < 0.05).

CONCLUSIONS

During the early post-operative period after uncomplicated major abdominal surgery, SIRS was reflected by the increase in plasma PCT and C3a concentrations. IL-6, CRP and WBC increased to the same extend in both the SIRS and the non-SIRS group of patients.

Complement activation in prestorage leucocyte-filtered plasma

Complement activation and generation of pro-inflammatory cytokines occur during storage of blood components. Prestorage leucocyte filtration of platelet concentrates and red cells diminishes the accumulation of leucocyte-derived cytokines during storage, however, transfusion reactions are not eliminated. We investigated inflammatory mediator release during storage of plasma and whole blood and the effect of prestorage leucocyte filtration of plasma. Twenty-four blood units were collected from healthy blood donors and stored for 35 days. Eight units were stored as whole blood, eight units as plasma and eight units as prestorage filtered plasma. Samples were collected weekly for analyses of potassium, leucocytes, free plasma haemoglobin, complement activation (C3a and SC5b-9) and pro-inflammatory cytokines [interleukin (IL)-6, IL-8 and tumor necrosis factor (TNF)-alpha]. Elevated levels of C3a and SC5b-9 were registered in filtered plasma, from the beginning of storage. C3a levels increased during storage. There was a higher rate of change during storage in C3a (P < 0.01) and SC5b-9 (P < 0.05) in plasma compared with filtered plasma. Interleukin (IL)-8 is released in whole blood. The cytokine levels generated in plasma and filtered plasma were low. Complement activation is present in whole blood, plasma and filtered plasma during storage. Prestorage filtration of plasma activates the complement cascade but does not influence cytokine generation.

Soluble form of the triggering receptor expressed on myeloid cells-1 as a marker of microbial infection

Sepsis is a common cause of morbidity and mortality in intensive care units. Unfortunately, there is no gold standard for diagnosing sepsis as clinical and laboratory signs are neither sensitive enough nor specific enough, and microbiological studies often remain negative. Thus, there is a need for clinical or laboratory tools to distinguish between sepsis and non-infectious inflammatory disorders. Among the potentially useful markers of sepsis, procalcitonin has been suggested to be the most promising, although results are variable depending on the severity of illness and degree of infection in the patient population studied. The triggering receptor expressed on myeloid cells-1 (TREM-1) is a member of the immunoglobulin superfamily, of which expression is upregulated on phagocytic cells in the presence of bacteria or fungi. Here we report on the potential usefulness of assessing the soluble form of TREM-1 (sTREM-1) in biological fluids for the diagnosis of microbial infection.

Serum procalcitonin and C-reactive protein levels as markers of bacterial infection: a systematic review and meta-analysis

A meta-analysis was performed to evaluate the accuracy of determination of procalcitonin (PCT) and C-reactive protein (CRP) levels for the diagnosis of bacterial infection. The analysis included published studies that evaluated these markers for the diagnosis of bacterial infections in hospitalized patients. PCT level was more sensitive (88% [95% confidence interval [CI], 80%-93%] vs. 75% [95% CI, 62%-84%]) and more specific (81% [95% CI, 67%-90%] vs. 67% [95% CI, 56%-77%]) than CRP level for differentiating bacterial from noninfective causes of inflammation. The Q value for PCT markers was higher (0.82 vs. 0.73). The sensitivity for differentiating bacterial from viral infections was also higher for PCT markers (92% [95% CI, 86%-95%] vs. 86% [95% CI, 65%-95%]); the specificities were comparable (73% [95% CI, 42%-91%] vs. 70% [95% CI, 19%-96%]). The Q value was higher for PCT markers (0.89 vs. 0.83). PCT markers also had a higher positive likelihood ratio and lower negative likelihood ratio than did CRP markers in both groups. On the basis of this analysis, the diagnostic accuracy of PCT markers was higher than that of CRP markers among patients hospitalized for suspected bacterial infections.

Toward resolving the challenges of sepsis diagnosis

Sepsis in the United States has an estimated annual healthcare cost of 16.7 billion dollars and leads to 120,000 deaths. Insufficient development in both medical diagnosis and treatment of sepsis has led to continued growth in reported cases of sepsis over the past two decades with little improvement in mortality statistics. Efforts over the last decade to improve diagnosis have unsuccessfully sought to identify a "magic bullet" proteic biomarker that provides high sensitivity and specificity for infectious inflammation. More recently, genetic methods have made tracking regulation of the genes responsible for these biomarkers possible, giving current research new direction in the search to understand how host immune response combats infection. Despite the breadth of research, inadequate treatment as a result of delayed diagnosis continues to affect approximately one fourth of septic patients. In this report we review past and present diagnostic methods for sepsis and their respective limitations, and discuss the requirements for more timely diagnosis as the next step in curtailing sepsis-related mortality. We also present a proposal toward revision of the current diagnostic paradigm to include real-time immune monitoring.

Procalcitonin and C-reactive protein kinetics in postoperative pediatric cardiac surgical patients

OBJECTIVE

To determine the kinetics of procalcitonin (PCT) and C-reactive protein (CRP) concentration after pediatric cardiac surgery with cardiopulmonary bypass.

DESIGN

Prospective, clinical cohort study.

SETTING

A fifteen-bed tertiary-care pediatric intensive care unit.

PATIENTS

Fourteen pediatric patients admitted for cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

Serum PCT and CRP were measured before cardiopulmonary bypass (CPB); after CPB; and on the first, second, and third days after surgery by means of immunoluminometry and nephelometry, respectively. Reference values for systemic inflammatory response syndrome are 0.5 to 2.0 ng/mL for PCT and <5 mg/L for CRP. Baseline serum PCT and CRP concentrations were 0.24 +/- 0.13 ng/mL and 4.06 +/- 3.60 mg/L (median 25th percentile-75th percentile), respectively. PCT concentrations increased progressively from the end of CPB (0.62 +/- 0.30 ng/mL), peaked at 24 hours postoperatively (POD1) (0.77 +/- 0.49 ng/mL), and began to decrease at 48 hours or POD2 (0.35 +/- 0.21 ng/mL). CRP increased just after CPB (58.82 +/- 42.23 mg/L) and decreased after 72 hours (7.09 +/- 9.81 mg/L).

CONCLUSION

An increment of both PCT and CRP was observed just after CPB. However, PCT values remained within reference values, whereas CRP concentrations increased significantly after CPB until the third day. These preliminary results suggest that PCT was more effective than CRP to monitor patients with SIRS and a favorable outcome.

Continuous subcutaneous injection reduces polymorphonuclear leukocyte activation by granulocyte colony-stimulating factor

The use of granulocyte colony stimulating factor (G-CSF) for recovery from neutropenia has been established; however, acute lung injury due to G-CSF-induced polymorphonuclear leukocyte (PMN) activation is a serious complication. This study was designed to compare the activation of PMN with single bolus administration and continuous administration of G-CSF. Healthy volunteers (age 33.8 ± 1.4 yr; n = 6) received a single bolus injection of 50 μm/m2of G-CSF (SI; n = 6) or continuous subcutaneous injection of 50 μm/m2of G-CSF for 24 h (CI; n = 6) and were followed for 48 h. Circulating leukocyte counts, markers of activation on PMN, and circulating levels of G-CSF, IL-6, and PMN elastase were measured. SI rapidly increased serum G-CSF levels, which peaked at 4 h, whereas CI gradually increased G-CSF levels, which remained at a steady level from 8 to 24 h. SI caused a rapid decrease in PMN counts at 0.5 h followed by sustained increase to peak at 12 h. CI gradually increased PMN counts, which peaked at 24 h, but the peak values were not significantly different between the groups. SI-induced activation of PMN, which was characterized by increased expression of CD11b, decreased expression of L-selectin, and increased F-actin content, led to increases in serum IL-6 and PMN elastase level. Such changes were all attenuated with CI ( P < 0.05). We conclude that continuous subcutaneous injection of G-CSF resulted in a marrow response similar to that to a single injection but yielded reduced PMN activation.

The Clinical Value of Procalcitonin and Neopterin in Predicting Sepsis and Organ Failure After Major Trauma

We examined whether procalcitonin (PCT) or neopterin (NT) are useful in predicting sepsis, multiple organ failure (MOF), or death after multiple trauma (MT). In a prospective clinical study, a total of 137 consecutive trauma patients (mean age 39 years, median injury severity score [ISS] 27 points) and 34 healthy volunteers were enrolled. Blood samples were collected on arrival in the emergency room until day 28 after trauma. Plasma NT was detected by enzyme-linked immunoassay and PCT plasma levels were determined using an immunoluminometric assay. The incidence of sepsis was 65%, MOF 48%, and death in hospital within 28 days 11%. After adjustment for age, gender, and ISS, PCT and NT levels during the first 2 days after injury were unable to differentiate between patients who developed sepsis or not. On the contrary, patients who developed MOF had higher PCT plasma levels on day 0 (0.60 vs. 0.15 ng/mL), and on days 1 and 2 combined (1.95 vs. 0.32 ng/mL). This difference remained significant in multivariate logistic regression (P = 0.01) and additional subgroup analyses for early and late MOF (P = 0.048 and 0.002). For NT, smaller differences were observed (4.39 vs. 3.68 nmol/L, and 7.20 vs. 5.79 nmol/L), which lost significance in multivariate analysis. On the basis of PCT, ISS, and age, a MOF prediction rule was developed and had a good predictive power (area under the curve: 0.77; P < 0.001). These findings demonstrate that high plasma concentrations of PCT in the early posttraumatic phase are an independent predictor of MOF but not of sepsis.

Lower levels of whole blood LPS-stimulated cytokine release are associated with poorer clinical outcomes in surgical ICU patients

BACKGROUND

In vitro pretreatment of human monocytes with lipopolysaccharide (LPS) induces "endotoxin tolerance" with blunted TNF and IL-6 release to rechallenge with LPS. The pro-inflammatory cytokines TNF and IL-6 are important mediators in sepsis. A high IL-6 concentration has been used as a marker of infection severity, but IL-6 may also have beneficial effects as an acute-phase protein. We sought to address two questions: (a) What is the relationship between TNF and IL-6 release? (b) Is the clinical outcome different for intensive care unit (ICU) patients with ex vivo characteristics of endotoxin tolerance (low levels of ex vivo LPS-stimulated cytokine release)?

MATERIALS AND METHODS

Heparinized whole blood was obtained from 62 surgical ICU patients and 15 control subjects and incubated for 3 h at 37 degrees C in the presence or absence of 10 ng/mL LPS. Concentrations of TNF and IL-6 were measured in plasma samples using an enzyme-linked immunosorbent assay (pg/mL). Clinical data on ICU length of stay (LOS), ventilator days, white blood cell count (WBC), and documented clinical infection were obtained by chart review. Outcome parameters for patients with low ex vivo LPS-stimulated cytokine release (low = IL-6 < 3000 pg/mL and TNF <2100 pg/mL) were compared to patients with Normal/High concentrations of cytokines.

RESULTS

Cytokines were essentially undetectable in ICU patients or controls without LPS stimulation, however a range of values was measured for LPS-stimulated release in both ICU patients (IL-6, 7847 +/- 857 pg/mL; TNF, 4390 +/- 457 pg/mL) and controls (IL-6, 7704 +/- 793 pg/mL; TNF, 6706 +/- 715 pg/mL). There were no differences in age between High/Normal concentrations of cytokines compared to the Low cytokine group, however there were significant differences in WBC, cytokine concentrations, ICU LOS, incidence of clinical infection, and mortality. The Low group also required an average of 6.9 more days of mechanical ventilation (p < 0.05). LPS-stimulated TNF release seemed to correlate better with the observed mortality than did IL-6 release.

CONCLUSION

The data suggest that ICU patients with characteristics of endotoxin tolerance (low LPS-stimulated cytokine release capacity) have significantly poorer clinical outcomes. Ex vivo LPS-stimulated whole blood cytokine production may be useful to identify ICU patients with severe sepsis.

Suppression of inflammatory cytokine production by carbon monoxide involves the JNK pathway and AP-1

The stress-inducible protein heme oxygenase-1 provides protection against oxidative stress and modulates pro-inflammatory cytokines. As the sepsis syndrome results from the release of pro-inflammatory mediators, we postulated that heme oxygenase-1 and its enzymatic product CO would protect against lethality in a murine model of sepsis. Mice treated with a lethal dose of lipopolysaccharide (LPS) and subsequently exposed to inhaled CO had significantly better survival and lower serum interleukin (IL)-6 and IL-1beta levels than their untreated counterparts. In vitro, mouse macrophages exposed to LPS and CO had significantly attenuated IL-6 production; this effect was concentration-dependent and occurred at a transcriptional level. The same effect was seen with increased endogenous CO production through overexpression of heme oxygenase-1. Mutation within the AP-1-binding site in the IL-6 promoter diminished the effect of CO on promoter activity, and treatment of macrophages with CO decreased AP-1 binding in an electrophoretic mobility shift assay. Electrophoretic mobility supershift assay indicated that the JunB, JunD, and c-Fos components of AP-1 were particularly affected. Upstream of AP-1, CO decreased JNK phosphorylation in murine macrophages and lung endothelial cells. Mice deficient in the JNK pathway had decreased serum levels of IL-6 and IL-1beta in response to LPS compared with control mice, and no effect of CO on these cytokine levels was seen in Jnk1 or Jnk2 genedeleted mice. In summary, these results suggest that CO provides protection in a murine model of sepsis through modulation of inflammatory cytokine production. For the first time, the effect of CO is shown to be mediated via the JNK signaling pathway and the transcription factor AP-1.

Comparison of procalcitonin and C-reactive protein as markers of sepsis

OBJECTIVE

To compare the clinical informative value of procalcitonin (PCT) and C-reactive protein (CRP) plasma concentrations in the detection of infection and sepsis and in the assessment of severity of sepsis.

DESIGN

Prospective study.

SETTING

Medicosurgical intensive care unit.

PATIENTS

Seventy consecutive adult patients who were admitted to the intensive care unit for an expected stay >24 hrs.

INTERVENTIONS

None.

MEASUREMENTS

PCT and CRP plasma concentrations were measured daily during the intensive care unit stay. Each patient was examined daily for signs and symptoms of infection and was classified daily in one of the following four categories according to the American College of Chest Physicians/Society of Critical Care Medicine criteria: negative, systemic inflammatory response syndrome, localized infection, and sepsis group (sepsis, severe sepsis, or septic shock). The severity of sepsis-related organ failure was assessed by the sepsis-related organ failure assessment score.

MAIN RESULTS

A total of 800 patient days were classified into the four categories. The median plasma PCT concentrations in noninfected (systemic inflammatory response syndrome) and localized-infection patient days were 0.4 and 1.4 ng/mL (p <.0001), respectively; the median CRP plasma concentrations were 79.9 and 85.3 mg/L (p =.08), respectively. The area under the receiver operating characteristic curve was 0.756 for PCT (95% confidence interval [CI], 0.675-0.836), compared with 0.580 for CRP (95% CI, 0.488-0.672) (p <.01). The median plasma PCT concentrations in nonseptic (systemic inflammatory response syndrome) and septic (sepsis, severe sepsis, or septic shock) patient days were 0.4 and 3.65 ng/mL (p <.0001), respectively, whereas those for CRP were 79.9 and 115.6 mg/L (p <.0001), respectively. The area under the receiver operating characteristic curve was 0.925 for PCT (95% CI, 0.899-0.952), compared with 0.677 for CRP (95% CI, 0.622-0.733) (p <.0001). The linear correlation between PCT plasma concentrations and the four categories was much stronger than in the case of CRP (Spearman's rho, 0.73 vs. 0.41; p <.05). A rise in sepsis-related organ failure assessment score was related to a higher median value of PCT but not CRP.

CONCLUSION

PCT is a better marker of sepsis than CRP. The course of PCT shows a closer correlation than that of CRP with the severity of infection and organ dysfunction.

Procalcitonin as a diagnostic test for sepsis: health technology assessment in the ICU

Elevation in the serum concentration of procalcitonin (PCT) is associated with systemic infection. This association has led to the proposed use of PCT as a novel biomarker of bacterial sepsis. The advantages and limitations of the American College of Chest Physicians/Society of Critical Care Medicine (ACCP/SCCM) definitions of sepsis are an important consideration that affects the impact of any diagnostic test for sepsis and these issues are discussed. Our main objective is to perform a systematic health technology assessment of PCT as a diagnostic test for sepsis. In an adult intensive care unit (ICU) population, we identify a specific and important question-can PCT accurately distinguish sepsis in patients with systemic inflammatory response syndrome (SIRS) who have a suspected infection? Likelihood ratios are calculated from published data to attempt to find the best answer. The published evidence does not support a general claim that PCT is a useful decision support tool for diagnosing sepsis in patients who have SIRS. Procalcitonin has a slightly better ability to exclude the diagnosis of sepsis. The role for using PCT testing in the ICU will continue to evolve along with our understanding and definition of sepsis.

Usefulness of procalcitonin for diagnosis of sepsis in the intensive care unit

INTRODUCTION

The diagnosis of sepsis in critically ill patients is challenging because traditional markers of infection are often misleading. The present study was conducted to determine the procalcitonin level at early diagnosis (and differentiation) in patients with systemic inflammatory response syndrome (SIRS) and sepsis, in comparison with C-reactive protein, IL-2, IL-6, IL-8 and tumour necrosis factor-alpha.

METHOD

Thirty-three intensive care unit patients were diagnosed with SIRS, sepsis or septic shock, in accordance with the American College of Chest Physicians/Society of Critical Care Medicine consensus criteria. Blood samples were taken at the first and second day of hospitalization, and on the day of discharge or on the day of death. For multiple group comparisons one-way analysis of variance was applied, with post hoc comparison. Sensitivity, specificity and predictive values of PCT and each cytokine studied were calculated.

RESULTS

PCT, IL-2 and IL-8 levels increased in parallel with the severity of the clinical condition of the patient. PCT exhibited a greatest sensitivity (85%) and specificity (91%) in differentiating patients with SIRS from those with sepsis. With respect to positive and negative predictive values, PCT markedly exceeded other variables.

DISCUSSION

In the present study PCT was found to be a more accurate diagnostic parameter for differentiating SIRS and sepsis, and therefore daily determinations of PCT may be helpful in the follow up of critically ill patients.

Procalciton: A new marker and mediator of systemic inflammatory response of the host to infection

<zakljucak> Prokalcitonin je medijator generalizovane reakcije domacina na infekciju, koji poseduje znacajan imunomodulatorni efekat. Indukcija PCT i porast njegovog nivoa u plazmi povezani su sa ekstenzivnoscu i tipom sistemske inflamacije, a njegova koncentracija se naglo smanjuje posle saniranja inflamacije. Kod bolesnika sa sepsom PCT je odlican dijagnosticki i prognosticki marker i veoma dobar parametar za procenu uspeha terapijskog tretmana i klinickog toka septickog procesa. Rutinsko odredjivanje njegove koncentracije u krvi moze popraviti laboratorijsko pracenje bolesnika sa sepsom.

Pathobiochemistry and clinical use of procalcitonin

Induction of the protein procalcitonin during infection and inflammation was first described approximately 10 years ago. A large number of publications, primarily clinical studies, demonstrate the increasing use of procalcitonin in modern clinical practice. However, data on the biological function and origin of procalcitonin is scarce. Findings regarding the possible role and source of procalcitonin in sepsis and infection were recently published, and the pathophysiology of the protein has meanwhile been investigated in various experimental models. Procalcitonin obviously has certain biological functions, and it is also known to be specifically induced. Given the hormonal origin of the mature protein and the inflammation-related functions of its propeptides, some investigators suggest that procalcitonin should be referred to as a "hormokine," although its biological functions should be studied in more detail. This review will survey the data now available in recent publications on the induction, production sources, possible biological functions and clinical uses of procalcitonin.

Calcitonin gene expression induced by lipopolysaccharide in the rat pituitary

Procalcitonin (PCT), the precursor protein of calcitonin (CT), has been considered recently as a significant indicator of bacterial infection and sepsis. However, the major source of PCT in sepsis remains unclear. The hypothalamic-pituitary-adrenal axis is activated during sepsis. Moreover, immunoreactive CT (iCT) can be detected in the pituitary. Therefore, we examined the effects of lipopolysaccharide (LPS) administration on CT mRNA expression in the pituitary. After administration of LPS, CT mRNA expression in the pituitary was increased significantly. The increase of CT mRNA was associated with significant elevations of the iCT levels in the serum. These results imply that the pituitary is one of the sources of the serum PCT during sepsis.

Markers of endothelial damage in organ dysfunction and sepsis

OBJECTIVES

To review the literature on direct and indirect markers of endothelial activation and damage in patients with sepsis and systemic inflammation and to assess their clinical usefulness for diagnosis and outcome. Various markers derived from or activated by endothelial cells are described, such as adhesion molecules, thrombomodulin, von Willebrand factor, parameters of the coagulation system, and interleukin-6. Furthermore, the association of these markers with the severity of sepsis, systemic inflammation, and outcome is evaluated.

DATA EXTRACTION AND SYNTHESIS

Published research and review articles related to these parameters, with special emphasis on clinical studies.

CONCLUSIONS

Endothelial activation and damage occur early during sepsis and play a major role in the pathophysiology of systemic inflammation. Various markers of endothelial activation are increased during sepsis and systemic inflammation, and in most studies, the level of markers such as soluble intercellular adhesion molecule, vascular cell adhesion molecule, and E selectin correlate well with the severity of inflammation and the course of the disease. However, to date, it remains unclear whether adhesion molecules and coagulation parameters are superior in this respect to interleukin-6 and procalcitonin, as direct comparisons are lacking. In addition, it is evident that markers of endothelial activation and coagulation parameters lack specificity for infection-induced endothelial damage and organ dysfunction.

Cytokine balance in infants undergoing cardiac operation

BACKGROUND

The control of the systemic inflammatory response taking place during cardiac operations depends on adequate antiinflammatory reaction. In this prospective study we tested the hypothesis that cytokine balance during pediatric cardiac surgical procedures would be influenced by the patients' preoperative clinical condition, defined as hypoxemia or heart failure.

METHODS

Twenty infants (median age, 8 months) with hypoxemia owing to intracardiac right-to-left shunt (group 1, n = 10) or with heart failure because of intracardiac left-to-right shunt (group 2, n = 10), scheduled for elective primary corrective operation, were enrolled. Plasma levels of the proinflammatory cytokine interleukin (IL) 6, the natural antiinflammatory cytokine IL-10, and the markers of the acute-phase response, C-reactive protein and procalcitonin, were sequentially measured before, during, and after cardiac operation up to the 10th postoperative day. The ratio of IL-10 to IL-6 levels served as a marker for the individual's antiinflammatory cytokine balance.

RESULTS

Group 1 showed higher preoperative IL-6 (p < 0.001), lower IL-10 levels (p < 0.02), and lower ratio of IL-10 to IL-6 levels (p < 0.001) than group 2. Preoperative C-reactive protein and procalcitonin were not detectable. In group 1, preoperative IL-6 levels inversely correlated with preoperative oxygen saturation (Spearman correlation coefficient, -0.74, p < 0.02). During cardiopulmonary bypass, IL-6 levels were higher, whereas IL-10 and ratio of IL-10 to IL-6 levels were lower in group 1 than in group 2. In all patients, postoperative IL-6 levels were positively correlated with duration of inotropic support and serum creatinine value and inversely correlated with oxygenation index and diuresis.

CONCLUSIONS

Infants with hypoxemia show a preoperative inflammatory state with low antiinflammatory cytokine balance in contrast to those with heart failure. This in turn is associated with lower perioperative antiinflammatory cytokine balance and might contribute to postoperative morbidity.

Procalcitonin and other markers of infection. What should be their role in clinical practice?

Clinicians are always faced with a decision when confronted with a febrile patient; they must decide between what is an infectious condition and what is not, and between what merits hospital observation, what requires empirical antibiotic treatment and what needs outpatient follow-up. In this respect, judgement based on medical history and physical examination outweigh the predictive value of various laboratory markers of infection, as the latter generally reflect a nonspecific reaction of the host to widely different infectious and inflammatory stimuli. In the evaluation of specific subgroups of patients, e.g. those in the intensive care unit, laboratory tests should also preferably form a continuum with medical history and physical examination, aimed at clarifying host condition, the setting and the source of a possible infection.

Neuro-immune-endocrine functional system and vascular pathology

A new interpretation of the response to injury by the nervous, immune and endocrine system is proposed, in order to integrate biochemical knowledge into the respective clinical areas. The discovery that the signaling molecules of the classical nervous, immune and endocrine systems, that is, the neurotransmitters, cytokines and hormones, respectively, are expressed and perceived by the three systems, has enabled us to establish a functional concept of these systems. The hypothetical integration of different pathological processes in a functional response made up by three phases, the immediate or nervous, intermediate or immune and late or endocrine ones, makes it possible to consider that all of them represent different forms of expression of a functional response whose meaning is always the same, that is, inflammation. If the functions that characterize each one of these three phases represent the activity of the nervous, immune and endocrine systems, the biochemical knowledge could be integrated into the functional meaning of each system.

Circulating inflammatory mediators in patients with fever: predicting bloodstream infection

The systemic host response to microbial infection involves clinical signs and symptoms of infection, including fever and elevated white blood cell (WBC) counts. In addition, inflammatory mediators are released, including activated complement product C3a, interleukin 6 (IL-6), and the acute-phase reactant secretory phospholipase A(2) (sPLA(2)). To compare the value of the latter with the former in predicting (the degree of) microbial infection at the bedside, we determined clinical variables and took blood samples daily for 3 consecutive days in 300 patients with a new fever (>38.0 degrees C rectally or >38.3 degrees C axillary). Microbiological culture results for 7 days after inclusion were collected. Patients were divided into clinical and microbial categories: those without and with a clinical focus of infection and those with negative cultures, with positive local cultures or specific stains for fungal (n = 13) or tuberculous infections (n = 1), and with positive blood cultures, including one patient with malaria parasitemia. The area under the curve (AUC) of the receiver operating characteristic (ROC) for prediction of positive cultures was 0.60 (P < 0.005) for peak temperature and 0.59 (P < 0.01) for peak WBC count, 0.60 (P < 0.005) for peak C3a, 0.63 (P < 0.001) for peak IL-6, and 0.61 (P < 0.001) for peak sPLA(2). The AUC under the ROC curve for prediction of positive blood cultures was 0.68 (P < 0.001) for peak temperature and 0.56 for peak WBC count (P < 0.05). The AUC for peak C3a was 0.69, that for peak IL-6 was 0.70, and that for sPLA(2) was 0.67 (for all, P < 0.001). The degree of microbial invasion is thus a major determinant of the clinical and inflammatory host response in patients with fever. Moreover, circulating inflammatory mediators such as C3a and IL-6 may help to predict positive blood cultures, together with clinical signs and symptoms of the host response to microbial infection, even before culture results are available. This may help in the designing of entry criteria for therapeutic intervention studies.

Cellular and molecular aspects of myocardial dysfunction

Disruption of any one of a large number of balanced systems that maintain cardiomyocyte structure and function can cause myocardial dysfunction. Such disruption can occur either in response to acute stresses such as cardiac surgery with cardiopulmonary bypass and cross-clamping of the aorta or because of more chronic stresses resulting from factors such as genetic abnormalities, infection, or chronic ischemia. Several currently available therapies such as beta-adrenergic receptor agonists and antagonists, phosphodiesterase inhibitors, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and other agents affect cardiomyocytes in ways that are more far reaching than initially appreciated when these agents were first introduced into clinical practice. As our knowledge and understanding of myocardial dysfunction increases, particularly in the neonatal and pediatric patient, we will be able to further target interventions to highly specific perturbations of cellular function and individual genetic variability.

Prognostic value of cytokines in SIRS general medical patients

We studied 174 patients with SIRS criteria, 45 with sepsis, eight with severe sepsis and 13 with septic shock. Serum TNF-alpha, IL-6, IL-8 and IL-10 levels were raised in SIRS patients, even in those cases in which an infection could not be documented, and more intensely in severe sepsis and in patients who died (11%). The slope of the regression line between IL-10 and TNF-alpha was sharper in patients with severe sepsis and in those who died; an imbalance between pro- and anti-inflammatory cytokines may be related to poor prognosis. Increased IL-6 and IL-10, decreased muscle mass, raised BUN and low body temperature were all independently related to prognosis.

Anaphylatoxins and infectious and non-infectious inflammatory diseases

In recent years a plethora of data has accumulated directing toward an important role of polypeptides C3a and C5a and its degradation product C5adesArg, summarized as anaphylatoxins (ATs), in microbial host defense and immune regulation. The ATs exert their various biologic functions by interacting with specific C3a- and C5a-receptors present on cells of myeloid origin, epithelial cells, smooth muscle cells as well as on activated B- and T-cells. Activation of AT receptors mediates signal transduction pathways triggering a variety of proinflammatory events. However, by interacting with the cytokine- and chemokine network C3a and C5a exhibit also anti-inflammatory properties. In this review the focus is on the pathogenetic role of the ATs in sepsis, immune complex disease, delayed type hypersensitivity and asthma. Discussed are data from animal models in which the ATs are blocked by specific C3a or C5a inhibitors or from mice with genetic deletions of the specific receptors of either C3a or C5a/C5adesArg.

Diagnostic value of procalcitonin, interleukin-6, and interleukin-8 in critically ill patients admitted with suspected sepsis

To assess the diagnostic value of procalcitonin (PCT), interleukin (IL)-6, IL-8, and standard measurements in identifying critically ill patients with sepsis, we performed prospective measurements in 78 consecutive patients admitted with acute systemic inflammatory response syndrome (SIRS) and suspected infection. We estimated the relevance of the different parameters by using multivariable regression modeling, likelihood-ratio tests, and area under the receiver operating characteristic curves (AUC). The final diagnosis was SIRS in 18 patients, sepsis in 14, severe sepsis in 21, and septic shock in 25. PCT yielded the highest discriminative value, with an AUC of 0.92 (CI, 0.85 to 1.0), followed by IL-6 (0.75; CI, 0.63 to 0.87), and IL-8 (0.71; CI, 0.59 to 0.83; p < 0.001). At a cutoff of 1.1 ng/ml, PCT yielded a sensitivity of 97% and a specificity of 78% to differentiate patients with SIRS from those with sepsis-related conditions. Median PCT concentrations on admission (ng/ ml, range) were 0.6 (0 to 5.3) for SIRS; 3.5 (0.4 to 6.7) for sepsis; 6.2 (2.2 to 85) for severe sepsis; and 21.3 (1.2 to 654) for septic shock (p < 0.001). The addition of PCT to a model based solely on standard indicators improved the predictive power of detecting sepsis (likelihood ratio test; p = 0.001) and increased the AUC value for the routine value-based model from 0.77 (CI, 0.64 to 0.89) to 0.94 (CI, 0.89 to 0.99; p = 0.002). In contrast, no additive effect was seen for IL-6 (p = 0.56) or IL-8 (p = 0.14). Elevated PCT concentrations appear to be a promising indicator of sepsis in newly admitted, critically ill patients capable of complementing clinical signs and routine laboratory parameters suggestive of severe infection.