Interleukin-6 concentrations in neonates evaluated for sepsis

EARLY FLUID PLUS NOREPINEPHRINE RESUSCITATION DIMINISHES KIDNEY HYPOPERFUSION AND INFLAMMATION IN SEPTIC NEWBORN PIGS

ABSTRACT

Sepsis is the most frequent risk factor for acute kidney injury (AKI) in critically ill infants. Sepsis-induced dysregulation of kidney microcirculation in newborns is unresolved. The objective of this study was to use the translational swine model to evaluate changes in kidney function during the early phase of sepsis in newborns and the impact of fluid plus norepinephrine resuscitation. Newborn pigs (3-7-day-old) were allocated randomly to three groups: 1) sham, 2) sepsis (cecal ligation and puncture) without subsequent resuscitation, and 3) sepsis with lactated Ringer plus norepinephrine resuscitation. All animals underwent standard anesthesia and mechanical ventilation. Cardiac output and glomerular filtration rate were measured noninvasively. Mean arterial pressure, total renal blood flow, cortical perfusion, medullary perfusion, and medullary tissue oxygen tension (mtPO 2 ) were determined for 12 h. Cecal ligation and puncture decreased mean arterial pressure and cardiac output by more than 50%, with a proportional increase in renal vascular resistance and a 60-80% reduction in renal blood flow, cortical perfusion, medullary perfusion, and mtPO 2 compared to sham. Cecal ligation and puncture also decreased glomerular filtration rate by ~79% and increased AKI biomarkers. Isolated foci of tubular necrosis were observed in the septic piglets. Except for mtPO 2 , changes in all these parameters were ameliorated in resuscitated piglets. Resuscitation also attenuated sepsis-induced increases in the levels of plasma C-reactive protein, proinflammatory cytokines, lactate dehydrogenase, alanine transaminase, aspartate aminotransferase, and renal NLRP3 inflammasome. These data suggest that newborn pigs subjected to cecal ligation and puncture develop hypodynamic septic AKI. Early implementation of resuscitation lessens the degree of inflammation, AKI, and liver injury.

Biomarkers of Neonatal Sepsis: Where We Are and Where We Are Going

Neonatal sepsis is a bacterial bloodstream infection leading to severe clinical manifestations frequently associated with death or irreversible long-term deficits. Antibiotics are the drug of choice to treat sepsis, regardless of age. In neonates, the lack of reliable criteria for a definite diagnosis and the supposition that an early antibiotic administration could reduce sepsis development in children at risk have led to a relevant antibiotic overuse for both prevention and therapy. The availability of biomarkers of neonatal sepsis that could alert the physician to an early diagnosis of neonatal sepsis could improve the short and long-term outcomes of true sepsis cases and reduce the indiscriminate and deleterious use of preventive antibiotics. The main aim of this narrative review is to summarize the main results in this regard and to detail the accuracy of currently used biomarkers for the early diagnosis of neonatal sepsis. Literature analysis showed that, despite intense research, the diagnosis of neonatal sepsis and the conduct of antibiotic therapy cannot be at present decided on the basis of a single biomarker. Given the importance of the problem and the need to reduce the abuse of antibiotics, further studies are urgently required. However, instead of looking for new biomarkers, it seems easier and more productive to test combinations of two or more of the presently available biomarkers. Moreover, studies based on omics technologies should be strongly boosted. However, while waiting for new information, the use of the clinical scores prepared by some scientific institutions could be suggested. Based on maternal risk factors and infant clinical indicators, sepsis risk can be calculated, and a significant reduction in antibiotic consumption can be obtained.

On the Move-Sensitive Fluorescent Aptassay on Board Catalytic Micromotors for the Determination of Interleukin-6 in Ultra-Low Serum Volumes for Neonatal Sepsis Diagnostics

A graphene oxide/nickel/platinum nanoparticle micromotor (MM)-based fluorescent aptassay is proposed to determine interleukin-6 (IL-6) in serum samples from low-birth-weight infants (gestational age of less than 32 weeks and birthweight below 1000 g) with sepsis suspicion. In this kind of patients, IL-6 has demonstrated good sensitivity and specificity for the diagnosis of sepsis, both for early and late onset sepsis. The approach was based on the adsorption of the aptamer for IL-6 tagged with 6-FAM as a fluorescent label (Apt_IL-6, λ_em = 520 nm) on the graphene oxide external layer (MM_GO-Apt_IL-6) inducing fluorescence quenching (OFF state) and a subsequent on-the-move affinity recognition of IL-6 from Apt_IL-6 (IL-6-Apt_IL-6 complex) recovering the fluorescence (ON state). An aptamer against IL-6 was selected and developed by the systematic evolution of ligands by exponential enrichment technology. This approach displayed a suitable linear range of 0.07-1000 pg mL^-1 (r = 0.995) covering the cut-off and clinical practice levels, allowing direct determination without any dilution and simplifying the analysis as well as exhibiting an excellent sensitivity (LOD = 0.02 pg mL^-1) in ultralow volumes of diagnostic clinical samples (2 μL). A high agreement between IL-6 levels obtained from our MM-based approach and the method used by the Hospital was obtained (relative error < 3%). The MM-based aptassay is competitive in comparison with that of the Hospital, in terms of a significant reduction of the sample volume (15 times less) and enhanced sensitivity, employing similar analysis times. These results position MM technology with enough potential to achieve high sensitivities in low sample volumes, opening new avenues in diagnosis based on low sample volumes.

Catheter-related bloodstream infections in infants hospitalized in neonatal intensive care units: a single center study

Sepsis in neonates carries a high morbidity and mortality rate and is among the most feared complications in the neonatal intensive care unit (NICU). Catheter-related bloodstream infections (CRBSI) are a common etiology of late-onset sepsis. The aim of this study was to compare risk factors and characteristics between patients according to the type of catheter that was utilized and according to birth weight classification. The study included 51 newborns with confirmed CRBSI, which were hospitalized in our level 3 NICU between January 2017 and December 2018. The study population was stratified according to the type of venous catheter utilized (peripherally inserted central catheter, central venous catheter (CVC), and peripheral venous catheter). Infants with low birth weight and those who required prolonged parenteral nutrition were most likely to develop CRBSI in our study group. The type of venous catheter was not associated with blood culture results. Also, infants with a birth weight of < 1500 g and > 1500 g did not differ in sepsis etiology. Further research is required to assess venous catheters relative risk of causing sepsis and if the outcome can be traced back specifically to catheter type or patient characteristics.

Micro- and nanosensors for detecting blood pathogens and biomarkers at different points of sepsis care

Severe infections can cause a dysregulated response leading to organ dysfunction known as sepsis. Sepsis can be lethal if not identified and treated right away. This requires measuring biomarkers and pathogens rapidly at the different points where sepsis care is provided. Current commercial approaches for sepsis diagnosis are not fast, sensitive, and/or specific enough for meeting this medical challenge. In this article, we review recent advances in the development of diagnostic tools for sepsis management based on micro- and nanostructured materials. We start with a brief introduction to the most popular biomarkers for sepsis diagnosis (lactate, procalcitonin, cytokines, C-reactive protein, and other emerging protein and non-protein biomarkers including miRNAs and cell-based assays) and methods for detecting bacteremia. We then highlight the role of nano- and microstructured materials in developing biosensors for detecting them taking into consideration the particular needs of every point of sepsis care (e.g., ultrafast detection of multiple protein biomarkers for diagnosing in triage, emergency room, ward, and intensive care unit; quantitative detection to de-escalate treatment; ultrasensitive and culture-independent detection of blood pathogens for personalized antimicrobial therapies; robust, portable, and web-connected biomarker tests outside the hospital). We conclude with an overview of the most utilized nano- and microstructured materials used thus far for solving issues related to sepsis diagnosis and point to new challenges for future development.

Diagnosis of Neonatal Sepsis: The Role of Inflammatory Markers

This is a narrative review on the role of biomarkers in the diagnosis of neonatal sepsis. We describe the difficulties to obtain standardized definitions in neonatal sepsis and discuss the limitations of published evidence of cut-off values and their sensitivities and specificities. Maternal risk factors influence the results of inflammatory markers as do gestational age, the time of sampling, the use of either cord blood or neonatal peripheral blood, and some non-infectious causes. Current evidence suggests that the use of promising diagnostic markers such as CD11b, CD64, IL-6, IL-8, PCT, and CRP, either alone or in combination, might enable clinicians discontinuing antibiotics confidently within 24-48 h. However, none of the current diagnostic markers is sensitive and specific enough to support the decision of withholding antibiotic treatment without considering clinical findings. It therefore seems to be justified that antibiotics are often initiated in ill term and especially preterm infants. Early markers like IL-6 and later markers like CRP are helpful in the diagnosis of neonatal sepsis considering the clinical aspect of the neonate, the gestational age, maternal risk factors and the time (age of the neonate regarding early-onset sepsis) of blood sampling.

Reliability of Interleukin-6 Alone and in Combination for Diagnosis of Early Onset Neonatal Sepsis: Systematic Review

Neonatal sepsis is a major cause of morbidity and mortality in both preterm and term infants. Early-onset neonatal sepsis (EONS) presents within the first 72 h of life. Diagnosis is difficult as signs and symptoms are non-specific, and inflammatory markers are widely used to confirm or rule out neonatal sepsis. Interleukin-6 (IL-6) is part of the fetal inflammatory response syndrome (FIRS) and therefore an interesting early marker for neonatal sepsis. The main objective for this review was to assess the diagnostic potential of IL-6, alone and in combination, for diagnosis of early neonatal sepsis (EONS) in term and preterm infants, in cord and peripheral blood, and in dependence of timing of sample collection. IL-6 diagnostic accuracy studies for diagnosing EONS published between 1990 and 2020 were retrieved using the PubMed database. We included 31 out of 204 articles evaluating the potential of IL-6 for the diagnosis of EONS in a study population of newborns with culture-proven and/or clinically suspected sepsis. We excluded articles dealing with neonatal bacterial infections other than sepsis and biomarkers other than inflammatory markers, those written in languages other than English or German, studies that did not distinguish between EONS and late-onset sepsis, and animal and in vitro studies. Full-text articles were checked for other relevant studies according to the PRISMA criteria. We identified 31 studies on IL-6 diagnostic accuracy for EONS diagnosis between 1990 and 2020 including a total of 3,276 infants. Sensitivity and specificity were reported, and subgroup analysis was performed. A STARD checklist adapted for neonates with neonatal sepsis was used for quality assessment. The range of IL-6 sensitivity and specificity in neonatal samples was 42.1-100% and 43-100%; the median values were 83 and 83.3%, respectively. IL-6 accuracy was better in preterm infants than in mixed-study populations. Early sample collection at the time of sepsis suspicion had the highest sensitivity when compared to other time points. Cord blood IL-6 had higher diagnostic value compared to peripheral blood. The biomarker combination of IL-6 and CRP was found to be highly sensitive, but poorly specific. Limitations of this review include use of only one database and inclusion of a heterogeneous group of studies and a small number of studies looking at biomarker combinations; a strength of this review is its focus on early-onset sepsis, since type of sepsis was identified as a significant source of heterogeneity in IL-6 diagnostic accuracy studies. We concluded that IL-6 has a good performance as an early diagnostic marker of EONS within a study population of preterm infants, with best results for cord blood IL-6 using cutoff values above 30 pg/ml.

Aberrant Hematopoiesis and Morbidity in Extremely Preterm Infants With Intrauterine Growth Restriction

Background and Objective: Intrauterine growth restriction (IUGR) poses additional challenges in extremely low gestational age newborns (ELGANs). We assessed disturbed hematopoiesis and morbidities associated with this disorder. Methods: This single-center retrospective case-control study compared perinatal hematological profiles, major morbidities, and mortality of 49 infants (gestational age <28 weeks, birth weight ≤ 3rd percentile, and compromised placental function) and 98 infants (birth weight >10th percentile) matched for gestational age, year, and sex. Results: IUGR-ELGANs had significantly elevated nucleated red blood cells and lower neutrophil and platelet counts at birth and on the third day of life. During the first week of life, IUGR-ELGANs received more red blood cell, platelet, and plasma transfusions and were more intensively treated with antibiotics. Rates of infections acquired during the first week (59.2 vs. 17.3%, p < 0.001), severe bronchopulmonary dysplasia or death (42.9 vs. 17.3%, p < 0.01), and mortality (36.7 vs. 7.1%, p < 0.001) were markedly elevated in IUGR-ELGANs, but not of hemorrhages or other morbidities. Conclusions: IUGR-ELGANs have high rates of acquired infections during the first week of life and display severe pulmonary morbidity leading to bronchopulmonary dysplasia or death. The high rate of transfusions observed in these infants warrants further scrutiny.

The Diagnostic Performance of Interleukin-6 and C-Reactive Protein for Early Identification of Neonatal Sepsis

Interleukin-6 (IL-6) and C-reactive protein (CRP) are being used for diagnosis of sepsis. However, studies have reported varying cut-off levels and diagnostic performance. This study aims to investigate the optimal cut-off levels and performance of IL-6 and CRP for the diagnosis of neonatal sepsis. The study was conducted at the University Hospital of Leipzig, Germany from November 2012 to June 2020. A total of 899 neonates: 104 culture proven sepsis, 160 clinical sepsis, and 625 controls were included. Blood culture was performed using BacT/ALERT 3D system. IL-6 and CRP were analyzed by electrochemiluminescent immunoassay and immunoturbidimetric assay, respectively. Data were analyzed using SPSS 20 statistical software. Among neonates with proven sepsis, the optimal cut-off value of IL-6 was 313.5 pg/mL. The optimal cut-off values for CRP in 5 days serial measurements (CRP1, CRP2, CRP3, CRP4, and CRP5) were 2.15 mg/L, 8.01 mg/L, 6.80 mg/L, 5.25 mg/L, and 3.72 mg/L, respectively. IL-6 showed 73.1% sensitivity, 80.2% specificity, 37.6% PPV, and 94.8% NPV. The highest performance of CRP was observed in the second day with 89.4% sensitivity, 97.3% specificity, 94.5% PPV, and 98.3% NPV. The combination of IL-6 and CRP showed increase in sensitivity with decrease in specificity. In conclusion, this study defines the optimal cut-off values for IL-6 and CRP. The combination of IL-6 and CRP demonstrated increased sensitivity. The CRP 2 at cut-off 8.01 mg/L showed the highest diagnostic performance for identification of culture negative clinical sepsis cases. We recommend the combination of IL-6 (≥313.5 pg/mL) and CRP1 (≥2.15 mg/L) or IL-6 (≥313.5 pg/mL) and CRP2 (≥8.01 mg/L) for early and accurate diagnosis of neonatal sepsis. The recommendation is based on increased sensitivity, that is, to minimize the risk of any missing cases of sepsis. The CRP2 alone at cut-off 8.01 mg/L might be used to identify clinical sepsis cases among culture negative sepsis suspected neonates in hospital settings.

Diagnostic Accuracy of Biomarkers for Early-Onset Neonatal Bacterial Infections: Evaluation of Serum Procalcitonin Reference Curves

To date, no clinical studies have compared the accuracy of serum procalcitonin (PCT) reference curves. We aimed to validate the diagnostic accuracy of previously reported serum PCT reference curves and to determine which biomarkers among a cut-off value over the 95th percentile in the serum PCT reference curve, white blood cell (WBC) count, and C-reactive protein (CRP) and immunoglobulin M (IgM) levels, have the highest diagnostic accuracy for early-onset neonatal bacterial infections. This retrospective cohort study assessed 16 preterm and 23 term infants with suspected bacterial infections within 72 h after birth. Each infant group was divided into two subgroups: confirmed- and non-infection. The diagnostic accuracy was determined using the Youden index. The reference curves by Fukuzumi et al. in preterm and term infants had the highest Youden indexes: 1.000 and 0.324, respectively. Among preterm infants, the Youden index for PCT was 1.000. Among term infants, the Youden index for a combination of PCT, CRP, and WBC and/or IgM was 1.000. In conclusion, a serum PCT level over the 95th percentile on the reference curve for preterm infants and a combination of PCT and CRP levels with WBC count and/or IgM levels for term infants provided sufficient diagnostic accuracy.

Assessment of C-Reactive Protein Diagnostic Test Accuracy for Late-Onset Infection in Newborn Infants: A Systematic Review and Meta-analysis

IMPORTANCE

Rapid and accurate diagnosis of late-onset infection in newborn infants could inform treatment decisions and avoid unnecessary administration of antibiotics.

OBJECTIVE

To compare the accuracy of serum C-reactive protein (CRP) with that of microbiological blood culture for diagnosing late-onset infection in newborns.

DATA SOURCES

MEDLINE (1946-2019), Embase (1946-2019), and Science Citation Index (1900-2019) databases were searched for references (any language). The MeSH search terms included were "exp infant, newborn/" or "premature birth/" plus free text synonyms; and "C-reactive protein/" plus free text synonyms; and "exp sepsis/" or "exp bacterial infections/" plus free text synonyms. The proceedings from relevant conferences and references of identified papers were scrutinized. Authors were contacted to request missing data.

STUDY SELECTION

Cohort and cross-sectional studies were included that compared the accuracy of serum CRP levels with microbiological culture results to diagnose late-onset (>72 hours after birth) infection in newborns (any gestational age) hospitalized after birth. Two reviewers assessed study eligibility. Among 10 394 records, 148 studies were assessed as full texts.

DATA EXTRACTION AND SYNTHESIS

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guideline extension for Diagnostic Test Accuracy (DTA) reviews was followed. Two reviewers assessed the method quality of each study using guidance from the Cochrane Screening and Diagnostic Test Methods Group (adapted from the Quality Assessment of Diagnostic Accuracy Studies 2).

MAIN OUTCOMES AND MEASURES

The primary meta-analysis outcome was diagnostic test accuracy of serum CRP level taken at initial investigation of an infant with suspected late-onset infection. The median specificity (proportion of true-negative results) and calculated pooled sensitivity (proportion of true-positive results) were determined by generating hierarchical summary receiver characteristic operating curves.

RESULTS

In total, 22 studies with 2255 infants were included (sample size range, 11-590 infants). Participants in most studies were preterm (<37 weeks) or very low-birth weight (<1500 g) infants. Two studies additionally enrolled infants born at term. Most studies (16) used a prespecified CRP level cutoff for a "positive" index test (5-10 mg/L), and most studies (17) used the culture of a pathogenic microorganism from blood as the reference standard. Risk of bias was low with independent assessment of index and reference tests. At median specificity (0.74), pooled sensitivity was 0.62 (95% CI, 0.50-0.72). Adding serum CRP level to the assessment of an infant with a 40% pretest probability of late-onset infection (the median for the included studies) generated posttest probabilities of 26% for a negative test result and 61% for a positive test result.

CONCLUSIONS AND RELEVANCE

The findings suggest that determination of serum CRP level at initial evaluation of an infant with suspected late-onset infection is unlikely to aid early diagnosis or to select infants to undergo further investigation or treatment with antimicrobial therapy or other interventions.

Serum C-Reactive Protein Levels in Healthy Neonates in Different Gestational and Postnatal Ages

There is paucity of normative data on serum C-reactive protein (CRP) in neonates. In Part I of study, we compared CRP in healthy neonates (from 28°/7 weeks to 416/7 weeks of gestation) between various gestational and postnatal age groups in first week. We planned recruitment of 50 participants each in 'term', 'late preterm' and 'moderate-to-very preterm' groups, equally divided in '24-95 h' and '96-168 h' postnatal age sub-groups. In Part II of study, we assayed CRP weekly in moderate-to-very preterm neonates until day 28 to evaluate its trend. Among 154 subjects, term neonates had higher CRP, with highest values among term infants aged 24-95 h. Barring postnatal age, maternal/perinatal factors did not affect CRP levels. CRP did not change significantly over 28 days in moderate-to-very preterm neonates. In conclusion, serum CRP in healthy neonates is highest among term infants aged 24-95 h and does not vary significantly in the first month of life among moderate-to-very preterm infants.

C-reactive protein for diagnosing late-onset infection in newborn infants

BACKGROUND

Late-onset infection is the most common serious complication associated with hospital care for newborn infants. Because confirming the diagnosis by microbiological culture typically takes 24 to 48 hours, the serum level of the inflammatory marker C-reactive protein (CRP) measured as part of the initial investigation is used as an adjunctive rapid test to guide management in infants with suspected late-onset infection.

OBJECTIVES

To determine the diagnostic accuracy of serum CRP measurement in detecting late-onset infection in newborn infants.

SEARCH METHODS

We searched electronic databases (MEDLINE, Embase, and Science Citation Index to September 2017), conference proceedings, previous reviews, and the reference lists of retrieved articles.

SELECTION CRITERIA

We included cohort and cross-sectional studies evaluating the diagnostic accuracy of serum CRP levels for the detection of late-onset infection (occurring more than 72 hours after birth) in newborn infants.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility for inclusion, evaluated the methodological quality of included studies, and extracted data to estimate diagnostic accuracy using hierarchical summary receiver operating characteristic (SROC) models. We assessed heterogeneity by examining variability of study estimates and overlap of the 95% confidence interval (CI) in forest plots of sensitivity and specificity.

MAIN RESULTS

The search identified 20 studies (1615 infants). Most were small, single-centre, prospective cohort studies conducted in neonatal units in high- or middle-income countries since the late 1990s. Risk of bias in the included studies was generally low with independent assessment of index and reference tests. Most studies used a prespecified serum CRP threshold level as the definition of a 'positive' index test (typical cut-off level between 5 mg/L and 10 mg/L) and the culture of a pathogenic micro-organism from blood as the reference standard.At median specificity (0.74), sensitivity was 0.62 (95% CI 0.50 to 0.73). Heterogeneity was evident in the forest plots but it was not possible to conduct subgroup or meta-regression analyses by gestational ages, types of infection, or types of infecting micro-organism. Covariates for whether studies used a predefined threshold or not, and whether studies used a standard threshold of between 5 mg/L and 10 mg/L, were not statistically significant.

AUTHORS' CONCLUSIONS

The serum CRP level at initial evaluation of an infant with suspected late-onset infection is unlikely to be considered sufficiently accurate to aid early diagnosis or select infants to undergo further investigation or treatment with antimicrobial therapy or other interventions.

Serial C-Reactive Protein Measurements in Newborn Infants without Evidence of Early-Onset Infection

BACKGROUND

C-reactive protein (CRP) is used to assist the diagnosis and monitoring of newborn infection. Little is known about CRP activity after birth in the absence of infection.

OBJECTIVE

The aim of this work was to describe postnatal CRP responses in the first days of life in asymptomatic infants with a negative blood culture.

METHODS

Data were collected from infants who had a blood culture taken at <72 h of age in a UK maternity hospital. All CRP values and their time from birth were recorded. Infants with signs of infection, positive blood culture, or major congenital anomalies were excluded. Infants were analysed by gestation (greater or less than 37 weeks). Normalised CRP curves were generated by linear interpolation and centile curves were derived. Comparisons of median CRP values between groups were made by Mann-Whitney U test at 24, 36, and 48 h.

RESULTS

During the study period a total of 219 babies were screened. After exclusions, 73 infants (58 term, 15 preterm) were analysed. In asymptomatic term neonates the CRP (mg/L) peaked at 9.4 after 34.6 h. In preterm babies the CRP peak was 1.75 at 43 h. The median (IQR) values were higher in the term group at 24 and 36 h: 2.5 (1-10.5) versus 0 (0-2.2; p = 0.02) and 3 (0-8.6) versus 0 (0-2.8; p = 0.031).

CONCLUSIONS

A CRP rise was demonstrated in term and preterm infants without evidence of infection. This rise was greatest in term infants. CRP values must be interpreted in the context of an infant's clinical condition and not used alone to guide clinical decision making.

Diagnostics for neonatal sepsis: current approaches and future directions

Progress has been made in the reduction of morbidity and mortality from neonatal sepsis. However, diagnosis continues to rely primarily on conventional microbiologic techniques, which can be inaccurate. The objective of this review is to provide the clinician with an overview of the current information available on diagnosing this condition. We review currently available diagnostic approaches for documenting neonatal sepsis and also describe novel approaches for diagnosing infection in neonates who are under development and investigation. Substantial progress has been made with molecular approaches and further development of non-culture-based methods offer promise. The potential ability to incorporate antimicrobial resistance gene testing in addition to pathogen identification may provide a venue to incorporate a predominantly molecular platform into a larger program of neonatal care.

Utility of cytokine, adhesion molecule and acute phase proteins in early diagnosis of neonatal sepsis

Background and Aim:

Neonatal infection, including bacterial sepsis, is a major health care issue with an annual global mortality in excess of one million lives. Therefore, this study aimed to evaluate the potential diagnostic value of C-reactive protein (CRP), E-selectin, procalcitonin (PCT), interleukins-6 (IL-6), and tumor necrosis factor-α (TNF-α) both independently and in combination for the diagnosis of neonatal sepsis in its earliest stages.

Materials and Methods:

A total of 320 subjects were included in this study. A prospective cross-sectional study was conducted among neonates admitted to Neonatal Intensive Care Unit at King Abdulaziz Medical City, Riyadh, KSA during January 2013 to August 2015, the study based on three study groups categorized according to clinical symptoms and blood culture result. Study groups include healthy control neonates (n = 80), clinical sepsis (CS) group (n = 80) with clinical signs of sepsis but their blood culture was negative, and sepsis group with clinical signs of sepsis and their blood culture was positive.

Results:

The study observed significant difference in plasma levels of CRP, IL-6, TNF-α, E-selectin, and PCT in patients group when compared with control group (P < 0.001). Furthermore, the levels are significantly different between patient groups including CS and neonatal sepsis group. Moreover, result observed significant difference in CRP and IL-6 in early onset sepsis (EOS) when compared with late onset sepsis (LOS) neonates (P < 0.001 and 0.01), respectively, while there were no significant difference in TNF-α, E-selectin, and PCT between EOS and LOS (P = 0.44, 0.27 and 0.24), respectively. Regarding biomarkers accuracy, the result showed that CRP has the best diagnostic accuracy with cutoff value of 3.6 ng/ml (sensitivity 78% and specificity of 70%). The best combination is shown with CRP and IL-6 in which sensitivity increased to 89% and specificity to 79%.

Conclusion:

It was concluded that infected new-born babies have a higher E-selectin, PCT, IL-6, TNF-α, and CRP compared with the neonates with CS and control. IL-6, TNF-α, and CRP should be measured in combination for mare diagnostic accuracy in neonatal sepsis. Likewise, PCT should be investigated as a part of sepsis screening for all suspected neonates.

Analysis of urine biomarkers for early determination of acute kidney injury in non-septic and non-asphyxiated critically ill preterm neonates

OBJECTIVE

We designed the present study to test the hypothesis that urinary biomarkers might predict acute kidney injury (AKI) development in non-septic and non-asphyxiated critically ill preterm infants. We evaluated urine (u) sistatin-C (uCys-C), kidney injury molecule-1 (uKIM-1) and neutrophil gelatinase associate lipocaline (uNGAL) as markers of AKI.

METHODS

Sixty-four preterm infants with gestational age between 28 and 32 weeks were included in this study. Biomarkers were measured on day of life (DOL) 1, 3, and 7.

RESULTS

uNGAL levels in the AKI group were significantly higher than in no-AKI group on DOL 1, 3 and 7 (p = 0.016, p = 0.007 and p = 0.0014, respectively).

CONCLUSIONS

uNGAL is sensitive, early, and noninvasive AKI biomarkers, increasing significantly in non-septic and non-asphyxiated critically ill preterm neonates.

Synbiotics for decreasing incidence of necrotizing enterocolitis among preterm neonates - a randomized controlled trial

OBJECTIVE

To study the effect of synbiotics in reducing incidence and severity of necrotizing enterocolitis (NEC) among preterm neonates.

METHODS

This randomized controlled trial conducted in a tertiary care teaching hospital, south India, included 220 enterally fed preterm neonates who were randomized to receive either synbiotics or no intervention. The synbiotic contained Lactobacillus, Bifidobacterium and fructo-oligosaccharide. The demographic parameters, risk factors for NEC and outcome including incidence of NEC, its severity, sepsis and mortality were evaluated.

RESULTS

Multiple pregnancies, preeclampsia and prolonged rupture of membranes were important maternal characteristics. The average birth weight and gestational age of the preterm neonates was 1.4 kg and 31 weeks, respectively. There was a 50% reduction in the incidence of NEC of all stages in preterm infants who received synbiotics compared to the non-intervention group (7.4% versus 14.5%). Administration of synbiotics did not reduce the severity of NEC, sepsis or mortality.

CONCLUSION

Enteral supplementation of synbiotics along with breastmilk results in a tendancy to decrease the incidence of NEC among preterm neonates.

Umbilical cord blood IL-6 as predictor of early-onset neonatal sepsis in women with preterm prelabour rupture of membranes

OBJECTIVE

To evaluate umbilical cord interleukin (IL)-6 and funisitis as independent predictors of early-onset neonatal sepsis (EONS) in preterm prelabor rupture of membranes (PPROM).

DESIGN

Prospective cohort study.

SETTING

Evaluation of umbilical cord IL-6 and funisitis as predictors of early-onset neonatal sepsis in PPROM.

POPULATION

176 women with PPROM between 23+0-36+6 weeks of gestation.

METHODS

Umbilical cord IL-6 was assayed by ELISA. Funisitis was defined according to the Salafia classification. Data was adjusted by gestational age at delivery and prenatal administration of corticosteroids and antibiotics.

MAIN OUTCOME MEASURES

Binary logistic regression was performed to assess the independence of umbilical cord IL-6 and funisitis to predict EONS in women complicated with PPROM.

RESULTS

The rate of EONS was 7%. Funisitis was present in 18% of women. Umbilical cord IL-6 was significantly higher in women complicated with EONS than without [median (range) 389.5 pg/mL (13.9-734.8) vs 5.2 (0.1-801-4), p<0.001]. Umbilical cord IL-6 was the only independent predictor of early-onset neonatal sepsis (odds ratio 13.6, p = 0.004).

CONCLUSION

Umbilical cord IL-6 was the only predictor of early-onset neonatal sepsis in PPROM. Contrary to what is reported, funisitis was not.

Biomarkers for diagnosis of neonatal infections: A systematic analysis of their potential as a point-of-care diagnostics

BACKGROUND

Neonatal infections annually claim lives of 1.4 million neonates worldwide. Until now, there is no ideal diagnostic test for detecting sepsis and thus management of possible sepsis cases often depends on clinical algorithm leading to empirical treatment. This often results in unnecessary antibiotic use, which may lead to emergence of antibiotic resistance. Biomarkers have shown great promise in diagnosis of sepsis and guiding appropriate treatment of neonates. In this study, we conducted a literature review of existing biomarkers to analyze their status for use as a point-of-care diagnostic in developing countries.

METHODS

PubMed and EMBASE database were searched with keywords, 'infections', 'neonates', and 'biomarkers' to retrieve potentially relevant papers from the period 1980 to 2010. Leading hospitals and manufacturers were communicated to inquire about the cost, laboratory requirements and current standing of biomarkers in clinical use.

RESULTS

The search returned 6407 papers on biomarkers; 65 were selected after applying inclusion and exclusion criteria. Among the studies, C-reactive protein (CRP), procalcitonin (PCT) and interleukin 6 (IL-6) were the most widely studied biomarkers and were considered to be most promising for diagnosing neonatal infections. About 90% of the studies were from developed countries; more than 50% were from Europe.

CONCLUSIONS

Extensive work is being performed to find the diagnostic and prognostic value of biomarkers. However, the methodologies and study design are highly variable. Despite numerous research papers on biomarkers, their use in clinical setting is limited to CRP. The methods for detection of biomarkers are far too advanced to be used at the community level where most of the babies are dying. It is important that a harmonized multi-site study is initiated to find a battery of biomarkers for diagnosis of neonatal infections.

What are the cut-off levels for IL-6 and CRP in neonatal sepsis?

Neonatal sepsis, characterized by systemic signs of infection in the first month of life, remains an important clinical syndrome. Despite advances in neonatology, it has high rates of mortality and morbidity. The combine or alone usage of interleukin-6 (IL-6) and C-reactive protein (CRP) has recently been proven to be useful in the early diagnosis of sepsis in newborns. The study included 282 patients; there were 232 in Group I (170 proven and 62 clinical sepsis) and 50 in Group II (control group). The optimum cut-off value in the diagnosis of neonatal sepsis was found to be 24.65 pg/ml for IL-6 and 4.82 mg/l for CRP. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of this IL-6 cut-off for neonatal sepsis were 72, 84, 95, and 42%, respectively. Sensitivity, specificity, PPV, and NPV of the CRP cut-off for neonatal sepsis were 67, 97, 99, and 39%, respectively. The combination of IL-6 (>24.65 pg/ml) and CRP (>4.82 mg/l) in the diagnosis of neonatal sepsis gave sensitivity, specificity, PPV, and NPV of 53, 100, 100, and 33%, respectively. To our knowledge, this is the largest reported study seeking to determine cut-off levels for IL-6 and CRP in the diagnosis of neonatal sepsis. In conclusion, we think that it is useful to evaluate IL-6 and CRP, in combination, for the early diagnosis of neonatal sepsis.

Diagnostic value of interleukin-6 and C-reactive protein on early onset bacterial infection in preterm neonates with respiratory distress

AIMS

To evaluate the C-reactive protein (CRP) and interleukin-6 (IL-6) as diagnostic tools for early onset infection in preterm infants with early respiratory distress (RD).

METHODS

CRP and IL-6 were quantified at identification of RD and 24 h after in 186 newborns. Effects of maternal hypertension, mode of delivery, Apgar score, birth weight, gestational age, mechanical ventilation, being small for gestational age (SGA), and the presence of infection were analyzed.

RESULTS

Forty-four infants were classified as infected, 42 as possibly infected, and 100 as uninfected. Serum levels of IL-6 (0 h), CRP (0 h), and CRP (24 h), but not IL-6 (24 h) were significantly higher in infected infants compared to the remaining groups. The best test for identification of infection was the combination of IL-6 (0 h) 36 pg/dL and/or CRP (24 h) 0.6 mg/dL, which yielded 93% sensitivity and 37% specificity. The presence of infection and vaginal delivery independently increased IL-6 (0 h), CRP (0 h) and CRP (24 h) levels. Being SGA also increased the CRP (24 h) levels. IL-6 (24 h) was independently increased by mechanical ventilation.

CONCLUSIONS

The combination of IL-6 (0 h) and/or CRP (24 h) is helpful for excluding early onset infection in preterm infants with RD but the poor specificity limits its potential benefit as a diagnostic tool.

Regulated on activation, normal T cell expressed and secreted and tumor necrosis factor-alpha in septic neonates

OBJECTIVE

Measuring serum tumour necrosis factor-alpha (TNF-alpha) and Regulated upon Activation Normal T cell Expressed and Secreated (RANTES) in neonatal sepsis and determining whether early and late onset sepsis were associated with differences in their concentrations.

STUDY DESIGN

In 15 neonates showing clinical signs of early- or late-onset infection, serum TNF-alpha and RANTES were determined at first suspicion of sepsis and before starting antibiotics. Fifteen healthy neonates were included as controls.

RESULTS

Serum TNF-alpha white blood cells and C-reactive protein (CRP) were significantly higher, whereas RANTES was significantly lower in the septic group compared with the non-septic group. There was no significant difference in RANTES or TNF-alpha levels between infants having early or late-onset sepsis. Similar to term neonates, premature neonates, responded to infection with increased TNF-alpha and decreased RANTES, with no statistical differences between both groups.

CONCLUSION

In this study TNF-alpha is the best diagnostic test of neonatal sepsis, followed by CRP, when evaluated at first suspicion of sepsis.

Fetal inflammatory response in women with proteomic biomarkers characteristic of intra-amniotic inflammation and preterm birth

OBJECTIVE

To determine the relationship between presence of amniotic fluid (AF) biomarkers characteristic of inflammation (defensins 2 and 1 and calgranulins C and A) and fetal inflammatory status at birth.

DESIGN

Prospective observational cohort.

SETTING

Tertiary referral University hospital.

POPULATION

One hundred and thirty-two consecutive mothers (gestational age, median [interquartile range]: 29.6 [24.1-33.1] weeks) who had a clinically indicated amniocentesis to rule out infection and their newborns.

METHODS

Intra-amniotic inflammation was diagnosed by mass spectrometry surface-enhanced-laser-desorption-ionization time of flight (SELDI-TOF). The AF proteomic fingerprint (mass-restricted [MR] score) ranges from 0-4 (none to all biomarkers present). The intensity of intra-amniotic inflammation was graded based on the number of proteomic biomarkers: MR score 0: 'no' inflammation, MR score 1-2: 'minimal' inflammation and MR score 3-4: 'severe' inflammation. At birth, cord blood was obtained for all women. Severity of histological chorioamnionitis and early-onset neonatal sepsis (EONS) was based on established histological and haematological criteria. Interleukin-6 (IL-6) levels were measured by sensitive immunoassays. The cord blood-to-AF IL-6 ratio was used as an indicator of the differential inflammatory response in the fetal versus the AF compartment.

MAIN OUTCOME MEASURES

To relate proteomic biomarkers of intra-amniotic infection to cord blood IL-6 and to use the latter as the primary marker of fetal inflammatory response.

RESULTS

Women with intra-amniotic inflammation delivered at an earlier gestational age (analysis of variance, P<0.001) and had higher AF IL-6 levels (P<0.001). At birth, neonates of women with severe intra-amniotic inflammation had higher cord blood IL-6 levels (P=0.002) and a higher frequency of EONS (P=0.002). EONS was characterised by significantly elevated cord blood IL-6 levels (P<0.001). Of the 39 neonates delivered by mothers with minimal intra-amniotic inflammation, 15 (39%) neonates had umbilical cord blood IL-6 levels above the mean for the group and 2 neonates had confirmed sepsis. The severity of the neutrophilic infiltrate in the chorionic plate (P<0.001), choriodecidua (P=0.002), umbilical cord (P<0.001) but not in the amnion (P>0.05) was an independent predictor of the cord blood-to-AF IL-6 ratio. Relationships were maintained following correction for gestational age, birthweight, amniocentesis-to-delivery interval, caesarean delivery, status of the membranes, race, MR score and antibiotics and steroid exposure.

CONCLUSIONS

We provide evidence that presence of proteomic biomarkers characteristic of inflammation in the AF is associated with an increased inflammatory status of the fetus at birth. Neonates mount an increased inflammatory status and have positive blood cultures even in the context of minimal intra-amniotic inflammation.

Early effects of lipopolysaccharide on cytokine release, hemodynamic and renal function in newborn piglets

BACKGROUND

Gram-negative sepsis in newborns is associated with high mortality and morbidity. Lipopolysaccharide (LPS) and cytokines released upon exposure to gram-negative sepsis are well known to be involved in the pathophysiology.

OBJECTIVE

In this report we investigate cytokine release, hemodynamic, and renal function induced by LPS in a newborn animal model with the intention to further examine early changes in gram-negative sepsis.

METHODS

Five 7- to 10-day-old domestic piglets were anesthetized and catheters placed in the jugular veins, left ventricle, and femoral artery. Urine output was monitored via suprapubic cystostomy. Mean arterial pressure, heart rate, and arterial blood gases were continuously monitored. Thirty minutes after line placement and obtaining baseline values, 0.06 mug/kg LPS were administered intravenously. One, 2, and 3 h later samples were taken to monitor tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, endothelin, and nitric oxide (NO)/nitrate via ELISA. In addition, blood flow was assessed by the microsphere method.

RESULTS

Our data show an initial surge of TNF-alpha and IL-1beta at 1 h after exposure to LPS. NO/nitrate, endothelin, and hemodynamic as well as metabolic changes became apparent mostly 3 h after exposure, by which time TNF-alpha and IL-1beta fell back to baseline.

CONCLUSIONS

Our sepsis model suggests a brief initial TNF-alpha and IL-1beta surge following LPS challenge; however, their effects become apparent by the time the levels are already subsiding. The emergence of vasoactive substances, NO and endothelin, precedes the first substantial clinical symptoms.

The diagnostic value of serum interleukins 6 and 8 in children with acute gastroenteritis

OBJECTIVES

Early identification of the pathogen causing acute gastroenteritis in children helps the physicians managing the disease and prevents unnecessary antibiotic treatment. C-reactive protein (CRP), interleukin (IL) 6 and IL-8 play a major role in immune responses and have been studied in a large number of infectious and noninfectious inflammatory diseases. The purpose of this study was to determine the serum IL-6 and IL-8 concentrations early in the course of acute gastroenteritis to see if these cytokines were useful diagnostic markers in differentiating viral from bacterial gastroenteritis.

METHODS

Interleukin 6, IL-8 and CRP were measured in 18 patients with bacterial gastroenteritis, 21 patients with viral gastroenteritis and 17 healthy children.

RESULTS

Interleukin 6 and CRP concentrations in patients with bacterial gastroenteritis were significantly higher than those in patients with viral gastroenteritis and healthy controls (P < 0.001). IL-8 concentrations in patients with viral and bacterial gastroenteritis were both increased and were not statistically different. IL-6 and IL-8 levels had diagnostic sensitivities of 79% and 50% and specificities of 86% and 67%, respectively. The combination of IL-6 and CRP had a sensitivity of 94%, specificity of 71%, a positive predictive value of 74% and a negative predictive value of 93.75%.

CONCLUSIONS

Serum IL-6 may be a useful marker for early differentiation of viral and bacterial gastroenteritis in children, especially in combination with CRP.

Special relationships between fetal inflammatory response syndrome and bronchopulmonary dysplasia in neonates

OBJECTIVE

To confirm previous known relationships between Fetal Inflammatory Response Syndrome (FIRS) and neonatal bronchopulmonary dysplasia (BPD) and to present information on previously unknown special relationships between inflammatory variables and BPD.

STUDY DESIGN

At delivery, we obtained biological specimens including umbilical cord venous blood for plasma interleukin-6 levels, as well as placental histology and bacteriology. Among other neonatal outcomes, we collected prospective information on BPD.

RESULTS

Of 141 newborns in the study, 16 had BPD; 79% of these had antecedent FIRS, 27% of those without FIRS had BPD. By multivariable regression, only very low birth weight (adjusted [adj] odds ratio [OR] 32.0, 95% Confidence Interval [CI] 5.0 to positive infinity) and FIRS (adj OR 5.7, 95% CI 1.1 to 42.3) remained significant risk factors. Escherichia coli, perhaps due to its pyogenic nature (strongly elicits inflammatory responses), may have had a special relationship with BPD.

CONCLUSIONS

In our data, FIRS and neonatal BPD are highly associated. It is possible that certain pyogenic bacteria in the chorioamnion space may be implicated more often than others.

CONDENSATION

Neonates having Fetal Inflammatory Response Syndrome at delivery may later develop BPD. Pyogenic bacteria, such as Escherichia coli, may be implicated more frequently.

Improved diagnostic approaches to infection/sepsis detection

Sepsis is a major healthcare problem from the perspective of mortality and economics. Advances in diagnostic detection of infection and sepsis have been slow, but recent advances in both soluble biomarker detection and quantitative cellular measurements promise the availability of improved diagnostic techniques. Though the promise of cytokine measurements reaching clinical practice have not matured, procalcitonin levels are currently available in many countries and appear to offer enhanced diagnostic distinction between bacterial and viral etiologies. Cellular diagnostics is poised to enter clinical laboratory practice in the form of neutrophil CD64 measurements, which offer superior sensitivity and specificity to conventional laboratory assessment of sepsis. Neutrophil CD64 expression is negligible in the healthy state. However, it increases as part of the systemic response to severe infection or sepsis. The combination of cellular proteomics, as in the case of neutrophil CD64 quantification, and selected soluble biomarkers of the inflammatory response, such as procalcitonin or triggering receptor expressed on myeloid cells (TREM)-1, is predicted to remove the current subjectivity and uncertainty in the diagnosis and therapeutic monitoring of infection and sepsis.

Immunologic markers in the neonatal period: diagnostic value and accuracy in infection

Diagnosis of early-onset neonatal infection has led to the development of several screening tests including C-reactive protein, a very commonly used marker, and cytokines (mainly interleukin-6 and -8), alone or in combination with C-reactive protein, based on the premise that their increases in response to infection may precede that of C-reactive protein. In recent years the search for diagnostic tests has turned to procalcitonin, a propeptide of calcitonin, which appears to be a promising marker of infection in newborn infants. Additionally, specific leukocyte cell surface antigens (mainly CD11b and CD64), detected by flow cytometry, are evaluated as markers of neonatal infection, since their expression on the cell membrane increases in substantial quantities after leukocyte activation by bacteria or their cellular products. This review aims to examine the role of these newly available immunologic indices and to assess their validity as diagnostic markers of infection during the neonatal period.

Development, validation, and implementation of a multiplex immunoassay for the simultaneous determination of five cytokines in human serum

Quantification of biomarkers can provide important information about the safety and efficacy of candidate drugs. Unfortunately, limited sample volume and excess costs often limit analysis of multiple biomarkers. We developed, optimized, validated, and implemented a multiplex immunoassay for simultaneous measurement of multiple circulating cytokines: IL-1beta, TNFalpha, IL-6, IL-8, and IL-10. Multiplex immuoassays were performed using the Luminex LabMAP instrument. Capture antibodies for each cytokine were covalently bound to distinct microsphere subsets distinguished by differing dye ratios. The concentration of each individual cytokine determined by measuring orange fluorescence produced by a complex of a biotinylated cytokine-specific antibody and streptavidin-phycoerythrin. The lower limit of quantification for all assays was 20 pg/mL with the exception of IL-8 which was 100 pg/mL. The inter-assay precision was less than 25%CV for all analytes at all control levels both pre-study and in-study. The percent recovery ranged from 83 to 108% pre-study and 90 to 125% in-study. In a linearity assessment, a 15,000 pg/mL multi-analyte control could be diluted 1:50 and maintain expected accuracy. We measured the cytokine concentrations in more than 2000 serum samples from patients with sepsis. Multiplex results for IL-6 were compared to a conventional commercially available ELISA kit. The degree of agreement between the two methods as measured by the concordance correlation coefficient was 84.5%. Multiplex results were 2.36-fold higher than ELISA values on the average. After adjusting for this mean difference, the 95% empirical limits of agreement for the ratio of individual sample values were 0.33, 2.65. This multiplex immunoassay provided simultaneous measurement of circulating cytokines using 80% less patient specimen compared to traditional approaches and at a significantly decreased cost. Efficient use of this platform requires process improvements to fully maximize the positive impact of multiplex assays in clinical drug development.

Lipopolysaccharide binding protein in preterm infants

OBJECTIVE

To assess serum concentrations of lipopolysaccharide binding protein (LBP) in preterm infants with neonatal bacterial infection (NBI).

METHODS

Blood samples were analysed of 57 preterm (28(+1) to 36(+6), median 33(+2) weeks gestation) and 17 term infants admitted to the neonatal intensive care unit within the first 72 hours of life with suspicion of NBI. Samples were obtained at first suspicion of sepsis and after 12 and 24 hours. Diagnosis of NBI was confirmed by raised concentrations of C reactive protein and/or interleukin 6. The influence of gestational age and labour was analysed.

RESULTS

Maximum LBP concentrations in infants with NBI were greatly increased compared with infants without NBI (13.0-46.0 microg/ml (median 20.0 microg/ml) v 0.6-17.4 microg/ml (median 4.2 microg/ml)). LBP concentrations in infected infants were not yet significantly raised when NBI was first suspected. The LBP concentrations of preterm infants were comparable to those of term infants. Regression analysis revealed no significant effect of labour or gestational age on LBP.

CONCLUSIONS

Raised LBP concentrations indicate NBI in preterm and term infants. Preterm infants of > 28 weeks gestation seem to be capable of producing LBP as efficiently as term infants. Neonatal LBP concentrations are not influenced by labour. LBP may be a useful diagnostic marker of NBI in preterm infants.

Linking the sepsis triad of inflammation, coagulation, and suppressed fibrinolysis to infants

Sepsis continues to be a significant cause of morbidity and mortality in hospitalized newborns and premature infants. The pathophysiology and disease state of sepsis appear to be similar between adults and children. Both groups display symptoms that indicate a systemic inflammatory response leading to coagulopathy, hypotension, inadequate perfusion of peripheral tissues and organs, and, ultimately, organ failure and death. By presenting a comparison of adult and neonatal pathophysiology, as well as a supporting literature review and clinical evidence, this article links the pathways of inflammation, activation of coagulation, and impaired fibrinolysis, known as the sepsis cascade, to neonatal sepsis. Knowledge of the pathophysiology has important clinical and research implications. Unlike traditional antimicrobial therapy, new potential therapies, currently under investigation for the treatment of sepsis, target the cellular response rather than the invading organism. A more complete understanding of the pathophysiology of sepsis may also lead to diagnostic tools with improved sensitivity and specificity for early recognition and treatment.

Measurement of interleukin 8 in combination with C-reactive protein reduced unnecessary antibiotic therapy in newborn infants: a multicenter, randomized, controlled trial

OBJECTIVE

Neonatal bacterial infections carry a high mortality when diagnosed late. Early diagnosis is difficult because initial clinical signs are nonspecific. Consequently, physicians frequently prescribe antibiotic treatment to newborn infants for fear of missing a life-threatening infection. This study was designed to test the hypotheses that a diagnostic algorithm that includes measurements of interleukin 8 (IL-8) and C-reactive protein (CRP) 1) reduces antibiotic therapy and 2) does not result in more initially missed infections compared with standard management that does not include an IL-8 measurement.

METHODS

Term and preterm infants who were <72 hours of age and had clinical signs or obstetric risk factors suggesting neonatal bacterial infection but stable enough to wait for results of diagnostic tests were enrolled into the study. A total of 1291 infants were randomly assigned to receive antibiotic therapy according to the guidelines of each center (standard group) or to receive antibiotic therapy when IL-8 was >70 pg/mL and/or CRP was >10 mg/L (IL-8 group). The primary outcome variables were 1) the number of infants treated with antibiotics and 2) the number of infants with infections missed at the initial evaluation.

RESULTS

In the IL-8 group, fewer infants received antibiotic therapy than in the standard group (36.1% [237 of 656] vs 49.6% [315 of 635]). In the IL-8 group, 24 (14.5%) of 165 infants with infection were not detected at the initial evaluation, compared with 28 (17.3%) of 162 in the standard group.

CONCLUSIONS

The number of newborn infants who received postnatal antibiotic therapy can be reduced with a diagnostic algorithm that includes measurements of IL-8 and CRP. This diagnostic strategy seemed to be safe.

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.

Neonatal sepsis: epidemiology and management

Neonatal sepsis is uncommon (2-4 per 1000 live births in developed countries), but the rate increases dramatically in premature newborns and those born to mothers with infections or prolonged rupture of the fetal membranes. While infections caused by organisms contracted from the mother at birth have decreased in the past two decades, there has been an increase in nosocomial infections. Today, most infants with sepsis have been hospitalized in neonatal intensive care units for weeks or months because of extreme prematurity, or because of a congenital malformation or surgical condition. Antimicrobial therapy is usually begun prior to the isolation of a pathogen and is based upon knowledge of the likely microbes in the particular clinical situation. The number of antimicrobial agents that can be safely used in neonates is relatively small, and dose administration usually needs to be adjusted based upon birthweight and post-gestational age. The decision whether to treat with antimicrobials should be made with consideration of the history, physical examination, and laboratory data. One should also consider the effects of the use of antimicrobials on the flora of the care unit. Bacterial resistance in the resident flora of the unit has become a major problem where there has been indiscriminate use of broad-spectrum agents.

Whole blood interleukin 8 and plasma interleukin 8 levels in newborn infants with suspected bacterial infection

AIM

To evaluate a new micro-method technique for measurement of interleukin 8 in detergent-lysed whole blood (whole blood IL-8) applicable to capillary blood sampling as a test for bacterial infections in neonates.

METHODS

Whole blood IL-8 was measured at the first suspicion of infection along with IL-8 determined in plasma (plasma IL-8), C-reactive protein and blood cultures in 154 consecutive newborn infants with clinical signs of bacterial infection. Only 20 microl of whole blood were required for the new assay.

RESULTS

Blood culture-proven infections were diagnosed in six infants and clinical infection (defined as a combination of clinical and laboratory signs) in 20 infants. 1000 pg/ml was determined as the suitable threshold for whole blood IL-8 by ROC-curve analysis. At that threshold, whole blood IL-8 detected blood culture-proven infections with a sensitivity of 83% and a specificity of 67%. The areas under the ROC curves were similar for whole blood IL-8 and plasma IL-8.

CONCLUSIONS

Compared with plasma IL-8, whole blood IL-8 offers the advantages that measurements of whole blood IL-8 require a smaller blood sample volume and are not altered by haemolysis. The diagnostic accuracy of whole blood IL-8 remains to be studied in more detail in the future.

Diagnostic markers of infection in neonates

Diagnostic markers of infection are useful indicators of neonatal sepsis. Serial measurements of infection markers can improve diagnostic sensitivity, and the use of multiple markers can enhance diagnostic accuracy. Current evidence suggests that promising markers may be useful for early termination of antimicrobial treatment, but none of the current diagnostic tests are sensitive and specific enough to influence the clinical decision for withholding antibiotic treatment at the onset of suspected infection.

Expression of CD64 as a potential marker of neonatal sepsis

The aim of this study was to identify a novel immunological indicator useful for the early diagnosis (through a rapid and single determination) of neonatal sepsis (NS). Peripheral blood samples were taken from 63 neonates, who were classified into four groups: proven NS (n = 17); clinical NS (n = 14); disease without infection (n = 17); and healthy newborns (n = 15). Neutrophil expression of CD64, CD43, CD44, CD50, CD62L and Mac-1, and plasma levels of interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha (TNF-alpha) and soluble L-selectin (sCD62L), were determined. Expression of CD64 was significantly enhanced in the group with proven sepsis and clinical NS compared to newborns without infection (p < 0.05). Eight newborns with proven or clinical sepsis, but only one with disease without infection, showed an increased percentage of CD64+ cells (diagnostic specificity = 96.8%). No significant differences were found in the expression of the other leucocyte differentiation antigens studied. As previously described, TNF-alpha and IL-6 levels were significantly elevated in newborns with proven or clinical sepsis compared to neonates without infection (p < 0.05). Our results suggest that, through a single determination, the enhanced expression of CD64 is a highly specific indicator of NS, although its diagnostic sensitivity is low (25.8%). In contrast, we found that plasma levels of IL-1beta and sCD62L, as well as the expression of Mac-1, CD43, CD44, CD50, and CD62L, do not appear to be useful for the diagnosis of NS.

NEWER CONCEPTS AND MANAGEMENT OF NEONATAL SEPSIS

Despite extensive research into its patho-physiology, investigations and treatment, sepsis remains an important cause of neonatal morbidity and mortality. The incidence in developing countries is 10 times that in the developed world. A large number of pro-and anti-inflammatory cytokines (interleukins, eicosanoids, tumour necrosis factor-alpha, nitric oxide) have been identified, the interplay of which leads to the Systemic Inflammatory Response Syndrome (SIRS) which can have devastating consequences on all systems of the body. In India the common organisms include Staphylococcus, E coli, Klebsiella and Candida. A number of maternal and neonatal risk factors have been identified. The initial signs and symptoms are subtle and can easily be missed. Early investigations and screening tests are important and a promising number of new tests are being studied. The gold standard for diagnosis is a positive culture from a body fluid or local source in the presence of SIRS. The threshold for starting antibiotics should be low in high-risk neonates and broad spectrum antibiotics covering the likely organisms should be given intravenously in all suspected cases in a hospital setting. This should be continued for at least 24-48 hours (till negative reports are available) in suspected cases and for 2-3 weeks in proven cases. Prophylaxis is aimed at preventing nosocomial and cross infections. Strict hand-washing, meticulous asepsis protocols, identification of high risk groups and prompt and better screening tests are essential in controlling this problem.

Umbilical vein interleukin-6 levels correlate with the severity of placental inflammation and gestational age

Interleukin-6 (IL6) and suppurating placental inflammation are markers of neonatal sepsis. The purpose of this study was to define a relationship between IL6 and acute chorioamnionitis and funisitis of the placenta, and to compare IL6 levels in term and preterm neonates. Umbilical venous IL6 was measured in 137 term and 110 preterm neonates. Acute chorioamnionitis was graded as none, mild, moderate, severe, and necrotizing. Funisitis was graded as none, 1 vessel, 2 vessels, 3 vessels, or necrotizing. A 2-way analysis of variance with interaction was used to compare the IL6 levels. There was a stepwise progression of IL6 levels with increasing severity of acute chorioamnionitis and funisitis. Term neonates showed an IL6 elevation with mild acute chorioamnionitis and single-vessel vasculitis, which increased progressively until the inflammation became severe. In contrast, IL6 levels in preterm neonates did not increase significantly until severe acute chorioamnionitis or 3-vessel vasculitis was seen. Statistically significant differences in IL6 levels were seen in term versus preterm infants when the acute chorioamnionitis was mild or moderate or when the funisitis involved either 1 or 2 vessels (P < 0.05). The difference may be related to the relative immaturity of the preterm immune system, as has been demonstrated in vivo and in vitro. However, differences in management could be confounding factors. In conclusion, umbilical venous IL6 levels correlate with the severity of acute placental inflammation, with greater IL6 elevations in term infants compared to preterm infants until the inflammation becomes severe.