Aims-To evaluate the commonly used markers-namely IL-6, TNF , IL-1 , C-reactive protein and E-selectin for identification of late onset neonatal sepsis; to define the optimal cutoV value for each marker in preterm neonates; to assess whether these markers could assist in early discontinuation of antibiotics in non-infected cases; and to delineate the profile of these markers during systemic infection and in relation to successful treatment. Methods-Very low birthweight infants in whom clinical sepsis was suspected when they were >72 hours of age were eligible for study. A full sepsis screen was performed in each episode. Cytokines, C-reactive protein, and E-selectin were serially measured on days 0 (at the time of sepsis evaluation), 1, 2, 4 and 7. The optimal cutoV value for each marker was calculated after minimising the number of misclassified episodes over all possible cutoV values for days 0 and 1. The sensitivity, specificity, positive and negative predictive values for each test and combination of tests for predicting systemic infection were also determined. Results-One hundred and one episodes of suspected clinical sepsis were investigated in 68 infants. Forty five episodes were proved to be infections. The optimal cutoV values were IL-6 31 pg/ml, TNF 17 pg/ml, IL-1 1 pg/ml, C reactive protein 12 mg/l and E-selectin 174 ng/ml. IL-6 had the highest sensitivity (89%) and negative predictive value (91%) for detecting late onset infection on day 0. However, between 24 and 48 hours of onset, C-reactive protein was the best single marker, with an overall sensitivity and specificity of 84% and 96%, respectively. The use of serial and multiple markers in the first 48 hours further enhanced the sensitivity and specificity of these tests. Performing IL-6 and C-reactive protein on day 0, together with either TNF on day 1 or C-reactive protein on day 2, showed the best overall sensitivity (98%) and specificity (91%) for the diagnosis of late onset infection. Conclusions-Optimal cutoV values for these markers in detecting late onset systemic infection in very low birthweight infants have been defined. Withholding antibiotic treatment at the onset of infection could be fatal and is not recommended, but the concomitant use of IL-6 and C-reactive protein or TNF should allow antimicrobial treatment to be discontinued at 48 hours without waiting for microbiological results, provided that the infants are in good clinical condition.

This study aims to evaluate the diagnostic utilities of four leukocyte surface antigens-two lymphocyte antigens (CD25 and CD45RO) and two neutrophil antigens (CD11b and CD64)-for identification of late-onset nosocomial bacterial infection in preterm, very low birthweight infants, and to define the optimal cutoff value for each marker so that it may act as a reference with which future studies can be compared. Very low birthweight infants in whom infection was suspected when they were Ͼ72 h of age were eligible for the study. A full sepsis screen was performed in each episode. IL-6, C-reactive protein, and leukocyte surface antigens (CD25, CD45RO, CD11b, and CD64) were measured at 0 (at the time of sepsis evaluation), 24, and 48 h by standard biochemical methods and quantitative flow cytometric analysis. The diagnostic utilities including sensitivity, specificity, and positive and negative predictive values of each marker and combination of markers for predicting late-onset neonatal infection were determined. One hundred twenty-seven episodes of suspected clinical sepsis were investigated in 80 infants. Thirty-seven episodes were proven infection. The calculated optimal cutoff values for CD25, CD45RO, CD11b, and CD64 were 3,100, 2,900, 10,450, and 4,000 phycoerythrinmolecules bound per cell, respectively. An interim analysis of data after 68 episodes suggested that CD25 and CD45RO were poor predictors of neonatal infection with sensitivity or specificity Ͻ75% during a single measurement. Thus, these two markers were excluded from further investigation. In the final analysis, CD64 has the highest sensitivity (95-97%) and negative predictive value (97-99%) at 0 and 24 h after the onset. The addition of IL-6 or C-reactive protein (0 h) to CD64 (24 h) further enhanced the sensitivity and negative predictive value to 100%, and has the specificity and positive predictive value exceeding 88% and 80%, respectively. Neutrophil CD64 expression is a very sensitive marker for diagnosing late-onset nosocomial infection in very low birthweight infants. If further validated, the use of CD64 as an infection marker should allow early discontinuation of antibiotic treatment at 24 h without waiting for the definitive microbiologic culture results. The quantitative flow cytometric analysis applied in this study could be developed into a routine clinical test with high comparability and reproducibility across different laboratories. Vol. 51, No. 3, 2002 Copyright © 2002 Printed in U.S.A. ABSTRACT296

Objective: A prospective study to investigate the pattern of proinflammatory and anti-inflammatory cytokine responses in preterm infants with systemic infection. Methods: Very low birthweight infants in whom infection was suspected when they were > 72 hours of age were eligible. A full sepsis screen was performed in each episode. Key cytokines of both proinflammatory and anti-inflammatory pathways, including interleukin (IL) 2, IL4, IL5, IL6, IL10, interferon (IFN) γ, and tumour necrosis factor (TNF) α, were measured at 0 (at the time of sepsis evaluation), 24, and 48 hours by flow cytometric analysis or immunoassay. Results: Thirty seven of the 127 episodes of suspected clinical sepsis were proven infection or necrotising enterocolitis. Both proinflammatory (IL2, IL6, IFNγ, TNFα) and anti-inflammatory (IL4, IL10) cytokines were significantly increased in infected infants compared with non-infected infants. Significant correlations were observed between IL6 and TNFα or IL10 as well as IL10 and IFNγ in infected infants. In the subgroup analysis, plasma IL6, IL10, and TNFα concentrations, and IL10/TNFα and IL6/IL10 ratios were significantly elevated in patients with disseminated intravascular coagulation compared with infected infants without. The IL10/TNFα ratios had decreased significantly 48 hours after the onset, whereas the IL6/IL10 ratio showed only a non-significant decreasing trend. Further, the IL6/IL10 ratio in the deceased infant was disproportionally increased at presentation and continued to increase despite treatment. Conclusion:The results indicate that the counter-regulatory mechanism between the proinflammatory and anti-inflammatory cytokine pathways is probably operational in preterm infants of early gestation. High plasma IL6, IL10, and TNFα concentrations, and IL10/TNFα and IL6/IL10 ratios signify severe infection, but transiently elevated plasma IL10 concentration or IL10/TNFα ratio does not necessarily indicate a poor prognosis.

This prospective study aimed to evaluate the diagnostic utilities of neutrophil CD64 expression for the identification of early-onset clinical infection and pneumonia in term infants and to define the optimal cutoff value so that it may act as a reference with which future studies can be compared. Term newborns in whom infection was suspected when they were Ͻ72 h of age were recruited into the study. C-reactive protein (CRP) and expression of CD64 on neutrophils were measured at 0 h (at the time of sepsis evaluation) and 24 h. The sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of CRP, CD64, and the combination of these two markers for predicting neonatal sepsis were determined. A total of 338 infants with suspected clinical sepsis were investigated, 115 of whom were found to be clinically infected. CRP and CD64 in infected infants were both significantly elevated at 0 and 24 h compared with noninfected infants (p Ͻ 0.001). The calculated optimal cutoff value for CD64 was 6136 antibody-phycoerythrin molecules bound/cell. CD64 has a very high sensitivity (96%) and NPV (97%) at 24 h. The addition of CRP only marginally enhanced the sensitivity and NPV (97 and 98%, respectively). In conclusion, neutrophil CD64 is a very sensitive diagnostic marker for the identification of early-onset clinical infection and pneumonia in term newborns. The results strongly suggest that measurement of neutrophil CD64 may allow neonatal clinicians to discontinue antibiotic treatment at 24 h in infants who are clinically stable and whose CD64 expressions are below the optimal cutoff level. Early-onset (Ͻ72 h of age) neonatal infection is associated with a high morbidity and mortality (1). Immature immunologic defenses in newborn infants, including low circulating levels of immunoglobulins, decrease in absolute number of T lymphocytes and neutrophils, and functionally impaired cytotoxic activity in leukocytes (2-4), are important risk factors that predispose these infants to life-threatening sepsis. Early clinical signs and symptoms of neonatal infection and pneumonia are often inconspicuous and can easily be confused with other noninfective causes, such as transient tachypnea of the newborns, meconium aspiration syndrome, congenital heart diseases, and hypoxic-ischemic encephalopathy (5). Thus, there is always a possibility that the attending neonatologists may overlook or miss subtle cases of early infection. In view of the potentially serious outcome associated with delayed treatment and the difficulty in distinguishing infected from noninfected cases, it has become common practice to prescribe broad-spectrum antibiotics for suspected infection that presents with nonspecific clinical features and maternal risk factors (5-7). Furthermore, as negative microbiologic culture results do not always suggest the absence of bacterial sepsis, continuation of antimicrobial therapy for presumptive infection frequently leads to unnecessary and prolonged treatment and increases in duration of hospitalizatio...

Preterm infants are highly susceptible to life-threatening infections that are clinically difficult to detect, such as late-onset septicemia and necrotizing enterocolitis (NEC). Here, we used a proteomic approach to identify biomarkers for diagnosis of these devastating conditions. In a case-control study comprising 77 sepsis/NEC and 77 nonsepsis cases (10 in each group being monitored longitudinally), plasma samples collected at clinical presentation were assessed in the biomarker discovery and independent validation phases. We validated the discovered biomarkers in a prospective cohort study with 104 consecutively suspected sepsis/NEC episodes. Proapolipoprotein CII (Pro-apoC2) and a des-arginine variant of serum amyloid A (SAA) were identified as the most promising biomarkers. The ApoSAA score computed from plasma apoC2 and SAA concentrations was effective in identifying sepsis/NEC cases in the case-control and cohort studies. Stratification of infants into different risk categories by the ApoSAA score enabled neonatologists to withhold treatment in 45% and enact early stoppage of antibiotics in 16% of nonsepsis infants. The negative predictive value of this antibiotic policy was 100%. The ApoSAA score could potentially allow early and accurate diagnosis of sepsis/NEC. Upon confirmation by further multicenter trials, the score would facilitate rational prescription of antibiotics and target infants who require urgent treatment.

Very low birth weight (VLBW) infants with suspected late-onset infection requiring sepsis screening were enrolled in a prospective study to evaluate the diagnostic utilities of a comprehensive panel of key chemokines and cytokines, both individually and in combination, to identify diagnostic markers for early recognition of bacterial sepsis and necrotizing enterocolitis (NEC). Plasma chemokines interleukin (IL)-8, interferon-␥-inducible protein 10 (IP-10), monokine induced by interferon-␥ (MIG), monocyte chemoattractant protein 1 (MCP-1), growth-related oncogene-␣ (GRO-␣), and regulated upon activation of normal T cell expressed and secreted (RAN-TES) and cytokines IL-1␤, IL-6, IL-10, IL-12p70, and tumor necrosis factor ␣ (TNF-␣) were measured at the onset of sepsis (0 h) and 24 h later. Of 155 suspected infection episodes, 44 were classified as infected. Concentrations of all studied inflammatory mediators (except IL-1␤ and RANTES) were significantly higher in the infected than in the noninfected group at 0 h, but the levels decreased precipitously by 24 h. IP-10 with a plasma cutoff concentration Ն1250 pg/mL could identify all septicemic and NEC cases and had the highest overall sensitivity (93%) and specificity (89%) at 0 h. We conclude that preterm infants have the ability to induce a robust chemokine and cytokine response during sepsis, and IP-10 is a sensitive early marker of infection. and NEC are important risk factors that predispose to increased morbidity and mortality in preterm VLBW infants (1-4). A recent multicenter survey suggested that 21% of VLBW infants who survived Ͼ72 h of age had at least one episode of septicemia (1). Preterm infants who developed NEC had threefold increased risk of mortality (4). As the immunologic defense of preterm infants is considered to be immature and/or deficient (5), this category of patients is particularly vulnerable to developing severe and opportunistic infections in the immediate postnatal period (1,3,4). However, early warning signs and symptoms of systemic infection and NEC are often nonspecific and inconspicuous and can easily be confused with noninfective causes such as apnea of prematurity, gastrointestinal dysmotility, and acute exacerbation of bronchopulmonary dysplasia (6 -8). Thus, early identification of infants with bacterial sepsis and NEC has been recognized to be a major diagnostic challenge (7,8).Exposure to microorganisms and their derived products triggers a rapid and coordinated sequence of host reactions resulting in recruitment of leukocytes into areas of inflammation or sites of microbial invasion (9 -12). The regulation and trafficking of leukocytes into specific body tissues are principally controlled by chemoattractant cytokines or chemokines (10). The activation of leukocytes coupled with interaction of pro-and anti-inflammatory cytokines can influence the orchestration of the anti-infectious process and the magnitude of tissue damage and ultimately can determine the outcome of infection (13-16). Up-regulation (or down-regula...

Background:The progression to disseminated intravascular coagulation (DIC) in infected very low birth weight (VLBW; <1500 g) infants is difficult to predict with precision at the onset of sepsis. We investigated the immunologic profiles of preterm infants with sepsis, using chemokine and cytokine measurements to predict the development of sepsis-induced DIC at the onset of infection.

The LIT score can effectively differentiate surgical NEC from nonsurgical NEC infants and nonsurvivors of NEC from survivors at the onset of clinical presentation. Frontline neonatologists and surgeons may, therefore, target NEC infants who are most in need of close monitoring and those who may benefit from early surgical intervention.