Diagnostic markers of infection in neonates

Influence of Gestational Age, Cesarean Section and Hematocrit on lnterleukin-8 Concentrations in Plasma and Detergent-Lysed Whole Blood of Noninfected Newborns

SUMMARY: BACKGROUND: Sensitivity of interleukin-8 (IL-8) in detecting early-onset bacterial infection (EOBI) is high. A high percentage is bound to nonspecific receptors on erythrocytes which can be determined via cell lysis. We have shown detergent-lysed whole blood (DLWB) IL-8 to be superior to plasma IL-8 in detecting EOBI. METHODS: To evaluate influence of pre- and perinatal factors on plasma and DLWB IL-8 concentrations, IL-8 was determined via ELISA (Immu-lite) in 146 noninfected newborns with risk factors for EOBI at two different time periods: 0-6 (group I) and 24-30 h (group II) after birth. The influence of gender, mode of delivery, gestational age and hematocrit was evaluated. RESULTS: While we found no influence of gender or gestational age, hematocrit was positively correlated with IL-8 plasma concentration (group I: r = 0.33, p < 0.001; group II: r = 0.30, p <0.01). IL-8 plasma concentrations after primary versus secondary cesarean section were lower (p < 0.05). Gestational age was correlated with DLWB IL-8 concentrations (group I: r = 0.46, p < 0.001; group II: r = 0.28, p < 0.001). CONCLUSION: Plasma IL-8 concentrations were positively correlated with hematocrit, whereas DLWB IL-8 concentrations increased with gestational age. This may be relevant to the interpretation of IL-8 in preterm infants and infants with anemia, polyglobulia or hematolytic diseases.

Does prenatal antibiotic therapy compromise the diagnosis of early-onset infection and management of the neonate?

AIM

To assess the impact of prenatal antibiotic treatment on procalcitonin (PCT) and C-reactive protein (CRP) concentrations in cord blood, and on the rate of positive neonatal blood cultures.

METHODS

Neonates with early-onset infection (Group A; n=46) were compared with healthy controls (Group B; n=240). We evaluated the relationship between prenatal antibiotic therapy and early-onset infection, and for interactions with antibiotic therapy in the neonate immediately after birth.

RESULTS

In the Group A antibiotics were administered significantly more often prenatally and more often to neonates just after birth. The percentage of negative blood cultures in infected neonates was higher when antibiotic treatment was instituted prenatally. Differences in cord blood PCT and CRP concentrations were significant between both groups and were independent of prenatal antibiotic treatment. Streptococcus agalactiae was the most frequent species.

CONCLUSIONS

Almost one-third of neonates present with early-onset infection in spite of prenatal antibiotic therapy. Cord blood PCT and CRP measurements may be helpful in the diagnosis of infection also in cases when antibiotic therapy was started prenatally. Prenatal antibiotic administration reduced the number of positive blood cultures in neonates with early-onset infection and was associated with a greater rate of antibiotic treatment after birth in neonates without infection.

Plasma IP-10 as a predictor of serious bacterial infection in infants less than 4 months of age

BACKGROUND

Early diagnosis of serious bacterial infection (SBI) in young infants is a difficult problem by clinical symptoms and signs. The goal of this study is to evaluate the predictive value of plasma IP-10 levels for early diagnosis of SBI in young infants <4 months of age.

METHODS

We enrolled pediatric patients who were <4 months of age with a clinical suspicion to have SBI admitted in neonatal intensive care unit or complete nursing unit of Pediatric Department of Kaohsiung Medical University Hospital. Blood was drawn for measurement of complete blood counts, C-reactive protein (CRP) and plasma IP-10 levels and microbiological cultures were obtained at the time of admission.

RESULTS

There were 60 patients enrolled in this study. The SBI group (n = 21) have higher plasma IP-10 levels than those infants without SBI (n = 39) [median 104.8 (range 0-1457.1) versus 0 (range 0-129.3) pg ml(-1), P = 0.0161 after adjusting age]. A plasma IP-10 level >48.2 pg ml(-1) had the best diagnostic accuracy for indicating SBI {sensitivity 81.0% [95% confidence interval (CI) 71.1-90.1%]; specificity 94.9% [95% CI 65.4-87.0%]; positive likelihood ratio 15.9, negative likelihood ratio 0.2}.

CONCLUSION

In infants who were <4 months of age with suspicion of SBI, IP-10 assay might be a good predictor. Key words: chemokine, IP-10, serious bacterial infection, young infant, C-reactive protein.

Tracking changes of lymphocyte subsets and pre-inflammatory mediators in full-term neonates with suspected or documented infection

Investigation was made of changes in immune system parameters during the course of neonatal infection. The study population consisted of 95 full-term neonates matched for chronological age and sex, divided into three groups: suspected infection (n=20), sepsis (n=25), infection-free control subjects (n=50). Serial measurements were made of the cytokines interleukin-6 (IL-6), interleukin-1b (IL-1b) and tumour necrosis factor-α (TNF-α), lymphocyte subsets [CD3+, CD4+, CD8+, natural killer (NK) cells and B cells], the immunoglobulins (Ig) (IgG, IgM and IgA), C-reactive protein (CRP), and the total blood count, before, 2 days after initiation of treatment and after stopping treatment (time periods first, second and third, respectively). IL6, TNF-α, IL1-b and CRP were higher at the first time period in the sepsis group, and IL6 and TNF-α continued to be higher in this group at the second period. IL-6 and TNF-α were precise sepsis predictors with sensitivity and specificity of 0.92, 0.98 and 0.91, 0.92, respectively. NK cells, B cells, CD3+, CD4+, CD8+ were higher in the sepsis and suspected infection groups, but the ratios CD3+/CD4+, CD3+/CD8+, CD4+/CD8+ showed no difference from the controls. IgG was lower and IgM higher in the sepsis group. In the control subjects CD3+, CD4+, CD8+ lymphocytes increased with increasing age. It is concluded that IL-6 and TNF are good diagnostic markers of sepsis in full-term neonates. Lymphocyte subsets were affected by both the clinical condition and the chronological age. NK and B cells may be elevated in suspected and documented sepsis, and further studies are needed to determine their clinical significance.

Predictive values of neutrophil CD64 expression compared with interleukin-6 and C-reactive protein in early diagnosis of neonatal sepsis

BACKGROUND

Despite major advances in the management of newborn infants, neonatal sepsis (NS) remain important causes of neonatal morbidity and mortality in the newborn, mainly among preterm and low birth weight infants.

OBJECTIVE

The aim of this study was to investigate the usefulness of neutrophil CD64 expression alone and together with other infection markers in NS.

METHODS

Peripheral blood samples were taken from 109 neonates, who were categorized into three groups: proven or clinical sepsis (n=35); disease without infection (n=42); and healthy controls (n=32). Complete blood count with differential, interleukin-6 (IL-6), C-reactive protein (CRP), and cell surface expression of CD64 on neutrophils have been evaluated in a prospective manner as a diagnostic aid for NS.

RESULTS

Expression of CD64 was significantly enhanced in neonates with sepsis compared with newborns with disease without infection and healthy controls (P=0.001 and P=0.001, respectively). Cutoff values of IL-6, CRP, CD64(MFI), and CD64(i) were 24.9  pg/ml, 4.05  mg/l, 87.7, and 4.39, respectively. Sensitivity-negative predictive values of IL-6, CRP, and CD64(MFI)/CD64(i) were 80.0-90.6%, 80.0-88.8%, and 88.6-94.0%, respectively. Combining all three tests increased the sensitivity to 100%; however, specificity and positive predictive value decreased to 62.1 and 55.5%, respectively.

CONCLUSIONS

CD64 might be used either alone or combined with IL-6 and CRP for early diagnosis of NS. The advantages of CD64 when compared with IL-6 and CRP are rapid quantitation, very small blood volume required, and easy handling.

A clinic-biological score for diagnosing early-onset neonatal infection in critically ill preterm infants

OBJECTIVE

To identify the best combination of serum cytokines and clinical parameters to diagnose rapidly early-onset neonatal infection (EONI) in critically ill preterm infants. At birth, most critically ill neonates are receiving broad-spectrum antibiotics pending bacterial culture results, because distinguishing infected from noninfected infants at birth is difficult.

DESIGN

Prospective study.

SETTING

Neonatal intensive care unit in a tertiary care hospital.

PATIENTS

Two hundred thirteen infants, born before 33 wks' gestation, admitted to the neonatal intensive care unit within 6 hrs of life with a presumptive diagnosis of EONI.

INTERVENTION

A presumptive diagnosis of EONI was associated with a 300-μL blood sample to measure six cytokine (interleukin [IL]-1β, IL-6, IL-8, IL-10, IL-12, tumor necrosis factor-α) concentrations, using the cytometric bead array technique.

MEASUREMENTS AND MAIN RESULTS

Of the 213 infants included, 31 had a definite or possible EONI and 182 were not infected. Concentrations of IL-6, IL-8, and IL-10 were significantly increased in infected neonates, in comparison with infants without EONI. In contrast, IL-1β, IL-12, and tumor necrosis factor-α concentrations were not. Logistic regression analyses were performed to construct multivariate predictive models that could distinguish infected from noninfected infants at birth. A clinical score was based on three parameters independently associated with EONI (i.e., interval of >12 hrs between the membranes rupture and delivery, prenatal maternal colonization and mechanical ventilation at birth). This score was compared with scores including clinical parameters and serum cytokines, alone or in combination. The best predictive model combined the three clinical parameters, IL-6 (positive threshold, 300 pg/mL) and IL-8 (positive threshold, 300 pg/mL) concentrations.

CONCLUSION

A predictive model combining serum IL-6 and IL-8 measurements and selected clinical variables could distinguish infected from noninfected preterm infants at birth and should help the clinician in reducing or shortening the unnecessary use of antibiotics.

Biomarkers for late-onset neonatal sepsis: cytokines and beyond

Acute phase reactants, pro and antiinflammatory mediators including chemokines and cytokines, and cell-surface antigens are nonspecific biomarkers that have been extensively studied for the diagnosis and management of late-onset neonatal sepsis (LONS) and necrotizing enterocolitis. It is expected that the next generation of biomarkers and tests will be more specific, will pinpoint the precise disease entity, and will provide crucial information on the exact pathogen or category of microorganism and its antibiotic profile within hours of clinical presentation. Research on molecular pathogen detection and proteomic profiling has shown promising results. Academic-industry partnerships are vital for successful development of new diagnostic biomarkers for LONS, which are sensitive, inexpensive, fully automated, and easy to measure, allowing a quick turnaround time for clinical decision making.

Host-response biomarkers for diagnosis of late-onset septicemia and necrotizing enterocolitis in preterm infants

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.

Pathophysiology and treatment of septic shock in neonates

Neonatal septic shock is a devastating condition associated with high morbidity and mortality. Definitions for the sepsis continuum and treatment algorithms specific for premature neonates are needed to improve studies of septic shock and assess benefit from clinical interventions. Unique features of the immature immune system and pathophysiologic responses to sepsis, particularly those of extremely preterm infants, necessitate that clinical trials consider them as a separate group. Keen clinical suspicion and knowledge of risk factors will help to identify those neonates at greatest risk for development of septic shock. Genomic and proteomic approaches, particularly those that use very small sample volumes, will increase our understanding of the pathophysiology and direct the development of novel agents for prevention and treatment of severe sepsis and shock in the neonate. Although at present antimicrobial therapy and supportive care remain the foundation of treatment, in the future immunomodulatory agents are likely to improve outcomes for this vulnerable population.

Role of innate host defenses in susceptibility to early-onset neonatal sepsis

Neonatal sepsis continues to take a devastating toll globally. Although adequate to protect against invasive infection in most newborns, the distinct function of neonatal innate host defense coupled with impairments in adaptive immune responses increases the likelihood of acquiring infection early in life, with subsequent rapid dissemination and death. Unique differences exist between neonates and older populations with respect to the capacity, quantity, and quality of innate host responses to pathogens. Recent characterization of the age-dependent maturation of neonatal innate immune function has identified novel translational approaches that may lead to improved diagnostic, prophylactic, and therapeutic modalities.

Evaluation of neutrophilic CD64, interleukin 10 and procalcitonin as diagnostic markers of early- and late-onset neonatal sepsis

The assay of infection markers can improve diagnostic sensitivity in neonatal sepsis. We determined the levels of neutrophilic CD64 (nCD64), procalcitonin (PCT) and interleukin 10 (IL-10) in infants with neonatal sepsis. Forty-nine newborn infants who met the criteria of sepsis were subjected to a routine sepsis evaluation as well as measurement of PCT and IL-10 levels and nCD64 expression. Of these 49 'infected' infants, 16 had a positive blood culture (culture-positive sepsis) and 33 infants were diagnosed to have clinical sepsis with negative blood cultures (culture-negative sepsis). Another 49 healthy newborn infants were included as a control group. The sensitivity, specificity, positive predictive value and negative predictive value of PCT, IL-10 and nCD64 for the diagnosis of sepsis were determined. IL-10 had the highest sensitivity of 92% and specificity of 84% using a cut-off of > or =17.3 pg/ml. For PCT, the highest sensitivity of 65% and specificity of 60% were found at a cut-off value of > or =36.4 pg/ml. nCD64 had a maximal sensitivity of 92% and specificity of 71% at a cut-off value of 2.6%. Combinations of different markers may improve the sensitivity and specificity of biomarker tests. We found that the best combination was IL-10 and nCD64, which together provided sensitivity of 95% and specificity of 83%, and a negative predictive value of 86%.

The host response to sepsis and developmental impact

Invasion of the human by a pathogen necessitates an immune response to control and eradicate the microorganism. When this response is inadequately regulated, systemic manifestations can result in physiologic changes described as "sepsis." Recognition, diagnosis, and management of sepsis remain among the greatest challenges shared by the fields of neonatology and pediatric critical care medicine. Sepsis remains among the leading causes of death in both developed and underdeveloped countries and has an incidence that is predicted to increase each year. Despite these sobering statistics, promising therapies derived from preclinical models have universally failed to obviate the substantial mortality and morbidity associated with sepsis. Thus, there remains a need for well-designed epidemiologic and mechanistic studies of neonatal and pediatric sepsis to improve our understanding of the causes (both early and late) of deaths attributed to the syndrome. In reviewing the definitions and epidemiology, developmental influences, and regulation of the host response to sepsis, it is anticipated that an improved understanding of this host response will assist clinician-investigators in identifying improved therapeutic strategies.

A prospective study of the sensitivity, specificity and diagnostic performance of soluble intercellular adhesion molecule 1, highly sensitive C-reactive protein, soluble E-selectin and serum amyloid A in the diagnosis of neonatal infection

BACKGROUND

Diagnosis of neonatal infection is difficult, because of it's non-specific clinical presentation and the lack of reliable diagnostic tests. The purpose of this study was to examine the potential diagnostic value of serum soluble intercellular adhesion molecule-1 (sICAM-1), soluble E-selectin (sE-selectin), highly sensitive C-reactive protein (hsCRP) and serum amyloid A (SAA) measurements, both individually and in combination in the setting of a neonatal intensive care unit.

METHODS

219 consecutive serum samples were taken from 149 infants undergoing sepsis work up in a neonatal intensive care unit. Clinical diagnosis was established in a prospective manner, blind to the results of the study measurements. Infants were classified by an experienced paediatrician as infected or not-infected, one week after presentation. Classification was based on clinical presentation, routine laboratory and radiological investigations and response to therapy. The infected group were sub-classified as (a) culture positive infection or (b) culture negative infection. sICAM-1, sE-selectin, hsCRP and SAA levels were determined from stored serum samples after diagnosis was established. Further sub-group analysis of results was undertaken according to early or late onset of infection and preterm or term status. Statistical analysis utilised Mann Whitney U test and ROC curve analysis.

RESULTS

There were significantly increased serum levels of sICAM-1, hsCRP, E selectin (p < 0.001) and SAA (p = 0.004) in infected infants compared with non-infected. ROC curve analysis indicated area under the curve values of 0.79 (sICAM-1), 0.73 (hsCRP), 0.72 (sE-selectin) and 0.61 (SAA). ROC curve analysis also defined optimum diagnostic cut-off levels for each measurement. The performance characteristics of sICAM-1, hsCRP and sE-selectin included a high negative predictive value (NPV) for culture positive infection and this was enhanced by combination of all 4 measurements. Clinical subgroup analysis suggested particularly high NPV for early onset symptoms, however further studies are required to elucidate this finding.

CONCLUSIONS

All four study measurements demonstrated some diagnostic value for neonatal infection however sICAM-1, hsCRP and sE-selectin demonstrated the highest NPV individually. The optimum diagnostic cut off level for hsCRP measurement in this study was much lower than currently used in routine clinical practice. Use of a combination of measurements enhanced diagnostic performance, demonstrating sensitivity of 90.3% and NPV of 91.3%. This study suggests there may be value in use of several of these markers, individually and in combination to assist in excluding neonatal infection. Further work is needed to confirm a specific role in the exclusion of early onset infection.

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.

Neutrophil CD64 (FcγRI) expression is a specific marker of bacterial infection: A study on the kinetics and the impact of major surgery

Neutrophil CD64 expression is a diagnostic marker for the early detection of bacterial infections. The aim was to investigate the kinetics of neutrophil CD64 expression during bacterial infection and the possible impact of surgical trauma. Blood samples were collected daily during 3 d after admission for analysis by flow cytometry of the surface expressions on neutrophils and monocytes of CD64, CD16, CD32, CD11b/CD18 and CD35, and analysis of serum CRP and blood WBC. Serum concentrations of IFNgamma, G-CSF, IL-6 and IL-8 were also analysed in adults. Eight children and 19 adult patients with bacterial infections, 12 patients admitted for hip-arthroplasty because of coxarthrosis and 30 healthy adults were studied. Neutrophil CD64 was increased all 3 d after start of treatment (p<0.0001) in children and adults with bacterial infections. The postoperative increase after surgery was less than the increase seen during bacterial infections (p<0.0001). CRP, G-CSF, IL-6 and IL-8 were raised both in bacterial infections and after surgery. Our results indicate that the expression of CD64 on neutrophils is a specific sign of bacterial infections. Neutrophil expression of CD64, therefore, seems to be a promising tool for the early detection of bacterial infections even during surgery.

A systematic review of intentional delivery in women with preterm prelabor rupture of membranes

OBJECTIVE

To evaluate the effect of intentional delivery versus expectant management in women with preterm prelabor rupture of membranes (PPROM).

METHODS

We searched electronic databases and trials registries, contacted experts, and checked reference lists of relevant studies. Studies were included if they were randomized controlled trials comparing intentional delivery versus expectant management after PPROM, the gestational age of participants was between 30 and 36 weeks, and the study reported one of several pre-determined outcomes.

RESULTS

Four studies were included in the meta-analysis. No difference was found between intentional delivery and expectant management in neonatal intensive care unit (NICU) length of stay (LOS) (weighted mean difference (WMD) -0.81 day, 95% confidence interval (CI) -1.66, 0.04), respiratory distress syndrome (risk difference (RD) -0.01, 95% CI -0.07, 0.06), and confirmed neonatal sepsis (RD -0.01, 95% CI -0.05, 0.04). One study found a significantly lower incidence of suspected neonatal sepsis among the intentional delivery group (RD -0.31, 95% CI -0.50, -0.12; number needed to treat (NNT) 3, 95% CI 2, 8). Maternal LOS was significantly shorter for the intentional delivery group (WMD -1.39 day, 95% CI -2.03, -0.75). There was a significant difference in the incidence of clinical chorioamnionitis favoring intentional delivery (RD -0.16, 95% CI -0.23, -0.10; NNT 6, 95% CI 5, 11). There was no significant difference in the incidence of other maternal outcomes, including cesarean section (RD 0.05, 95% CI -0.01, 0.11).

CONCLUSIONS

Intentional delivery may be favorable to expectant management for some maternal outcomes (chorioamnionitis and LOS). There is insufficient evidence to suggest that either strategy is beneficial or harmful for the baby. Large multicenter trials with primary neonatal outcomes are required to assess whether intentional delivery is associated with less neonatal morbidity.

Plasma IP-10 as a predictor of serious bacterial infection in infants less than 4 months of age

BACKGROUND

Early diagnosis of serious bacterial infection (SBI) in young infants is a difficult problem by clinical symptoms and signs. The goal of this study is to evaluate the predictive value of plasma IP-10 levels for early diagnosis of SBI in young infants <4 months of age.

METHODS

We enrolled pediatric patients who were <4 months of age with a clinical suspicion to have SBI admitted in neonatal intensive care unit or complete nursing unit of Pediatric Department of Kaohsiung Medical University Hospital. Blood was drawn for measurement of complete blood counts, C-reactive protein (CRP) and plasma IP-10 levels and microbiological cultures were obtained at the time of admission.

RESULTS

There were 60 patients enrolled in this study. The SBI group (n = 21) have higher plasma IP-10 levels than those infants without SBI (n = 39) [median 104.8 (range 0-1457.1) versus 0 (range 0-129.3) ng ml(-1), P = 0.0161 after adjusting age]. A plasma IP-10 level >48.2 ng ml(-1) had the best diagnostic accuracy for indicating SBI [sensitivity 81.0% [95% confidence interval (CI) 71.1-90.1%]; specificity 94.9% [95% CI 65.4-87.0%]; positive likelihood ratio 15.9, negative likelihood ratio 0.2}.

CONCLUSION

In infants who were <4 months of age with suspicion of SBI, IP-10 assay might be a good predictor.

Comparison of serum amyloid A concentrations with those of C-reactive protein and procalcitonin in diagnosis and follow-up of neonatal sepsis in premature infants

OBJECTIVE

The purpose of this study was to determine the role of serum amyloid A (SAA) in diagnosis of neonatal sepsis and evaluation of clinical response to antibiotic therapy. We also aimed to compare the efficiency of SAA with that of C-reactive protein (CRP) and procalcitonin (PCT) in diagnosis and follow-up of neonatal sepsis in preterm infants.

STUDY DESIGN

A total of 163 infants were enrolled in this prospective study. The infants were classified into four groups: group 1 (high probable sepsis), group 2 (probable sepsis), group 3 (possible sepsis) and group 4 (no sepsis, control group). Blood samples for whole blood count, CRP, PCT, SAA and culture were obtained before initiating antibiotic treatment. This procedure was repeated three times at 48 h, 7 and 10 days.

RESULT

Initial CRP, PCT and SAA levels were found to be positive in 73.2, 75.6 and 77.2% of all infants, respectively. Sensitivities of CRP, PCT and SAA at 0 h were 72.3, 74.8 and 76.4%, respectively. Although it was not statistically significant, SAA was found to be more sensitive than CRP and PCT in diagnosis of neonatal sepsis. The area under the curve (AUC) for CRP, PCT and SAA at 0 h were 0.870, 0.870 and 0.875, respectively. Although the AUC for SAA at 0 h was higher than PCT and CRP, the difference was not statistically significant.

CONCLUSION

SAA is an accurate and reliable marker for diagnosis and follow-up of neonatal sepsis. It is especially useful at the onset of inflammation for rapid diagnosis of neonatal sepsis and can be safely and accurately used in combination with other sepsis markers such as CRP and PCT in diagnosis and follow-up of neonatal sepsis in preterm infants.

Management of neonatal sepsis by Gram-negative pathogens

For the pediatrician and neonatologist who care for term and preterm infants, the challenge remains to keep these infants free of infection after delivery in special-care nurseries and neonatal intensive care units. Studies of complications associated with term infants at risk due to maternal factors, as well as preterm infants after early delivery, have demonstrated that sepsis is a major cause of neonatal mortality and morbidity. Infections due to Gram-negative organisms are increasingly being reported from neonatal units. Moreover, Gram-negative organisms that are multidrug resistant are on the increase and pose a formidable clinical challenge. In this article, we review current epidemiology, risk factors, clinical features, diagnosis, therapy and preventive measures related to Gram-negative infections in neonates.

Identification of diagnostic biomarkers for infection in premature neonates

Infection is a leading cause of neonatal morbidity and mortality worldwide. Premature neonates are particularly susceptible to infection because of physiologic immaturity, comorbidity, and extraneous medical interventions. Additionally premature infants are at higher risk of progression to sepsis or severe sepsis, adverse outcomes, and antimicrobial toxicity. Currently initial diagnosis is based upon clinical suspicion accompanied by nonspecific clinical signs and is confirmed upon positive microbiologic culture results several days after institution of empiric therapy. There exists a significant need for rapid, objective, in vitro tests for diagnosis of infection in neonates who are experiencing clinical instability. We used immunoassays multiplexed on microarrays to identify differentially expressed serum proteins in clinically infected and non-infected neonates. Immunoassay arrays were effective for measurement of more than 100 cytokines in small volumes of serum available from neonates. Our analyses revealed significant alterations in levels of eight serum proteins in infected neonates that are associated with inflammation, coagulation, and fibrinolysis. Specifically P- and E-selectins, interleukin 2 soluble receptor alpha, interleukin 18, neutrophil elastase, urokinase plasminogen activator and its cognate receptor, and C-reactive protein were observed at statistically significant increased levels. Multivariate classifiers based on combinations of serum analytes exhibited better diagnostic specificity and sensitivity than single analytes. Multiplexed immunoassays of serum cytokines may have clinical utility as an adjunct for rapid diagnosis of infection and differentiation of etiologic agent in neonates with clinical decompensation.

C-Reactive Protein, Detected with a Highly Sensitive Assay, in Non-Infected Newborns and Those with Early Onset Infection

SUMMARY: BACKGOUND: The aim of this study was to investigate C-reactive protein (CRP), measured by a highly sensitive method (hsCRP) in non-infected newborns and in those with suspected early onset bacterial infection (EOBI) as well as to test whether EOBI would be detectable earlier by hsCRP than by a nephelometric CRP (nsCRP) assay (thresholds > 10 mg/l) or IL-8. PATIENTS AND METHODS: 106 neonates with signs of infection comprised the suspected EOBI group. 134 neonates with risk factors but confirmed exclusion of EOBI served as non-infected controls. RESULTS: In the non-infected group, hsCRP in the first 6 h after birth was low (0.7 mg/l; SD 0.16 mg/l) but showed an increase to 4.11 mg/l (SD 3.33 mg/l) at 72 h (p < 0.001 vs. 6 h). The sensitivity of hsCRP (cut-off 0.3 mg/l) vs. nsCRP for EOBI was 0.46 vs. 0.23 at 6 h after clinical suspicion. Of all parameters measured, IL-8 had the highest sensitivity and specificity to detect EOBI at 6 h (0.60 and 0.90), but declined after 12 and 24 h. CONCLUSION: Lowering the CRP detection threshold by a highly sensitive assay did not improve diagnostic accuracy for EOBI.

Elevation of high-mobility group box 1 concentration in asphyxiated neonates

BACKGROUND

In asphyxiated neonates, abnormal proinflammatory cytokine/chemokine production may be induced. High-mobility group box 1 (HMGB-1) protein is a new type of proinflammatory cytokine that induces abnormal inflammatory responses involving proinflammatory cytokine production. However, the physiological significance of HMGB-1 in asphyxia is poorly understood.

OBJECTIVES

We aimed to evaluate whether serum HMGB-1 levels were changed in asphyxia by measuring the serum concentration of HMGB-1 in both asphyxiated and normally delivered neonates at birth.

METHODS

Using enzyme-linked immunosorbent assay, we measured the concentration of HMGB-1 in sera obtained from 53 asphyxiated neonates and 32 normally delivered neonates immediately after birth.

RESULTS

The serum concentrations of HMGB-1 in asphyxiated neonates were significantly higher than those in normally delivered neonates without asphyxia (p = 0.033).

CONCLUSION

We suggest that the elevation of HMGB-1 might be associated with abnormal inflammatory responses involving the excessive production of proinflammatory cytokines in neonates with asphyxia.

Cytokine expression in response to bacterial antigens in preterm and term infant cord blood monocytes

BACKGROUND

Neonatal susceptibility to bacterial infection is associated with an immature immune system, but the role of different bacterial antigens in specific responses is largely unknown.

OBJECTIVE

To evaluate differences in intracellular cytokine response to physiologically relevant bacterial antigens in term and preterm infants as compared with adults.

METHODS

Cord blood samples from preterm and term neonates and adult peripheral blood samples were cultured ex vivo with and without whole heat-killed bacteria. Intracellular leukocyte production of interleukin (IL)-6, IL-10, IL-12, and IL-8 responses was assessed by flow cytometry.

RESULTS

Monocytes were the primary producers of all mediators. Escherichia coli was the most potent stimulant. Lactobacillus plantarum 299v activated fewer monocytes as compared with E. coli for all responses (p < 0.05), except for IL-12 in term neonates. IL-6 response to Staphylococcus epidermidis was lower in both groups of neonates as compared with adults (p = 0.023 and p = 0.001). IL-8 response to S. epidermidis was lower in term as compared with preterm neonates and adults (p = 0.003). IL-10 response to group B streptococci was lower in term neonates as compared with adults and higher in preterm as compared with term neonates (p = 0.015).

CONCLUSIONS

Monocytes from term neonates compared to preterm neonates show a downregulated anti-inflammatory response to specific bacteria. High neonatal response to pathogenic E. coli in the preterm infant could cause uncontrolled inflammatory response, while lower IL-6 response to S. epidermidis in neonates may indicate a basis for vulnerability to S. epidermidis infection.

Biomarkers in neonatal infection

Infected newborn infants are often difficult to differentiate from patients suffering from noninfective diseases. Whilst delaying treatment with antibiotics of infected infants may be fatal, widespread indiscriminate use in all cases with suspected bacterial infection could lead to both drug-induced complications and the development of multidrug-resistant organisms. Conventional biomarkers, such as blood cell counts and morphology, have serious limitations. Investigators in this area of research have, therefore, made strenuous efforts to discover more reliable biomarkers with superior diagnostic utilities and clinically relevant characteristics to help neonatal clinicians differentiate between infected and noninfected infants. The major classes of biomarkers in neonatal infection of recent interest will be discussed, including: acute phase reactants, cytokines, chemokines and leukocyte surface antigens. The application of these biomarkers to derive prognostic information useful to neonatal clinicians will also be considered.

IP-10 is an early diagnostic marker for identification of late-onset bacterial infection in preterm infants

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-gamma-inducible protein 10 (IP-10), monokine induced by interferon-gamma (MIG), monocyte chemoattractant protein 1 (MCP-1), growth-related oncogene-alpha (GRO-alpha), and regulated upon activation of normal T cell expressed and secreted (RANTES) and cytokines IL-1beta, IL-6, IL-10, IL-12p70, and tumor necrosis factor alpha (TNF-alpha) 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-1beta 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 > or = 1250 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.

Early Prediction of Sepsis-Induced Disseminated Intravascular Coagulation with Interleukin-10, Interleukin-6, and RANTES in Preterm Infants

Background: The progression to disseminated intravascular coagulation (DIC) in infected very low birth weight (VLBW; &lt;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.

Methods: We measured a panel of chemokines and cytokines at 0 and 24 h after clinical presentation in VLBW infants with suspected infection requiring full sepsis screening. The chemokines measured were interleukin (IL)-8, interferon-γ-inducible protein-10 (IP-10), monokine induced by interferon-γ, monocyte chemoattractant protein-1, and regulated upon activation normal T-cell expressed and secreted (RANTES), and the cytokines were IL-6, IL-10, and tumor necrosis factor-α.

Results: Of 195 episodes of suspected clinical sepsis investigated, 62 were culture-confirmed septicemia or necrotizing enterocolitis (28 of these infants developed DIC), 22 were culture-negative clinical infections, and 111 involved noninfected episodes. All studied inflammatory mediators except RANTES showed significantly greater up-regulation in culture-positive infected infants than in noninfected infants at 0 and 24 h, whereas RANTES showed significant down-regulation. The model that used plasma IL-10 (&gt;208 ng/L), IL-6 (&gt;168 ng/L), and RANTES (&lt;3110 ng/L) at 0 h had sensitivity, specificity, and positive and negative predictive values of 100%, 97%, 85%, and 100%, respectively, for identifying infected patients who subsequently developed DIC.

Conclusions: IL-10, IL-6, and RANTES measured at clinical presentation sensitively and accurately predicted the development of DIC in severely infected infants. This information could be vital for early and effective treatment of neonatal sepsis.

Biochemistry testing associated with pregnancy and the newborn period -- a lot has changed since you were a baby!

Everyone has been a newborn, and everyone's mother has been pregnant. Despite the commonality of these events, medical care and the clinical chemistry laboratory's role in it have changed remarkably over the last 50 years. This review is a historical overview of clinical chemistry testing that is related to pregnancy and the newborn period.

Molecular pathology: future issues

CONTEXT

The field of molecular pathology is expanding in complexity. To achieve competency, vigilance is required.

OBJECTIVE

To review the advances in clinically useful molecular biologic techniques and to identify their applications in clinical practice, as presented at the 13th Annual William Beaumont Hospital DNA Symposium.

DATA SOURCES

The 4 manuscripts submitted were reviewed and their major findings were compared with the literature on the same or related topics.

STUDY SELECTION

Manuscripts address the use of molecular or immunophenotyping by flow cytometry to evaluate the origin or presence of sepsis, respectively; the use of imatinib mesylate to treat chronic myeloid leukemia and the nature of resistance to imatinib; and the use of 9 and 10 fluorochromes during clinical flow cytometric studies.

DATA SYNTHESIS

The epidemiologic evaluation of a septic outbreak may be monitored using molecular techniques that track the relatedness of isolates. A potential biomarker for the presence of early sepsis is CD64. Intracellular signal transduction pathways are altered in malignancy. Imatinib mesylate inhibits the BCR-ABL kinase created by translocation of the long arms of chromosomes 9 and 22 in chronic myeloid leukemia. Resistance to imatinib may be secondary to mutation in the BCR-ABL kinase domain or residual leukemic stem cells that imatinib does not kill. The use of 9 or 10 fluorochromes simultaneously during flow cytometry has many clinical advantages; however, software for data analysis is needed.

CONCLUSION

The current postgenomic era will continue to emphasize the use of microarrays and database software for genomic, transcriptomic, proteomic, nutrigenomic, and pharmacogenomics screening to search for a useful clinical assay. The number of molecular pathologic techniques will expand as additional disease-associated mutations are defined.

Newer approaches to the diagnosis of early onset neonatal sepsis

Accurate and timely diagnosis of early onset neonatal sepsis remains challenging to the clinician and the laboratory. A test with a rapid turnaround time with 100% sensitivity, rather than high specificity, which allows accurate diagnosis and appropriate antimicrobial treatment or which allows antibiotics to be safely withheld in non-infected infants, is desirable. Many potential markers (acute phase reactants, cell surface markers, cytokines) are not routinely available to the laboratory, and most likely combinations of markers will ensure greater diagnostic accuracy. In the future, molecular biology techniques offer the prospect of rapid identification of both pathogens and antimicrobial resistance markers.

Diagnostic markers for neonatal sepsis

PURPOSE OF REVIEW

To review the current evidence on the use of infection markers for diagnostic evaluation of sepsis in neonates.

RECENT FINDINGS

Recent research in immunology has led to the discovery of cell surface antigens, chemokines, cytokines and acute phase proteins that can potentially be used to 'rule in' or 'rule out' sepsis. The diagnostic utilities of key inflammatory mediators, including CD11b, CD64, interleukin-6 and interleukin-8, are promising and likely to become increasingly used as markers of infection for both diagnostic and prognostic purposes.

SUMMARY

Serial measurements and use of combinations of markers have been reported to improve sensitivity and negative predictive value of these tests. Current markers are not infallible, however, and do not permit neonatologists to withhold antibiotics in sick infants with suspected infection. Thus, many have emerged as useful indicators for early discontinuation of unnecessary antimicrobial therapy. Some infection markers are also useful for identifying infants with severe infection and adverse prognosis. Advances in flow cytometry have allowed simultaneous measurement of key markers using only minimal blood volume. Judicious selection of a panel of markers with complementary properties could greatly increase the ability of neonatologists to diagnose infection and discern valuable prognostic information.

Inflammatory mediators for the diagnosis and treatment of sepsis in early infancy

Interleukin-6 (IL-6), interleukin-8 (IL-8), and procalcitonin (PCT) are important parameters in the diagnosis of sepsis and for differentiating between viral and bacterial infection in children. We compared the value of IL-6, IL-8, and PCT with C-reactive protein (CRP) in the diagnosis and treatment of late-onset sepsis among infants admitted to the neonatal intensive care unit (group I) and febrile infants admitted to general hospitals from home (group II). Group I was divided into subgroups Ia, positive blood culture (all Gram-positive cocci); Ib, negative blood culture; and Ic, controls. Group II was divided into subgroups IIa, systemic enterovirus infection, and IIb, no enterovirus infection. Enterovirus was identified by real-time (RT) polymerase chain reaction (PCR) and/or by culture in blood and cerebrospinal fluid (CSF). The positive predictive values of IL-6, IL-8, and PCT (78%, 72%, and 83%, respectively) were better than that of CRP (63%) in the diagnosis of neonatal sepsis. After 48 h of antibiotic treatment, IL-6 and IL-8 levels significantly decreased and PCT stabilized in clinically recovered patients, suggesting that these markers may be useful in distinguishing patients in which antibiotic treatment may be discontinued. Among infants of subgroup IIa, 80%-90% had normal values of IL-6, IL-8, and PCT, whereas CRP was increased in 40%. In conclusion, IL-6, IL-8, and PCT are better parameters than CRP in the diagnosis and follow-up of neonatal sepsis due to coagulase-negative staphylococci (CoNS) and in the exclusion of bacterial infection among those with enteroviral infection among febrile infants presenting from home.

Quantitative Measurement of Monocyte HLA-DR Expression in the Identification of Early-Onset Neonatal Infection

BACKGROUND

This study aimed to evaluate the diagnostic utilities of monocyte HLA-DR as an infection marker in the identification of early-onset clinical infection and pneumonia in newborn infants.

METHODS

Term newborns in whom infection was suspected when they were <72 h of age were eligible for enrollment in the study. C-reactive protein (CRP), monocyte HLA-DR and neutrophil CD64 expressions were quantitatively measured at the time of sepsis evaluation (0 h) and 24 h afterwards by flow cytometry and standard laboratory method.

RESULTS

A total of 288 infants with suspected sepsis were investigated, and 93 were found to be clinically infected. There were no significant differences in monocyte HLA-DR expression between the infected, non-infected and control groups at 0 h (median (interquartile range): 13,986 (10,994-18,544), 14,234 (12,045-17,474) and 18,441 (14,250-21,537) antibody phycoerythrin (PE) molecules bound/cell), and between infected and non-infected infants at 24 h (median (interquartile range): 17,772 (12,933-25,167) and 19,406 (14,885-24,225) antibody PE molecules bound/cell). The areas under the receiver operating characteristics (ROC) curves for HLA-DR, CD64 and CRP were 0.52-0.54, 0.88-0.94 and 0.75-0.77, respectively. We were unable to determine an optimal cutoff value for HLA-DR, as the diagnostic utilities of any cutoff point on the ROC curves were unable to satisfy the criteria (i.e. sensitivity and specificity >or=80%) for consideration as an useful diagnostic marker of infection.

CONCLUSIONS

Our findings did not support the use of monocyte HLA-DR alone or in combination with other infection markers in the diagnosis of early-onset clinical infection and pneumonia in term newborns.

Lipopolysaccharide-binding protein in noninfected neonates and those with suspected early-onset bacterial infection

OBJECTIVES

To investigate postnatal lipopolysaccharide-binding protein (LBP) kinetics in term neonates and to test its diagnostic accuracy for early-onset bacterial infection (EOBI).

STUDY DESIGN

A total of 99 neonates with clinical and serological signs of EOBI comprised the study group; 198 neonates with risk factors, but without EOBI, served as controls. LBP, C-reactive protein (CRP) and interleukin-8 (IL-8) were determined.

RESULTS

LBP in the noninfected group increased until 24 h after birth (P < 0.05 vs 6 h). LBP and CRP correlated strongly in neonates with suspected EOBI (r = 0.63). Although LBP reached a higher sensitivity than CRP 6 and 12 h after clinical suspicion (45 (24-68) and 79% (54-94) vs 9 (0-24) and 39% (17-64); P < 0.05)), EOBI was most reliably detected by IL-8.

CONCLUSION

LBP kinetics were age-dependent. LBP was not sufficiently sensitive in the prediction of EOBI.

C-reactive protein and cytokines in the diagnosis of neonatal sepsis

Introduction. Accurate evaluation and correct treatment of neonates for possible sepsis still represent the most challenging clinical tasks. Early diagnosis of neonatal sepsis is largely based on the measurement of serum concentrations of different mediators of systemic inflammation, as well as, on a group of proteins named acute phase reactants. Among acute phase reactants, C-reactive protein (CRP) has been the most extensively used and investigated so far. Synthesis and biological role of CRP. This article reviews current knowledge on the synthesis, structure and biologic roles of CRP. Also, we present our original results in regard to the kinetics of serum CRP concentration during the first 24 hours of systemic infection, as well as different patterns of CRP dynamics associated with the initial choice of antibiotics, complications and the final outcome of systemic infection. Interleukins and procalcitonin in diagnosis of sepsis. Because CRP is specific, but somewhat late marker of neonatal sepsis, possible diagnostic use of other indicators of inflammation, i.e. interleukins 6 and 8, and procalcitonin during neonatal sepsis is also considered. The theoretical advantage of these early indicators is discussed in comparative analysis of the time of their activation after initial infectious stimuli. Conclusion. In conclusion, we point to the diagnostic accuracy of serial measurements of serum CRP levels. As an alternative, simultaneous measurement of CRP and serum levels using a faster marker, such as procalcitonin, is recommended.

Expression of toll-like receptors in neonatal sepsis

Despite recent identification of specific pattern recognition receptors (PRR) for distinct microbial structures, data indicating their relevance in human infectious diseases are limited. We determined the expression levels of the Toll-like receptor (TLR)2 and TLR4 by flow cytometry on granulocytes and monocytes of healthy neonates compared with healthy adults. The basal expression of TLR2 was only slightly lower in neonatal phagocytes, whereas no differences could be detected for TLR4. Analyzing neonates with sepsis, we found an impressive up-regulation of TLR2 on blood phagocytes already at initial presentation of symptoms. Comparison with C-reactive protein, IL-8, and IL-6 suggested that TLR2 expression on monocytes is comparably valuable as an early sepsis marker. TLR2 was differentially regulated during neonatal sepsis, showing a constant up-regulation on monocytes but only a transient increase on granulocytes. Surprisingly, TLR4 showed no remarkable changes. Our results revealed a mild deficiency of TLR2 expression in newborns and demonstrated a differential expression of TLR2 but not TLR4 in the course of neonatal sepsis, which could reflect specific inflammatory responses to distinct pathogens. The definition of TLR expression patterns might open a new field of therapeutic targets for neonatal 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.

Neutrophil CD64 is a sensitive diagnostic marker for early-onset neonatal infection

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 <72 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 < 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.