Serum C-reactive protein in normal and infected neonates

The association between higher maternal pre-pregnancy body mass index and increased birth weight, adiposity and inflammation in the newborn

BACKGROUND

Excess adiposity and adiposity-related inflammation are known risk factors for cardiovascular disease in adults; however, little is known regarding the determinants of adiposity-related inflammation at birth.

OBJECTIVES

The aim of this study was to investigate the association between maternal pre-pregnancy BMI and newborn adiposity and inflammation.

METHODS

Paired maternal (28-week gestation) and infant (umbilical cord) blood samples were collected from a population-derived birth cohort (Barwon Infant Study, n = 1074). Data on maternal comorbidities and infant birth anthropomorphic measures were compiled, and infant aortic intima-media thickness was measured by trans-abdominal ultrasound. In a selected subgroup of term infants (n = 161), matched maternal and cord lipids, high-sensitivity C-reactive protein (hsCRP) and maternal soluble CD14 were measured. Analysis was completed by using pairwise correlation and linear regression. Because of their non-normal distribution, pathology blood measures were log transformed prior to analysis.

RESULTS

Maternal pre-pregnancy BMI was positively associated with increased birth weight (mean difference 17.8 g per kg m^-2 , 95% CI 6.6 to 28.9; p = 0.002), newborn mean skin-fold thickness (mean difference 0.1 mm per kg m^-2 , 95% CI 0.0 to 0.1; p < 0.001) and cord blood hsCRP (mean difference of 4.2% increase in hsCRP per kg m^-2 increase in pre-pregnancy BMI, 95% CI 0.6 to 7.7%, p = 0.02), but not cord blood soluble CD14. Inclusion of maternal hsCRP as a covariate attenuated the associations between pre-pregnancy BMI and both newborn skin-fold thickness and cord blood hsCRP.

CONCLUSION

Higher maternal pre-pregnancy BMI is associated with increased newborn adiposity and inflammation. These associations may be partially mediated by maternal inflammation during pregnancy.

Synthesis of grafted phosphorylcholine polymer layers as specific recognition ligands for C-reactive protein focused on grafting density and thickness to achieve highly sensitive detection

We studied the effects of layer thickness and grafting density of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) thin layers as specific ligands for the highly sensitive binding of C-reactive protein (CRP).

C-reactive protein: a marker of neonatal stress?

AIM

To assess whether blood values of C-reactive protein (CRP) in healthy term newborns, are influenced by stress.

MATERIAL AND METHODS

Since different types of delivery (vaginal delivery [VD], emergency C-section [EMCS] and elective C-section [ELCS]) are notoriously characterized by different levels of stress for the baby, these three groups were used as models of different levels of stress. The mean CRP values of the three groups obtained in the first hours of life were compared.

RESULTS

We retrieved 1012 babies. Median values (3rd-97th ct) were: 0.05 (0.01-0.46), 0.17 (0.02-1.54), 0.30 (0.04-1.77), 0.43 (0.05-1.31), 0.40 (0.04-1.13) at 12, 24, 48, 72 and 96 h, respectively. Mean values in babies born after VD were statistically higher than those born after C-section, and higher CRP values were present in EMCS with respect to ELCS.

CONCLUSION

This study described normal blood CRP values in a wide population of term babies. An influence of the type of delivery on blood CRP is evident, and this may be explained by the different amount of perinatal stress induced by anyone of the three types of delivery we considered.

Neonatal infections in Saudi Arabia: association with C-reactive protein, CRP -286 (C>T>A) gene polymorphism and IgG antibodies

Background

C-reactive protein (CRP) is a nonspecific, acute-phase protein that rises in response to infectious and non-infectious inflammatory processes. Infections are the single largest cause of neonatal deaths globally.

The primary aim of this study is to examine the association between CRP gene polymorphism and serum levels of CRP in correlation with early onset sepsis (EOS) infection in newborns living in Taif city, Saudi Arabia. The second aim is to examine the relationship between specific IgG/IgG subclasses and early onset sepsis (EOS) infection among these newborns.

Methods

Staphylococcus aureus (S. aureus) is one of the most common organisms related to sepsis infection in the newborn at King Abdel Aziz Specialist Hospital (KAASH). This study was conducted in Taif city, at KAASH’s neonatal intensive care unit between March and August 2012. Neonates were consecutively enrolled onto the study having met our inclusion criteria (as per our research protocol).

The CRP concentration level was analysed using NycoCard® CRP Single Test. CRP -286 (C>T>A) A polymorphisms were analyzed using Pyrosequencing technology for CRP genotyping. IgG subclasses were analysed in the study population using ELISA.

Result

Logistic regression analyses showed that the AA and AC genotypes were negatively associated amongst EOS neonates compared to suspected neonates. The frequency of CC and CT were significantly associated with the EOS neonates compared to the suspected group. The levels of specific IgG1, IgG2 and IgG3 antibodies were significantly lower amongst EOS compared to the suspected group.

Conclusions

Taken together, the CRP-286 (C>T>A) A genotype polymorphism and specific IgG antibodies isotype levels can contribute to a reduced risk of EOS. Furthermore, CRP has a potential use in detecting EOS in neonates, which may mean earlier detection and management of EOS and subsequently better clinical outcome.

Predictors of fibrostenotic Crohn's disease

Intestinal fibrosis is a common and serious complication of Crohn's disease (CD) and as it can occur at any time during the disease course, it is crucial to identify patients at risk. The aim is not only to understand the pathophysiology of fibrogenesis but to be able to accurately inform subjects about their disease course, design future trials of potentially useful antifibrotic therapies, and, most important, identify those CD patients at risk, with the view to early, more aggressive medical therapy. This review summarizes the current status of our understanding and ability to predict fibrostenosing CD. The review encompasses three distinct areas: genetic variants, clinical phenotypes, and serologic markers in order to develop a conceptual framework for an understanding of fibrostenotic CD. It also aims to highlight where our knowledge is insufficient in order to identify areas that require future research.

Procalcitonin as a screening test for late-onset sepsis in preterm very low birth weight infants

OBJECTIVE

To compare the utility of procalcitonin (PCT) vs C-reactive protein (CRP) as indicators of late-onset neonatal sepsis in very low birth weight (VLBW) infants.

METHODS

PCT and CRP levels were measured in VLBW infants with suspected sepsis and controls. Comparisons were made between infected vs noninfected infants. Using cutoff values of 0.5 and 1.0 ng/ml for PCT and 0.8 mg/dl for CRP, sensitivity, specificity, positive and negative predictive values were calculated to evaluate these assays as potential predictors of late-onset sepsis.

RESULTS

A total of 67 infants were evaluated. Mean PCT levels were significantly higher in the infected group (5.41 ng/ml) compared to the noninfected group (0.43 ng/ml) (p < 0.001). At a cut off value of 0.5 ng/ml, the sensitivity of PCT was 97%, whereas that of CRP was 73% in predicting late-onset sepsis. At a PCT cutoff of 1.0 ng/ml, sensitivities of PCT and CRP were similar (72% each).

CONCLUSION

PCT (0.5 ng/ml) is more sensitive than CRP in predicting late-onset sepsis in VLBW infants.

The role of C-reactive protein in the evaluation and management of infants with suspected sepsis

C-reactive protein (CRP) is a nonspecific, acute-phase protein that rises in response to infectious and noninfectious inflammatory processes. Good evidence exists to support the use of CRP measurements in conjunction with other established diagnostic tests (such as a white blood cell (WBC) count with differential and blood culture) to establish or exclude the diagnosis of sepsis in full-term or near-term infants. This article reviews the immunologic function of CRP and the history of CRP testing. The 3 methods for measuring CRP and the sensitivity and specificity of this diagnostic test are analyzed. Guidelines for the use of CRP in the evaluation and management of infants with suspected sepsis are presented. Quantitative serial CRP levels, obtained 24 hours after the onset of signs and symptoms of infection, with serial measurements 12 to 24 hours apart, offer the most sensitive and reliable information. At least 2 CRP levels, obtained 24 hours apart, with levels < or = 10 mg/L, are needed to identify infants unlikely to be infected. The use of CRP to exclude infection may allow clinicians to discontinue antibiotics at 48 hours in select infants, limiting extended unnecessary antibiotic exposure.

Serial Measurements of C-Reactive Protein and Interleukin-6 in the Immediate Postnatal Period: Reference Intervals and Analysis of Maternal and Perinatal Confounders

Background: There is a wide range of reported sensitivities and specificities for C-reactive protein (CRP) and interleukin-6 (IL-6) in the detection of early-onset neonatal infection. This prompted us to assess reference intervals for CRP and IL-6 during the 48-h period immediately after birth and to identify maternal and perinatal factors that may affect them.

Methods: CRP and IL-6 values were prospectively obtained for 148 healthy babies (113 term, 35 near-term) at birth and at 24 and 48 h of life, and from their mothers at delivery.

Results: Upper reference limits for CRP at each neonatal age were established. At birth, CRP was significantly lower than at 24 and 48 h of life. Rupture of membranes ≥18 h, perinatal distress, and gestational hypertension significantly affected the neonatal CRP dynamics, but at specific ages. There was no correlation between CRP concentrations in mothers and their offspring at birth. The IL-6 values observed in the delivering mothers and in their babies at all three neonatal ages were negatively associated with gestational age. In the immediate postnatal period, IL-6 dynamics for term babies were significantly different from those for near-term babies. Maternal IL-6 concentrations correlated with babies’ IL-6 concentrations only for term deliveries. Apgar score had a significant effect on babies’ IL-6 values at birth.

Conclusions: The patterns of CRP and IL-6 responses in the healthy neonate should be taken into account to optimize their use in the diagnosis of early-onset neonatal sepsis.

Serum amyloid-A (SAA) and haptoglobin (Hp) plasma concentrations in newborn calves

The concentrations of 2 major bovine acute-phase proteins, haptoglobin (Hp) and serum amyloid-A (SAA), were measured in plasma obtained shortly after birth from 22 healthy calves. In a separate group of diseased calves (n = 8), Hp and SAA concentrations were measured to determine whether newborn calves (up to 4 d old) are able to produce SAA and Hp. In blood samples taken directly after birth, the Hp plasma concentrations were all below the limit of detection. The mean SAA concentration was independent of weight (r = 0.063), degree of acidosis (r = -0.125), sex (p > 0.05), and were not different in calves born after different types of obstetrical help (p > 0.05). In the group of diseased calves, an increased Hp concentration was measured in only 2 of 8 animals, whereas the mean SAA concentration was significantly higher (p < 0.05) than in the healthy newborn calves. These data suggest that prenatal stress due to parturition does not form a stimulus for the production of acute-phase proteins in the fetal calf. The low Hp plasma concentrations might indicate that either it takes a few days to establish a detectable concentration of this protein, or that Hp production is not fully developed in newborn calves.

The value of acute phase protein measurements in clinical practice

There is clearly a role for the measurement of acute phase proteins and other indices of the acute phase reaction but it is equally clear that no one laboratory test is suitable for use in all clinical situations. The choice of acute phase protein measurement depends on the diagnostic sensitivity and specificity of the measurement in the particular clinical situation. The choice of measurement must also include a decision on time of sampling and whether single or serial sampling would be more appropriate. In most situations where acute phase measurement is useful CRP is the assay of choice with alpha 1-antichymotrypsin also being useful in inflammatory bowel disease and other situations where a wider time window is required. The ESR or plasma viscosity can be useful to screen for disease. Cytokine and enzyme-inhibitor complex measurements may be important assays in the future.

Microparticle-enhanced nephelometric immunoassay for human C-reactive protein

Polyfunctional hydrophilic microspheres of 125-nm diameter can be produced by copolymerization of acrylic monomers. Purified c-reactive protein (CRP) was covalently bound to these new micropheres, and the conjugate obtained was used as reagent in a microparticle-enhanced nephelometric immunoassay for human CRP. This assay was based on the measure, with a specially designed nephelometer, of the light scattered by aggregates formed during the immunoagglutination of the conjugate with anti-CRP antiserum. Sensitive inhibition of this agglutination by free CRP (6 ng/ml) allowed CRP quantitation in highly diluted serum samples (1/500-1/2,000), excluding any interference or sample pretreatment. The CRP assay was easy to perform (no washing or phase separation), reliable (coefficients of variation ranged from 1.3% to 9.3% for within-run and between-run determinations), and accurate (mean percentage of recovery: 104%; correlation coefficients with accepted analytical methods greater than or equal to 0.97) over a large range of concentrations. The inhibition mode excluded errors in the antigen excess zone and provided total security at high concentrations.

Comparative study of C reactive protein and serum amyloid A protein in experimental inflammation

The responses of C reactive protein, measured by radial immunodiffusion and radioimmunoassay, and serum amyloid A protein, measured by radial immunodiffusion, were compared in eight subjects with inflammation induced experimentally by intradermal injection of monosodium urate crystals. A significant increase in serum amyloid A was noted after a lag phase of eight hours, the increase in median concentration at 48 hours being about eightfold. A parallel but less marked increase was found in C reactive protein when measured by radioimmunoassay (fourfold increase in median concentration at 48 hours) after a small but significant decrease during the lag phase. The changes in C reactive protein remained within the reference range and were not detectable by radial immunodiffusion.

C-reactive protein during normal pregnancy

Serum C-reactive protein (CRP) is determined in a prospective longitudinal study of 60 low-risk pregnant women. CRP is also measured in umbilical-cord blood after delivery. The serum CRP concentrations seem to be independent of pregnancy and gestational age. The 95th percentile is estimated to be 20 mg/l, and this value is considered as the upper limit of normal. A rise in CRP level is considered more predictive of infection than a determination of a single high value. CRP does not cross the placental barrier, and may therefore be useful in diagnosing infections in newborns.

C-reactive protein and bacterial infection in preterm infants

Serum C-reactive protein (CRP) concentration was measured by a new solid phase ligand-binding radiometric monoclonal antibody immunoassay in a prospective study of 193 consecutively born preterm infants. In 104 with no clinical or laboratory evidence of infection the median CRP in cord serum was 0.125 mg/l (range 0.011-6.0 mg/l), at 24 h it was 1 mg/l (0.016-7.0) and at 48 h 2 mg/l (0.400-8.0). The present highly sensitive assay has enabled these normal ranges to be defined for the first time, at levels below the threshold of non-labelled immunoassays and of all commercially available CRP assays. The values in cord serum were significantly lower than in normal healthy adults (median 0.8 mg/l, range 0.07-29 mg/l, n = 468). Arterial catheterisation and endotracheal intubation, in the absence of infection, did not appear to elevate CRP, nor did cerebral germinal layer or intraventricular haemorrhage. Among nine infants with confirmed septicaemia eight had a serum CRP level raised at least once during the first 48 h and serum CRP in the other one increased 250-fold in 24 h before treatment was started. Using this assay, serum CRP is a useful and rapidly available adjunct to clinical assessment in diagnosis and exclusion of bacterial infection in the early neonatal period, has encouraged us to withhold or discontinue antibiotics and also has a role in monitoring response to treatment.

Evaluation of C. reactive protein values in neonatal sepsis

C. reactive protein (CRP) estimations were performed prospectively on 30 consecutive admissions of very low birth weight infants to a Regional neonatal intensive care unit. The samples were analysed by a recently described, rapid intralipid agglutination assay and by a reference turbidimetric technique. Two hundred and ninety samples were assayed by both techniques. The intralipid agglutination was positive on two occasions when the reference method found normal levels. No false negative reactions occurred. Bacterial micro-organisms were isolated on 32 occasions but 19 of the organisms were considered to represent bacterial colonisation or contamination. The CRP remained negative in 17 cases. There were 13 episodes of clinical deterioration associated with positive bacterial cultures. In each of the six infants with severe systemic infections (septicaemia (4), meningitis (1), and osteomyelitis (1)), the levels were raised. In five of these infants the CRP was elevated before, or at the time of, the clinical deterioration. The CRP remained normal during seven (54%) of the culture positive events. We believe that the CRP estimations provide additional information in the evaluation of the infant with suspected sepsis. Serial measurements are helpful in distinguishing bacterial contamination from invasive infection but are not helpful in predicting infection during the pre-clinical phase. The intralipid agglutination technique is a rapid and reliable test and could be performed on the neonatal unit outside normal laboratory hours.

Development and validation of a particle-enhanced turbidimetric immunoassay for C-reactive protein

The development of a particle-enhanced turbidimetric immunoassay for C-reactive protein is described. The method demonstrates excellent precision, with the calibration curve remaining stable for at least 16 weeks. The method compares well with established techniques and there is no interference from a variety of autoantibodies, endogenous serum constituents or commonly used drugs.