Sequential study of C reactive protein in neonatal septicaemia using a latex agglutination test

Capillary plasma elastase alpha 1-proteinase inhibitor in infected and non-infected neonates

Capillary heel prick plasma elastase alpha 1-proteinase inhibitor (E alpha 1-PI) measured by an immunoassay (using commercially available reagents) was examined as an early indicator of neonatal sepsis. Fifty five infants were studied within 24 hours of birth; 60 (including 10 studied on the first day of life) were examined between two and 30 days after birth. Reference ranges for the neonatal period were developed. Raised E alpha 1-PI concentrations (range 440-2600 micrograms/l) were found at the outset of each of the 24 infectious episodes including five with concomitant neutropenia. On the first day of life, obstetric and neonatal complications were also associated with high concentrations (range 190-2400 micrograms/ml). In infants who survived infection, E alpha 1-PI normalised with antibiotic treatment. It is concluded that capillary heel prick plasma is suitable for E alpha 1-PI testing and raised concentrations provide a sensitive but non-specific index of infection in the first 24 hours after birth. Sequential testing may provide early warning of infectious complications and serve as a guide to the cessation of antibiotic treatment.

Early hemodynamic indicators of gram-negative sepsis and shock in an infant pig model

To assess the hemodynamics of early shock and to determine to what extent hemodynamic indicators of sepsis and shock can be predictive, we evaluated data from several series of experiments (including 136 piglets) in which animals were subjected to fecal-Escherichia coli peritonitis-induced septic shock. Serial measurements of 39 parameters were obtained and their values taken at baseline, at hyperdynamic sepsis, and at shock were compared by analysis of variance. Piglet weights ranged from 1.2 to 7 kg (mean, 3.5) and ages ranged from 5 to 29 days (mean, 15). Of the 39 parameters assessed, 9 (CO*, CI*, SVI*, LVSWI*, SVR*, a-vDO2, VO2, O2 delivery*, and CaO2*) proved valuable as indicators of sepsis and shock. Of these parameters, seven (*) can be measured or calculated by noninvasive techniques and easily can be determined in human neonates. Serial determinations of these hemodynamics in high-risk neonates may be able to accurately predict gram-negative sepsis and shock before these entities are otherwise clinically apparent.

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.

Serum C-reactive protein in the early diagnosis of neonatal septicemia and bacterial meningitis

The usefulness of serum C-reactive protein (CRP) in the early detection of neonatal infection was studied using a special laser nephelometric apparatus (CRP-1), by which CRP concentrations could be quickly determined in the nursery, with only a small amount of serum (20 microL). Initial serum CRP concentrations of samples obtained from 90 infants suspected to have sepsis and/or meningitis were evaluated. Of the 90 infants, 25 showed culture-proven septicemia and/or bacterial meningitis, while 18 were considered to be infectious based on clinical signs and positive sepsis work-up even though cultures were negative. 47 infants had negative cultures and sepsis work-up and showed a favorable clinical courses. Statistical analysis for the evaluation of serum CRP at the level of one mg/dL was performed. False negative CRP was demonstrated in seven of 25 infants with culture-proven sepsis and/or meningitis (28%) and in 4 of 18 infants with other infections (22%). On the other hand, seven of 47 (15%) non-infected infants showed false positive results. The specificity and sensitivity of serum CRP determination were 85% and 74%, respectively, for all patients, and 85% and 72%, respectively, for patients with sepsis and/or meningitis. The sensitivity varied with the pathogens. We conclude that, while the initial CRP values alone are unsatisfactory for deciding the need for antibiotic therapy, CRP is useful in the early detection of neonatal infections, and its measurement by this new equipment should available in the nursery.

Rapid determination of C-reactive protein by enzyme immunoassay using two monoclonal antibodies

Several monoclonal antibodies for human C-reactive protein (CRP) were characterized, and two antibodies binding to separate domains were used to construct a rapid and simple immunoenzymometric assay for CRP. The assay consists of a single 15 min immunological reaction during which CRP forms a complex with a peroxidase-labelled antibody and with another antibody attached to the test-tube wall. The immobilized complex is detected by a 3 min colour reaction using peroxidase substrate. The quantitative measuring range of the assay is 0.04-5 mg/l, and no hook occurs at five-fold higher values. The sensitivity of the method allows reliable determination of low CRP levels, eg. in paediatric samples. The values obtained with the present assay correlated well with turbidimetric results.

Evaluation of a semiquantitative C-reactive protein latex slide test as compared to quantitative turbidimetric measurement in hospital laboratory practice

Serum C-reactive protein (CRP) concentrations of 708 patients with suspected bacterial disease were estimated with a semiquantitative CRP latex slide test using cut-off levels of 20 and 40 mg/l and with quantitative turbidimetric technique. Latex slide tests gave 11.8% (80/708) discordant results. About 7% of tests gave clear disconcordant results (5% of those were positive and 2% negative tests). We conclude that CRP latex slide test is not useful in emergency laboratory in hospital material with a high incidence of bacterial infections.

Serum C-reactive protein in normal and infected neonates

Serum C-reactive protein determinations were performed on well and sick neonates, in order to gain information about normal values and its value in the diagnosis of neonatal septicaemia. The median value in 48 cord sera was 200 micrograms/l (range 15 to greater than 6,000 micrograms/L); there was no correlation between paired maternal and cord serum CRP levels (12 pairs). Thirty-six children were followed from birth for a mean of 20 days. There were 21 episodes of confirmed infection in 16 children, each associated with a sustained rise in C-reactive protein, often commencing before there was clinical evidence of infection. In four patients with raised levels, infection was suspected, but no firm evidence was obtained. In the remaining 16 children there were no values above 10 mg/l, and the 95th centile was about 6 mg/l, with no difference between values obtained in the first three days of life and those found subsequently. Hyaline membrane disease and jaundice were not associated with a rise. Raised serum C-reactive proteins is a good indicator of the presence of infection in the neonatal period.