Effective immunological markers for Neonatal Sepsis: Comparison of C- reactive protein with Interleukin - 6 and Blood culture

Abstract

Background: Neonatal sepsis occurs from 1 to 21 newborns out of 1 000 live births with mortality rates as high as 30% up to 69%. The most important risk factors are prematurity, low birth weight, invasive medical procedure and prolonged hospitalization in neonatal intensive care units. Infection in neonates is difficult to identify solely on the basis of physical findings, because signs are not specific. C reactive protein (CRP) is an acute phase reactant which has been used in diagnosis of bacterial infection in neonates. Interleukin-6 is a proinflammatory cytokine produced by monocytes and macrophages activated by bacterial infection. Interleukin-6(IL-6) can be detected in blood earlier than CRP during the course of bacterial infection. The objective of this study was to compare the usefulness of the level of interleukin-6 with CRP as early markers of neonatal sepsis with Blood culture.

Methods: This prospective study was carried out for a period of three months in a tertiary care hospital. Blood samples collected from 90  newborn babies  were tested for Blood culture,CRP level detection by latex agglutination test and IL-6 determination by ELISA. The cut-off values recommended by the respective manufacturers were used to determine the sensitivity and specificity.

Results: Out of the blood samples collected from 90 participants, positive blood culture was found in 28 neonates(31%). Escherichia coli  was the most common organisms for causing both Early Onset Neonatal Sepsis and Late Onset Neonatal Sepsis in the present study. Sensitivity of detection of IL-6 by ELISA method was 100% when evaluated against culture , a reference test. Specificity of this test was 41.94%  compared to culture and positive and negative predictive value were 40.63% and 100% respectively. Sensitivity of CRP latex agglutination test was 64.28% when evaluated against culture, a reference test. Specificity of CRP latex agglutination test was 56.45% compared to culture and positive and negative predictive value were 40% and 77.77% respectively. The findings of the present study confirm that the serum level of IL-6  is a more reliable marker than the serum levels of CRP.  

Conclusions: IL-6 was mostly positive within 24 hours of onset of sepsis in comparison with other tests. So IL-6 is more useful both to early (24-48 h) detection  of neonatal sepsis and to monitor the antibiotic treatment while waiting for the results of cultural examinations.