Serum Interleukin 8 Level as a Diagnostic Marker in Late Neonatal Sepsis

Objective: Late-onset sepsis is responsible for high morbidity and mortality in newborn infants in the world and in particular in developing countries. In this study, we evaluated whether clinical characteristics, laboratory parameters and measurements of serum interleukin-8 (IL-8) are able to discriminate between late neonatal sepsis and normal baby.
Methods: This was a prospective (case-control) study conducted between March 2007 and April 2008, at the neonatal intensive care unit, Ghaem Hospital, Mashhad, Iran. The study comprised 93 neonates ≥72 hours of life. The infants were categorized in two groups based on the clinical presentation, and biochemical markers including complete blood count, C-reactive protein (CRP) and blood culture: 1) Control group including 42 infants with routine screening and 2) Case group consisting of 38 infants with definitive infection (positive blood and/or cerebrospinal fluid culture) or clinical sepsis (clinical and laboratory signs of infection without positive blood or CSF culture). Receiver-operating characteristic curves were used for the determination of thresholds for the infection group versus healthy neonate group.
Findings: Eighty infants were enrolled in this study. IL-8 and CRP decreased in order of definitive infection, clinical sepsis and healthy subjects respectively (P<0.001). Sensitivity, specificity, positive predictive value, negative predictive value for serum levels were 0.95, 0.1, 0.97, 0.1 for IL-8 and 0.83, 0.86, 0.83, 0.69 for CRP respectively (cut-off point for IL-8 >60pg/ml and for CRP>6mg/dl).
Conclusion: IL-8 may be a valid and early predictive marker of neonatal infection. Also, IL-8 is associated with severity of infection.