Neutrophil CD11b expression and circulating interleukin-8 as diagnostic markers for early-onset neonatal sepsis

Objective. To assess neutrophil CD11b and circulating interleukin 8 (IL-8) as markers of early-onset infection in neonates. Methods. The study comprised 39 neonates, with a gestational age of 29 to 4 1 weeks, suspected of infection within 48 hours of life. Neutrophil surface expression of CD11b was quantified with flow cytometry and plasma IL-8 wit h an enzyme-linked immunosorbent assay. Both data were available from 35 of 39 neonates. Serum C-reactive protein was determined at initial evaluation and, later, on the basis of the clinical picture. Neonates were allocated retrospectively into 2 groups. In the sepsis group (N = 22), 4 had culture- proven sepsis, and 14 had an antenatal risk factor for infection. In the po ssible-infection group (N = 13), each neonate had a noninfective disorder, but co-occurring infection remained a possibility. Twelve healthy term infa nts served as controls. Results. CD11b expression and IL-8 levels both increased in order of sepsis > possible infection > healthy. Sensitivity and specificity by the CD11b t est for sepsis were equal, at 1.00, and those by the IL-8 test 0.91 and 1.0 0, respectively; 6 (17.1%) of the 35 neonates had CD11b and IL-8 below cuto ff levels. Conclusions. Measuring neutrophil CD11b expression and circulating IL-8 pro vides a means to identify early-onset neonatal sepsis. The findings may be helpful in planning strategies to safely reduce the use of antimicrobials i n neonates.