Ratios of CD64 expressed on neutrophils, monocytes, and lymphocytes may be a novel method for diagnosis of neonatal sepsis.

INTRODUCTION Neutrophil CD64 expression has been demonstrated as an improved diagnostic marker of infection and sepsis. The purpose of this study was to develop a new method to evaluate neutrophil CD64 expression for diagnosis of neonatal sepsis. METHODOLOGY Eighty neonates with neonatal sepsis (21 culture positive, 59 negative) were enrolled in this prospective study along with 19 neonates with no symptoms or signs of infection as controls. Expressions of CD64 on monocytes, lymphocytes, and neutrophils were evaluated with flow cytometry (FCM). Ratios were calculated with these levels of CD64 expression. Blood culture and other laboratory exams were done at the same time for the diagnosis of neonatal sepsis. Results were compared between the neonatal sepsis and control groups. RESULTS CD64 ratios showed significant difference between the groups (p < 0.01). Receiver operating curve (ROC) analysis showed that the CD64 ratios possessed high sensitivity (90%) and specificity (89.5%) in neonatal sepsis identification. CONCLUSIONS The novel CD64 evaluation method, CD64 ratio, can be used as a supplementary method for diagnosis of neonatal sepsis.