CD64: diagnostic accuracy compared with the hematologic scoring system and CRP in neonatal sepsis

Background: Despite the advances in prenatal and neonatal care, there is still a high incidence of neonatal sepsis and new accurate and rapid tests are required that facilitate the identification of this condition in order to initiate an early effective treatment for a successful outcome.Objective: To evaluate the diagnostic performance of CD64 expression in relation to the hematologic scoring system (HSS) and C-reactive protein (CRP) either individually or in combination in neonatal sepsis.Participants and methods: This study included 36 neonates, 13 with culture proven sepsis (group I), 13 with clinically suspected sepsis and culture-negative results (group II), and 10 age-matched and sex-matched healthy neonates (control group). All neonates were examined thoroughly. Complete blood counts were performed, from which HSS was formulated and CRP was measured. Bacterial blood cultures (urine and cerebrospinal fluid when indicated) were carried out only for patients. Neutrophil surface expression of CD64 was assessed by flow cytometry.Results: Neutrophil CD64 expression was significantly higher in neonates with proven sepsis than the other groups (P=0.0001). A significant positive correlation was found between CD64 expression and HSS (r=0.6581, P 0.001) and CRP (r=0.7531, P 0.001). In terms of the validity of CD64 expression compared with HSS and CRP, the accuracy was 86.1% with a specificity and a positive predictive value (PPV) of 82.6 and 75%, respectively; HSS and CRP sensitivities were 92.3 and 100%, respectively, but with lower specificities (73.9 and 52.2%, respectively) and PPVs (66.7 and 54.2%, respectively). Combinations of CD64 with the two parameters showed that the best was that of CD64 and CRP as sensitivity reached 100% with a constant specificity and slightly increased PPV and accuracy (76.5 and 88.9%, respectively).Conclusion: CD64 expression is significantly related to definite sepsis and correlated to HSS and CRP. It is a reliable diagnostic test to differentiate infected from noninfected neonates.