RESUMEN
Early onset neonatal sepsis < 72 hour is associated with high morbidity and mortality, early clinical signs and symptoms of neonatal infection are often inconspicuous and can be confused with non infective causes furthermore a negative microbiologic culture results don't always suggest absence of bacterial cause thus a good indicator of infection would be clinically desired to differentiate infected from non infected patients. To evaluate the detection of activated surface marker CD64 on peripheral blood neutrophils as a diagnostic tool for early detection of neonatal sepsis, and as a highly negative predictive marker ruling out the non-septic cases, and to compare the diagnostic accuracy of CD64 expression as a marker for early neonatal sepsis with that of CRP and Procalcitonin. The study was conducted on 45 high risk neonates in the first 7days of their lives, admitted to the Neonatal Intensive Care Unit at Tanta University Hospital from January 2012 to March 2013, 30 of them were diagnosed as suspected sepsis [group I], by clinical sepsis score >/=10 and hematological sepsis scoring system >/= 3 but the blood culture were negative and 15 were diagnosed as proven sepsis [group II] based on the same soring systems and positive blood culture .15 healthy newborns were chosen as a control group .All subjects were subjected to Blood culture Quantitative Measuring of CRP level by means of immunonephlometry., procalcitonin [PCT] measurement by ELISA, Flowcytometric measuring of CD64 expression level on peripheral blood neutrophils. Klebsiella [40%] was the commonest microorganism isolated from blood cultures followed by E. coli [20%], Pseudomona [13.3%], Staph aureus [13.3%],, and Coagulase Negative Staph. [13.3%], CRP test had, 80% Sensitivity, 60% Specificity, 66.7% PPV, 75% NPV, and 63% Accuracy .PCT test had, 66.7%Sensitivity, 60% Specificity, 62.5% PPV, 64.3% NPV, and 59.6% Accuracy, while CD64 test had, 100%Sensitivity, 80% Specificity, 83.3% PPV, and 100% NPV and accuracy of 82%