[Expression of peripheral blood neutrophil CD64 in neonatal septicemia]

Neonatal septicemia is a common and severe infection, which often results in death. Early diagnosis and treatment of neonatal septicemia may help decrease neonatal mortality. Recently, many studies sought to explore the possibility of early diagnosis of this disease. The high affinity Fcgamma-receptor I (CD(64)) was purposefully chosen as a potential marker for identifying neonatal septicemia. The present study was designed to evaluate neutrophil CD(64) level for early diagnosis of neonatal septicemia.

Eighty-nine suspected neonatal septicemia cases were recruited into the study. Five non-specific indices, i.e., C-reactive protein (CRP), micro-erythrocyte sedimentation rate (mESR), white blood cell count, platelet count and the ratio of immature neutrophil count to total neutrophil count were measured for each patient. The patients were divided into septicemia group (n = 39) and non-septisemic infection group (n = 50) according to the diagnostic criteria for neonatal septicemia. Nineteen hospitalized neonates with non-infectious diseases were enrolled as controls (n = 19). The levels of peripheral blood neutrophil CD(64) were measured by using flow cytometry. The positive rate, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of CD(64) were calculated.

The levels of peripheral blood neutrophil CD(64) in septicemia patients were (75.6 +/- 8.9)%, which were significantly higher than those of non-septisemic infection group (29.1 +/- 6.2)% and control group (5.1 +/- 1.1)% (P < 0.05), respectively. There were no significant differences in the levels of CD(64) expression between the patients with Gram-negative (79.5 +/- 3.5)% and Gram- positive (76.4 +/- 5.0)% (P > 0.05) bacterial infection. The levels of CD(64) of the cases with septicemia significantly decreased at day 10 of treatment with antibiotics. The detection of CD(64) (cutoff value > 30%) for suspected septicemia showed high sensitivity (97.4%), specificity (84.0%), PPV (82.6%), and NPV (97.6%). The positive rate of CD(64) detection (62.9%) was much higher than that of the blood culture test (19.1%) and that of the five nonspecific indices (29.2%, P < 0.05, respectively).

The expression of CD(64) increased in neonatal septicemia cases. The measurement of cell surface expression of CD(64) on neutrophils may be helpful to early diagnosis, evaluation of severity of infection and observation of therapeutic effects for neonatal septicemia.