OBJECTIVETo study the clinical value of the expression of neutrophil surface CD64 in the diagnosis of community acquired pneumonia in children.

METHODSNinety-eight children with community acquired pneumonia were recruited into the study and were classified into three groups according to pathogene: bacterial pneumonia (n=48), viral pneumonia (n=29) and Mycoplasmal pneumonia (n=21). Twenty healthy children were enrolled as controls. The bacterial infection group was subdivided into mild infection (n=36) and severe infection groups (n=12). The levels of peripheral blood neutrophil CD64 were measured using flow cytometry. Dynamic changes of C-reactive protein were also detected for each patient.

RESULTSThe CD64 index and CRP levels in the bacterial pneumonia group were significantly higher than in the other three groups (P<0.05). The CD64 index in the severe bacterial infection group was significantly higher than in the mild group (P<0.05). After antibiotic treatment, expression of CD64 in the severe bacterial infection group decreased significantly (P<0.05). The CD64 index was positively correlated with CRP value (r=0.545, P<0.01). ROC curve analysis showed that the threshold of CD64 and CRP was 2.8 and 8 mg/L respectively. Specificity of CD64 index (90%) was much higher than CRP (74%).

CONCLUSIONSThe determination of peripheral blood neutrophil CD64 contributes to the early diagnosis of pulmonary bacterial infection and the evaluation of anti-infection effect.