Early diagnosis of sepsis with C-reactive protein, serum amyloid A and CD64 in very low birth weight infants

Abstract

Objective To investigate the value of C-reactive protein (CRP),serum amyloid A (SAA) and CD64 in early diagnosis of sepsis in very low birth weight infants (VLBWI).Methods Fifty-four VLBWI suspected to sepsis and 20 VLBWI without infection in neonatal intensive care unit of the Second Hospital of Wenzhou Medical College from May 2010 to May 2012 were enrolled in this study.CRP,SAA and CD64 of sepsis group were measured at 0 and 24 hour after suspected bacterial infection; and those of control group were measured at corresponding age.CRP and SAA were detected by enzyme-linked immunosorbent assay,and CD64 was detected by flow cytometry.The difference between groups was compared by Mann-Whitney U test.Receiver operating characteristic curve was used to predict the sensitivity and specificity of the three biomarkers on sepsis.Results Fifty-four VLBWI were suspected with sepsis,and 37 patients were finally diagnosed.The levels of the three biomarkers in sepsis group were higher than those of control group not only at 0 h [CRP:13.3 mg/L(4.6-67.2 mg/L) vs 4.4 mg/L(1.6-11.2 mg/L),Z=-2.308; SAA:95.7 mg/L(4.5-265.9 mg/L) vs 7.3 mg/L(2.5-16.9 mg/L),Z=-2.425; CD64:7306 fluorescent antibody molecules/cell (2667-10 853 fluorescent antibody molecules/cell) vs 2502 fluorescent antibody molecules/cell (1839-3017 fluorescent antibody molecules/cell),Z=-3.704],but also at 24 h[CRP:35.4 mg/L (7.7 106.5 mg/L) vs 3.2 mg/L (1.1-7.8 mg/L),Z-5.501; SAA:359.3 mg/L (3.8-503.2 mg/L) vs 6.6 mg/L (3.0-12.7 mg/L),Z =-2.818; CD64:8304 fluorescent antibody molecules/cell (2819-11 758 fluorescent antibody molecules/cell) vs 2563 fluorescent antibody molecules/cell (1760-3154 fluorescent antibody molecules/cell),Z =-7.670],P＜0.05 respectively.The best cutoff value of CD64 was 2934 fluorescent antibody molecules/cell,with the sensitivity of 81.1％ at 0 h and 91.9％ at 24 h; and the specificity of 90.0％ at 0 h and 80.0％ at 24 h.Although SAA had similar sensitivity (0 h:83.8％; 24 h:86.5％) as CD64,its specificity was relatively low(0 h:65.0％; 24 h:55.0％).Both the sensitivity (0 h:62.2％; 24 h:70.3％) and specificity (0 h:70.0％; 24 h:70.0％) of CRP were low.Combination of the three infection biomarkers could increase the sensitivity (0 h:91.9％; 24 h:97.2％) and specificity (0 h:95.0 ％ ; 24 h:90.0％).Conclusions Combination of CRP,SAA and CD64 might improve the diagnostic accuracy of sepsis in VLBWI. Key words: Infant, very low birth weight; Bacterial infections; C-reactive protein; Serum amyloid A protein; Receptors, IgG; Early diagnosis