Role of Neutrophil CD64 Index as a Screening Marker for Late-Onset Sepsis in Very Low Birth Weight Infants

Introduction
The role of CD64 in late onset sepsis (LOS) in preterm infants has been described in several studies. Aim of this study was to investigate whether CD64 expression is increased in the days before clinical manifestation of LOS.
Methods
Patients with birth weight below 1,500g were eligible for study participation. During routine blood sampling CD64 index was determined between day of life 4 and 28. Patients were allocated to one of four groups: (1) blood-culture positive sepsis, (2) clinical sepsis, (3) symptoms of infection without biochemical evidence of infection, or (4) patients without suspected infection. Kinetics of CD64 expression were compared during a period before and after the day of infection in the respective groups.
Results
50 infants were prospectively enrolled and allocated to each group as follows: group (1) n = 7; group (2) n = 10; group (3) n = 8; and group (4) n = 25. CD64 index was elevated in 57% of patients in group (1) at least two days before infection. In contrast only 20% in the clinical sepsis group and 0% in group (3) had an elevated CD64 index in the days before infection. 10 of the 25 patients in the control group (4) presented increased CD64 index values during the study period.
Conclusions
The CD64 index might be a promising marker to detect LOS before infants demonstrate signs or symptoms of infection. However, larger prospective studies are needed to define optimal cut-off values and to investigate the role of non-infectious inflammation in this patient group.

Introduction
多项研究已阐明CD64（CD64）在早产儿晚发型脓毒症（late onset sepsis, LOS）中的作用。本研究旨在探究在晚发型脓毒症临床表现显现前数日，CD64的表达是否出现升高。

Methods
出生体重低于1500g的患儿符合本研究的纳入标准。在常规采血过程中，于生后第4天至第28天期间检测CD64指数。将受试者分为四组：(1) 血培养阳性脓毒症组；(2) 临床脓毒症组；(3) 存在感染症状但无生化感染证据组；(4) 无疑似感染的对照组。比较各组在感染日前后时段内CD64表达的动态变化情况。

Results
本研究共前瞻性入组50例患儿，各组分配例数如下：(1)组n=7；(2)组n=10；(3)组n=8；(4)组n=25。在(1)组中，57%的患儿至少在感染前2天即出现CD64指数升高。与之相比，(2)组临床脓毒症患儿中仅20%、(3)组中0%的患儿在感染前数日出现CD64指数升高。对照组(4)的25例患儿中，有10例在研究期间出现CD64指数升高。

Conclusions
CD64指数或可成为在患儿出现感染体征或症状前，检出晚发型脓毒症的有潜力的生物标志物。然而，仍需开展更大样本量的前瞻性研究，以确定最佳截断值，并探究非感染性炎症在该患者群体中的作用。