Abstract: Background　Neonatal sepsis is one of the main causes of premature infant death，especially early-onset sepsis（EOS），so early diagnosis and timely treatment are particularly important.Blood culture is the gold standard in the diagnosis of sepsis，but the peripheral blood volume of newborns is limited.As the earliest blood sample after birth，the umbilical cord blood volume is sufficient and the collection is convenient.Objective　To explore the clinical value of umbilical cord blood culture in preterm infants with EOS，and to observe the changes of inflammatory indexes in infants with positive results of blood culture，in order to provide a basis for the clinical treatment of EOS.Methods　A total of 150 pairs of pregnant women who were suspected or diagnosed with intrauterine infection and their preterm infants（gestational age ≤37 weeks）were selected from the Second Hospital of Tianjin Medical University from June 2018 to June 2019，of which 102 premature infants were diagnosed with EOS.Umbilical cord blood was collected immediately and peripheral venous blood was collected for culture within 24 hours after infants were born.Inflammatory indicators were detected at 0-<24 h，24-<48 h，and 48-72 h after the birth of premature infants，including hypersensitive C-reactive protein（hs-CRP），procalcitonin（PCT），white blood cell count（WBC），and platelet count（PLT）.The inflammatory indexes of premature infants with positive and negative results of cord blood culture were compared at different time periods mentioned above.After positive alarm of cord blood and peripheral blood culture，the bacterial identification was performed.The treatment and outcome of EOS infants with positive cord blood culture were recorded.Results　There was no significant difference in the positive rates of cord blood culture〔19.6%（20/102）〕and peripheral blood culture〔16.7%（17/102）〕in infants with EOS（P>0.05），and the positive rates of cord blood culture and peripheral blood culture in infants without EOS were both 0.EOS infants with positive results of cord blood culture had a higher level of hs-CRP and PCT than those with negative results at 0-<24 h，24-<48 h，and 48-72 h（P<0.05）.EOS infants with positive results of cord blood culture had a lower level of WBC than those with negative results at 0-<24 h（P<0.05）.EOS infants with positive results of cord blood culture had a lower level of PLT than those with negative results at 48-72 h（P<0.05）.A total of 20 pathogenic bacteria were identified in the cord blood culture of infants with EOS，including 15 strains of Gram-positive bacteria（including 10 strains of Staphylococcus，3 strains of Listeria monocytogenes，and 2 strains of Streptococcus lactis），and 5 Gram-negative strains（including 3 strains of Escherichia coli，1 strain of Klebsiella pneumoniae subpneumoniae，and 1 strain of Acinetobacter baumannii）.A total of 17 pathogenic bacteria were identified in peripheral blood culture，of which 15 cases were consistent with the identification results of cord blood culture.Conclusion　The positive rate of cord blood culture is similar to the positive rate of peripheral blood culture in infants with EOS，but cord blood is convenient for blood collection and has sufficient blood retention，which is conducive to the diagnosis of EOS.After the newborn is born，if hs-CRP and PCT increase，WBC and PLT decrease，suggesting that the infant may have EOS and antibiotics can be adjusted as appropriate.The anti-infective therapy，further diagnosis and treatment plan should be formulated after the bacterial culture results come out.

Key words: Sepsis, Early-onset sepsis, Intrauterine infection, Cord blood, Peripheral blood culture, Bacteria

摘要： 背景　新生儿败血症是导致早产儿死亡的主要原因之一，尤其是早发型败血症（EOS），因此早诊断、及时治疗尤为重要。血培养是诊断败血症的金标准，但新生儿外周血采血量有限，而脐血作为新生儿出生后最早的血液标本，血量充分，且收集方便。目的　探讨EOS早产儿脐血培养的临床应用价值，同时观察脐血培养阳性患儿炎性指标变化，以期为EOS的临床治疗提供依据。方法　选取天津医科大学第二医院2018年6月—2019年6月疑似或确诊宫内感染的产妇及其早产儿（胎龄≤37周）共150对，其中102例早产儿诊断为EOS，48例早产儿未诊断为EOS。于早产儿出生后即刻留取脐血，出生后24 h内留取外周静脉血，行血培养。分别于EOS患儿出生后0~<24、24~<48、48~72 h检测炎性指标〔超敏C反应蛋白（hs-CRP）、降钙素原（PCT）、白细胞计数（WBC）、血小板计数（PLT）〕，比较脐血培养阳性与脐血培养阴性EOS患儿不同时间炎性指标。EOS患儿脐血、外周血培养报警阳性后，进行脐血、外周血细菌鉴定。结果　EOS患儿脐血培养阳性率〔19.6%（20/102）〕与外周血培养阳性率〔16.7%（17/102）〕比较，差异无统计学意义（P>0.05）。非EOS患儿脐血、外周血培养阳性率均为0。脐血培养阳性EOS患儿出生后0~<24、24~<48、48~72 h hs-CRP、PCT高于脐血培养阴性EOS患儿（P<0.05）；脐血培养阳性EOS患儿出生后0~<24 h WBC低于脐血培养阴性EOS患儿（P<0.05）；脐血培养阳性EOS患儿出生后48~72 h PLT低于脐血培养阴性EOS患儿（P<0.05）。EOS患儿脐血培养共鉴定出20株致病菌，其中革兰阳性菌15株（包括葡萄球菌10株、单核细胞增生李斯特菌3株、无乳链球菌2株），革兰阴性菌5株（包括大肠埃希菌3株、肺炎克雷伯菌肺炎亚种1株、鲍曼不动杆菌1株）。EOS患儿外周血培养共鉴定出17株致病菌，其中15例患儿外周血培养鉴定结果与脐血培养鉴定结果一致。结论　EOS患儿脐血培养阳性率与外周血培养阳性率相似，但脐血取血方便，留血量充分，有利于进行EOS的诊断。新生儿出生后若hs-CRP、PCT升高，WBC、PLT降低，提示可能存在EOS，可酌情调整抗生素用药，并依据细菌培养结果及时确定抗感染疗程及进一步诊治方案。

关键词: 败血症, 早发型败血症, 宫内感染, 脐带血, 外周血培养, 细菌