基于全基因组测序的儿科病区黏质沙雷菌血培养阳性的溯源调查与处置

Traceability investigation and disposal of positive blood cultures of Serratia marcescens in pediatric wards based on whole-genome sequencing

    摘要
  • 摘要:
    目的 探讨黏质沙雷菌血培养阳性患儿流行病学和分子流行病学特征, 为医院防控措施的制定提供科学依据。
    方法 对2024年10月郑州大学第三附属医院儿科病区11例血培养黏质沙雷菌阳性患儿开展流行病学调查, 采用全基因组测序方法分析菌株的耐药基因、毒力基因、质粒携带情况、菌株同源性以及可能的传播途径。
    结果 11例黏质沙雷菌血培养阳性患儿中, 2例确诊为医院感染败血症, 9例为血培养污染；11株黏质沙雷菌菌株均携带aac(6′)-Ic等7个相同的耐药基因和cheY等4个毒力基因, 其中9株携带IncFII质粒。基于全基因组测序的单核苷酸多态性(SNP)系统发育树和贝叶斯时序树表明, 11株菌株间遗传差异较小(≤16 SNPs), 菌株间可能存在共同的传染源。共采集相关医务人员及环境样本125份, 但均未检出黏质沙雷菌。在采取更换水槽、水龙头, 将患儿血液采集皮肤消毒剂更换为氯己定-乙醇, 加强手卫生监管等集束化感染防控措施后, 一个月内未再出现新病例。
    结论 此次儿科病区黏质沙雷菌血培养集中检出事件，水池污染、皮肤消毒剂可能是污染源和传播媒介，由于消毒不彻底、医护人员手卫生不到位、人员交叉等导致病原体在病区间传播，及时采取集束化感染防控措施可以防止感染事件的进一步扩散。

     

    Abstract:
    OBJECTIVE To explore the epidemiological and molecular epidemiological characteristics of children with positive blood cultures for Serratia marcescens, providing a scientific basis for formulating hospital prevention and control measures.
    METHODS An epidemiological investigation was conducted on 11 children with positive blood cultures for S. marcescens in the pediatric ward of the Third Affiliated Hospital of Zhengzhou University in Oct. 2024, whole-genome sequencing was used to analyze the drug resistance genes, virulence genes, plasmid carriage, strain homology and possible transmission routes of the strains.
    RESULTS Among the 11 children with positive blood cultures for S. marcescens, 2 were diagnosed with hospital-associated sepsis, and 9 were cases of blood culture contamination. The 11 S. marcescens strains carried 7 identical drug resistance genes, including aac(6)-Ic, and four virulence genes, including cheY. Among them, 9 strains carried the IncFII plasmid. The single nucleotide polymorphism (SNP) phylogenetic tree and Bayesian time series tree based on whole-genome sequencing indicated minimal genetic differences (≤16 SNPs) among the 11 strains, suggesting a possible common source of infection. A total of 125 samples were collected from relevant medical staff and the environment, but no S. marcescens was detected. After implementing bundled infection prevention and control measures, such as replacing sinks and faucets, changing the skin disinfectant for blood collection in children to chlorhexidine-ethanol, and strengthening hand hygiene supervision, no new cases emerged within one month.
    CONCLUSIONS Investigation revealed that the transmission cluster of blood culture-positive S. marcescens across pediatric wards was linked to contaminated sinks, with inadequately disinfected skin antiseptics may a potential vehicle for transmission. Contributing factors included inadequate environmental disinfection, poor hand hygiene compliance, and staff cross-transmission. Effective bundled infection prevention and control measures can prevent the further spread of infections.

     

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