老年血流感染患者分离鲍曼不动杆菌全基因组分析

Whole genome analysis of Acinetobacter baumannii isolated from an elderly patient with bloodstream infections

中文关键词: 鲍曼不动杆菌  全基因组测序  生物信息学  耐药基因

英文关键词: Acinetobacter baumannii  whole genome sequencing  bioinformatics  resistant gene

中文摘要:

      目的 对老年患者血培养分离的广泛耐药鲍曼不动杆菌行全基因组测序及毒力和耐药基因分析.方法 2023年1月从一例老年重症肺炎患者的血培养标本中分离XDR鲍曼不动杆菌AB_HD1,进行鉴定和药敏试验,采用二代+三代测序技术进行细菌全基因组测序,再通过生物信息学方法进行质控、组装和分析.结果 菌株组装出一个染色体和3个质粒,全基因组的可移动元件包含17个基因组岛、6个前噬菌体、1个整合子、7个插入序列和7个转座子.该菌株的MLST分型为ST208,药敏实验提示,除多黏菌素敏感外,该菌对临床常用抗菌素包括β内酰胺类、喹诺酮类、大环内酯类、四环素类、氨基糖苷类、磺胺类抗菌药物等均耐药.AB-HD1菌株有3个耐药基因组岛,耐药基因分析包括blaADC-25、blaOXA-66、blaTEM-1D、blaOXA-23、armA、aadA1、aac(6′)-Ib3、aph(3′)-Ia、aac(3)-Ia、aadA24、aph(3″)-Ib、aph(6)-Id、mph(E)、msr(E)、catB8、sul1、tet(B)、qacE、gyrA突变.它的毒力基因参与粘附、生物膜形成、营养摄取、毒素、免疫逃逸因子、双组分调控系统、分泌效应蛋白杀伤宿主细胞.通过SNP系统进化树分析发现特定进化分支的菌株携带共同的耐药基因.结论 鲍曼不动杆菌基因组有较高的可塑性,耐药基因周围有插入序列、转座酶、整合酶基因,其可通过水平转移和基因组重组获取外源遗传信息.针对携带特定耐药基因的进化分支,需加强感染防控措施.

英文摘要:

      Objective To perform whole-genome sequencing(WGS)and analyze virulence and resistance gene profiles of an extensively drug-resistant Acinetobacter baumannii(XDR-AB)strain isolated from a blood culture of an elderly patient.Methods In January 2023,an XDR-AB strain AB_HD1 was isolated from a blood culture sample of an elderly patient with se-vere pneumonia.The strain was identified,and antimicrobial susceptibility testing(AST)was performed.The whole genome of bacteria was sequenced using second-generation and third-generation sequencing technologies,and then quality control,as-sembly and analysis were carried out through bioinformatics methods.Results The strain assembled a chromosome and three plasmids.The mobile genetic elements in the genome included 17 genomic islands,6 prophages,1 integron,7 insertion se-quences,and 7 transposons.The multilocus sequence typing(MLST)of this strain was ST208.The drug sensitivity test indi-cates that,in addition to being sensitive to polymyxin,the strain was resistant to commonly used antibiotics in clinical practice,including β-lactam,quinolones,macrolides,tetracyclines,aminoglycosides,and sulfonamides.The AB-HD1 strain has three drug-resistant genomic islands.Drug-resistant genes were found,including blaADC-25、blaOXA-66、blaTEM-1D、blaOXA-23、armA、aadA1、aac(6′)-Ib3、aph(3′)-Ia、aac(3)-Ia、aadA24、aph(3″)-Ib、aph(6)-Id、mph(E)、msr(E)、catB8、sul1、tet(B)、qacE、gyrA mutations.The virulence genes of the strain were involved in adhesion,biofilm formation,nutrient uptake,toxins,immune escape factors,two-component regulatory systems,and secretion of effector proteins to kill host cells.Phylogenetic analysis based on single-nucleotide polymorphisms(SNPs)revealed that the strain within a specific evolutionary clade shared common resistance genes.Conclusion The Acinetobacter baumannii exhibits high genomic plasticity.There are insertion sequences,transposase and integrase genes around the drug resistance genes.It can obtain exogenous genetic informa-tion through horizontal transfer and genomic recombination.For evolutionary branches carrying specific drug resistance genes,infection prevention and control measures need to be strengthened.