Molecular characterization of blaNDM-1 in an Acinetobacter baumannii strain isolated in Germany in 2007
Molecular characterization of blaNDM-1 in an Acinetobacter baumannii strain isolated in Germany in 2007
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DOI：
10.1093/jac/dkr256
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发表时间：
2011-09-01
影响因子：
5.2
通讯作者：
Higgins, Paul G.
中科院分区：
文献类型：
--
作者：
Pfeifer, Yvonne;Wilharm, Gottfried;Higgins, Paul G.
目的：为了解2007年德国某医院分离的鲍曼不动杆菌金属β-内酰胺酶基因bla（NDM-1）的遗传环境，对分离菌株进行药敏试验，并通过PCR扩增和测序鉴定耐药基因。通过肉汤交配试验和质粒转化检测β-内酰胺类耐药的可转移性。用引物步移法分析了bla（NDM-1）的遗传背景。A的类型结果：多重耐药鲍曼不动杆菌的基因外回文序列重复PCR（repe-PCR）扩增结果与临床分离株一致，表明多重耐药鲍曼不动杆菌基因外回文序列重复PCR扩增结果与临床分离株一致。β-内酰胺酶基因bla（NDM-1）和内源性bla（OXA-64），但不含常位于上游的插入序列ISAba 1。通过接合和转化转移碳青霉烯耐药性失败。分离的质粒DNA与bla（NDM）探针杂交不成功。鸟枪法克隆的全基因组DNA和序列分析表明，bla（NDM-1）位于ISAba 125的两个插入元件之间。此外，这种含有bla（NDM-1）的转座子结构被整合到编码推定的A.结论：该株鲍曼不动杆菌金属β-内酰胺酶基因bla（NDM-1）与鲍曼不动杆菌主要易化剂超家族（MFS）代谢产物/H+同向转运体的表达有关。鲍曼不动杆菌菌株整合在染色体上的一个新的转座子结构上，该结构由两个拷贝的插入序列ISAba 125组成。bla（NDM-1）的遗传环境的可变性可能促进该基因在许多革兰氏阴性细菌物种内的快速传播。
Objectives: To investigate the genetic environment of the metallo-beta-lactamase gene bla(NDM-1) in an Acinetobacter baumannii isolated in 2007 in a German hospital.Methods: Antimicrobial susceptibility testing was performed and resistance genes were characterized by PCR amplification and sequencing. Transferability of beta-lactam resistance was tested by broth mating assays and transformation of plasmids. The genetic background of bla(NDM-1) was analysed by primer walking. Typing of the A. baumannii strain was performed by repetitive extragenic palindromic sequence-based PCR (rep-PCR) using the DiversiLab system.Results: The multidrug-resistant A. baumannii isolate harboured beta-lactamase genes bla(NDM-1) and intrinsic bla(OXA-64), but without the insertion sequence ISAba1 often located upstream. Transfer of carbapenem resistance by conjugation and transformation failed. Hybridization of isolated plasmid DNA with bla(NDM) probes was not successful. Shotgun cloning of whole genomic DNA and sequence analyses revealed that bla(NDM-1) was located between two insertion elements of ISAba125. Furthermore, this bla(NDM-1)-containing transposon structure was integrated into a chromosomal gene encoding a putative A. baumannii major facilitator superfamily (MFS) metabolite/H+ symporter.Conclusions: The metallo-beta-lactamase gene bla(NDM-1) in this A. baumannii strain was integrated in the chromosome on a new transposon structure composed of two copies of insertion sequence ISAba125. The variability of the genetic environment of bla(NDM-1) likely facilitates the rapid dissemination of this gene within many Gram-negative bacterial species.