Servicio de Microbiología, Hospital Vall d'Hebron, Barcelona, Spain.
Int J Antimicrob Agents. 2012 Jun;39(6):514-7. doi: 10.1016/j.ijantimicag.2012.01.006. Epub 2012 Apr 4.
Seven Enterobacter cloacae isolates and seven Klebsiella pneumoniae isolates harbouring a phenotype compatible with the production of a metallo-β-lactamase were recovered between 2009 and 2011 in three Intensive Care Units of Hospital Vall d'Hebron (Barcelona, Spain). The presence of bla(VIM), bla(IMP), bla(NDM), bla(CTX-M), aac(6')-Ib, qnrA, qnrB and qnrS genes was screened by polymerase chain reaction (PCR) and sequencing. Clonal relatedness of the isolates was assessed by pulsed-field gel electrophoresis (PFGE) and, in the case of K. pneumoniae isolates, by multilocus sequence typing (MLST). PCR-based replicon typing, Southern hybridisation, plasmid double-locus sequence typing and MOB relaxase classification methods were used to identify and characterise the plasmids carrying the resistance genes. Transferability of the identified plasmids was tested by conjugation assays. All 14 isolates were found to carry bla(VIM-1), bla(CTX-M-9) (except one isolate), aac(6')-Ib and qnrA genes. Clonality assessment demonstrated that E. cloacae isolates were distributed in three clonal clusters, whereas all of the K. pneumoniae isolates belonged to one unique clone, identified as sequence type ST252. All studied isolates harboured a large conjugative IncHI2 MOB(H11) plasmid carrying all of the detected resistance genes. Plasmid DNA analysis showed that all of them belonged to the ST1 IncHI2 plasmid cluster and shared the same relaxase partial sequence. In conclusion, the present study describes the dissemination within a hospital of multiresistant E. cloacae and K. pneumoniae isolates producing VIM-1. A complex clonal epidemiology of the E. cloacae isolates was observed and plasmid DNA analysis strongly supports horizontal exchanges of the same IncHI2 plasmid between different strains and species.
2009 年至 2011 年期间，在西班牙巴塞罗那 Vall d'Hebron 医院的三个重症监护病房中，共分离出 7 株阴沟肠杆菌和 7 株产金属β-内酰胺酶表型的肺炎克雷伯菌。采用聚合酶链反应（PCR）和测序法筛选 bla(VIM)、bla(IMP)、bla(NDM)、bla(CTX-M)、aac(6')-Ib、qnrA、qnrB 和 qnrS 基因。通过脉冲场凝胶电泳（PFGE）评估分离株的克隆相关性，对于肺炎克雷伯菌分离株，还采用多位点序列分型（MLST）进行评估。采用基于 PCR 的复制子分型、Southern 杂交、质粒双重位点序列分型和 MOB 松弛酶分类方法鉴定和描述携带耐药基因的质粒。通过接合试验测试鉴定出的质粒的可转移性。所有 14 株分离株均携带 bla(VIM-1)、bla(CTX-M-9)（除一株外）、aac(6')-Ib 和 qnrA 基因。克隆性评估表明，阴沟肠杆菌分离株分布在三个克隆群中，而所有肺炎克雷伯菌分离株均属于一个独特的克隆，鉴定为 ST252 型序列。所有研究分离株均携带一个大型可接合的 IncHI2 MOB(H11)质粒，携带所有检测到的耐药基因。质粒 DNA 分析表明，它们均属于 ST1 IncHI2 质粒群，并且共享相同的松弛酶部分序列。总之，本研究描述了产 VIM-1 的多药耐药阴沟肠杆菌和肺炎克雷伯菌在医院内的传播。观察到阴沟肠杆菌分离株的复杂克隆流行病学，质粒 DNA 分析强烈支持不同菌株和物种之间相同 IncHI2 质粒的水平交换。
