4th Department of Internal Medicine, Athens University School of Medicine, University General Hospital ATTIKON, 1 Rimini Str., 124 62 Chaidari, Greece.
Int J Antimicrob Agents. 2011 Nov;38(5):390-7. doi: 10.1016/j.ijantimicag.2011.06.014. Epub 2011 Aug 27.
The molecular epidemiology of VIM-producing Enterobacteriaceae isolated at the beginning of an epidemic in the Intensive Care Unit (ICU) of a university hospital in Athens, Greece, was studied. All Gram-negative organisms isolated from March 2004 to November 2005 positive for metallo-β-lactamase (MBL) production were submitted to polymerase chain reaction (PCR) and sequencing, to repetitive sequence-based PCR (Rep-PCR) for molecular typing, and to S1 nuclease digestion for plasmid DNA characterisation. Conjugation experiments and isoelectric focusing were performed to identify co-existing β-lactamases. Amongst 23 patients, 12 suffered one or more clinical infections. Eighty-two isolates representing one isolate per clone, source and ICU patient were studied, including Klebsiella pneumoniae (77), Enterobacter cloacae (2), Citrobacter freundii (1) and Pseudomonas aeruginosa (2). High clonal diversity was detected amongst the K. pneumoniae, with 10 distinct clones identified. Conjugation was successful in 54.5% of K. pneumoniae, and five different-sized plasmids were detected. All K. pneumoniae and both E. cloacae isolates shared the same bla(VIM-1)-containing class 1 integron structure also carrying aacA7, dhfrI and aadA1 gene cassettes. The C. freundii isolate carried a different integron that included bla(VIM-1) and aac(6')-IIc. Both P. aeruginosa isolates were positive for bla(VIM-2). It was not possible to identify specific clones with the potential to cause clinical infections. In conclusion, a multiclonal cluster of MBL-producers was responsible for the first cases of colonisation and/or infection in the ICU. A single integron structure, common in Greek hospitals, efficiently disseminated between clones and species, suggesting that the epidemic was mainly the result of successful horizontal transfer of mobile genetic material rather than the result of horizontal transfer of one or a few clones.
在希腊雅典一家大学医院的重症监护病房（ICU）爆发疫情之初，研究了产 VIM 肠杆菌科的分子流行病学。从 2004 年 3 月至 2005 年 11 月，所有对金属-β-内酰胺酶（MBL）生产呈阳性的革兰氏阴性菌均进行聚合酶链反应（PCR）和测序、重复序列基 PCR（Rep-PCR）进行分子分型和 S1 核酸酶消化进行质粒 DNA 特征分析。进行了接合实验和等电聚焦以鉴定共存的β-内酰胺酶。在 23 名患者中，有 12 名患者患有一次或多次临床感染。研究了代表每个克隆、来源和 ICU 患者的 82 个分离物，包括肺炎克雷伯菌（77）、阴沟肠杆菌（2）、弗氏柠檬酸杆菌（1）和铜绿假单胞菌（2）。在肺炎克雷伯菌中检测到高度克隆多样性，确定了 10 个不同的克隆。54.5%的肺炎克雷伯菌成功进行了接合，检测到 5 种不同大小的质粒。所有肺炎克雷伯菌和 2 株阴沟肠杆菌分离株都含有相同的 bla(VIM-1) 基因，位于 1 类整合子结构中，该结构还携带 aacA7、dhfrI 和 aadA1 基因盒。弗氏柠檬酸杆菌分离株携带不同的整合子，其中包括 bla(VIM-1)和 aac(6')-IIc。2 株铜绿假单胞菌均携带 bla(VIM-2)。无法确定具有引起临床感染潜力的特定克隆。总之，多克隆 MBL 生产者群是 ICU 定植和/或感染的首例病例的原因。一个普遍存在于希腊医院的单一整合子结构在克隆和物种之间有效地传播，这表明该流行主要是由于移动遗传物质的成功水平转移，而不是一个或几个克隆的水平转移的结果。
