Servei de Microbiologia, Hospital de la Santa Creu i Sant Pau, Universitat Autònoma de Barcelona, Institut d'Investigacions Biomèdiques Sant Pau, Barcelona, Spain.
J Antimicrob Chemother. 2011 Oct;66(10):2266-70. doi: 10.1093/jac/dkr286. Epub 2011 Jul 13.
To characterize the vectors involved in the dissemination of bla(CMY-2) genes in clinical isolates of Proteus mirabilis collected between 1999 and 2007.
Plasmid analysis of 19 P. mirabilis carrying ampC genes was performed by PCR-based replicon typing, S1-PFGE and Southern hybridization with ampC and replicon probes. Isolates that could not be characterized were examined for the presence of SXT/R391-like elements. To demonstrate the involvement of these elements in the dissemination of bla(CMY-2), we performed a PCR amplification of the integrase (int) and toxin/antitoxin (TA) genes from SXT/R391-like integrative conjugative elements (ICEs). Later on, I-Ceu-I PFGE gels and hybridization with bla(CMY-2), int and prfC probes were performed. The genetic organization of bla(CMY-2) was also studied.
ampC genes were located on large conjugative plasmids in 11 of the 19 (58%) P. mirabilis studied. However, in eight of these isolates a plasmid was not involved in the mobilization of ampC genes. I-Ceu-I PFGE and hybridization analyses revealed that bla(CMY-2) were chromosomally located in these eight P. mirabilis isolates. The genetic organization of bla(CMY-2) and hybridization analyses revealed that bla(CMY-2) was carried by an ICE almost identical to ICEPmiJpan1 in seven out of these eight isolates.
The prevalence of ICEs carrying bla(CMY-2) was surprisingly high [37% (7 out of 19)]. This is the first study giving prevalence data on ICEs carrying bla(CMY-2) genes. These results suggest the need to study these mobile genetic elements in the context of dissemination of acquired AmpC β-lactamases and also of other β-lactamases, such as extended-spectrum β-lactamases and carbapenemases.
分析 1999 年至 2007 年间收集的奇异变形杆菌临床分离株中 bla(CMY-2)基因传播所涉及的载体。
采用基于 PCR 的复制子分型、S1-PFGE 和 Southern 杂交（针对 ampC 和复制子探针）对携带 ampC 基因的 19 株奇异变形杆菌进行质粒分析。对于无法鉴定的菌株，检测 SXT/R391 样元件的存在。为了证明这些元件在 bla(CMY-2)传播中的作用，我们对 SXT/R391 样整合性接合性元件（ICE）中的整合酶（int）和毒素/抗毒素（TA）基因进行 PCR 扩增。随后，进行 I-Ceu-I PFGE 凝胶电泳和 bla(CMY-2)、int 和 prfC 探针杂交。还研究了 bla(CMY-2)的遗传结构。
在 19 株奇异变形杆菌中，有 11 株（58%）的 ampC 基因位于大型可移动质粒上。然而，在其中 8 株菌中，质粒并没有参与 ampC 基因的转移。I-Ceu-I PFGE 和杂交分析显示，bla(CMY-2)在这 8 株奇异变形杆菌中均位于染色体上。bla(CMY-2)的遗传结构和杂交分析显示，在这 8 株菌中的 7 株中，bla(CMY-2)由一个与 ICEPmiJpan1 几乎相同的 ICE 携带。
携带 bla(CMY-2)的 ICE 的流行率非常高[37%（19 株中有 7 株）]。这是首次对携带 bla(CMY-2)基因的 ICE 进行流行率数据研究。这些结果表明，需要在获得性 AmpC β-内酰胺酶和其他β-内酰胺酶（如扩展谱β-内酰胺酶和碳青霉烯酶）传播的背景下研究这些可移动遗传元件。
