Health Protection Agency, West Midlands Public Health Laboratory, Heart of England NHS Foundation Trust, Bordesley Green East, Birmingham B9 5SS, UK.
J Antimicrob Chemother. 2011 Mar;66(3):505-11. doi: 10.1093/jac/dkq482. Epub 2010 Dec 23.
To establish the prevalence and diversity of clinically significant extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae harbouring bla(CTX-M) in the West Midlands region of the UK.
During a 2 month period, 370 consecutive, non-duplicate isolates were collected from 13 laboratories. Isolates were screened for the presence of bla(CTX-M) by multiplex PCR and genotyped using denaturing HPLC (DHPLC). Clonal relationships were studied by PFGE and O25b-ST131 Escherichia coli were identified by PCR.
Two hundred and ninety-four out of 345 ESBL-producing isolates (85.2%) carried bla(CTX-M). CTX-M group 1 enzymes were expressed in 284 (96.6%) isolates, with the other 10 carrying group 9, 2 and 25/26 genes. All group 1 isolates had bla(CTX-M-15) DHPLC profiles. The bla(CTX-M) E. coli were split into 23 PFGE clusters. The largest cluster (RE1) was indistinguishable from the previously described strain A and all but one harboured bla(CTX-M-15.) A total of 66% of E. coli were O25b-ST131 positive.
The CTX-M-15-producing RE1 clone (strain A) is the predominant clone in the West Midlands. This clone has spread throughout the region since its emergence in an outbreak 3 years earlier. Most, but not all, RE1 isolates belong to the O25b-ST131 lineage, providing further evidence that this lineage plays a pivotal role in the clonal dispersal of CTX-M-15-producing Enterobacteriaceae. Strain A was found to be considerably more heterogeneous than when first described and has acquired greater resistance to gentamicin. Approximately one-third of CTX-M producers represented a wide variety of unrelated strains. The study shows the rapid spread and diversification of CTX-M-producing Enterobacteriaceae over a 3 year period.
在英国西米德兰兹地区建立流行和多样性的临床显著的产超广谱β-内酰胺酶（ESBL）的肠杆菌科，携带bla（CTX-M）。
在两个月的时间内，从 13 个实验室收集了 370 个连续的非重复分离株。通过多重 PCR 筛选 bla（CTX-M）的存在，并通过变性高效液相色谱（DHPLC）进行基因分型。通过 PFGE 研究克隆关系，通过 PCR 鉴定 O25b-ST131 型大肠埃希菌。
在 345 株产 ESBL 的分离株中，有 294 株（85.2%）携带 bla（CTX-M）。CTX-M 组 1 酶在 284 株（96.6%）分离株中表达，其余 10 株携带组 9、2 和 25/26 基因。所有组 1 分离株的 bla（CTX-M-15）DHPLC 图谱均相同。bla（CTX-M）大肠杆菌被分为 23 个 PFGE 簇。最大的簇（RE1）与之前描述的菌株 A 无法区分，除了一个之外，所有的菌株都携带 bla（CTX-M-15）。大肠杆菌的 66%为 O25b-ST131 阳性。
CTX-M-15 产生的 RE1 克隆（菌株 A）是西米德兰兹地区的主要克隆。该克隆自 3 年前爆发以来已在该地区传播。虽然大多数但并非全部的 RE1 分离株属于 O25b-ST131 谱系，这进一步证明该谱系在 CTX-M-15 产生的肠杆菌科的克隆传播中起着关键作用。与最初描述的菌株相比，菌株 A 发现具有更大的异质性，并获得了对庆大霉素的更高抗性。大约三分之一的 CTX-M 产生者代表了广泛的无关菌株。该研究表明，CTX-M 产生的肠杆菌科在 3 年内迅速传播和多样化。
