Antibiotic Resistance Monitoring & Reference Laboratory, HPA Microbiology Services-Colindale, London, UK.
J Antimicrob Chemother. 2011 Sep;66(9):2002-5. doi: 10.1093/jac/dkr226. Epub 2011 Jun 13.
The global accumulation of Escherichia coli with CTX-M extended-spectrum β-lactamases partly reflects the dissemination of clonal lineages, notably ST131 and ST405. More recently, E. coli have emerged that produce NDM carbapenemase. We sought to determine the clonal diversity of E. coli with this enzyme from English hospitals, and to compare them with isolates from Pakistan and India.
The 18 NDM-positive E. coli were from hospitals in England (n = 10), Pakistan (n = 7) and India (n = 1). Isolates were compared by phylogenetic grouping, multilocus sequence typing and PFGE of XbaI-digested DNA. Isolates were screened by PCR for acquired AmpC genes, bla(CTX-M), and the 16S rRNA methylase genes armA and rmtC.
Most of the isolates belonged to phylogenetic groups B1 (n = 9) or D (n = 7); two were group A and none was group B2. Nine isolates from England and Pakistan belonged to the B1 lineage ST101, with seven of these clustering at >77% similarity by PFGE. Other lineages included ST405 (n = 3, group D), ST648 (n = 3, group D), the ST23 complex (one each of ST90 and ST410, both group A) and ST156 (n = 1, group D). Sixteen of 18 isolates had a group 1 CTX-M gene, 13 had a CIT-type acquired AmpC, and 16 had either or both of armA and rmtC.
The E. coli isolates producing NDM-1 carbapenemase belonged to six sequence types and included diverse clonal lineages. Nevertheless, isolates of B1-ST101 accounted for half the collection, and included isolates from both England and Pakistan. None of the isolates belonged to ST131 or to phylogroup B2.
具有 CTX-M 型扩展谱β-内酰胺酶的大肠杆菌在全球的积累部分反映了克隆谱系的传播，特别是 ST131 和 ST405。最近，出现了能产生 NDM 碳青霉烯酶的大肠杆菌。我们试图确定英国医院中具有这种酶的大肠杆菌的克隆多样性，并将其与来自巴基斯坦和印度的分离株进行比较。
18 株 NDM 阳性大肠杆菌来自英国（n=10）、巴基斯坦（n=7）和印度（n=1）的医院。通过进化群、多位点序列分型和 XbaI 消化 DNA 的 PFGE 对分离株进行比较。通过 PCR 筛选分离株获得获得性 AmpC 基因、bla(CTX-M)和 16S rRNA 甲基化酶基因 armA 和 rmtC。
大多数分离株属于进化群 B1（n=9）或 D（n=7）；两组为 A，没有一组为 B2。来自英国和巴基斯坦的 9 株分离株属于 B1 谱系 ST101，其中 7 株通过 PFGE 聚类相似度大于 77%。其他谱系包括 ST405（n=3，D 组）、ST648（n=3，D 组）、ST23 复合物（A 组各 1 株，分别为 ST90 和 ST410）和 ST156（n=1，D 组）。18 株分离株中有 16 株携带 1 型 CTX-M 基因，13 株携带 CIT 型获得性 AmpC，16 株分离株均携带 armA 和 rmtC 或其中之一。
产生 NDM-1 碳青霉烯酶的大肠杆菌分离株属于 6 种序列类型，包括不同的克隆谱系。尽管如此，B1-ST101 分离株占了一半，包括来自英国和巴基斯坦的分离株。没有分离株属于 ST131 或 B2 进化群。
