State Key Laboratory of Biotherapy, Sichuan University, Chengdu, PR China.
West China Hospital, Sichuan University, Chengdu, PR China.
J Med Microbiol. 2011 Apr;60(Pt 4):435-441. doi: 10.1099/jmm.0.026997-0. Epub 2010 Dec 16.
Escherichia coli clinical isolate WCE307 was found to belong to phylogroup B2, O25b and sequence type (ST) 131 and had blaCTX-M-65, which was carried by an IncN conjugative plasmid, pWCE307. On pWCE307, the ISEcp1Δ-blaCTX-M-65-IS903D-ironΔ structure was located in a Tn1722-like element flanked by 5 bp direct target repeats. This context was highly similar to that on pKC396, an IncN plasmid from E. coli isolate KC396 of ST131 from Germany. The Tn1722-like elements carrying blaCTX-M-65 on pWCE307 and pKC396 are likely to be hybrids of Tn1722 and Tn5051, resulting from double crossover at the res sites and the tnpA genes. The left end of the Tn1722-like elements was partially missing. As ISEcp1 and Tn1722 were both incomplete, blaCTX-M-65 might have been trapped in this context. A plasmid multilocus sequence typing (pMLST) scheme with five targets, repN, stbB, traI, traB and the korB-orfI spacer region, was developed for IncN plasmid typing. pMLST revealed that the five alleles of pWCE307 and pKC396 were identical, indicating that WCE307 and KC396 are likely to have originated very recently from a common strain, suggesting the international spread of blaCTX-M-65 mediated by ST131 E. coli.
大肠杆菌临床分离株 WCE307 被发现属于 B2 群、O25b 和序列型（ST）131，并且带有 blaCTX-M-65，该 blaCTX-M-65 由一个 IncN 可接合质粒 pWCE307 携带。在 pWCE307 上，ISEcp1Δ-blaCTX-M-65-IS903D-ironΔ 结构位于 Tn1722 样元件中，该元件由 5bp 直接靶重复序列侧翼。这种情况与德国 ST131 大肠杆菌分离株 KC396 的 IncN 质粒 pKC396 上的情况非常相似。pWCE307 和 pKC396 上携带 blaCTX-M-65 的 Tn1722 样元件很可能是 Tn1722 和 Tn5051 的杂种，这是由于 res 位点和 tnpA 基因的双交换导致的。Tn1722 样元件的左端部分缺失。由于 ISEcp1 和 Tn1722 都是不完整的，blaCTX-M-65 可能被困在这种情况下。开发了一种带有五个靶标（repN、stbB、traI、traB 和 korB-orfI 间隔区）的 IncN 质粒的质粒多位点序列分型（pMLST）方案。pMLST 显示，pWCE307 和 pKC396 的五个等位基因完全相同，表明 WCE307 和 KC396 很可能源自一个共同的菌株，这表明 ST131 大肠杆菌介导的 blaCTX-M-65 的国际传播。
