Antibiotic Resistance Monitoring and Reference Laboratory, Health Protection Agency Microbiology Services-Colindale, London, UK.
J Antimicrob Chemother. 2011 May;66(5):1005-12. doi: 10.1093/jac/dkr041. Epub 2011 Feb 24.
The genetic surroundings of bla(CTX-M-15) in Escherichia coli recovered from faeces of travellers returning to the UK from overseas were compared with those among established UK strains to provide further insights into the spread of bla(CTX-M-15) in the UK.
From August 2006 to January 2008, 1031 faecal specimens were collected at the North West London NHS Trust from general practice patients with a clinical history of diarrhoea following recent international travel. Cefuroxime-resistant E. coli were isolated on cystine-lactose-electrolyte deficient agar and those that produced extended-spectrum β-lactamases (ESBLs) were identified by double disc synergy test (DDST). The molecular environments surrounding bla(CTX-M-15) were investigated by PCR, DNA sequencing, gene cloning and northern blotting.
182/1031 (18%) E. coli isolated from returning travellers gave a positive DDST, and were confirmed by PCR to produce CTX-M ESBLs; 174 (96%) had bla(CTX-M-15), including 21 belonging to clone ST131. Among these 174 isolates, the environment upstream of bla(CTX-M-15) consisted of either: (i) an intact ISEcp1 (n = 108); (ii) various lengths of truncated ISEcp1 (n = 58); or (iii) a 24 bp remnant of ISEcp1 (n = 8). Two different promoters were found to transcribe bla(CTX-M-15), resulting in different levels of cephalosporin resistance.
E. coli with CTX-M-15 ESBL from returning travellers harboured previously seen UK bla(CTX-M-15) genetic environments (intact or 24 bp remnant of ISEcp1) as well as bla(CTX-M-15) genetic environments previously unseen in the UK (various lengths of truncated ISEcp1), which suggest overseas acquisition and highlight the difficulty of control in a time of population mobility and travel.
比较从海外旅行返回英国的旅行者粪便中分离出的大肠埃希菌bla(CTX-M-15)的遗传环境与英国已建立的bla(CTX-M-15)的遗传环境，以进一步了解 bla(CTX-M-15)在英国的传播。
2006 年 8 月至 2008 年 1 月，西北伦敦国民保健服务信托基金会（North West London NHS Trust）从有腹泻临床病史的全科医学患者粪便中收集了 1031 份标本，这些患者近期有国际旅行史。在胱氨酸-乳糖-电解质缺乏琼脂上分离出头孢呋辛耐药的大肠埃希菌，并通过双碟协同试验（DDST）鉴定产生超广谱β-内酰胺酶（ESBLs）的菌株。通过 PCR、DNA 测序、基因克隆和 Northern blot 分析bla(CTX-M-15)周围的分子环境。
从返回旅行者中分离出的 1031 株大肠埃希菌中有 182 株（18%）DDST 阳性，PCR 证实这些菌株产生 CTX-M ESBLs；174 株（96%）携带 bla(CTX-M-15)，其中 21 株属于 ST131 克隆。在这 174 株分离株中，bla(CTX-M-15)上游的环境包括：（i）完整的 ISEcp1（n=108）；（ii）不同长度的截短 ISEcp1（n=58）；或（iii）ISEcp1 的 24 个碱基残基（n=8）。发现两种不同的启动子转录 bla(CTX-M-15)，导致不同水平的头孢菌素耐药性。
来自旅行者的携带 CTX-M-15 ESBL 的大肠埃希菌携带先前在英国看到的 bla(CTX-M-15)遗传环境（完整或 ISEcp1 的 24 个碱基残基）以及以前在英国未见过的 bla(CTX-M-15)遗传环境（不同长度的截短 ISEcp1），这表明海外获得的细菌以及在人口流动和旅行时代控制细菌的困难。
