Variation in the genetic environments of blaCTX-M-15 in Escherichia coli from the faeces of travellers returning to the United Kingdom

Hiran Dhanji, Rajesh Patel, Robert Wall, Michel Doumith, Bharat Patel, Russell Hope, David M. Livermore, Neil Woodford

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Abstract

Objective The genetic surroundings of blaCTX-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 blaCTX-M-15 in the UK. Methods 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 ß-lactamases (ESBLs) were identified by double disc synergy test (DDST). The molecular environments surrounding blaCTX-M-15 were investigated by PCR, DNA sequencing, gene cloning and northern blotting. Results 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 blaCTX-M-15, including 21 belonging to clone ST131. Among these 174 isolates, the environment upstream of blaCTX-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 blaCTX-M-15, resulting in different levels of cephalosporin resistance. Conclusion E. coli with CTX-M-15 ESBL from returning travellers harboured previously seen UK blaCTX-M-15 genetic environments (intact or 24 bp remnant of ISEcp1) as well as blaCTX-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.
Original languageEnglish
Pages (from-to)1005-1012
Number of pages8
JournalJournal of Antimicrobial Chemotherapy
Volume66
Issue number5
DOIs
Publication statusPublished - May 2011

Keywords

  • Anti-Bacterial Agents
  • Blotting, Northern
  • Cefuroxime
  • Cloning, Molecular
  • Culture Media
  • DNA, Bacterial
  • Diarrhea
  • Escherichia coli
  • Feces
  • Humans
  • London
  • Microbial Sensitivity Tests
  • Polymerase Chain Reaction
  • Sequence Analysis, DNA
  • Travel
  • beta-Lactamases

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