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

H. Dhanji, R. Patel, R. Wall, M. Doumith, B. Patel, R. Hope, D. M. Livermore, N. Woodford
2011 Journal of Antimicrobial Chemotherapy  
Objective: The genetic surroundings of bla 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. 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
more » ... actose-electrolyte deficient agar and those that produced extended-spectrum b-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. 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 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 ¼108); (ii) various lengths of truncated ISEcp1 (n¼ 58); or (iii) a 24 bp remnant of ISEcp1 (n¼ 8). Two different promoters were found to transcribe bla CTX-M-15 , resulting in different levels of cephalosporin resistance. Conclusion: 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.
doi:10.1093/jac/dkr041 pmid:21393166 fatcat:gq5jurel3vhrvcmqrxdhgagnjm