Prevalence and mechanisms of cephalosporin resistance in Enterobacteriaceae in London and South-East England

Nicola A.C. Potz*, Russell Hope, Marina Warner, Alan P. Johnson, David A. Livermore

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

80 Citations (Scopus)


Objectives: To investigate the molecular epidemiology of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) in London and South-East England. Methods: A prospective study involvin g 16 hospital microbiology laboratories in London and South-East England was undertaken over a 12 week period. Each laboratory submitted up to 100 consecutive cephalosporin-resistant Enterobacteriaceae isolates judged clinically significant by microbiology staff. Centralized testing was undertaken to confirm organism identification and cephalosporin resistance and to analyse resistance mechanisms. Results: The predominant mechanism of cephalosporin resistance in isolates from both hospital and community settings was the production of CTX-M-type ESBLs, with CTX-M-producing Escherichia coli as the most numerous resistant organism overall. Other major mechanisms of cephalosporin resistance included production of non-CTX-M ESBLs and AmpC β-lactamases. Most ESBL (both CTX-M and non-CTX-M) producers were multiply resistant to non-β-lactam antibiotics, including trimethoprim, ciprofloxacin and gentamicin. Conclusions: CTX-M enzymes, which were unrecorded in the UK prior to 2000, have become the major mechanism of cephalosporin resistance in Enterobacteriaceae in South-East England. E. coli has overtaken Klebsiella and Enterobacter spp. to become the major host for ESBLs. Due to the multiple antibiotic resistance exhibited by many ESBL-producers, these changes have major implications for antimicrobial therapy.

Original languageEnglish
Pages (from-to)320-326
Number of pages7
JournalJournal of Antimicrobial Chemotherapy
Issue number2
Publication statusPublished - Aug 2006

Bibliographical note

Funding Information:
St Peter’s Hospital, Chertsey: S. Baillie; St Thomas Hospital, London: G. French, K. Shannon; Southampton HPA Laboratory: H. Humphrey; University College Hospital, London: C. Palmer, N. Shetty; Worthing Hospital: H. Plumb. This study was partly sponsored by Merck, Sharp & Dohme (US & UK).


  • CTX-M enzymes
  • E. coli
  • ESBLs


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