Prevalence of carbapenem resistance and carbapenemase production among Enterobacteriaceae isolated from urine in the UK: results of the UK infection-Carbapenem Resistance Evaluation Surveillance Trial (iCREST-UK)

Research output: Contribution to journalArticlepeer-review


  • Neil Woodford
  • Li Xu-McCrae
  • Shazad Mushtaq
  • Houdini Ho Tin Wu
  • Matthew J Ellington
  • Owen Lancaster
  • Frances Davies
  • Hugo Donaldson
  • G Gopal Rao
  • Anita Verma
  • David W Wareham
  • Holly Ciesielczuk
  • Gregory G Stone
  • Paurus M Irani
  • Simon Bracher

Colleges, School and Institutes

External organisations

  • Antimicrobial Resistance and Healthcare Associated Infections (AMRHAI) Reference Unit, National Infection Service, Public Health England, London NW9 5EQ, UK.
  • Specialist Microbiology Service, National Infection Service, Public Health England, Birmingham B9 5SS, UK.
  • Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom.
  • Imperial College Healthcare NHS Trust
  • Department of Hematology, London North West Healthcare NHS Trust, London, United Kingdom.
  • King's College Hospital NHS Foundation Trust, Denmark Hill, London, SE5 9RS UK.
  • Barts Health NHS Trust
  • AstraZeneca, Waltham, MA, USA.
  • AstraZeneca, London, UK.
  • IndigoMedical Limited, Milton Keynes, UK.


Objectives: Although carbapenem susceptibility testing has been recommended for all Enterobacteriaceae from clinical specimens, for practical reasons a carbapenem is not included in many primary antibiotic panels for urine specimens. The 'iCREST' study sought carbapenemase-producing Enterobacteriaceae (CPE) in routine urine specimens yielding Gram-negative growth in five diagnostic laboratories in the UK. We sought also to compare locally and centrally determined MICs of meropenem and ceftazidime/avibactam.

Methods: Positive growth from up to 2000 urine specimens per laboratory was plated onto chromID® CARBA SMART agar. Suspected CPE colonies were tested locally by Etest for susceptibility to meropenem and ceftazidime/avibactam, and referred to central laboratories for PCR confirmation of CPE status and microbroth MIC determination.

Results: Twenty-two suspected CPE were identified from 7504 urine specimens. Ten were confirmed by PCR to have NDM (5), IMP (2), KPC (2) or OXA-48-like (1) carbapenemases. Locally determined ceftazidime/avibactam MICs showed complete categorical agreement with those determined centrally by microbroth methodology. The seven ceftazidime/avibactam-resistant isolates (MICs ≥256 mg/L) had NDM or IMP metallo-carbapenemases.

Conclusions: The frequency of confirmed CPE among Gram-negative urinary isolates was low, at 0.13% (10/7504), but CPE were found in urines at all five participating sites and the diversity of carbapenemase genes detected reflected the complex epidemiology of CPE in the UK. These data can inform local policies about the cost-effectiveness and clinical value of testing Gram-negative bacteria from urine specimens routinely against a carbapenem as part of patient management and/or infection prevention and control strategies.


Original languageEnglish
JournalJournal of Antimicrobial Chemotherapy
Early online date15 Dec 2017
Publication statusE-pub ahead of print - 15 Dec 2017


  • antibiotics, Polymerase Chain Reaction, carbapenem