BACKGROUND:Carbapenem-resistant Enterobacteriaceae are an emerging global infection threat. However, there are few data describing their clinical importance in children. AIM:This retrospective study reviewed the prevalence and resistance mechanisms of carbapenem-resistant Enterobacteriaceae grown from clinical and surveillance samples in a large tertiary referral children's hospital in the UK. METHODS:Carbapenem-resistant Enterobacteriaceae were sought in specimens submitted for diagnostic and surveillance purposes at Alder Hey Children's NHS Foundation Trust, Liverpool, between September 2011 and August 2012. Mechanisms of resistance were identified using phenotypic and/or molecular methods. Variable number tandem repeat profiling was used to type carbapenemase-producing strains. FINDINGS:During the 12-month study period, carbapenem-resistant Enterobacteriaceae were recovered from 24 patients. Five isolates were from clinical diagnostic specimens whereas 19 of 421 patients had positive rectal surveillance swabs (4.5%). Of the 24 isolates, seven (all Klebsiella spp.) harboured carbapenemases: three had blaKPC and four blaNDM, whereas 17 had resistance due to combinations of AmpC or extended-spectrum β-lactamase activity plus impermeability. CONCLUSION:Carbapenem-resistant Enterobacteriaceae and, in particular, those with carbapenemases, are an emerging infection problem in a major paediatric hospital in the UK. Active surveillance is required to monitor and control their spread.