Epidemiology of extended-spectrum beta-lactamase-producing Enterobacteriaceae in a UK district hospital; an observational study

J Hosp Infect. 2012 Aug;81(4):270-7. doi: 10.1016/j.jhin.2012.05.006. Epub 2012 Jun 27.


Background: Extended-spectrum beta-lactamases (ESBLs) are an increasingly important cause of resistance in Gram-negative bacteria throughout the world.

Aim: We investigated the clinical and molecular epidemiology of infections caused by ESBL-producing Enterobacteriaceae in a UK hospital, to identify the types of ESBL produced and risk factors for acquisition.

Methods: Between July 2008 and June 2009, all patients yielding ESBL-producing Enterobacteriaceae from any clinical specimen were prospectively investigated using a questionnaire. API20E was used for bacterial identification; susceptibility testing and ESBL production were assessed by BSAC disc diffusion and cefpodoxime-clavulanate synergy tests, respectively. Polymerase chain reaction was used to screen a subset of isolates for bla(CTX-M) genes, to assign Escherichia coli isolates to their phylogenetic groups, and to identify members of the uropathogenic ST131 lineage.

Results: The overall prevalence of ESBL producers among clinical samples yielding Enterobacteriaceae was 1%; ESBL producers, obtained from 124 patients, were E. coli (N = 105), Klebsiella pneumoniae (N = 12), and others (N = 7). The main risk factors identified include recent antibiotic use (93%) and presence of a urinary catheter (24%). CTX-M group 1 ESBLs dominated (in 59 of 78, 76%, isolates studied). Most E. coli (35 of 56 tested) were phylogroup B2; of these, 23 belonged to the ST131 clone, 12 were phylogroup D, and four each belonged to phylogroups A and B1.

Conclusion: ESBLs are an uncommon but significant problem in north-west Cambridgeshire. CTX-M-type enzymes were found in 75% of ESBL-positive isolates. All but two patients had at least one recognized risk factor. This study supports the requirement for interventions to reduce inappropriate urinary catheterization and antibiotic prescribing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Child
  • Child, Preschool
  • Cluster Analysis
  • DNA, Bacterial / genetics
  • Enterobacteriaceae / classification
  • Enterobacteriaceae / enzymology*
  • Enterobacteriaceae / genetics
  • Enterobacteriaceae / isolation & purification
  • Escherichia coli Infections / epidemiology*
  • Escherichia coli Infections / microbiology
  • Female
  • Genotype
  • Hospitals, District
  • Humans
  • Infant
  • Klebsiella Infections / epidemiology*
  • Klebsiella Infections / microbiology
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Molecular Epidemiology
  • Molecular Typing
  • Polymerase Chain Reaction
  • Prevalence
  • Surveys and Questionnaires
  • United Kingdom / epidemiology
  • Young Adult
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism*


  • DNA, Bacterial
  • beta-Lactamases