title: Escherichia coli bacteraemia: 2 years of prospective regional surveillance (2010-12).
abstract: OBJECTIVE
  To determine the prevalence of antibiotic resistance and the epidemiology of Escherichia coli bacteraemia isolates across the Yorkshire and Humber National Health Service region over 2 years.
  
  
  METHODS
  Ten percent of all E. coli blood culture isolates were collected per month from 14 laboratories across the Yorkshire and Humber region. Individual laboratories submitted antibiotic susceptibility data and isolates were re-tested centrally using the VITEK2(®) system (bioMérieux, France). Isolates were also characterized using PCR to test for the presence of sequences encoding extended-spectrum β-lactamases (ESBLs) and genotyped using amplified fragment length polymorphism (AFLP). Selected isolates were further characterized using multilocus sequence typing.
  
  
  RESULTS
  Between July 2010 and June 2012, 770 isolates were examined: 63%, 40%, 14% and 7% of isolates were non-susceptible to ampicillin, trimethoprim, ciprofloxacin and gentamicin, respectively. Eight percent of isolates (n = 63) were ESBL positive; CTX-M group 1 enzymes were the most common (68%). There was a fluctuating trend in the prevalence of resistance to amoxicillin/clavulanic acid (MIC >8 mg/L): July-September 2010, 16%; July-September 2011, 38%; and April-June 2012, 22%. AFLP identified 106 types. The majority of isolates belonged to one of two AFLP types: AFLP 1 [sequence type (ST) 131; 17%] and AFLP 2 (ST73; 18%). ST131 and ST73 were both associated with hospital- and community-onset bacteraemia, and with urinary, hepatobiliary and gastrointestinal sources of infection. ESBL-positive isolates were predominantly ST131 (60%).
  
  
  CONCLUSIONS
  Continued surveillance of antibiotic resistance among E. coli bacteraemia isolates is necessary to enhance these early baseline data. The variable prevalence of resistance to amoxicillin/clavulanic acid raises concerns, as both E. coli bacteraemia and empirical use of this antibiotic are common.
authors.affiliation: Leeds Teaching Hospitals NHS Trust, Department of Microbiology, Old Medical School, Leeds General Infirmary, Leeds LS1 3EX, UK.
authors.forename: C
authors.initials: C
authors.lastname: Horner
authors.forename: W
authors.initials: W
authors.lastname: Fawley
authors.forename: K
authors.initials: K
authors.lastname: Morris
authors.forename: P
authors.initials: P
authors.lastname: Parnell
authors.forename: M
authors.initials: M
authors.lastname: Denton
authors.forename: M
authors.initials: M
authors.lastname: Wilcox
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology*; D015373:Bacterial Typing Techniques; D024881:Drug Resistance, Bacterial; D062665:Epidemiological Monitoring; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology*; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D011446:Prospective Studies; D006113:United Kingdom / Q000453:epidemiology
keywords: antibiotic susceptibility; epidemiology; genetic background