title: Homogeneity of antimicrobial policy, yet heterogeneity of antimicrobial resistance: antimicrobial non-susceptibility among 108,717 clinical isolates from primary, secondary and tertiary care patients in London.
abstract: OBJECTIVE
  We examined the 4 year trend in antimicrobial susceptibilities and prescribing across levels of care at two London teaching hospitals and their multisite renal unit, and for the surrounding community.
  
  
  METHODS
  Laboratory and pharmacy information management systems were interrogated, with antimicrobial use and susceptibilities analysed between hospitals, within hospitals and over time.
  
  
  RESULTS
  A total of 108,717 isolates from 71,687 patients were identified, with significant differences (at P < 0.05) in antimicrobial susceptibility between and within hospitals. Across the 4 years, rates of ESBL-/AmpC-producing Enterobacteriaceae ranged from 6.4% to 10.7% among community isolates, 17.8% to 26.9% at ward level and 25.2% to 52.5% in critical care. Significant variations were also demonstrated in glycopeptide-resistant enterococci (ward level 6.2%-17.4%; critical care 21.9%-56.3%), MRSA (ward level 18.5%-38.2%; critical care 12.5%-47.9%) and carbapenem-resistant Pseudomonas spp. (ward level 8.3%-16.9%; critical care 19.9%-53.7%). Few instances of persistently higher resistance were seen between the hospitals in equivalent cohorts, despite persistently higher antimicrobial use in Hospital 1 than Hospital 2. We found significant fluctuations in non-susceptibility year on year across the cohorts, but with few persistent trends.
  
  
  CONCLUSIONS
  The marked heterogeneity of antimicrobial susceptibilities between hospitals, within hospitals and over time demands detailed, standardized surveillance and appropriate benchmarking to identify possible drivers and effective interventions. Homogeneous antimicrobial policies are unlikely to continue to be suitable as individual hospitals join hospital networks, and policies should be tailored to local resistance rates, at least at the hospital level, and possibly with finer resolution, particularly for critical care.
authors.affiliation: National Centre for Infection Prevention and Management, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0HS, UK Imperial College Healthcare NHS Trust, Fulham Palace Road, London W6 8RF, UK.
authors.forename: Luke S P
authors.initials: LS
authors.lastname: Moore
authors.affiliation: National Centre for Infection Prevention and Management, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0HS, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Freeman
authors.affiliation: National Centre for Infection Prevention and Management, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0HS, UK Imperial College Healthcare NHS Trust, Fulham Palace Road, London W6 8RF, UK.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Gilchrist
authors.affiliation: National Centre for Infection Prevention and Management, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0HS, UK.
authors.forename: Myriam
authors.initials: M
authors.lastname: Gharbi
authors.affiliation: Imperial College Healthcare NHS Trust, Fulham Palace Road, London W6 8RF, UK.
authors.forename: Eimear T
authors.initials: ET
authors.lastname: Brannigan
authors.affiliation: Imperial College Healthcare NHS Trust, Fulham Palace Road, London W6 8RF, UK.
authors.forename: Hugo
authors.initials: H
authors.lastname: Donaldson
authors.affiliation: Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, UK Antimicrobial Resistance & Healthcare Associated Infection Reference Unit, Public Health England, 61 Colindale Avenue, London NW9 5EQ, UK.
authors.forename: David M
authors.initials: DM
authors.lastname: Livermore
authors.affiliation: National Centre for Infection Prevention and Management, Imperial College London, Hammersmith Campus, Du Cane Road, London W12 0HS, UK Imperial College Healthcare NHS Trust, Fulham Palace Road, London W6 8RF, UK alison.holmes@imperial.ac.uk.
authors.forename: Alison H
authors.initials: AH
authors.lastname: Holmes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001419:Bacteria / Q000187:drug effects*; D001424:Bacterial Infections / Q000453:epidemiology / Q000382:microbiology*; D015331:Cohort Studies; D024881:Drug Resistance, Bacterial; D004358:Drug Therapy / Q000592:standards; D005260:Female; D006291:Health Policy; D006784:Hospitals, Teaching; D006801:Humans; D008131:London / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care / Q000379:methods; D063127:Secondary Health Care / Q000379:methods; D063128:Tertiary Health Care / Q000379:methods; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents
keywords: antibiograms; antimicrobial stewardship; healthcare-associated infections; multidrug-resistant organisms