title: Persistence of related bla-IMP-4 metallo-beta-lactamase producing Enterobacteriaceae from clinical and environmental specimens within a burns unit in Australia - a six-year retrospective study.
abstract: BACKGROUND
  To describe the clinical epidemiology, environmental surveillance and infection control interventions undertaken in a six-year persistence of bla-IMP-4 metallo-beta-lactamase (MBL) producing Enterobacteriaceae within a separately confined hospital burns unit in a tertiary hospital in Sydney, Australia.
  
  
  METHODS
  MBL positive clinical and environmental isolates were collected from the Burns Unit, from the first detection of isolates in September 2006 to August 2012. Unit-acquired clinical isolates were included, and patient outcomes analyzed amongst those who acquired clinically significant infections. Environmental isolates were analyzed with regard to relationship to clinical isolates, bacterial species, and persistence despite cleaning efforts.
  
  
  RESULTS
  Thirty clinical isolates detected from 23 patients were identified. Clinically significant infection developed in 7 (30%) patients - 2 bacteremias, 2 central venous catheter tip infections without bacteremia, and 3 wound infections. All patients survived at 30 days. Seventy-one environmental isolates were confirmed to be MBL-positive, with 85% sourced from shower facilities or equipment. MBL organisms persisted at these sites despite both usual hospital cleaning, and following targeted environmental disinfection interventions.
  
  
  CONCLUSIONS
  Clear association exists between environmental Burns Unit contamination by MBLs and subsequent patient colonization. Clinical infection occurred in a small proportion of patients colonized by MBLs, and with generally favorable outcomes. Its persistence in the Burns Unit environment, despite concerted infection control measures, pose concern for ongoing clinical transmission.
authors.forename: Grace Hy
authors.initials: GH
authors.lastname: Leung
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Gray
authors.forename: Elaine Yl
authors.initials: EY
authors.lastname: Cheong
authors.forename: Peter
authors.initials: P
authors.lastname: Haertsch
authors.affiliation: Department of Microbiology and Infectious Diseases, Sydney Local Health District Concord Hospital Human Research Ethics Committee, Hospital Rd, Concord, Sydney, NSW 2139, Australia. thomas.gottlieb@sswahs.nsw.gov.au.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gottlieb