title: ESBL-producing Gram-negative organisms in the healthcare environment as a source of genetic material for resistance in human infections.
abstract: BACKGROUND
  The increasing prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in the healthcare setting and in the community despite established infection control guidelines indicates that these microorganisms may possess survival strategies that allow them to persist in the environment.
  
  
  OBJECTIVE
  To determine the extent and variation in endemic ESBL-carrying species in different ward environments, and to investigate the potential for cephalosporin resistance to be transferred from environmental isolates to human pathogens.
  
  
  METHODS
  Conventional microbiological methods were used to sample 1436 environmental surfaces for ESBL-producing bacteria. Transconjugation assays (broth mating experiments) were performed using environmental ESBL-producing isolates as donors and streptomycin-resistant Escherichia coli (NCTC 50237) as the recipient.
  
  
  RESULTS
  The prevalence of ESBL-producing bacteria on surfaces in a non-outbreak setting was low (45/1436; 3.1%). The sites most likely to be contaminated were the drains of handwash basins (28/105; 26.7%) and floors (14/160; 8.8%). Fifty-nine ESBL-carrying organisms were isolated. Of these, Klebsiella spp. (33.9%), Enterobacter spp. (20.3%), Pantoea spp. (15.3%) and Citrobacter spp. (13.6%) were the most common isolates. ESBL determinants were transferred successfully from three representative environmental isolates (Pantoea calida, Klebsiella oxytoca, Raoultella ornithinolytica) to the human pathogen E. coli.
  
  
  CONCLUSIONS
  ESBL-producing Gram-negative isolates were recovered from the hospital environment in the absence of any ESBL infection on the wards. The drains of handwash basins should be considered potential long-term reservoirs of multi-drug-resistant bacteria and drug resistance genes. These genes can reside in various genera of hardy environmental organisms and be a potential source of ESBL for more common human pathogens.
authors: Environmental Research Laboratory, University College London Hospitals NHS Foundation Trust, London, UK. Electronic address: Monika.Muzslay@uclh.nhs.uk.
authors: M
authors: M
authors: Muzslay
authors: Biosafety, Air and Water Microbiology Group, Public Health England, Porton Down, UK.
authors: G
authors: G
authors: Moore
authors: Infection and Immunity, University College London, London, UK.
authors: N
authors: N
authors: Alhussaini
authors: Clinical Microbiology and Virology, University College London Hospitals NHS Foundation Trust, London, UK.
authors: A P R
authors: AP
authors: Wilson
mesh_terms: D001431:Bacteriological Techniques; D018550:Cephalosporin Resistance; D003227:Conjugation, Genetic; D004197:Disease Reservoirs; D004783:Environmental Microbiology; D022761:Gene Transfer, Horizontal; D005796:Genes; D006090:Gram-Negative Bacteria / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D006268:Health Facilities; D006801:Humans; D011795:Surveys and Questionnaires; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases
keywords: Environmental contamination; Extended-spectrum β-lactamase-producing bacteria; Gene transfer; Hospital drains; Pantoea calida