title: Waste water effluent contributes to the dissemination of CTX-M-15 in the natural environment.
abstract: OBJECTIVE
  Multidrug-resistant Enterobacteriaceae pose a significant threat to public health. We aimed to study the impact of sewage treatment effluent on antibiotic resistance reservoirs in a river.
  
  
  METHODS
  River sediment samples were taken from downstream and upstream of a waste water treatment plant (WWTP) in 2009 and 2011. Third-generation cephalosporin (3GC)-resistant Enterobacteriaceae were enumerated. PCR-based techniques were used to elucidate mechanisms of resistance, with a new two-step PCR-based assay developed to investigate bla(CTX-M-15) mobilization. Conjugation experiments and incompatibility replicon typing were used to investigate plasmid ecology.
  
  
  RESULTS
  We report the first examples of bla(CTX-M-15) in UK river sediment; the prevalence of bla(CTX-M-15) was dramatically increased downstream of the WWTP. Ten novel genetic contexts for this gene were identified, carried in pathogens such as Escherichia coli ST131 as well as indigenous aquatic bacteria such as Aeromonas media. The bla(CTX-M-15) -gene was readily transferable to other Gram-negative bacteria. We also report the first finding of an imipenem-resistant E. coli in a UK river.
  
  
  CONCLUSIONS
  The high diversity and host range of novel genetic contexts proves that evolution of novel combinations of resistance genes is occurring at high frequency and has to date been significantly underestimated. We have identified a worrying reservoir of highly resistant enteric bacteria in the environment that poses a threat to human and animal health.
authors.affiliation: School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: G C A
authors.initials: GC
authors.lastname: Amos
authors.affiliation: Health Protection Agency, West Midlands Public Health Laboratory, Heart of England NHS Foundation Trust, Bordesley Green East, Birmingham, UK Institute of Microbiology and Infection, Biosciences, University of Birmingham, Birmingham, UK.
authors.forename: P M
authors.initials: PM
authors.lastname: Hawkey
authors.affiliation: School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: W H
authors.initials: WH
authors.lastname: Gaze
authors.affiliation: School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK e.m.h.wellington@warwick.ac.uk.
authors.forename: E M
authors.initials: EM
authors.lastname: Wellington
mesh_terms: D058491:Bacterial Load; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics; D004755:Enterobacteriaceae / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D022761:Gene Transfer, Horizontal; D008969:Molecular Sequence Data; D010957:Plasmids / Q000032:analysis / Q000145:classification; D016133:Polymerase Chain Reaction; D045483:Rivers; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*; D006113:United Kingdom; D062065:Wastewater / Q000382:microbiology*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D012722:Sewage; D062065:Wastewater; D001618:beta-Lactamases; C473109:beta-lactamase CTX-M-15
keywords: CTX-M; antibiotic resistance; carbapenem resistance; environmental pathogens; β-lactamases