title: Hospital-wide Eradication of a Nosocomial Legionella pneumophila Serogroup 1 Outbreak.
abstract: BACKGROUND
  Two proven nosocomial cases of Legionella pneumonia occurred at the Wesley Hospital (Brisbane, Australia) in May 2013. To trace the epidemiology of these cases, whole genome sequence analysis was performed on Legionella pneumophila isolates from the infected patients, prospective isolates collected from the hospital water distribution system (WDS), and retrospective patient isolates available from the Wesley Hospital and other local hospitals.
  
  
  METHODS
  Legionella pneumophila serogroup 1 isolates were cultured from patient sputum (n = 3), endobronchial washings (n = 3), pleural fluid (n = 1), and the Wesley Hospital WDS (n = 39). Whole genome sequencing and de novo assembly allowed comparison with the L. pneumophila Paris reference strain to infer phylogenetic and epidemiological relationships. Rapid disinfection of the hospital WDS with a chlorinated, alkaline detergent and subsequent superchlorination followed by maintenance of residual free chlorine, combined with removal of redundant plumbing, was instituted.
  
  
  RESULTS
  The 2011 and 2013 L. pneumophila patient isolates were serogroup 1 and closely related to all 2013 hospital water isolates based on single nucleotide polymorphisms and mobile genetic element profiles, suggesting a single L. pneumophila population as the source of nosocomial infection. The L. pneumophila population has evolved to comprise 3 clonal variants, each associated with different parts of the hospital WDS.
  
  
  CONCLUSIONS
  This study provides an exemplar for the use of clinical and genomic epidemiological methods together with a program of rapid, effective remedial biofilm, plumbing and water treatment to characterize and eliminate a L. pneumophila population responsible for nosocomial infections.
authors.affiliation: School of Medicine, University of Queensland, Herston.|Wesley-St Andrew's Research Institute, Auchenflower.
authors.forename: Paul B
authors.initials: PB
authors.lastname: Bartley
authors.affiliation: School of Chemistry and Molecular Biosciences.|Australian Infectious Diseases Research Centre, University of Queensland, St Lucia.
authors.forename: Nouri L
authors.initials: NL
authors.lastname: Ben Zakour
authors.affiliation: School of Chemistry and Molecular Biosciences.|Australian Infectious Diseases Research Centre, University of Queensland, St Lucia.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Stanton-Cook
authors.affiliation: CETECPty Ltd, Melbourne.
authors.forename: Raghuram
authors.initials: R
authors.lastname: Muguli
authors.affiliation: School of Medicine, University of Queensland, Herston.|Wesley-St Andrew's Research Institute, Auchenflower.
authors.forename: Luis
authors.initials: L
authors.lastname: Prado
authors.affiliation: CETECPty Ltd, Melbourne.
authors.forename: Vyt
authors.initials: V
authors.lastname: Garnys
authors.affiliation: Wesley-St Andrew's Research Institute, Auchenflower.
authors.forename: Katherine
authors.initials: K
authors.lastname: Taylor
authors.affiliation: School of Chemistry and Molecular Biosciences.|Australian Infectious Diseases Research Centre, University of Queensland, St Lucia.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Barnett
authors.affiliation: Biotech Laboratories Ltd.
authors.forename: Glen
authors.initials: G
authors.lastname: Pinna
authors.affiliation: Sullivan Nicolaides Pathology, Brisbane.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Robson
authors.affiliation: Australian Infectious Diseases Research Centre, University of Queensland, St Lucia.|University of Queensland Clinical Research Centre, Herston, Queensland, Australia.
authors.forename: David L
authors.initials: DL
authors.lastname: Paterson
authors.affiliation: School of Chemistry and Molecular Biosciences.|Australian Infectious Diseases Research Centre, University of Queensland, St Lucia.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Walker
authors.affiliation: School of Chemistry and Molecular Biosciences.|Australian Infectious Diseases Research Centre, University of Queensland, St Lucia.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schembri
authors.affiliation: School of Chemistry and Molecular Biosciences.|Australian Infectious Diseases Research Centre, University of Queensland, St Lucia.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Beatson
mesh_terms: D000368:Aged; D001315:Australia / Q000453:epidemiology; D001980:Bronchi / Q000382:microbiology; D003428:Cross Infection / Q000453:epidemiology* / Q000517:prevention & control; D004196:Disease Outbreaks; D004203:Disinfection / Q000379:methods; D005260:Female; D016680:Genome, Bacterial; D006801:Humans; D017053:Infection Control / Q000379:methods*; D016952:Legionella pneumophila / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D007877:Legionnaires' Disease / Q000453:epidemiology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D010994:Pleura / Q000382:microbiology; D017422:Sequence Analysis, DNA; D065288:Serogroup; D013183:Sputum / Q000382:microbiology; D014871:Water Microbiology
keywords: Legionnaires' disease; bacterial genomics; genomic epidemiology; hospital disinfection; transmission pathway