title: Replacement of healthcare-associated MRSA by community-associated MRSA in Queensland: confirmation by genotyping.
abstract: OBJECTIVE
  To describe the changing prevalence of healthcare- and community-associated MRSA.
  
  
  METHODS
  Susceptibility phenotypes of MRSA were observed from 2000 to 2012 using routine susceptibility data. Phenotypic definitions of major clones were validated by genotyping isolates from a nested period prevalence survey in 2011.
  
  
  RESULTS
  The predominant healthcare-associated (AUS-2/3 like) MRSA phenotype decreased from 42 to 14 isolates per million occasions of service in outpatients (P < 0.0001) and from 650 to 75 isolates per million accrued patient days in inpatients (P 0.0005), while the respective rates of the healthcare-related EMRSA-15 like phenotype increased from 1 to 19 in outpatients (P < 0.0001) and from 11 to 83 in inpatients (P < 0.0001) and those of the community-associated MRSA phenotype increased from 17 to 296 in outpatients (P < 0.0001) and from 71 to 486 in inpatients (P < 0.0001). When compared with single nucleotide polymorphism genotyping the AUS-2/3 like phenotype had a sensitivity and positive predictive value (PPV) for CC239 of 1 and 0.791 respectively, while the EMRSA-15 like phenotype had a sensitivity and PPV for CC22 of 0.903 and 0.774. PVL-positive CA-MRSA, predominantly ST93 and CC30, accounted for 60.8% of MRSA, while PVL-negative CA-MRSA, mainly CC5 and CC1, accounted for 21.4%.
  
  
  CONCLUSIONS
  The initially dominant healthcare-associated MRSA clone has been progressively replaced, mainly by four community-associated lineages.
authors.affiliation: Pathology Queensland Central Laboratory, Herston, Queensland 4029, Australia; Griffith University School of Medicine, Southport, Queensland 4215, Australia. Electronic address: Graeme_Nimmo@health.qld.gov.au.
authors.forename: Graeme R
authors.initials: GR
authors.lastname: Nimmo
authors.forename: Haakon
authors.initials: H
authors.lastname: Bergh
authors.forename: Jennifer
authors.initials: J
authors.lastname: Nakos
authors.forename: David
authors.initials: D
authors.lastname: Whiley
authors.forename: John
authors.initials: J
authors.lastname: Marquess
authors.forename: Flavia
authors.initials: F
authors.lastname: Huygens
authors.forename: David L
authors.initials: DL
authors.lastname: Paterson
mesh_terms: D016009:Chi-Square Distribution; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology*; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D005838:Genotype; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D058889:Molecular Typing; D011446:Prospective Studies; D011793:Queensland / Q000453:epidemiology; D015203:Reproducibility of Results; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification
keywords: Australia; Community-associated; Epidemiology; Genotyping; Healthcare-associated; MRSA; Staphylococcus aureus