title: The recent emergence in hospitals of multidrug-resistant community-associated sequence type 1 and spa type t127 methicillin-resistant Staphylococcus aureus investigated by whole-genome sequencing: Implications for screening.
abstract: Community-associated spa type t127/t922 methicillin-resistant Staphylococcus aureus (MRSA) prevalence increased from 1%-7% in Ireland between 2010-2015. This study tracked the spread of 89 such isolates from June 2013-June 2016. These included 78 healthcare-associated and 11 community associated-MRSA isolates from a prolonged hospital outbreak (H1) (n = 46), 16 other hospitals (n = 28), four other healthcare facilities (n = 4) and community-associated sources (n = 11). Isolates underwent antimicrobial susceptibility testing, DNA microarray profiling and whole-genome sequencing. Minimum spanning trees were generated following core-genome multilocus sequence typing and pairwise single nucleotide variation (SNV) analysis was performed. All isolates were sequence type 1 MRSA staphylococcal cassette chromosome mec type IV (ST1-MRSA-IV) and 76/89 were multidrug-resistant. Fifty isolates, including 40/46 from H1, were high-level mupirocin-resistant, carrying a conjugative 39 kb iles2-encoding plasmid. Two closely related ST1-MRSA-IV strains (I and II) and multiple sporadic strains were identified. Strain I isolates (57/89), including 43/46 H1 and all high-level mupirocin-resistant isolates, exhibited ≤80 SNVs. Two strain I isolates from separate H1 healthcare workers differed from other H1/strain I isolates by 7-47 and 12-53 SNVs, respectively, indicating healthcare worker involvement in this outbreak. Strain II isolates (19/89), including the remaining H1 isolates, exhibited ≤127 SNVs. For each strain, the pairwise SNVs exhibited by healthcare-associated and community-associated isolates indicated recent transmission of ST1-MRSA-IV within and between multiple hospitals, healthcare facilities and communities in Ireland. Given the interchange between healthcare-associated and community-associated isolates in hospitals, the risk factors that inform screening for MRSA require revision.
authors.affiliation: Microbiology Research Unit, Dublin Dental University Hospital, University of Dublin, Trinity College, Dublin, Ireland.
authors.forename: Megan R
authors.initials: MR
authors.lastname: Earls
authors.affiliation: Microbiology Research Unit, Dublin Dental University Hospital, University of Dublin, Trinity College, Dublin, Ireland.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kinnevey
authors.affiliation: Microbiology Research Unit, Dublin Dental University Hospital, University of Dublin, Trinity College, Dublin, Ireland.|National MRSA Reference Laboratory, St. James's Hospital, Dublin 8, Ireland.
authors.forename: Gráinne I
authors.initials: GI
authors.lastname: Brennan
authors.affiliation: Microbiology Research Unit, Dublin Dental University Hospital, University of Dublin, Trinity College, Dublin, Ireland.
authors.forename: Alexandros
authors.initials: A
authors.lastname: Lazaris
authors.affiliation: Department of Microbiology, Beaumont Hospital, Dublin, Ireland.
authors.forename: Mairead
authors.initials: M
authors.lastname: Skally
authors.affiliation: National MRSA Reference Laboratory, St. James's Hospital, Dublin 8, Ireland.|Department of Clinical Microbiology, School of Medicine, Trinity College Dublin, St. James's Hospital, Dublin 8, Ireland.
authors.forename: Brian
authors.initials: B
authors.lastname: O'Connell
authors.affiliation: Department of Microbiology, Beaumont Hospital, Dublin, Ireland.|Department of Clinical Microbiology, Royal College of Surgeons in Ireland Education and Research Centre, Beaumont Hospital, Dublin, Ireland.
authors.forename: Hilary
authors.initials: H
authors.lastname: Humphreys
authors.affiliation: Microbiology Research Unit, Dublin Dental University Hospital, University of Dublin, Trinity College, Dublin, Ireland.
authors.forename: Anna C
authors.initials: AC
authors.lastname: Shore
authors.affiliation: Microbiology Research Unit, Dublin Dental University Hospital, University of Dublin, Trinity College, Dublin, Ireland.
authors.forename: David C
authors.identifier: http://orcid.org/0000-0003-1797-2888
authors.initials: DC
authors.lastname: Coleman
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D006761:Hospitals; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D020641:Polymorphism, Single Nucleotide
chemical_list: D000900:Anti-Bacterial Agents