title: High prevalence of EMRSA-15 in Portuguese public buses: a worrisome finding.
abstract: BACKGROUND
  The nosocomial prevalence of methicillin resistant Staphylococcus aureus (MRSA) in Portugal remains one of the highest in Europe and is currently around 50%. Transmission of S. aureus, including MRSA, occurs principally by direct human-to-human skin contact. However, S. aureus can survive for long periods on inanimate objects, which may represent an important reservoir for dissemination as well.
  
  
  RESULTS
  Between May 2009 and February 2010, handrails of 85 public urban buses circulating in Oporto, Portugal, were screened for the occurrence of MRSA. Twenty-two (26%) buses showed MRSA contamination. The molecular characterization of a total of 55 MRSA, by pulsed-field gel electrophoresis (PFGE), staphylococcal cassette chromosome (SCC) mec typing, spa typing, and multilocus sequence typing (MLST), clustered the isolates into three clonal types. However, the overwhelming majority (n = 50; 91%) of the isolates belonged to a single clone (PFGE A, spa types t747, t032, t025 or t020, ST22, SCCmec type IVh) that exhibits the characteristics of the pandemic EMRSA-15, currently the major lineage circulating in Portuguese hospitals, namely in the Oporto region. Two additional clones were found but in much lower numbers: (i) PFGE B, ST5, spa type t002, SCCmec IVa (n = 3), and (ii) PFGE C, spa type t008, ST8, SCCmec IVa (n = 2). None of the 55 isolates was PVL positive.
  
  
  CONCLUSIONS
  Public buses in Oporto seem to be an important reservoir of MRSA of nosocomial origin, providing evidence that the major hospital-associated MRSA clone in Portugal is escaping from the primary ecological niche of hospitals to the community environment. Infection control measures are urgently warranted to limit the spread of EMRSA-15 to the general population and future studies are required to assess the eventual increase of MRSA in the Portuguese community, which so far remains low.
authors.affiliation: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica, Oeiras, Portugal.
authors.forename: Roméo Rocha
authors.initials: RR
authors.lastname: Simões
authors.forename: Marta
authors.initials: M
authors.lastname: Aires-de-Sousa
authors.forename: Teresa
authors.initials: T
authors.lastname: Conceição
authors.forename: Filipa
authors.initials: F
authors.lastname: Antunes
authors.forename: Paulo Martins
authors.initials: PM
authors.lastname: da Costa
authors.forename: Hermínia
authors.initials: H
authors.lastname: de Lencastre
mesh_terms: D002999:Clone Cells; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D018986:Motor Vehicles; D058873:Pandemics; D011174:Portugal / Q000453:epidemiology; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology