title: Methicillin-resistant Staphylococcus aureus bacteraemia diagnosed at hospital admission: distinguishing between community-acquired versus healthcare-associated strains.
abstract: BACKGROUND
  Methicillin-resistant Staphylococcus aureus (MRSA) infections diagnosed at hospital admission are often referred to as community-acquired. This designation may include MRSA strains previously acquired in a healthcare setting (healthcare-associated) as well as those that have emerged from community-based S. aureus strains.
  
  
  METHODS
  To understand further the epidemiology of MRSA from the community, a case-control study was performed. During 1997-2002, 254 patients with and without MRSA bacteraemia at hospital admission were studied.
  
  
  RESULTS
  All patients with MRSA bacteraemia in the first 24 h of hospital admission had a recent exposure to a healthcare setting: true community-acquired MRSA was not detected. Independent risk factors for healthcare-associated MRSA bacteraemia, defined as MRSA bacteraemia in the first 24 h of hospital admission among patients with a recent exposure to a healthcare setting or intervention, included previous MRSA infection or colonization (OR = 17, P < 0.001), cellulitis (OR = 4, P = 0.006), presence of a central venous catheter (OR = 3, P < 0.001) and skin ulcers (OR = 3, P = 0.007).
  
  
  CONCLUSIONS
  In this study, MRSA bacteraemia diagnosed in the first 24 h of hospital admission represented healthcare-associated MRSA strains and not true community-acquired strains. The clinical characteristics associated with healthcare-associated MRSA bacteraemia can assist clinicians in targeting measures to prevent cross-transmission and may help to streamline empirical vancomycin therapy.
authors.affiliation: Division of Infectious Diseases and Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA. etaccone@bidmc.harvard.edu
authors.forename: E
authors.initials: E
authors.lastname: Tacconelli
authors.forename: L
authors.initials: L
authors.lastname: Venkataraman
authors.forename: P C
authors.initials: PC
authors.lastname: De Girolami
authors.forename: E M C
authors.initials: EM
authors.lastname: DAgata
mesh_terms: D000368:Aged; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology*; D001900:Boston / Q000453:epidemiology; D017714:Community-Acquired Infections / Q000453:epidemiology* / Q000382:microbiology*; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D012307:Risk Factors; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects*