Community- and healthcare-associated Staphylococcus aureus bacteremia: 10-year review

  • Owen Robinson, Royal Perth Hospital and Gram-positive Bacteria Typing and Research Unit, School of Biomedical Sciences, Curtin University, Australia
  • Dr Sabrina Pozzi Langhi, PathWest Laboratory Medicine WA, Royal Perth Hospital, Australia
  • Mrs Julie Pearson, Royal Perth Hospital and Gram-positive Bacteria Typing and Research Unit, School of Biomedical Sciences, Curtin University, Australia
  • Keryn Christiansen, Royal Perth Hospital and Gram-positive Bacteria Typing and Research Unit, School of Biomedical Sciences, Curtin University, Australia
  • Mr Geoffrey Coombs, Royal Perth Hospital and Gram-positive Bacteria Typing and Research Unit, School of Biomedical Sciences, Curtin University, Australia
  • Dr Ronan Murray, Royal Perth Hospital and Gram-positive Bacteria Typing and Research Unit, School of Biomedical Sciences, Curtin University, Australia

    • Background: Staphylococcus aureus bacteremia (SAB) is associated with considerable morbidity and mortality. We aimed to compare community-associated and healthcare-associated S. aureus bacteremia (CA-SAB and HA-SAB).
    Methods: Episodes of methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) S. aureus bacteraemia between 1997 and 2007 were identified as part of a retrospective case-control study. Episodes were classified as community-associated according to published criteria (Klevens et al JAMA 2007).
    Results: 1125 SAB episodes occurred during the study period: data were collected on 197/204 MRSA and 402/921 MSSA episodes. There were 117 CA-SAB and 482 HA-SAB episodes. CA-SAB patients were younger (median 53 vs 64.5y; p<0.001) and more likely to be intravenous drug users (23.9% vs 3.5%; p<0.001), but fewer had a malignancy or were immunosuppressed. No source for the bacteremia was identified in 29.1% and 23.4% of the CA-SAB and HA-SAB episodes respectively. Bone/joint infection and IV drug use were more frequently identified as the source of the bacteremia in CA-SAB than in HA-SAB (20.5% vs 9.1%, and 17.1% vs 1.7% respectively, both p<0.001). MRSA was responsible for 16.2% of CA-SAB and 36.9% of HA-SAB episodes (p<0.001). Whilst SAPS-II scores were lower in CA-SAB than in HA-SAB episodes (27 vs 36; p<0.001), need for ICU admission, endocarditis and metastatic seeding were all more frequent in CA-SAB. 7- and 30-day all-cause mortality rates were 12.8% and 16.3% in the CA-SAB group vs 12.9% and 23.2% in the HA-SAB group (p=NS).
    Conclusion: Community and healthcare-associated SAB differ with regards to risk factors, methicillin resistance rate, source and extent of infection, but have a similar poor outcome.