A seven-year review of Staphylococcus aureus bloodstream infection (SAB) surveillance data in Western Australian health services (2011 to 2017)

Ms Simone Tempone 1, Ms Rebecca McCann1, Dr Paul Armstrong1

1Department of Health Western Australia, Perth, Australia


Introduction: Since 2010, Healthcare Infection Surveillance Western Australia (HISWA) have reviewed all Staphylococcus aureus positive blood cultures processed by PathWest Laboratory Medicine. Utilising a standardized case definition, Staphylococcus aureus bloodstream infections (SABs) were classified as either a healthcare associated (HA) or a community associated (CA) event. The objective of this study was to investigate the rising rates of CA-SAB that had been previously identified in both Victoria and Western Australia.

Methods: HISWA SAB surveillance data were extracted for the period 2011-2017. Data included demographics (age, gender, geographic distribution), if the SAB was CA or HA, the proportion of MRSA to MSSA infections, and MRSA strain types.

Results: In total, 3,542 SABs were investigated over the 7 years, of which 71% (2,508) were classified as CA-SAB. Total SAB crude incidence increased from 18.7 to 20.8 SABs/100,000 person-years and from 12.3 to 15.1 SABs/100,000 person-years for CA-SAB. The HA-SAB reduced from 6.4 to 5.6 SAB/100,000 person years. Males were most frequently represented (64%). The majority (83%) of all SAB were methicillin-sensitive and 45% of patients developing a MRSA SAB were known to be colonised prior to the event.

Conclusion: SABs continue to represent a significant burden to the WA healthcare system, with the majority being attributed to an increasing frequency of community associated infections. Further work is needed to better understand risk factors for in this population so appropriate public health intervention strategies can be effectively implemented.

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