Worth LJ1, Imam N1, Tempone S2, Armstrong PK2, McCann R2, Johnson S1, Richards MJ1
1Victorian Healthcare Associated Infection Surveillance System (VICNICC) Coordinating Centre, Doherty Institute, 792 Elizabeth Street, Melbourne, VIC, 3000. E: firstname.lastname@example.org
2Western Australia Department of Health, Perth, WA, 6004.
Background: Increased rates of community-onset Staphylococcus aureus bloodstream (CA-SAB) infections have been observed internationally. In recent years, increased infections have also been reported in many Australian hospitals. The objective of this study was to determine the incidence of CA-SAB and review time-trends of infections in two Australian jurisdictions.
Method: Retrospective analysis of surveillance data captured for the period 2011-2016 from public hospitals participating in the Victorian Healthcare Associated Infection Surveillance System (VICNISS) (n=93) and Healthcare Infection Surveillance Western Australia (HISWA) (n=58). All data were captured in parallel with surveillance for healthcare-associated SAB events and using standardised definitions.
Results: A total of 10,320 SAB events were reported; 6800 infections (65.9%) were community-associated, corresponding to a crude aggregate rate of 13.3 CA-SABs per 100 000 person-years. The incidence in both states increased significantly: 8% per year in Victoria and 6% per year in WA. Most CA-SAB events (83.8%) were caused by methicillin-susceptible S. aureus (MSSA), with a significant annual increase in the proportion of methicillin-susceptible infections observed in Victoria. The incidence of CA-SABs was highest among men over 60 years.
Conclusions: Increasing incidence of CA-SAB has been observed in two Australian jurisdictions, with a predominance of MSSA. This is consistent with reports of increased CA-SAB in UK and US, although incidence rates in Australia are lower than international reports. Characterising the isolates responsible for infection in studied centres is necessary to determine the relatedness of isolates. Enhanced surveillance is also necessary to identify preventable risks and to inform future targeted prevention strategies.