A Major Reduction in Hospital-Onset Staphylococcus aureus Bacteremia in Australia-12 Years of Progress: An Observational Study

Background. Staphylococcus aureus bacteremia (SAB) is a serious cause of morbidity and mortality. This longitudinal study describes significant reductions in hospital-onset SAB (HO-SAB) in Australian hospitals over the past 12 years. Methods. An observational cohort study design was used. Prospective surveillance of HO-SAB in 132 hospitals in Australia was undertaken. Aggregated data from all patients who acquired HO-SAB was collected (defined as 1 or more blood cultures positive for S. aureus taken from a patient who had been admitted to hospital for >48 hours). The primary outcome was the incidence of HO-SAB, including both methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) S. aureus strains. Results. A total of 2733 HO-SAB cases were identified over the study period, giving an aggregate incidence of 0.90 per 10 000 patient-days (PDs) (95% confidence interval [CI],.86-.93). There was a 63% decrease in the annual incidence, from 1.72 per 10 000 PDs in 2002 (95% CI, 1.50-1.97) to 0.64 per 10 000 PDs (95% CI,.53-.76) in 2013. The mean reduction per year was 9.4% (95% CI, -8.1% to -10.7%). Significant reductions in both HO-MRSA (from 0.77 to 0.18 per 10 000 PDs) and HO-MSSA (from 1.71 to 0.64 per 10 000 PDs) bacteremia were observed. Conclusions. There was a major and significant reduction in incidence of HO-SAB caused by both MRSA and MSSA in Australian hospitals since 2002. This reduction coincided with a range of infection prevention and control activities implemented during this time. It suggests that national and local efforts to reduce the burden of healthcare-associated infections have been very successful.