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

Background: Staphylococcus aureus bacteraemia (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 one hundred and thirty-two hospitals in Australia was undertaken. Aggregated data from all patients who acquired HO-SAB; defined as one or more blood cultures positive for Staphylococcus aureus taken from a patient who had been admitted to hospital for more than 48 hours. The primary outcome was the incidence of HO-SAB, including both methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) strains. Results: A total of 2,733 HO-SAB cases were identified over the study period giving an aggregate incidence of 0.90/10,000 patient days (95%CI, 0.86-0.93). There was a 63% decrease in the annual incidence, from 1.72/10,000 PDs in 2002 (95% CI, 1.50-1.97) to 0.64/10,000 PDs (95%CI, 0.53-0.76) in 2013. The mean reduction per year was 9.4% (95% CI, -8.1%, -10.7%). Significant reductions in both HO-MRSA (0.77 to 0.18 per 10,000 PDs) and HO-MSSA (1.71 to 0.64 per 10,000 PDs) bacteraemia were observed. Conclusion: 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.