Mortality associated with healthcare-associated Staphylococcus aureus bacteraemia in Aotearoa New Zealand

Our aim was to determine the 30- and 90-day all-cause mortality of healthcare-associated Staphylococcus aureus bacteraemia (HA-SAB) and determine mortality risk factors.

We collected HA-SAB events from 1 July 2022 to 30 June 2024. Patient age, sex, ethnicity and source of HA-SAB were submitted via a secure portal. Patients' National Health Index numbers were matched to the National Minimum Dataset, and 30- and 90-day all-cause mortality was determined. The mortality rate was calculated as a percentage of all HA-SAB events and by age, sex, ethnicity and source.

There were 961 HA-SAB events: a rate of 0.15 cases per 1,000 inpatient bed days. Thirty- and 90-day all-cause mortality were 13.8% and 20.7%, respectively. There was no difference in mortality by sex or ethnicity. Mortality increased with age and increased significantly for ≥75 years of age. Invasive medical devices were the source of 70% of HA-SAB events, organs were the source of 12% of HA-SAB events, and surgical site infections were the source of 8% of HA-SAB events. There was no significant difference in mortality by attributable source.

The 30- and 90-day all-cause mortality associated with HA-SAB is high. The most common sources are vascular access devices. The use of a "care bundle" incorporating proven interventions, applied using a quality improvement framework, should reduce patient harm from these events.