Enhanced Surveillance of Staphylococcus Aureus Bacteraemia to Identify Targets for Infection Prevention

Background: Surveillance of Staphylococcus aureus bacteraemia (SAB) in Scotland is limited to the number of infections per 100,000 acute occupied bed-days and susceptibility to meticillin.

Aim: To demonstrate the value of enhanced SAB surveillance to identify targets for infection prevention.

Methods: Prospective cohort study of all patients identified with SAB over a five-year period in a single health board in Scotland. All patients were reviewed at the bedside by a clinical microbiologist.

Findings: In all, 556 SAB episodes were identified: 261 (46.6%) were hospital-acquired; 209 (37.9%) were healthcare-associated; 80 (14.4%) were community-acquired; and in six (1.1%) the origin of infection was not hospital-acquired, but could not be separated into healthcare-associated or community-acquired. These were classified as non-hospital-acquired. Meticillin-resistant S. aureus (MRSA) bacteraemia was associated with hospital-acquired and healthcare-associated infections. In addition, there was a significantly higher 30-day mortality associated with hospital-acquired (31.4%) and healthcare-associated (16.3%) infections compared to community-acquired SAB (8.7%). Vascular access devices were associated with hospital-acquired SAB and peripheral venous cannulas were the source for most of these (43.9%). Community-acquired infections were associated with intravenous drug misuse, respiratory tract infections and skeletal and joint infections. Skin and soft tissue infections were more widely seen in healthcare-associated infections.

Conclusion: The data indicate that enhanced surveillance of SAB by origin of infection and source of bacteraemia has implications for infection prevention, empirical antibiotic therapy, and health improvement interventions.