Fig. 2

Methodology of the SALT study. A. Cases of S. aureus SSI were identified by crossmatching bacteriology laboratory data of all S. aureus isolates with data of all patients undergoing surgery, thus generating a list of all possible S. aureus SSI cases. Presence of S. aureus SSI among these possible cases was verified by single-case evaluation which was performed by infectious diseases specialists and surgeons in each hospital. True cases were ascertained as having S. aureus presence and either a documented diagnosis of SSI or as exhibiting both, a clinical picture suspicious of SSI and having undergone an intervention. Patients with non-SSI S. aureus (e.g., contamination, colonization, etc.) were excluded. B. To allow data assessment for outcomes, S. aureus SSI cases were matched to controls who underwent the same procedure using optimal propensity score matching based on cohort data, in particular age, diabetes, duration of procedure as percentile for this procedure