Epidemiology of Staphylococcus aureus Surgical Site Infections

Surgical site infections (SSI) due to Staphylococcus aureus are associated with substantial mortality rates and morbidity. Hence, various strategies are being investigated to prevent them. We explore time trends and risk factors associated with S. aureus SSI to identify high risk patients who might benefit the most from these strategies.

This is a retrospective cross-sectional study on a prospectively maintained database. We identified organism specific risk factors for S. aureus SSI as a whole, methicillin-sensitive S. aureus (MSSA), and methicillin-resistant S. aureus (MRSA). We also identified procedure-specific risk factors for S. aureus SSI for colectomy, hip, and knee arthroplasty, herniorrhaphy, and cholecystectomy.

We compared 249 patients with S. aureus SSI with 54,988 uninfected control patients. The rate of S. aureus SSI was steady throughout the study period with MSSA being more common than MRSA. Independent risk factors for S. aureus SSI from multivariable analysis were length of hospitalization prior to surgery [odds ratio (OR) 1.01; 95% confidence interval (CI), 1.00-1.02)], colectomy (OR 2.81; 95% CI, 1.94-4.07), hip or knee arthroplasty (OR 1.52; 95% CI, 1.04-2.21), extended duration of surgery (OR 1.61; 95% CI, 1.10-2.37), NNIS score of two or more (OR 2.04; 95% CI, 1.24-3.36), and re-interventions for non-infectious reasons (OR 1.82; 95% CI, 1.16-2.86). Minimally invasive (OR 0.21; 95% CI, 0.13-0.34) and emergency operations (OR 0.61; 95% CI, 0.41-0.92) were protective against S. aureus SSI.

Future S.aureus SSI prevention measures should focus on patients with risk profiles identified from this and other similar studies.