Risk factors for Staphylococcus aureus surgical site infections after orthopaedic and trauma surgery in a French university hospital

Background: Surgical site infections (SSI) after orthopaedic surgery are responsible for reduced quality of life, increased length of hospital stay and costs. The most commonly identified organism is Staphylococcus aureus but risk factors for S. aureus SSI are not well-known. The aim of this study was to evaluate the incidence rate trend of S. aureus SSI over the years and risk factors of these infections in a French University Hospital Methods: SSI rates were expressed as cumulative incidence rates per year. A case-control study nested within a prospective cohort of patients undergoing orthopaedic or trauma surgery from January 1st, 2012 to April 30th, 2015 was performed. Cases were patients with S. aureus SSI; controls were patients without SSI. Risk factors of S. aureus SSI were identified by univariate and multivariable analysis. Results: Of 7438 interventions, 50 (0.7%) S. aureus SSI were identified, without significant increase by years. A total of 46 S. aureus SSI was matched to 91 controls. Risk factors for S. aureus SSI were smoking (odds-ratio (OR) = 8.4, 95%CI 1.2-59.6) and National Nosocomial Infections Surveillance System score (NNISS) >= 1 (OR = 5.8, 95%CI 1.8-19.1). Having 1 or 2 preoperative antiseptic showers (OR = 0.3, 95%CI 0.1-0.7) was a protective factor. Conclusion: The rate of S. aureus SSI is not negligible after orthopaedic and trauma surgery. It seems imperative to strengthen smoking cessation recommendations, and to recall the importance of preoperative antiseptic showers. Systematic screening and decolonization for S. aureus carriage before orthopaedic and trauma surgery could be a means to prevent these infections.