Surgical site infections are a major postoperative complication and are mostly due to colonization with endogenous germs, like Staphylococcus aureus, Staphylococcus epidermidis or Propionibacterium acnes. In literature, preoperative decolonization procedures showed a trend in lowering surgical site infection rates, but especially in orthopedic surgery data is controversial and randomized controlled trials are lacking. In the main study, the study investigators aim at performing a controlled prospective randomized interventional trial to measure the impact of preoperative decolonization of nasal Staphylococcus aureus carriers on surgical site infection rates in orthopedic surgery. In an alongside study a controlled prospective randomized interventional trial to measure the impact of preoperative skin decolonization of patients undergoing an orthopedic procedure will be conducted.

All participants will be assessed for eligibility during preoperative othopedic consultation. 2-3 weeks prior operation date participants will be screened for Staph. aureus carriage by nose-swab. According to nose-swab results randomizaton and allocation to study arm will be performed.

After one and three months post-operatively participants will be asked by phone interview if surgical site infections occured. Results have to be confirmed by orthopedic surgeon if possible.

Inclusion Criteria:

• patient older than 16 years
• patient undergoing elective orthopedic procedure at the Sonnenhof hospital
• decolozination protocol can be performed timely
• signed informed consent

Exclusion Criteria:

• no orthopedic surgery planned
• allergy to mupirocin or chlorhexidine
• presence of a nasal foreign body
• no informed consent
• pregnancy
• decolozination protocol can't be followed timely
• patients undergoing treatment/surgery for a documented infection