Inclusion Criteria:  Over 18 years old Patients who are going to undergo knee or hip replacement surgery. Patients with a positive result in the first nasal smear to S. aureus, and follow the decolonization protocol. Patients who give their informed consent to participate in the study.  Exclusion Criteria:  Patients scheduled for VPE less than 2 days after surgery. Patients unable to give their informed consent freely. Inadequate cognitive ability