Lower limb joint replacement surgery is one of the most prevalent globally. In our center, more than 400 lower limb arthroplasties (LLA) are performed annually. Developing a Surgical Site Infection (SSI) after (LLA) increases morbidity, mortality and healthcare costs. Staphylococcus aureus is the main causative agent of SSI and especially in LLA. One third of the population is a nasal carrier of Staphylococcus aureus, being a risk factor for patients who have to undergo knee replacement or hip replacement. Several studies have confirmed that the detection of S. aureus carriers and their subsequent decolonization reduces SSI rates

Implementation of a screening of all patients who have to undergo lower limb arthroplasty in our center, decolonization of patients with a positive screening result for S. aureus and subsequent follow-up.The circuit is established in the following phases:

1. Preoperative Nurse Visit:

   Oral and written information on the study and procedure is given, the informed consent will be signed, and the sample (nasal swab) is collected from all patients scheduled for lower limb arthroplasty surgery in our center. The sample is sent to microbiology.

   It will be recorded in the computerized medical history.

2. Control of results:

   If the sample has been run by rapid circuit at 24 hours or conventional at 4 days, the Consultation Nurse reviews the results of the screened patients.

   c. In case of negative screening, patients follow the usual clinical practice circuit.

   d. In case of positive screening, the patients are summoned the next day to Consultations to give and explain the decolonization treatment.

3. Indication of decolonization to S. aureus:

   The following treatment is prescribed and facilitated in the nurse's office and will be recorded in the history:

   • Intranasal mupirocin every 8h. for 5 days (in case of resistance, intranasal fusidic acid is given every 12 hours for 5 days). Treatment is always carried out 7 days before the day of admission for surgery.
   • Chlorhexidine gluconate (single-dose sachets) daily shower until the day of admission for the intervention.

4. Post-decolonization control S. aureus:

   The patient is asked about adherence to treatment and a nasal smear is performed in the Presurgical Unit. In the event that the Innervencion is before the end of the treatment. It is not deprogrammed, but the treatment will continue until it is completed. The control nasal smear, in these cases, will be collected at the first treatment in the nurse's office. The satisfa

5. The patients will be followed for 6 weeks, a period in which an infection is considered an acute surgical site, it will be recorded if the infection is due to S. aureus.

6. The circuit will be evaluated in relation to efficacy and impact (number of patients operated on, number of screening, number of S. aureus positives, number of decolonizations and if they have been effective, number of S. aureus infections after The proposed intervention and treatment will be compared with the infections of the same period of the year 2019.ction survey of the decolonization protocol (VAS 0-10) will be carried out.

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

All the patients who are going to be operated