Pilot non comparative study assessing the clinical control of infection of DAIR + SAT +NaCl and DAIR + SAT + Phages anti-Staphylococcus aureus in patients with Staphylococcus aureus Prosthetic Joint Infection with an indication of DAIR + SAT.

Inclusion Criteria:

1. Male or female ≥ 18 years
2. Staphylococcus aureus monomicrobial knee or hip PJI ˃3 months after prosthesis implantation with clinical signs of infection and with indication of DAIR with direct closure and Suppressive Antibiotics Therapy (SAT)
3. Staphylococcus aureus only in joint fluid within 6 months before randomization or in case of relapse of infection under antibiotics therapy after a DAIR performed within 6 months before pre-inclusion visit
4. Without preoperative diagnosis of superinfection due to another pathogen
5. Phagogram displaying the susceptibility of the strain to at least one of the phages.
6. Patient with a life expectancy of 2 years and more as determined by the principal investigator
7. Females of childbearing potential/Sexually active males with partner of childbearing potential: commitment to consistently and correctly use an acceptable method of birth control (oral, transdermal, systemic or implant contraception birth control, intrauterine devices) for 1 month after the last study drug administration
8. Females of non-childbearing potential: either surgically sterilized or at least 1 year postmenopausal (amenorrhea duration at least 12 months)
9. Negative pregnancy test

Exclusion Criteria:

1. Early Staphylococcus aureus Prosthesis Joint infection (˂3months after the prosthesis implantation)
2. Other germ found in culture of joint fluid sample
3. Phagogram displaying no susceptibility of the strain to anti-Staphylococcus aureus bacteriophages
4. Patients with ASA score ≥ 4
5. Severe sepsis or Septic shock or hemodynamic instability
6. Patients with an indication to prosthesis replacement or amputation
7. Immunosuppressed patients
8. ALT or AST > 5 x ULN, creatinine > 1.53 mg/dl in men and > 1.24 mg/dl in women
9. Known allergic reactions to components of phages products
10. Medical history which in the opinion of the investigator would mean that the patient is unsuitable for participation in the study
11. Patients who are pregnant or breastfeeding. Patients should not be enrolled if they plan to become pregnant during the treatment period and 1 month after the last administration of study drug
12. Women/Men refusing to use an effective contraception during 1 month after the last administration of study drug.

All persons will be blinded, except the pharmacist will be unmasking.