Antimicrobial Prophylaxis for Skin Colonization With Propionibacterium Acnes in Primary Open Shoulder Surgery

This is a double blinded randomized clinical trial comparing two different prophylactic antibiotics used for primary open shoulder surgery. The participants are volunteer patients scheduled for a primary open elective or trauma shoulder surgery. Patients with positive MRSA screening test will be excluded from the randomised study as they will receive vancomycin for prophylaxis. If they accept to participate, they will be included in the observational MRSA+ arm. The investigators will take from the participants the same data as the randomised patients and the investigators will take biopsies.

4 equals group will be form: Female-elective: 22 envelops, 11 cefazolin, 11 ceftriaxone in a randomly order Female-trauma: 22 envelops, 11 cefazolin, 11 ceftriaxone in a randomly order Male-elective: 22 envelops, 11 cefazolin, 11 ceftriaxone in a randomly order Male-trauma: 22 envelops, 11 cefazolin, 11 ceftriaxone in a randomly order The surgeons, anesthesiologist, patients and laboratory technician, microbiologist will be blinded to the antibiotics received by the patient.

Inclusion criteria

• 18 years and older
• Male or female
• Presenting normal skin on the shoulder aria

Exclusion criteria

• Used antibiotics or treated their skin with antibiotic gel, alcohol gel or cream or acne treatment in the last three months
• Active infection at the surgical site or anywhere
• Affected shoulder previously received radiotherapy
• Allergic to one of the antimicrobial prophylaxis used
• Open fracture
• Life threatening or a limb threatening pathology
• Liver or kidney failure