The purpose of this study is to identify bacterial and/or clinical features involved in the pathogenesis of Staphylococcus aureus implant-associated infections (IAI). Materials & methods: In total, 57 IAI S. aureus and 31 nasal carriage (NC) S. aureus isolates were studied. Staphylococcus aureus genetic background was obtained by microarray analysis. Multilocus sequence typing was performed to determine clonal complexes (CC). Biofilm production was investigated by resazurin and crystal violet methods

Inclusion Criteria:

• infected patients with S. Aureus IAI infection
• noninfected patients screened for S. aureus nasal colonization at the orthopedic consultation ward

Exclusion Criteria:

• minor

Fifty-five IAI patients were included; two of them had two different S. aureus IAI episodes. The median age was 73 years (range: 21-96 years) with 29 women (52.7%). Twenty seven percent of patients suffered from diabetes and were smokers.

Nine patients including six women were immunosuppressed with a median age of 71 years. The main diagnosis for arthroplasty was arthrosis (38%). Implants were hip prosthesis (n = 35), knee prosthesis (n = 18) and osteosynthesis (n = 4). Main local consequences of IAI were scarce alteration (n = 34) and skin fistulization (n = 22). These IAI were treated by surgical removal of all infected tissue and implant or a combination of debridement with implant retention associated to long-term antimicrobial therapy active against biofilm microorganisms. Eighteen early, nine delayed and 30 late infections occurred. Blood group phenotypes were available for 54 patients and were distributed as follows: 26 O group, 17 A group, 10 B group and one AB group.