Outcome of orthopedic implant infections due to different staphylococci

BackgroundComparisons of different staphylococci in orthopedic implant infections have rarely been reported. In this study we assessed total joint arthroplasty infections and other orthopedic implant infections due to methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), and coagulase-negative staphylococci (CoNS).MethodsThis was a retrospective study performed at the Geneva University Hospitals for the period January 1996 to June 2008.ResultsThere were 44 infections due to MRSA, 58 due to MSSA, and 61 due to CoNS. Overall cure was achieved in 57% (25/44) of MRSA infections, 72% (42/58) of MSSA infections, and 82% (50/61) of CoNS infections, after a minimum follow-up of 1 year. In the subgroup of arthroplasty infections only, cure was achieved in 39% (7/18) of MRSA, 60% (15/25) of MSSA, and 77% (30/39) of CoNS episodes. In multivariate analysis, arthroplasty (odds ratio (OR) 0.2, 95% confidence interval (95% CI) 0.1–0.6) and MRSA infections (OR 0.3, 95% CI 0.1–0.9) were inversely associated with overall cure for all implants. CoNS infection (OR 3.0, 95% CI 1.2–8.0) and the insertion of a new implant (OR 4.5, 95% CI 1.6–13.1) were associated with higher cure results. Methicillin resistance, immunosuppression, sex, age, duration of antibiotic therapy, one-stage revision, rifampin use, and total number of surgical interventions did not influence cure. MRSA-infected patients had more post-infection sequelae than patients with MSSA or CoNS (Chi-square test 13/44 vs. 93/119, OR 3.4, 95% CI 1.3–8.9, p = 0.004).ConclusionsIn orthopedic implant infections, S. aureus is more virulent than CoNS. MRSA has the worst outcome and CoNS the best.