Staphylococcus epidermidis implant-associated bone and joint infections: high rates of multiresistance associated with treatment failure

OBJECTIVES: Staphylococcus epidermidis is a leading pathogen of implant-associated bone and joint infection (BJI) and is frequently resistant to multiple antibiotics. In this study, we aimed to analyse risk factors for multiresistance and the association of multiresistance with treatment outcomes in patients with S. epidermidis implant-associated BJI. METHODS: We performed a single-center cohort study including patients with implant-associated BJI due to S. epidermidis at the University Hospital Basel, Switzerland, between January 2013 and December 2020. Risk factors for multiresistance and their association with treatment failure as primary outcome were assessed using logistic models and piecewise Cox models, respectively. RESULTS: Of 1,776 patients screened with intraoperative S. epidermidis, 279 were eligible, of which 250 patients (90%) were included with implant-associated BJI: Half had a monomicrobial implant-associated BJI (125/250) and 56% (141/250) presented with multiresistant S. epidermidis. Previous antibiotic treatment exhibited the strongest association with multiresistance in S. epidermidis implant-associated BJI (adjusted odds ratios, 2.13; 95% confidence interval [CI], 1.21-3.81). Overall, 32% of patients (80/250) experienced a treatment failure. Multiresistance was associated with treatment failure occurring more than two weeks after revision surgery (adjusted hazard ratio, 4.29; 95% CI, 1.51-12.19). CONCLUSIONS: Our results suggest that previous antibiotic treatments select for multiresistant S epidermidis, which increases the risk of treatment failure in implant-associated BJI. This study emphasizes the need for prudent antibiotic use and calls for new strategies against this still underestimated pathogen.