Abstract. Introduction: Staphylococcus epidermidis is a leading coagulase-negative pathogen in periprosthetic joint infection (PJI), but the outcome impact of key resistance phenotypes is unclear. Methods: We retrospectively studied consecutive monomicrobial S. epidermidis PJIs treated at a tertiary hospital (2010–2024). PJI was defined according to 2018 ICM criteria. Success required infection eradication without suppressive antibiotics or further infection-related surgery after ≥ 12 months. Results: Among 516 evaluable PJIs, 105 (20.3 %) were monomicrobial PJIs due to S. epidermidis. The mean age was 71, and 56 % of cases were women; 51 % of cases involved the knee, and 49 % involved the hip. Chronic infection accounted for 79 %. Surgical strategies were DAIR in 27.6 % of cases, one-stage revision in 28.6 % of cases, and two-stage revision in 39.0 % of cases. Overall success was 78.1 % (DAIR – 75.9 %, one-stage – 93.3 %, two-stage – 73.2 %). Resistance rates were as follows: methicillin – 72.3 %, fluoroquinolone – 53.3 %, rifampin – 24.8 %, and multidrug resistance or extensive drug resistance (MDR/XDR) – 43.8 %. Rifampin resistance (73.1 % vs. 91.3 %, p = 0.021) and MDR/XDR (67.4 % vs 84.7 %, p = 0.035) were associated with failure; methicillin (p = 0.853) and fluoroquinolone resistance (p = 0.129) were not. In the univariable analyses, levofloxacin resistance was significantly associated with treatment failure (OR (odds ratio): 3.71; 95 % CI (confidence interval): 1.58–8.69; p = 0.002), as was rifampicin resistance (OR: 5.83; 95 % CI: 2.22–15.34; p < 0.001). Double resistance to levofloxacin and rifampicin showed the strongest association with failure (OR: 8.01; 95 % CI: 2.82–22.77; p < 0.001). Conclusion: Rifampin-resistant and MDR/XDR S. epidermidis PJIs represent higher-risk infections and should prompt early optimization of biofilm-active therapy and surgical source control. Univariable analysis confirmed rifampin resistance; levofloxacin resistance; and, in particular, their combination as strong predictors of treatment failure.
Auñón et al. (Tue,) studied this question.