S. epidermidis isolates (n = 183) were obtained during various surgical procedures due to suspected or verified PJI at the University Hospitals of Örebro and Linköping from 1999 to 2015 and from 1993 to 2015, respectively. The finding of S. epidermidis in multiple tissue samples (≥2) was interpreted as a PJI in accordance with the proposed definition of PJI [3 (link), 4 (link)]. Isolates were collected from patients with infected hip (n = 126), knee (n = 41), shoulder (n = 12), or elbow (n = 4) joint prostheses, then identified to the species level according to routine laboratory procedures and confirmed by MALDI-TOF MS (MicroflexLT and Biotyper 3.1, Bruker Daltonics, Bremen, Germany).
Standard antibiotic susceptibility testing by disc diffusion test (DDT) and MIC determination was performed according to EUCAST guidelines. MIC was determined by Etest for tedizolid, linezolid (Liofilchem, Roseto degli Abruzzi, Italy), and vancomycin (BioMérieux, Marcy-l’Etoile, France). DDT was performed for cefoxitin (30 μg), fusidic acid (10 μg), erythromycin (15 μg), clindamycin (2 μg), trimethoprim/sulfamethoxazole (25 μg), gentamicin (10 μg), norfloxacin (10 μg), and rifampin (5 μg) (Oxoid, Basingstoke, Hampshire, England).