To Örebro University

Background and objectives: Staphylococcus epidermidis is a major cause of prosthetic joint infections (PJIs). Multidrug resistant (MDR), hospital-adapted clones constitute most cases globally, though regional differences in lineage dissemination likely exist. The aim was to explore the population structure of S. epidermidis from PJIs in Sweden and France, with a focus on the presence of antimicrobial resistance (AMR).

Methods: This study included genome sequence data from 191 clinical S. epidermidis isolates collected from patients with PJI in central Sweden (2007-16; n = 138) and the Lyon region in France (2015-20; n = 53).

Results: Hospital-adapted lineages with a high burden of AMR dominated the cases in both countries. However, the ST2 lineage was significantly more prevalent in Sweden (43% versus 11% in France), while ST5 and ST87 were more common in France (55% versus 10% in Sweden). ST215 was only present in Sweden (25%). A significantly higher prevalence of streptogramin resistance genes [vat(B), vga(A), vga(B)] was found in French (26%) versus Swedish (2%) isolates. These genes were present in all ST87 isolates and in 20% of the French ST5 isolates. The erm(C) gene (resistance to streptogramin A, macrolides and lincosamides) was also more common in the French isolates (77% versus 55% of Swedish isolates), and so was the fusidic acid resistance gene fusB (France: 66%, Sweden: 39%).

Conclusions: This study highlights significant regional differences in S. epidermidis variants causing PJI. Despite similar MDR levels, certain AMR genes, particularly those related to streptogramin resistance, were significantly more prevalent among French isolates. This suggests that S. epidermidis undergoes local adaptation to region-specific antibiotic usage.