Cluster analysis of ribotyping profiles of Staphylococcus epidermidis isolates recovered from foreign body-associated orthopedic infections

Staphylococcus epidermidis is an opportunistic pathogen of major clinical interest for its high prevalence in implant-associated infections. However, only little information is available on the phylogeny of its major clonal entities and their virulence and resistance markers. Therefore, purpose of this study was to characterize four clusters identified by automated ribotyping of 70 isolates derived from orthopedic, mostly foreign body-related infections. The ica locus, encoding the polysaccharide intercellular adhesin, the IS256 insertion element as well as the resistance to gentamicin, clindamycin, chloramphenicol, and ciprofloxacin were all traits uniquely observed in two of these clusters. The phylogenetic analysis of the S. epidermidis clusters offered a detailed insight into the clonal origin of exopolysaccharide- producing and multiresistant strains with transposons appearing to be actively involved in genetic exchanges.