Search for Potentially Virulent Staphylococcus epidermidis Isolated from Healthy Human Skin

Genomic studies suggest that the skin microbiota of healthy individuals may harbor Staphylococcus epidermidis strains with putative virulence-associated characteristics, and that contamination of medical devices can originate from the patient's own skin microbiota. However, the virulence potential of these strains and their ability to contaminate medical devices have not been directly validated experimentally. Therefore, this study evaluated whether S. epidermidis isolates recovered from the skin of healthy individuals possess the capacity to colonize implanted catheters and form device-associated biofilms. Fifty-two isolates obtained from five dermatologically healthy individuals were phenotypically and genotypically characterized. Principal component analysis (PCA) was used to visualize the distribution of isolates according to their phenotypic and genotypic characteristics. Based on biofilm-forming capacity and antimicrobial resistance/susceptibility profiles, the isolates were assigned to four categories: virulent-like (n = 3), low virulent-like (n = 7), commensal-like (n = 20), and non-virulent-like (n = 22). Representative isolates from the resulting groups were evaluated using a catheter contamination assay in a mouse back model (CCAMM). In this model, virulent-like isolates exhibited levels of catheter colonization and device-associated biofilm formation comparable to those observed for the reference strain RP62A, whereas the non-virulent-like isolate displayed substantially lower biofilm formation. In conclusion, these findings suggest that the skin of dermatologically healthy individuals may harbor S. epidermidis isolates with virulence-associated traits and highlight its potential role as a reservoir of isolates capable of contaminating implanted medical devices.