An in vitro investigation of the protective role of Staphylococcus Epidermidis extracts on Staphylococcus Aureus induced toxicity in human keratinocytes.

PURPOSE

Staphylococcus aureus infections are a major cause of concern in nosocomial infections and especially so, in the hospitalized immunocompromised patients. Staphylococcus epidermidis is a skin commensal that could have a role in preventing colonization on human skin by potential pathogen.

METHODS

The probable protective role of S. epidermidis, its lysate (S.epi lysate) and spent culture fluid (SCF) has been explored against S. aureus using human epidermal keratinocytes as a model system. The viability of keratinocytes and bacterial adhesion was investigated pre- and post-exposure to S. epi lysate and SCF.

RESULTS

The viability of keratinocytes was significantly reduced when incubated with S. aureus for 24 ​h while S. epidermidis and its extracts exhibited no significant effect. S. aureus infected keratinocytes showed increased viability when incubated with viable S. epidermidis which was even greater with its lysate and SCF. The timing of the application of lysate and SCF affected the degree of protection conferred to the keratinocytes against S. aureus induced toxicity. Co-exposed and post-exposed keratinocytes were afforded equal protection. However, a pre-exposure of 2 ​h was not efficient enough to provide significant protection. S. epi lysate and SCF reduced the number of adherent cells considerably even after 8 ​h of pathogen exposure.

CONCLUSIONS

S. epidermidis and its extracts protect human epidermal keratinocytes from the toxic effects of S. aureus by competitive displacement of pathogen and reduction in adhesion. S. epi lysate and SCF are safer options for the treatment of pathogen induced skin damage.