Antimicrobials as potential adjunctive agents in the treatment of biofilm infection with Staphylococcus epidermidis

Background: This study was performed to evaluate the interaction of erythromycin or rifampin with vancomycin against Staphylococcus epidermidis biofilms. Methods: Biofilm-forming S. epidermidis strains (ATCC 35983, 35984) and polyurethane (PU) sheets were incubated for the formation of bacterial biofilms. Biofilms on PU sheets were treated with various antibiotic regimens. The number of viable bacteria on the sheets was counted. Results: While erythromycin or vancomycin alone did not significantly reduce the biofilm bacterial concentration, the combination of vancomycin and erythromycin resulted in a clear reduction in bacterial concentration compared with the single agents. Rifampin was the most active single agent against biofilm-forming S. epidermidis, while the combination of rifampin and vancomycin showed further reduction in bacterial concentration. Conclusions: These data suggest that the combination of erythromycin or rifampin and vancomycin is more effective than vancomycin alone in the treatment of biofilm infections caused by biofilm-forming S. epidermidis.