Objective   To investigate the inhibitory effect of Berberine hydrochloride alone or combined with antibiotics on the formation of Staphylococcus epidermidis biofilm and the expressions of relative genes in order to explore a new way to treat the infection induced by the bacteria.    Methods   Biofilm of Staphylococcus epidermidis was constructed in vitro first

and then Berberine hydrochloride alone or combined with norvancomycin

ciprofloxacin or erythromycin was used to affect the biofilm formation. Then the inhibition was detected by CRA

and the expressions of icaA and agr by the way of fluorescent quantitation RT-PCR.     Results   The effectiveness of Berberine hydrochloride on the expressions of icaA and agr in Staphylococcus epidermidis was not as better as the other antibiotics. When different-dosed berberine hydrochloride was combined with norvancomycin

ciprofloxacin or erythromycin to affect the biofilm

the inhibition on the expressions of icaA and agr showed a negatively dose-dependent fashion.     Conclusion    Berberine hydrochloride can inhibit the formation of the biofilm of Staphylococcus epidermidisthrough suppressing the relative genes

though not as good as the antibiotics

such as norvancomycin

ciprofloxacin and erythromycin. It should not be combined with these antibiotics because the effectiveness is antagonism.