摘要Background:To investigate the effect of flavaspidic acid BB(BB)on biofilms and quorum sensing-related genes of drug-resistant Staphylococcus epidermidis(SE)and to provide a theoretical basis for the development of BB as a new type of quorum sensing inhibitor.Methods:The microdilution method was applied to screen 15 clinical isolates of S.epidermidis for drug-resistant S.epidermidis to be used as the test strain.The effects of BB on the biofilms of drug-resistant S.epidermidis at different growth stages were studied using the cell counting kit-8 assay and scanning electron microscopy.The gene expression of sigB,sarA,and luxS,regulators involved in quorum sensing of biofilm formation,was measured by PCR.Results:The minimum inhibitory concentrations of BB against 15 clinical strains of S.epidermidis ranged 11.67-66.67 μg/mL.BB significantly inhibited biofilm formation by drug-resistant SE06 in the aggregation and maturation stages,with an activity superior to those of mupirocin and fusidic acid(P<0.05).At 40 μg/mL,BB reduced the secretion of extracellular polymers and promoted the disruption of biofilm structure.At 80 μg/mL,BB specifically interfered with the quorum sensing system of drug-resistant SE06 by downregulating sarA and luxS,thereby inhibiting this microbe's biofilm formation.Conclusion:BB exhibited strong inhibitory activity against SE06 by suppressing biofilm formation and downregulating quorum sensing-related genes and was identified as a new potential quorum sensing inhibitor against S.epidermidis.