Inhibition of quorum sensing in drug-resistant Staphylococcus epidermidisbyflavaspidic acid BB.

Background: To investigate the effect of flavaspidic acid BB (BB) on biofilms and quorumsensing-related genes of drug-resistant Staphylococcus epidermidis (SE) and to provideatheoretical basis for the development of BB as a new type of quorumsensing 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 BBonthe biofilms of drug-resistant S. epidermidis at different growth stages were studied usingthecell 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 measuredby 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 biofilmformationbydrug-resistant SE06 in the aggregation and maturation stages, with an activity superior tothose of mupirocin and fusidic acid (P < 0.05). At 40 µg/mL, BB reduced the secretionof extracellular polymers and promoted the disruption of biofilm structure. At 80 µg/mL, BBspecifically interfered with the quorum sensing system of drug-resistant SE06bydownregulating sarA and luxS, thereby inhibiting this microbe’s biofilmformation. Conclusion: BB exhibited strong inhibitory activity against SE06 by suppressing biofilmformation and downregulating quorum sensing-related genes and was identified as anewpotential quorum sensing inhibitor against S. epidermidis. [ABSTRACT FROM AUTHOR]