Effect of thymol combined with oxacillin on methicillin-resistant Staphylococcus aureus (MRSA) biofilm

Abstract:

[Background] methicillin-resistant Staphylococcus aureus (MRSA) can exist in the state of biofilms, which results in multiple resistance and persistent infections. [Objective] By investigating the inhibition and clearance of thymol and oxacillin separately and concurrently on the biofilm formation of MRSA, the effects of combined medications on MRSA biofilms were explored to provide the theoretical basis for clinical combined application of anti-MRSA drugs. [Methods] Broth microdilution method was used to measure oxacillin minimal inhibitory concentration against USA300 strain. The effect of thymol and oxacillin separately and concurrently on the inhibition and clearance of biofilm formation in USA300 was evaluated by crystal violet staining method and colony counting method. [Results] Thymol and oxacillin inhibited the formation of USA300 biofilm at subinhibitory concentrations. At high concentrations, thymol had good removal effects on the biofilm formed in 24 and 72 hours, while oxacillin had no removal effect. The inhibition and clearance effect of the combination of the two drugs on biofilms was further enhanced, and it had a better inhibition and clearance effect at low concentrations. [Conclusion] Compared with thymol and oxacillin alone, the combination of thymol and oxacillin has an enhanced inhibitory and clearance effect on the biofilm of USA300. The combination of the two drugs has a synergistic antibacterial effect.