Inhibition Mechanism Of Honokiol On Biofilm Formation By Methicillin-resistant Staphylococcus Aureus

Methicillin-resistant S.aureus(MRSA)is one of the key etiological factors of hospital-acquired and communit-acquired infections.It has been considered a global public health problem.MRSA has multiple drug resistance,which biofilm is one of the main resistance mechanism.MRSA biofilm has been one of the vital reasons for causing serious infection beyond cured controlled and repeated attack.In recent years,the study found that Chinese traditional medicine shows the unique advantages in prevention and treatment of chronic infection.This paper selected MRSA41573 strains to study the inhibition mechanism of honokiol on biofilm formation by MRSA.The results are follows:(1)This study used the Congo red agar method and Crystal violet semi-quantitative method selected for strong biofilm producer MRSA41573;At the same time,the process of biofilm formation is detected by Crystal violet semi-quantitative.The results show that it will take three days to form mature biofilm.(2)The MIC and MBC of honokiol inhibit biofilm formation are 10 μg/ml and 20μg/ml,respectly.So,honokiol showed strong antimicrobial activity on biofilm formation.(3)The MIC and MBC of honokiol inhibit mature biofilm are 50 μg/ml and 100μg/ml,respectly.So,honokiol showed strong antimicrobial activity on mature biofilm.(4)Honokiol combined with vancomycin show synergy effect on mature biofilm.When the concentration of vancomycin is less than 64μg/ml,it cannot destroy the mature biofilm.but25μg/ml honokiol combined with 4μg/ml vancomycin can significantly inhibit mature biofilm.The results indicate that honokiol can destroy the mature biofilm,promoting vancomycin to infiltrate into biofilm to kill bacteria.(5)PIA formation and eDNA release were effectively inhibited by honokiol.It indicate that honokiol inhibit biofilm formation through inhibit the synthesis of PIA and eDNA release.(6)When honokiol was used at 1/2MIC,the relative expression of icaA,cidA,agr A and sarA of MRSA41573 were reduced by 59.1%,56%,72.3% and 91% respectively.It indicate that honokiol inhibition of biofilm formation through inhibition the expression of the biofilm-related genes.