Inhibition mechanism of gallnut on biofilm formation by methicillin-resistant Staphylococcus aureus / 中国生化药物杂志

ABSTRACT

Objective To investigate the inhibition mechanism of gallnut on biofilm formation by MRSA 41577.Methods TTC assay was used to detect inhibitory effects of biofilms formation and mature biofilms.The of PIA on biofilm formation was studied using Congo red agar method.Micro-Ultraviolet Spectrophotometer was used to detect inhibitory effects of the release of eDNA.The influence for Baicalein on icaA and cidA gene expression were detected by RT-PCR method.Results The inhibitory concentration (MIC) and minimum bactericidal concentration (MIC) of MRSA 41577 BF were 0.5 mg/mL and 1 mg/mL, respectively.The inhibitory effect of galla on MRSA 41577BF formation and mature BF was significantly inhibited.Inhibition of MRSA 41577,the MIC and MBC of mature BF were 4 mg/mL and 16 mg/mL.Congo red test results show that Galla can inhibit the synthesis of MRSA 41577 PIA, and the concentration was dose-dependent.The results showed that gallnut could inhibit the release of MRSA 41577 eDNA, and the release amount of eDNA was 3.61μg/OD595 and 11.91μg/OD595 , respectively, when the concentration of gall was 1/2MIC.The release of eDNA was reduced by 69.7% (P<0.01).The expression of icaA and cidA genes in the control group was 9.7% and 6.67%, respectively.The expression of icaA and cidA in the control group was significantly lower than that in the control group ( icaA and cidA, and cidA gene expression were 100%, the expression of icaA and cidA genes were reduced by 90.3%and 93.3%, respectively (P<0.01).Conclusion The inhibitory effect of gallnut on the biofilm of MRSA 41577 is mainly through inhibiting the expression of icaA and cidA genes, and then affecting the synthesis of PIA and the secretion of eDNA .