To explore the inhibition and scavenging effects of TH-w3 extracted from Tetrastigma hemsleyanum on the formation of Staphylococcus aureus biofilm.

TH-w3 was prepared from dried root of Tetrastigma hemsleyanum by reducing pressure and boiling dry after extraction with 80% ethanol. 30 strains of Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive staphylococcus aureus (MSSA) were isolated, cultured and preserved respectively. Colony-counting method was used to draw the biofilm formation curve of Staphylococcus aureus. The minimum inhibitory concentration (MIC) of TH-w3 were determined by visual inspection and absorbance detection via double ratio dilution method. The inhibition and scavenging effects of TH-w3 on the formation of Staphylococcus aureus biofilm were observed by Crystal violet staining.

22 strains of MRSA (73.3%) and 3 strains of MSSA (10.0%) were observed positive membrane formation. The biofilm formation rates between MRSA and MSSA were statistically significant (χ²=43.35, P＜0.01). The MIC of TH-w3 for MRSA and MSSA in positive biofilm-forming groups were both 8.00 μg/ml. The inhibition and scavenging effects of TH-w3 on MRSA and MSSA showed concentration-dependent, and the inhibition and scavenging rates reached the highest (more than 68%) at the concentration of 1 MIC. The inhibitory and clearing effects of TH-w3 with the same MIC on the biofilm of Staphylococcus aureus expressed a smooth increase after 48 hrs. The inhibition and scavenging rates for MSSA showed higher than MRSA in 1/2 and 1/4 MIC group after induction for 24 hours　(P＜0.05).

The trifoliate extract TH-w3 showed significant inhibition and scavenging effects on Staphylococcus aureus biofilm, which promised a potential clinical translational value.