Abstract: Objective Two in vitro drug sensitivity test methods, ager plate diffusion method (punch method) and microliquid-based dilution method, were used to observe the in vitro antibacterial activity of Medi hair spray dressing and its main components(Microbial antimicrobial peptide) against common Malassezia on the surface of seborrheic dermatitis lesions of the head. Methods Medi Hair Spray Dressing with different concentration, microbial antimicrobial peptide were used as the experimental group, and Caile lotion (concentration 2% ketoconazole lotion), blank solvent of Medi Hair Spray Dressing were used as the control group,and the diameters of the inhibition zone were compared in each group. The inhibitory effect on Malassezia in vitro was tested by agar plate diffusion method (punch method) and microdilution method, and the MIC (minimum inhibitory concentration) values were also determined. Results Medi Hair Spray Dressing and microbial antimicrobial peptide inhibited Malassezia to varying degrees in vitro,and the effect was positively correlated with drug concentration. Medi Hair Spray Dressing MIC was 0.977 μL/mL;microbial antimicrobial peptide MIC was 3.907 μL/mL. Conclusion Medi Hair Spray Dressing is safe,and has a better inhibition of Malassezia effect.

Key words: Medi Hair Spray Dressing, seborrheic dermatitis, Malassezia, microbial antimicrobial peptide, in vitro antifungal activity, MIC