Abstract: [Objective] The purpose of this study was to isolate and identify the isolated strains of ducks with clinical fungal infections in Baoding city, and screening the antibacterial drugs for the isolated strains in vitro. [Method] The strains were identified by morphological observation, PCR amplification, sequencing and animal regression test. Microdilution method was used to determine the minimum inhibitory concentration (MIC) and in vitro drug sensitivity test was used to calculate the colony count and diameters to investigate the in vitro antibacterial activities of Acorus gramineus, Phellodendron chinensis, Cassia obtusifolia, Sophora flavescens, Polygonum hydropiper, Pulsatilla adans and Herba taraxaci against Aspergillus fumigatus and Aspergillus flavus. [Result] Aspergillus fumigatus and Aspergillus flavus were successfully isolated. The results of the animal regression test showed that the chicks had the symptoms similar with diseased ducks, the liver had gray-white nodules on autopsy, and granulomatous lesions appeared in the diseased tissues, indicating that both pathogens could infect the chicks. The MIC₈₀ results of Aspergillus fumigatus showed that the MIC₈₀ of Acorus gramineus Phellodendron chinensis, Cassia obtusifolia and Sophora flavescens were 8, 16, 32 and 64 μg/μL, respectively, and Polygonum hydropiper, Pulsatilla adans and Herba taraxaci were all 128 μg/μL. The MIC₈₀ results of Aspergillus flavus showed that the MIC₈₀ of Acorus gramineus, Cassia obtusifolia and Phellodendron chinensis were 8, 16 and 32 μg/μL, respectively, and Sophora flavescens and Polygonum hydropiper were both 64 μg/μL, and Pulsatilla adans and Herba taraxaci were both 128 μg/μL. The results of drug sensitivity test in vitro showed that when the concentration of Acorus gramineus was 16 μg/μL, Aspergillus fumigatus and Aspergillus flavus colonies were grown on the medium, and when the concentration of Cassia obtusifolia was 32 μg/μL, colonies of Aspergillus flavus were grown on the medium, and the concentration of Phellodendron chinensis was 32 μg/μL, Aspergillus fumigatus colonies grew in the medium, while the larger diameter Aspergillus fumigatus and Aspergillus flavus colonies were grown in the medium with a concentration of 128 μg/μL of Sophora flavescens, Polygonum hydropiper, Pulsatilla adans and Herba taraxaci. [Conclusion] Acorus gramineus, Phellodendron chinensis, Cassia obtusifolia had significant inhibitory effects on the growth of Aspergillus fumigatus and Aspergillus flavus, among which Acorus gramineus had the most significant inhibitory effect. This experiment could provide new ideas for the research and development of traditional Chinese medicines against poultry aspergillosis.

Key words: Aspergillus fumigatus; Aspergillus flavus; isolation and identification; traditional Chinese medicine; MIC; bacteriostatic action