PURPOSE: An antibiotic composition containing plant or extract thereof against pathogenic microorganism is provided to ensure strong antibacterial activity against Burkholderia sp. CONSTITUTION: An antibiotic composition against Burkholderia sp. contains Sesbania grandiflora L. or plant thereof as an active ingredient. The extract is isolated using an organic solvent. The organic solvent is ethanol, methanol, propanol, butanol, methyl acetate, ethyl acetate, methyl ethyl ether, methylene chloride, chloroform, benzene, or acetone. The composition is used for preventing or treating respiratory diseases.본 발명은 식물 또는 그 추출물을 유효성분으로 포함하는 병원성 미생물에 대한 항생용 조성물, 그 제조방법 및 상기 조성물의 사료에 응용에 관한 것이다.