Haemophilus parasuis (H. parasuis), the cause of the Glasser’s disease, is a potentially pathogenic gram-negative organism that colonizes the upper respiratory tract of pigs. The extraction of Blumea balsamifera DC., as a traditional Chinese herb, has shown great bacteriostatic effect against several common bacteria. To study the antibacterial effect on H. parasuis in vitro, this study evaluated the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Blumea balsamifera DC. essential oil (BBO) as well as morphological changes in H. parasuis treated with it. Furthermore, changes in expression of total protein and key virulence factors were also assessed. Results showed that the MIC and MBC were 0.625 and 1.25 μg/mL, respectively. As the concentration of BBO increased, the growth curve inhibition became stronger. H. parasuis cells were damaged severely after treatment with BBO for 4 h, demonstrating plasmolysis and enlarged vacuoles, along with broken cell walls and membranes. Total protein and virulence factor expression in H. parasuis was significantly downregulated by BBO. Taken together, these results indicated a substantial antibacterial effect of BBO on H. parasuis.

中文翻译：

---

Blumea balsamifera DC 的抗菌作用。抗副猪嗜血杆菌精油

副猪嗜血杆菌（H. parasuis）是格拉瑟氏病的病因，是一种定植于猪上呼吸道的潜在致病性革兰氏阴性菌。Blumea balsamifera DC.作为传统中草药的提取物，对几种常见细菌均表现出很好的抑菌作用。为研究体外对副猪嗜血杆菌的抗菌作用，本研究评估了香脂木兰 DC 的最低抑菌浓度 (MIC) 和最低杀菌浓度 (MBC)。精油 (BBO) 以及用它处理的副猪嗜血菌的形态变化。此外，还评估了总蛋白和关键毒力因子表达的变化。结果显示MIC和MBC分别为0.625和1.25μg/mL。随着BBO浓度的增加，生长曲线抑制作用变得更强。H。用 BBO 处理 4 小时后，副猪细胞受到严重破坏，表现出质壁分离和液泡增大，以及细胞壁和细胞膜破裂。BBO显着下调副猪嗜血菌的总蛋白和毒力因子表达。总之，这些结果表明 BBO 对副猪嗜血杆菌具有显着的抗菌作用。