100种中草药对无乳链球菌和海豚链球菌体外抑杀研究

Efficacy of 100 Chinese herbal medicines against Streptococcus agalactiae and Streptococcus iniae in vitro

无乳链球菌(Streptococcus agalactiae)和海豚链球菌(Streptococcus iniae)给罗非鱼(Oreochromis sp.)养殖带来了严重的经济损失,而抗生素等药物的使用会造成细菌的耐药性和环境污染,因此,研究了100种中草药对罗非鱼链球菌体外抑杀效果,以筛选出替代抗生素的绿色中草药。其中16种中草药具有较好的抑菌作用,但将其pH值调至7.0±0.04后,大部分中草药的抑菌效果会显著下降(P<0.01),只有桑白皮(Morus alba)、藿香(Agastache rugosa)、豨莶草(Siegesbeckia orientalis)、槐角(Sophora japonica)的抑菌效果比较明显。将pH值调至7.0±0.04后,采用二倍梯度稀释法测定这4种中草药的最低抑菌浓度(Minimal Inhibitory Concentration,MIC)和最小杀菌浓度(Minimal Bactericidal Concentration,MBC),结果显示,桑白皮抑杀无乳链球菌的效果最好,MIC和MBC均为0.3906mg·mL^-1;豨莶草抑杀无乳链球菌的效果次之, MIC为0.3906 mg·mL^-1, MBC为0.7813 mg·mL^-1;藿香、豨莶草、槐角抑杀海豚链球菌的效果最好, MIC和MBC均为0.3906 mg·mL^-1。

With the development of selective and intensive culture, tilapia have been reported to be severely infected by pathogenic Streptococcus agalactiae and Streptococcus iniae. The resultant streptococcosis outbreak is one of the key fish diseases with high mortality rates, and results in severe economic losses as high as ten billion dollars annually. Chinese herbal medicines have been widely acknowledged as a promising strategy owing to multiple advantages in environment, ecology and safety aspects. In this study, extracts of 16 Chinese herbal medicines were discovered to show anti-Streptococcus activities in vitro, after the pH values were adjusted to 7.0±0.04, the antibacterial effect of most Chinese herbal medicines decreased significantly(P<0.01), only Morus alba, Pogostemon cablin, Siegesbeckia orientalis, Sophora japonica, which had well antibacterial efficacy. M. alba had the best effect against S. agalactiae, with the minimal inhibitory concentration(MIC) and the minimal bactericidal concentration(MBC) of 0.3906 mg·mL-1. The efficacy of S. orientalis against S. agalactiae was second, with MIC of 0.3906 mg·mL^-1 and MBC of 0.7813 mg·mL^-1;P. cablin, S. orientalis, S.japonica had the best efficacy against S. iniae, with both MIC and MBC of 0.3906 mg·mL^-1.