Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Guangxi University, Nanning, China.
School of Marine Sciences, Guangxi University, Nanning, China.
J Fish Dis. 2022 Jun;45(6):815-823. doi: 10.1111/jfd.13606. Epub 2022 Mar 22.
Streptococcus agalactiae, also known as Group B Streptococcus (GBS), can infect humans, terrestrial animals and fish. The emergence of bacterial resistance of S. agalactiae to antibiotics leads to an urgent need of exploration of new antimicrobial agents. In the study, the antibacterial activity of natural component plumbagin (PLB) against S. agalactiae was investigated in vitro and in vivo. The results showed that the minimal inhibitory concentration (MIC) of PLB against S. agalactiae was 8 mg/L. The growth curve assay revealed that PLB could inhibit the growth of S. agalactiae. In addition, the time-killing curve showed that S. agalactiae was killed almost completely by 2-fold MIC of PLB within 12 h. Transmission electron microscopy results showed obvious severe morphological destruction and abnormal cells of S. agalactiae after treated with PLB. The pathogenicity of S. agalactiae to zebrafish was significantly decreased after preincubation with PLB for 2 h in vitro, further indicating the bactericidal activity of PLB. Interestingly, PLB could kill S. agalactiae without inducing resistance development. Furthermore, pretreatment and post-treatment assays suggested that PLB also exhibited the antibacterial activity against S. agalactiae infection in vivo by effectively reducing the bacterial load and improving the survival rate of S. agalactiae-infected zebrafish. In summary, PLB had potent antibacterial activity against S. agalactiae in vitro and in vivo, and it could be an excellent antimicrobial candidate to prevent and control S. agalactiae infection.
无乳链球菌，也称为 B 群链球菌（GBS），可感染人类、陆地动物和鱼类。由于无乳链球菌对抗生素的细菌耐药性的出现，迫切需要探索新的抗菌药物。在这项研究中，研究人员研究了天然成分白花丹醌（PLB）对无乳链球菌的体外和体内抗菌活性。结果表明，PLB 对无乳链球菌的最小抑菌浓度（MIC）为 8mg/L。生长曲线测定表明，PLB 能抑制无乳链球菌的生长。此外，时程杀菌曲线表明，2 倍 MIC 的 PLB 在 12 小时内几乎能完全杀死无乳链球菌。透射电镜结果显示，PLB 处理后无乳链球菌的形态严重破坏，细胞异常。体外预孵育 2 小时后，PLB 显著降低了无乳链球菌对斑马鱼的致病性，进一步表明了 PLB 的杀菌活性。有趣的是，PLB 可以杀死无乳链球菌而不诱导耐药性的产生。此外，预处理和后处理实验表明，PLB 还通过有效降低细菌负荷和提高无乳链球菌感染斑马鱼的存活率，表现出对无乳链球菌感染的体内抗菌活性。综上所述，PLB 对无乳链球菌具有强大的体外和体内抗菌活性，可能是预防和控制无乳链球菌感染的优秀抗菌候选药物。
