银黄可溶性粉对猪耐药链球菌的体外抗菌作用及其机理的研究

Study on in vitro antibacterial activity and mechanism of Yinhuang soluble powder against drug-resistant Streptococcus suis

关键词:  银黄可溶粉  耐药链球菌  最小抑菌浓度

Key words:  the soluble powder of silver yellow  swine resistant streptococcus  minimal inhibit concentration

摘要:

摘要：本研究旨在探究银黄可溶性粉对猪耐药链球菌的体外抗菌作用和机理。从5株猪链球菌临床分离株中筛选出耐药菌和敏感菌。采用牛津杯法分别对筛选出的敏感菌和耐药菌以及标准菌进行体外抑菌试验，筛选出各菌的最佳药物浓度。采用生长曲线绘制、蛋白质测定、细胞膜电镜观察等方法揭露其抗菌机理。结果表明，在5株临床分离株中，①为敏感菌，④为耐药菌，采用牛津杯法进行体外抑菌试验后筛选出各菌的最佳药物浓度均为800 mg/mL；测得敏感菌①、耐药菌④和标准菌的MIC分别为25 mg/mL、25 mg/mL、12.5 mg/mL，MBC分别为50 mg/mL、25 mg/mL、12.5 mg/mL；随着时间的推移，各菌OD值均增加，药物浓度越高，对细菌生长的推迟作用越强；在敏感菌①和标准菌中，加入银黄可溶性粉可使碱性磷酸酶（AKP）增加，耐药菌④在12.5 mg/mL药液中的AKP含量最高，在6.25 mg/mL中最低；电镜图显示，未加药的细菌菌体边界清楚，个体独立，而加药的细菌菌膜破裂，失去原有的形态，细菌间相互粘连，且耐药菌④细胞膜破损程度与药物浓度呈梯度依赖性，随着药物浓度的增加，细胞膜破损愈严重，在12.5 mg/mL时，链球菌抑制效果最为明显。综上所述，银黄可溶性粉对猪耐药链球菌具有抗菌作用，其作用途径之一为损伤细菌的细胞膜，药液最低有效浓度为12.5 mg/mL。

Abstract:

Abstracts：The aim of this study was to investigate the antibacterial effect and mechanism of Yinhuang soluble powder on drug-resistant Streptococcus suis. Drug-resistant and susceptible bacteria were screened out from 5 clinical isolates of Streptococcus suis. Using Oxford cup method to carry out in vitro bacteriostatic tests on the selected sensitive bacteria, resistant bacteria and standard bacteria, and screened out the best drug concentration of each bacteria. The bacteriostatic mechanism was revealed by the methods of growth curve drawing, protein determination, electron microscope observation, etc. The results showed that among the 5 clinical isolates, ① was the sensitive bacteria and ④ was the drug-resistant bacteria, and the optimum concentrations of drug were 800 mg/mL for all the bacteria. The MICs of sensitive, drug-resistant and standard bacteria were 25mg/mL, 25mg/mL, 12.5mg/mL and 50mg/mL, 25mg/mL,12.5mg/mL for MBCs, respectively. And with the passage of time, the OD value of each bacteria increased, the higher the drug concentration, the stronger the delayed effect on growth of bacteria; in sensitive and standard bacteria, the addition of drug solution could increase AKP, while in drug-resistant bacteria, AKP was the highest in the concentration of 12.5 mg/mL and the lowest in the concentration of 6.25mg/mL. In the electron microscopic observation, the bacteria without drug had clear boundary and individual independence; nevertheless, the bacterial membrane of drug-added bacteria break down, lost their original form, and adhered to each other. The degree of cell membrane damage of drug-resistant bacteria ④ was gradient-dependent with the drug. With the increase of drug concentration, cell membrane damage was more serious. At 25mg/mL, drug-resistant bacteria④had the most obvious inhibition effection. In conclusion, Yinhuang soluble powder has inhibitory effect on Streptococcus suis, one of the ways of which is to damage the cell membrane of bacteria , and the minimum effective concentration is 25mg/ mL.