双歧杆菌的药敏性及其质粒DNA的检测

利用药敏纸片琼脂扩散法检测了10株具有粘附性的双歧杆菌对临床常用的12大类38种抗菌药物的药敏性。结果显示，对于同一菌株，其对同类抗菌药物表现出基本一致的药物敏感性；不同菌株间在对于同一类药物的敏感性上也有着较好的吻合，如对青霉素类、喹诺酮类、氨基糖甙类及多肽类的表现几乎全为耐药，对头孢类、大环内酯类、磺胺、氯霉素、克林霉素则基本表现为敏感。但在此基础上，不同来源的菌株问也存在着一定的差异。采用碱裂解法提取并检测了受试双歧杆菌的耐药性质粒，仅在一株受试双歧杆菌H-3中发现有1条质粒带，其对应的核酸分子量参照在5148～21226bps之间，其他受试菌株中未发现有质粒存在。

Antibiotic Susceptibility and Plasmid DNA Isolation for Bifidobacteria

To study the relation between antibiotic resistance and plasmids for Bifidobacteria, experiments as below were conducted. With Staphylococcus aureus ATCC 25923 as the control bacterium, the antibiotic susceptibility patterns of 10 strains of adhesive Bifidobacteria were tested by the agar diffusion method. Twelve groups of antibiotics, thirty-eight kinds in total, are involved in the testing. Also the plasmids of the strains tested were extracted by using the alkaline lysis method. The results showed, the same strain exhibited accordant sensibility to the antibiotics of the same group; different strains tested shared great coincidence to the same group of drugs. Nearly all of them were resistant to penicillin group, quinoline group, aminoglycoside group and peptide group, while showing sensitivity to cephalosporin group, macrolide group, sulphonamide group, chloram- phenicol and clindamycin. There were also differences existed between the strains of different origins. Analysis of the plasmid DNA from 10 strains of Bifidobacteria, revealed that the number of plasmid DNA was only one for strain H-3, and that the size of the isolated plasmid DNA was in the range of 5148bps to 21226bps,with no plasmids DNA found in the other Bifidobacterial strains tested.