无乳链球菌和停乳链球菌的几种耐药基因对其毒力的影响

发布时间：2018-07-04 22:42

本文选题：无乳链球菌 + 停乳链球菌　；参考：《内蒙古农业大学》2015年硕士论文

【摘要】：目的：通过体外诱导细菌产生耐药性,分析诱导前后细菌耐药基因与毒力的变化,探讨耐药基因与毒力之间的关系,从而为特定耐药病原体专用新药的研发提供科学依据,亦为链球菌产生耐药性的风险评估提供试验基础。方法：本试验采用微量肉汤稀释法测定抗微生物药对细菌的最小抑菌浓度(MIC)；采用体外逐渐增加药物浓度的方法对标准菌株无乳链球菌CVCC1886和停乳链球菌CVCC3701进行耐药性诱导；采用PCR扩增技术对诱导耐药前后的菌株进行耐药基因和毒力基因的检测；采用形态学观察法对诱导前后菌株的生理生化性质进行对比；通过测定受试菌株对小鼠的LD50比较诱导前后菌株的毒力变化。结果：1、经体外诱导,无乳链球菌CVCC1886和停乳链球菌CVCC3701对7种抗菌药均达到了耐药水平；2、经PCR检测,除青霉素诱导的停乳链球菌CVCC3701在诱导后耐药基因和毒力基因均发生了增加外,用其他抗菌药诱导前后菌株的耐药基因和毒力基因均无变化；3、经形态学观察表明CVCC3701-青霉素的生长繁殖速度明显低于停乳链球菌CVCC3701的生长繁殖速度；4、小鼠毒力试验表明诱导前停乳链球菌CVCC3701和诱导后CVCC3701-青霉素的LD50值分别为5.45x106CFU/mL、5.82x108CFU/mL,诱导后的毒力较诱导前减弱了1.1×102倍,诱导后CVCC3701-青霉素菌株的毒力明显低于诱导前的停乳链球菌CVCC3701。
[Abstract]:Objective: to investigate the relationship between drug resistance genes and virulence by inducing drug resistance of bacteria in vitro, and to provide scientific basis for the development of new drugs for specific drug resistant pathogens. It also provides experimental basis for risk assessment of streptococcus resistance. Methods: the minimal inhibitory concentration (MIC) of antimicrobial agents to bacteria was determined by broth dilution method, and the drug resistance of standard strains CVCC1886 and CVCC3701 was induced by increasing drug concentration in vitro. PCR amplification technique was used to detect the resistance genes and virulence genes of the strains before and after induction of drug resistance, and morphological observation was used to compare the physiological and biochemical properties of the strains before and after induction. The toxicity of the tested strain to LD50 in mice was compared before and after induction. Results: after in vitro induction, both Streptococcus actinomycis CVCC1886 and Streptococcus punctatus CVCC3701 reached the level of resistance to 7 antimicrobial agents, which were detected by PCR. The resistance genes and virulence genes of Streptococcus deltostans CVCC3701 induced by penicillin were increased, but the resistance genes and virulence genes were not changed before and after induced by other antimicrobial agents. 3. Morphological observation showed that the growth and reproduction rate of CVCC3701-penicillin was obviously lower than that of Streptococcus acuminatum CVCC3701. 4. The virulence test of mice showed that the LD50 values of CVCC3701 and CVCC3701-penicillin were 5.45x106CFU / mL5.82x108CFU / mLrespectively, the virulence of induced streptococci CVCC3701-penicillin was 1.1 脳 102.The virulence of induced strain CVCC3701-penicillin was obviously lower than that of CVCC3701before induction.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S852.61

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