苦豆子碱对耐药性大肠杆菌PBP3及I类整合子作用的研究

发布时间：2018-11-24 19:57

【摘要】：大肠杆菌对β-内酰胺类抗生素的耐药性发展迅速,细菌可以产生多种耐药机制,其中PBP3是β-内酰胺类抗生素主要作用靶位点,靶位蛋白的任何改变都能使大肠杆菌对β-内酰胺类抗生素产生耐药。整合子在水平传递细菌耐药性方面发挥重要作用,是细菌多重耐药性形成的主要手段,大部分耐药性的水平传播都是由Ⅰ类整合子介导的。本研究选取苦豆子碱作为受试药物,分析临床分离菌株对苦豆子碱及β-内酰胺类抗生素的敏感性,进一步用苦豆子碱亚抑菌浓度作用于稳定表达PBP3的耐药菌株,研究苦豆子碱对PBP3基因序列及mRNA表达量的影响。结果表明,8mg/mL的苦豆子碱作用于产PBP3耐药菌株36h利48h后,能使菌株对抗生素的敏感性发生变化,MIC值下降了8-16倍；苦豆子碱与头孢噻肟、头孢曲松体外联合对大肠杆菌具有协同作用；苦豆子碱虽未能改变PBP3基因序列；但作用后耐药菌株的PBP3mRNA表达量下调,从而使耐药性大肠杆菌恢复相对敏感性。对临床分离的大肠杆菌进行Ⅰ类整合子的分布特性研究。用苦豆子碱亚抑菌浓度作用于Ⅰ类整合子中携带基因盒的阳性菌株,研究药物作用前后对1类整合子的影响。结果表明,临床分离菌株均呈现多重耐药性,耐药种类集中在7-12种抗生素之间；整合酶基因(intI1)检出率为66.7%,基因盒检出率为75%,其中共检测到两种基因盒类型,苦豆子碱亚抑菌浓度作用于基因盒阳性菌株,导致其耐药程度和耐药种类均发生了改变；将药物处理后的基因盒阳性菌株与标准株进行水平培养,研究苦豆子碱对耐药性水平传播的影响。结果表明,豆子碱亚抑菌浓度能够减弱耐药性传播的程度,初步表明苦豆子碱在延缓Ⅰ类整合子散播方面发挥了积极作用。
[Abstract]:The drug resistance of Escherichia coli to 尾 -lactam antibiotics develops rapidly, and bacteria can produce a variety of drug resistance mechanisms, among which PBP3 is the main target of 尾 -lactam antibiotics. Any changes in target proteins can make Escherichia coli resistant to 尾-lactam antibiotics. Integron plays an important role in the horizontal transmission of bacterial drug resistance and is the main method for the formation of multidrug resistance of bacteria. Most of the horizontal transmission of drug resistance is mediated by class I integron. In this study, the sensitivity of clinical isolates to kaliurine and 尾 -lactam antibiotics was analyzed, and the drug resistant strains expressing PBP3 stably were further treated with subinhibitory concentration of kaliudine. Objective: to study the effect of Sophorin on PBP3 gene sequence and mRNA expression. The results showed that the sensitivity of 8mg/mL to antibiotics was changed after treatment of PBP3 resistant strains for 36 h and 48 h, and the MIC value decreased by 8-16 times. The combination of balsicine, cefotaxime and ceftriaxone has synergistic effect on Escherichia coli in vitro. However, the expression of PBP3mRNA was down-regulated in drug-resistant strains, so that the relative sensitivity of drug-resistant Escherichia coli was restored. The distribution of class I integron in clinical isolated Escherichia coli was studied. The effect of subinhibitory concentration of Sophora alopecuroides on class I integron carrying gene cassette positive strains was studied before and after treatment. The results showed that the clinical isolates showed multidrug resistance, and the drug resistance was concentrated in 7-12 antibiotics. The detectable rate of integrase gene (intI1) and gene box was 66.7% and 75% respectively. Two types of cassette were detected. As a result, the degree of drug resistance and the types of drug resistance have been changed. In order to study the effect of Sophorin on the transmission of drug resistance, the gene cassette positive strain and standard strain were cultured at different levels. The results showed that the subinhibitory concentration of soybean alkaloids could reduce the spread of drug resistance, which indicated that kaliuridine played an active role in delaying the dissemination of class I integron.
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R3416

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