乳酸菌与Escherichia coli共培养后对诺氟沙星耐药性变化研究

发布时间：2018-01-31 02:03

本文关键词： 乳酸菌大肠埃希氏菌诺氟沙星最小抑菌浓度　出处：《内蒙古农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：本试验对分离自内蒙古四子王旗和达尔罕茂明安联合旗的自然发酵乳制品中的9株乳酸菌与大肠埃希氏菌(Escherichiacoli)进行共培养,采用试管二倍稀释法测定共培养后菌株对临床诺氟沙星抗菌药的最小抑菌浓度(MIC),观察其共培养前后对诺氟沙星药物的耐药性是否发生变化,之后进一步确定影响其耐药改变的因素。结果表明从不同培养基中共培养后分离得到乳酸菌18株,大肠埃希氏菌18株,其中共培养分离得到的乳酸菌的MIC值有所变化,其中有4株菌的MIC值升高,6株菌的MIC值不变,8株菌的MIC值降低,但耐药表型均未发生变化,都表现为耐药;共培养后分离得到的大肠埃希氏菌的MIC也都有所变化,其中有有4株菌的MIC值升高,5株菌的MIC值不变,9株菌的MIC值降低,其中菌株MRS-HZ18-DC、MRS-B26-DC和LB-B26-DC三株菌的耐药表型也发生变化,由耐药菌株变为敏感菌株,其余菌株耐药表型也未发生改变。对耐药表型改变菌株进行不同pH值、不同培养基耐药试验、模拟胃肠液耐药试验、生理生化试验以及16SrRNA同源性分析,结果得出不同培养基和不同pH值对菌株的耐药性都具有一定的影响、试验菌株在人体胃液中,对诺氟沙星药物均表现敏感,而乳酸菌在人工模拟肠液中对诺氟沙星耐药,大肠埃希氏菌在人工模拟肠液中对诺氟沙星耐药中介、耐药改变菌株生理生化表型不同程度的发生了改变。经16SrRNA同源性分析得出MRS-HZ18-DC、MRS-B26-DC和LB-B26-DC与标准菌株DC(ATCC25922)对比同源性达98.2%,共培养后没有改变菌株的基因序列片段。
[Abstract]:In this experiment, 9 strains of lactic acid bacteria isolated from natural fermented dairy products from Sizi Wang Banner of Inner Mongolia and combined flag of Dalmama'an were co-cultured with Escherichia coli (Escherichia coli). The minimal inhibitory concentration of norfloxacin was determined by double dilution method in vitro, and the resistance to norfloxacin was observed before and after co-culture. The results showed that 18 strains of lactic acid bacteria and 18 strains of Escherichia coli were isolated from different culture medium. Among them, the MIC value of lactic acid bacteria isolated from co-culture was changed, and the MIC value of 4 strains was increased. The MIC value of 6 strains was unchanged and the MIC value of 8 strains was decreased. But the phenotypes of drug resistance did not change, all of them showed drug resistance. The MIC of Escherichia coli was also changed after co-culture. The MIC value of 4 strains of Escherichia coli was increased and the MIC value of 5 strains of Escherichia coli was unchanged. The MIC value of 9 strains of Escherichia coli decreased. Among them, the resistant phenotypes of MRS-HZ18-DCG MRS-B26-DC and LB-B26-DC also changed from resistant strains to sensitive strains. The drug resistance phenotypes of other strains were not changed. Different pH values, different medium resistance tests, simulated gastrointestinal fluid drug resistance tests were carried out. Physiological and biochemical tests as well as 16s rRNA homology analysis the results showed that different media and different pH values have a certain effect on the drug resistance of the strains in human gastric juice. All of them were sensitive to norfloxacin, while lactic acid bacteria were resistant to norfloxacin in artificial simulated intestinal fluid, and Escherichia coli to norfloxacin in artificial simulated intestinal fluid. The physiological and biochemical phenotypes of drug-resistant strains changed in different degrees. MRS-HZ18-DC was obtained by 16s rRNA homology analysis. The homology of MRS-B26-DC and LB-B26-DC was 98.2 with the standard strain DCCC25922. The gene sequence of the strain was not changed after co-culture.
【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】：2017
【分类号】：TS201.3

【参考文献】