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摘要：本试验通过给饲喂不同铜水平日粮的大鼠灌喂blaCTX-M阳性接合子，探讨高铜和抗生素对blaCTX-M在大肠杆菌间水平传播的影响。试验以32只SPF级大鼠为对象，分为正常铜对照组, 正常铜灌药组，高铜对照组，高铜灌药组。在特定时期给所有大鼠灌胃菌液，给灌药组大鼠灌喂治疗剂量的盐酸头孢噻呋，未灌药组大鼠灌喂等体积食用油。采集大鼠粪样，进行平板计数，对分离株进行抗生素敏感性检测。结果表明：灌喂抗生素后，灌药组耐药菌数量极显著高于其相对应对照组，且停止用药后高铜组耐药菌消失的速度慢于正常组。综上所述，高铜促进了耐药基因的水平传播和文持，但在高铜与抗生素共同存在时，抗生素对于耐药菌的文持效果更加明显。26244
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毕业论文关键词：铜；头孢噻呋；肠杆菌；抗生素耐药性；接合转移
Impact of high level of long-term in feed copper and ceftiofur on blaCTX-M gene conjugational transfer between E.coli obtained from feces of rats
Abstract：In this study, rats fed with different levels of copper were orally inoculated with an rifampicin-resistant E.coli EC600 strain harboring a conjugative plasmid carrying a gene conferring resistance blaCTX-M. This experiment aimed to evaluate the impact of high level of long-term in feed copper and ceftiofur on horizontal transfer of blaCTX-M among the E.coli. 32 male rats were randomly assigned to two control groups (C-:Cu:6mg/kg, without ceftiofur treatment or C+: Cu:6mg/kg, with ceftiofur treatment), and two treatment groups (H-:Cu:240mg/kg, without ceftiofur treatment or H+: Cu:240mg/kg, with ceftiofur treatment). All rats were orally inoculated with an rifampicin-resistant E.coli EC600 strain carrying blaCTX-M at 20, 22, 24 days. The ceftiofur (CTO) groups (C+ and H+) were given 10 mg/kg of body weight ceftiofur hydrochloride at 26, 27, 28 days, while the control groups (C- and H-) were given salad oil at the same dose. Fecal samples obtained from rats were used for enumeration of total Enterobacterium on Mac plates and resistant Enterobacterium on cefotaxime (CTX)-Mac plates. The antibiotic resistance was also detected using agar dilution method according to the recommendation of CLSI. After administration of ceftiofur, the counts of CTX-resistant Enterobacterium in CTO group were significantly higher than that in corresponding control group（p＜0.01）. Compared with the corresponding control group, the rate of disappearance of the total Enterobacterium was faster in the C- group compared with the H- group after the treatment of ceftiofur. In conclusion, high copper facilitates the horizontal transfer and maintenance of the resistant genes. However, in the presence of high copper and antibiotics, antibiotics for the maintenance effect is more obvious.
Key words: copper; ceftiofur; Enterobacterium; antibiotic resistance; conjugation transfer
目 录
摘要 1
关键词 1
Abstract 1
Key words 2
引言 2
1 材料与方法 3
1.1 菌株来源 3
1.2 试剂和仪器 3
1.3 灌喂接合子菌株的制备 3
1.3.1 接合转移试验 3
1.3.2 接合子的鉴定与保存 3
1.4 动物试验设计 4
1.4.1 试验准备与分组 4
1.4.2 动物试验过程 5
1.5 肠道细菌平板计数及肠杆菌的分离保存 5
1.6 抗生素敏感性检测 5
1.7 铜敏感性检测 6
1.8 抗性基因检测 6
1.9 数据处理与分析 7
2 结果与分析 7