饲料高铜对大肠杆菌blaCTX-M基因在大鼠肠道内转移的影响
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