鸡源大肠杆菌中耐药基因bla_(CTX-M)的水平转移研究
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摘要
本研究对四川省规模化鸡场分离出的29株产ESBLs的大肠杆菌进行了bla_(CTX-M)耐药基因检测和接合试验,并对供体菌和得到的接合子进行了耐药表型及基因型比较。结果显示:29株产ESBLs的大肠杆菌中均检出bla_(CTX-M)基因,包括7个亚型;29株大肠杆菌中有11株接合成功,接合效率在在10~(-5)～10~(-3)之间;所有接合子均表现出头孢噻肟耐药性,11株接合子中有3株接合子为多重耐药菌;与供体菌相比,100%接合子的耐药谱变窄;所有接合子的bla_(CTX-M)基因型与其供体菌相同。试验表明:规模化鸡场中产ESBLs大肠杆菌中的耐药基因bla_(CTX-M)可通过接合的方式水平传播。
In this study, 29 strains of ESBLs-producing Escherichia coli isolated from large-scale chicken farms in Sichuan province were tested for bla_(CTX-M)and the conjugation experiments were carried out.Resistant phenotypes and genotypes of donor bacteria and zygotes were compared. The results showed that bla_(CTX-M)gene was detected in 29 ESBLs-producing Escherichia coli strains,including 7 subtypes. Among 29 Escherichia coli strains,11 were successfully joined and the transconjugative efficiency was between 10~(-5)～10~(-3).All of the transconjugants showed cefotaxime resistance. Three of the 11 zygotes were multi-resistance,with 100% of the zygoticarms narrowing compared with the donor bacteria;all zygotes bla_(CTX-M)genotype was the same as its donor bacteria. This research indicated that in the large-scale chicken farms,the bla_(CTX-M)resistance gene in Escherichia coli prducing ESBLs could be transmitted horizontally by conjugation.
In this study, 29 strains of ESBLs-producing Escherichia coli isolated from large-scale chicken farms in Sichuan province were tested for bla_(CTX-M)and the conjugation experiments were carried out.Resistant phenotypes and genotypes of donor bacteria and zygotes were compared. The results showed that bla_(CTX-M)gene was detected in 29 ESBLs-producing Escherichia coli strains,including 7 subtypes. Among 29 Escherichia coli strains,11 were successfully joined and the transconjugative efficiency was between 10~(-5)～10~(-3).All of the transconjugants showed cefotaxime resistance. Three of the 11 zygotes were multi-resistance,with 100% of the zygoticarms narrowing compared with the donor bacteria;all zygotes bla_(CTX-M)genotype was the same as its donor bacteria. This research indicated that in the large-scale chicken farms,the bla_(CTX-M)resistance gene in Escherichia coli prducing ESBLs could be transmitted horizontally by conjugation.
引文
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[2]常洪美.2005~2008年临床常见细菌耐药性分析[J].现代预防医学,2009,36(19):3 718-3 720.
[3]Eckert C,Gautier V,Saladin-Allard M,et al.Dissemination of CTX-M-typeβ-lactamases among clinical isolates of Enterobacteriaceae in Paris,France[J].Antimicrobial Agents and Chemotherapy,2004,48(4):1249-1 255.
[4]Clewell D B,An F Y,White B A,et al.Sexpheromones and plasmid transfer in Streptococcus faecalis:apheromone,c AM373,which is also excreted by Staphylococcus aureus[J].Basic Life Sciences,1985,30(5):489-503.
[5]应永飞.滥用兽药是自毁养殖“长城”——畜禽产品的兽药残留问题及其解决对策[J].中国动物保健,2008(3):21-26.