鸡源弯曲菌Ⅰ型整合子-耐药基因盒结构分析及接合消除研究

Structure analysis and the connection-elimination investigation of class Ⅰ integron-resistance gene cassette in Campylobacter isolates from chicken source

为了解Ⅰ型整合子-耐药基因盒对弯曲菌耐药性产生和传播的影响,本研究针对前期实验分离得到的312株弯曲菌,检测其Ⅰ型整合子流行情况及耐药基因盒结构,对整合子-耐药基因盒阳性菌株采用自然转化法和化学消除法进行接合消除研究,采用药敏纸片法检测其耐药变化。结果显示:本研究中312株弯曲菌Ⅰ型整合子的流行率为18.6%,15株菌携带有aadA1耐药基因盒;采用自然转化法进行转化试验,自然转化成功率为40%(6/15),自然转化子能够检测出完整I型整合子结构,转化子获得整合子结构后能够产生耐药性;15株弯曲菌经过0.1%SDS化学处理后其耐药基因盒消除,耐药率降低。本研究结果表明虽然化学消除能够在一定程度消除细菌对抗生素的耐药性,但其携带的耐药基因盒能够随着转化使敏感菌株获得耐药性。本研究为家禽养殖生产过程控制耐药性细菌的产生和传播提供科学参考。

To understand the drug resistance and the spread of integron-gene cassette,a total of 312 Campylobacter isolated previously were detected for classⅠintegron and gene cassette,and the isolates with the gene cassette were tested for the connection-elimination study by the natural transformation and chemical elimination methods,and detected the resistance change by Kirby-Bauer(K-B)method.The result showed that 18.6%of Campylobacter isolates were positive for classⅠintegron and the addA1 gene cassette encoding resistance to streptomycin was identified in 15 isolates.Natural transformation contributed to the transfer of aadA1 cassette from 40%(6/15)of the isolates tested to C.jejuni NCTC11168 with a complete integron structure.The aadA1 gene cassette of the 15 isolates was eliminated by treatment with 0.1%sodium dodecyl sulfate,resulting in a loss of integron and a reduction of resistance.Our results illustrated that the drug resistance could be weaken by the chemical elimination,while the drug resistance was restored when the gene cassette was joint with the sensitive strains.This study provides a scientific guidance for controling the emergence and spread of antibiotic-resistant bacteria strains in poultry production.