猪场环境中大肠杆菌的耐药性检测及其耐药机理

为探讨猪场环境中大肠杆菌的耐药性及其耐药机理,随机选取从规模养猪场环境中分离的31株大肠杆菌,采用药敏纸片法检测其耐药性、PCR法检测其qnrA和aac(6’)-Ib基因存在状况,然后采用高温-SDS法对其中1株分离菌进行耐药质粒消除试验。结果显示,所分离的31株大肠杆菌对青霉素、四环素、洁霉素、红霉素、罗红霉素等抗生素呈现不同程度的耐药性;在所有试验菌株中未检出qnrA基因,而可检出aac(6’)-Ib基因的有8株;通过对含aac(6’)-Ib基因质粒的消除,分离菌株可获得对氨基糖苷类和喹诺酮类抗生素的敏感性。表明猪场环境中的大肠杆菌对临床常用药物产生了广泛的耐药性,而含aac(6’)-Ib基因质粒可介导环境中的大肠杆菌对氨基糖苷类和喹诺酮类抗生素耐药。

Drug-resistance and its mechanism of Escherichia coli isolates from environment of scaled pig farms

To investigate drug-resistance and its mechanism of Escherichia coli isolated from environment of scaled pig farms,31 strains of E.coli were randomly selected from the bacteria from six scaled pig farms and used for analysis of drug-resistance by susceptibility disk diffusion method and detection of qnrA and aac(6’)-Ib gene by PCR,and one strain was picked for elimination test of resistance plasmid by high temperature-SDS method.The results showed that the isolated 31 strains appeared varying degrees of resistance to penicillin,tetracycline,lincomycin,erythromycin,roxithromycin and other antibiotics.And the drug-resistance gene of qnrA was not detected in all the strains,while the aac(6’)-Ib gene existed in eight isolates.The strain could possess the susceptibility to aminoglycosides and quinolones by eliminating the plasmid with aac(6’)-Ib gene.The results suggested that the clinical isolates of E.coli produced a wide range of resistance to the common antibiotics,and the plasmid with aac(6’)-Ib gene in E.coli mediated the resistance to quinolones and aminoglycosides.