牛源大肠杆菌质粒介导喹诺酮类耐药基因的检测分析

为研究近年来新疆地区牛源大肠杆菌中质粒介导喹诺酮类药物耐药基因的分布及其对喹诺酮类抗生素的耐药情况，本研究于2016-2018年从新疆石河子、沙湾、奎屯、玛纳斯和伊犁5个地区12个规模化奶牛场分离出116株牛源大肠杆菌，药敏试验检测其耐药性，同时利用PCR扩增PMQR耐药基因。药敏试验结果显示，62.93%的菌株对氨苄西林耐药，耐药率最高。对链霉素、四环素、卡那霉素和恩诺沙星的耐药率依次为56.90%、54.31%、43.10%和42.24%。对头孢他啶和头孢噻肟的耐药率较低，分别为7.76%和11.21%。分离菌主要携带qnrA、qnrS和aac（6'）-Ⅰb-cr 3种耐药基因；116株大肠杆菌中有31株携带PMQR的耐药基因，检出阳性率为26.72%，其中26株仅携带1种PMQR耐药基因，占所有菌株的22.41%，4株携带2种PMQR耐药基因，占所有菌株的3.45%，1株携带3种PMQR耐药基因，占所有菌株的0.86%。综上所述，新疆地区牛源大肠杆菌质粒介导喹诺酮类药物基因主要为qnrA、qnrS和aac（6'）-Ⅰb-cr 3种，且对恩诺沙星、诺氟沙星、环丙沙星、左氧氟沙星均产生不同程度的耐药性。

Analysis and Detection of Plasmid-mediated Quinolone Resistance Genes in Bovine Escherichia coli

In order to understand the gene distribution of plasmid-mediated quinolone resistance and its resistance to quinolone antibiotics in bovine E.coli in Xinjiang in recent years.116 strains of E.coli were isolated from 12 large-scale dairy farms in Shihezi, Shawan, Kuitun, Manas and Yili of Xinjiang in 2016-2018.The PMQR resistance gene was amplified by PCR and its resistance was detected by drug sensitivity test.The results showed that 62.93% of the 116 bovine derived E.coli strains were resistant to ampicillin, which was the strongest among the 15 tested antibiotics followed by streptomycin, tetracycline, kanamycin and enrofloxacin, whose resistance rates were 56.90%, 54.31%, 43.10% and 42.24%, respectively.The resistance rates to ceftazidime and cefotaxime were lower (7.76% and 11.21%).The PMQR resistance genes carried by the E.coli in Xinjiang were mainly qnrA, qnrS and aac (6')-Ⅰb-cr.The PCR results showed that there were 31 strains carrying PMQR resistance genes in 116 strains, and the positive rate was 26.72%.26, 4 and 1 strains carried 1, 2 and 3 kinds of PMQR resistance gene, accounting for 22.41%, 3.45% and 0.86% of all strains, respectively.In conclusion, the PMQR resistance genes mediated by the E.coli in Xinjiang were mainly qnrA, qnrS and aac (6')-Ⅰb-cr, and it was common for the E.coli resistance to enrofloxacin, norfloxacin, ciprofloxacin and levofloxacin in this area.