2010-2016年四川省食品动物源大肠杆菌的耐药性研究

Drug resistance of Escherichia coli isolates from food-animals obtained from 2010 to 2016 in Sichuan

【目的】了解2010-2016年四川省食品动物源大肠杆菌产超广谱β内酰胺酶(ESBLs)情况及其耐药基因的变迁。【方法】以2010―2016年收集的444株食品动物源大肠杆菌(鸡源225株,猪源219株)为对象,采用纸片扩散法和微量肉汤稀释法分别检测其产ESBLs情况和药物敏感性;采用PCR测序法和脉冲场凝胶电泳(PFGE)检测携带ESBLs菌株的基因型特征和部分菌株的亲缘关系。【结果】444株大肠杆菌中,产ESBLs菌株的检出率为27.7%,其中鸡源菌和猪源菌检出率分别为42.2%和12.8%。2010-2016年产ESBLs菌株从16.9%升高至40.4%,鸡源菌株ESBLs检出率随时间变化比猪源菌更明显;ESBLs阳性菌株对大多数药物的耐药率显著高于阴性菌株,且多重耐药性问题更严重;产ESBLs菌株携带的耐药基因以bla TEM和bla CTX-M为主,并以bla TEM-1(63.3%)、bla TEM-52(32.1%)、bla CTX-M-55(42.2%)、bla CTX-M-65(27.8%)和bla CTX-M-14(21.1%)为主要流行亚型,且检出率及ESBLs基因亚型复杂性呈逐年上升趋势;ESBLs阳性菌株有广泛PFGE谱型,即便携带相同基因型的菌株也不存在亲缘关系。【结论】四川食品动物源大肠杆菌产ESBLs菌株检出率及其耐药基因亚型的复杂程度呈逐年上升趋势,ESBLs是造成多重耐药性的主要原因,ESBLs耐药基因以水平传播为主。

【Objective】This study obtained the prevalence of extended-spectrumβ-1actamases(ESBLs)and ESBL genes in Escherichia coli isolates from food animals in different farms of Sichuan from 2010 to 2016.【Method】A total of 444 Escherichia coli isolates were collected during 2010-2016 from food animals(225 from chicken and 219 from swine)in Sichuan.The K-B and Microdilution broth methods were used to test ESBLs and antibiotic sensitivity,respectively.PCR-sequencing and PFGE were used to identify ESBL genes and homology of isolates.【Result】The detection rate of ESBLs from 444 Escherichia coli isolates was 27.7%,and that from chicken and swine were 42.2%and 12.8%,respectively.The prevalence of ESBL-producing Escherichia coli isolates during 2010-2016 increased from 16.9%to 40.4%,and the rate of ESBLs-producing isolates from chicken was higher than that of swine.ESBL-producing isolates had significantly higher resistance to different antibiotics than ESBL-negative isolates.Genes bla TEM and bla CTX-M were the most common,and main sub-types included bla TEM-1(detection rate 63.3%),bla TEM-52(32.1%),bla CTX-M-55(42.2%),bla CTX-M-65(27.8%)and bla CTX-M-14(21.1%).The detection rate of ESBLs genes and the complexity of gene subtypes increased year by year.The extensive PFGE types were found in ESBLs-producing isolates,and hereditary background was variable although the genotypes were the same in ESBL-producing isolates.【Conclusion】Detection rates of ESBL-producing isolates and ESBL gene types increased during 2010-2016.ESBLs were the main source of resistance and there was horizontal transmission of ESBL genes among different isolates.