四川省食品动物源大肠杆菌mcr-1与ESBLs基因共转移分析

为了解四川省食品动物源大肠杆菌mcr-1耐药基因流行情况，及其与超广谱β-内酰胺酶基因(ESBLs)共存和共转移的特征，采用微量肉汤稀释法检测菌株对不同抗菌药物的敏感性；采用PCR检测菌株mcr-1，以及mcr-1阳性菌株中ESBLs基因类型；采用质粒接合转移试验分析了mcr-1与ESBLs基因共转移的耐药机制。结果显示:190株大肠杆菌的mcr-1检出率为36.84%，75.71% mcr-1阳性菌株中同时检出ESBLs基因，主要以blaTEM-1、blaCTX-M-55和blaCTX-M-14为优势基因；mcr-1阳性菌对氨曲南(ATM)、头孢噻肟(CTX)和多黏菌素E(COL)耐药率极显著高于mcr-1阴性菌(P<0.01)；质粒转移率为47.14%，其中获得mcr-1和ESBLs基因共转移的接合子表现出与供体菌相同的耐药表型及耐药基因。综上，在四川省食品动物源大肠杆菌中，mcr-1与ESBLs基因共存现象广泛存在，且耐药基因易发生水平传播，对菌株多重耐药性的产生具有重要意义。

Analysis of co-transfer of mcr-1 and ESBLs genes in Escherichia coli isolates from food-producing animals in Sichuan Province

The aim of this study was to investigate the prevalence of mcr-1 and the co-tansfer of mcr-1 with ESBLs genes in Escherichia coli from food-producing animals in Sichuan Province. The sensitivity of mcr-1 to different antibiotics was detected by broth microdilution method; The ESBLs gene type of mcr-1 positive strains were detected by PCR; The drug resistance mechanism of co-transfer of mcr-1 and ESBLs gene was analyzed by plasmid conjugation transfer test. The results showed that: The detection rate of mcr-1 in 190 E. coli isolates was 36. 84%, and 75. 71% mcr-1 positive strains was detected ESBLs gene simultaneously, mainly blaTEM-1, blaCTX-M-55and blaCTX-M-14as the dominant genes; The resistant rate of mcr-1 positive strains to aztreonam, cefotaxime and colistin was very significantly higher than that of negative strains(P<0. 01); The rate of plasmid conjugation was 47. 14%. The transconjugants with mcr-1 and ESBLs of co-transfer had acquired resistant phenotype and genotypes from parental strains. In conclusion, in the food-producing animals source of E. coli in Sichuan Province, the coexistence of mcr-1 and ESBLs genes is widespread and the resistant genes is easy to spread horizontally, which is of great significance to the production of multiple drug resistance of strains.