Characterization of an mcr-1-positive multidrug-resistant Escherichia coli isolate from a supermarket vegetable
MEI Cai-yue1, MA Qin-chun1, WANG Yan1,2, ZHOU Yan-yang1, LI Yun-yun1, SHEN Peng-cheng1,2, WANG Jing1,2, JIAO Xin-an1,2
1. Jiangsu Key Laboratory of Zoonosis/Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China; 2. Key Laboratory of Prevention and Control of Biological Hazard Factors (Animal Origin) for Agrifood Safety and Quality, Ministry of Agriculture and Rural Affairs, Yangzhou University, Yangzhou 225009, China
Abstract：To analyze the characterization of mcr-1-positive multidrug-resistant Escherichia coli isolated from vegetables, 251 vegetable samples were collected from two supermarkets in Yangzhou in 2019. Enterobacteriaceae were isolated with MacConkey plates and MacConkey plates containing 2 mg/L cefotaxime. PCR and sequencing were used to detect the colistin resistance gene mcr-1. The species of the mcr-1-positive Enterobacteriaceae isolate was identified by 16S rRNA gene amplification and sequencing. Antimicrobial susceptibility to 16 commonly used antibiotics was determined with the broth microdilution method. The characteristics of this isolate were analyzed by whole genome sequencing. A total of 189 Enterobacteriaceae isolates were obtained, and mcr-1 was detected in only one Escherichia coli strain isolated from lettuce. This isolate exhibited a minimal inhibitory concentration of 8 mg/L to colistin, and it belonged to ST359. It carried numerous resistance genes, such as blaTEM-1B, blaCTX-M-14, fosA3, oqxAB, tet(A), strAB, floR, sul2 and dfrA12. In addition, mutations in gyrA (S83L and D87N) and parC (S80I) were observed. The strain was resistant to ampicillin, cefazolin, cefotaxime, streptomycin, tetracycline, chloramphenicol, florfenicol, nalidixic acid, ciprofloxacin, fosfomycin, and sulfamethoxazole/trimethoprim. The mcr-1 gene was located on the IncI2 plasmid, which was highly similar to other reported mcr-1-carrying IncI2 plasmids. mcr-1 has been found in vegetables in this region, and mcr-1 is associated with the globally prevalent IncI2 plasmid. Therefore, monitoring of drug-resistant bacteria in vegetables must be strengthened.
梅彩月, 马沁春, 王燕, 周艳阳, 李云赟, 沈鹏程, 王晶, 焦新安. 1株蔬菜源mcr-1阳性多重耐药大肠杆菌特征分析[J]. 中国人兽共患病学报, 2021, 37(7): 618-622.
MEI Cai-yue, MA Qin-chun, WANG Yan, ZHOU Yan-yang, LI Yun-yun, SHEN Peng-cheng, WANG Jing, JIAO Xin-an. Characterization of an mcr-1-positive multidrug-resistant Escherichia coli isolate from a supermarket vegetable. Chinese Journal of Zoonoses, 2021, 37(7): 618-622.
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