【摘要】 目的对蔬菜源mcr-1阳性多重耐药大肠杆菌的菌株特征进行分析。方法 2019年从扬州2个超市采集251份零售蔬菜样品,通过麦康凯平板和含2 mg/L头孢噻肟的麦康凯板进行肠杆菌的分离,PCR和测序检测黏菌素耐药基因mcr-1的携带情况,利用16S rRNA基因扩增和测序对mcr-1阳性肠杆菌进行菌种鉴定,采用微量稀释法测定其对常见16种抗菌药物的敏感性,并通过全基因组测序分析该菌株的特征。结果共分离得到189株肠杆菌,其中仅在1株分离自生菜的大肠杆菌中检测到mcr-1。该菌株对黏菌素最小抑菌浓度为8 mg/L,多序列位点分型结果为ST359,携带bla_TEM-1b、bla_CTX-M-14、fosA3、oqxAB、tet（A）、strAB、floR、sul2、dfrA12等多种耐药基因,染色体GyrA在第83位（S83L）和第87位（D87N）氨基酸发生突变,ParC在第80位氨基酸（S80I）发生突变。该菌对氨苄西林、头孢唑啉、头孢噻肟、链霉素、四环素、氯霉素、氟苯尼考、奈啶酸、环丙沙星、磷霉素和复方新诺明耐药。mcr-1基因位于IncI2质粒上,与国内外报道的携带mcr-1的IncI2质粒高度相似。结论已在蔬菜沾染细菌中发现mcr-1基因,且mcr-1基因位于全球流行的IncI2质粒上,应加强对蔬菜中耐药菌的监测。更多还原

【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 16 S 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 bla_{TEM-1 B}, bla_CTX-M-14, fosA3, oqxAB, tet（A）, strAB, floR, sul2 and dfrA12. In addition, mutations in gyrA（S83 L and D87 N） and parC（S80 I） 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.更多还原