为深入了解食品源大肠杆菌O157的生物学特点，本研究对2014-2015年分离的39株大肠杆菌O157进行了PCR鉴定，毒力基因和耐药性检测，并利用规律成簇的间隔短回文重复序列（CRISPR）分型技术对菌株的遗传特性进行了分析。结果表明，39株菌株中有8株鉴定为O157:H7，31株为O157；检测的11种毒力基因中，eae存在于所有菌株中，stx2存在于82.50%菌株中，stx1未检出，其他毒力岛基因espA、etpD、tir、toxB、iha和katP携带率分别为92.31%、94.87%、87.18%、79.49%、69.23%和46.15%。药敏试验结果表明，菌株对四环素、复方新诺明、链霉素、氯霉素和氨苄西林等抗生素高度耐药，超过30%菌株具有多重耐药性。CRISPR分型结果表明菌株具有较高的遗传多样性，39株菌株中有33株存在CRISPR1位点，8株E. coli O157:H7产生了相同的CRISPR spacer图谱，而26株E. coli O157产生了13种spacer图谱。本研究为食源性疾病的监测、疾病溯源和流行病学研究提供重要的基础数据。

Escherichia coli O157 is an important food-borne pathogen. 39 E. coli O157 strains identified during 2014 and 2015 in retail foods in china were identified by double PCR to understand the biological characteristics of food-borne E. coli O157. The virulence genes and antimicrobial susceptibility of isolates were also detected, and the genetic diversity of Escherichia coli O157 was analyzed by Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR) typing. The results showed that 8 were identified as O157:H7 and 31 were O157 among the 39 strains. , Eae gene was detected in all the isolates, and stx2 was in 82.50% strains of isolates, while stx1 was not detected in the tested 11 virulence genes. Other virulence genes such as espA, etpD, tir, toxB, iha, and katP were detected with the carrying rate of 92.31%, 94.87%, 87.18%, 79.49%, 69.23%, and 46.15%, respectively. Antimicrobial susceptibility results indicated that the isolates strains were highly resistant to TE, SXT, S, C, and AMP. More than 30% of the isolates were resistance to three and more antibiotics. The CRISPR typing indicated that these isolates strains had a high genetic diversity. Thirty-three of the 39 strains had CRISPR1 loci, including 8 E. coli O157:H7 and 26 E. coli O157. The 8 E. coli O157:H7 produced the same spacer maps, while 26 E. coli O157 produced 13 diversified spacer spectra. This study can provide important basic data for food borne disease surveillance, disease traceability and epidemiological research.

“十三五”国家重点研发计划项目（2016YFD0401204）；广东省科技计划项目（2016A040403088、201704020089）