The Virulence Genes, Antimicrobial Susceptibility, and CRISPR Molecular Typing of Escherichia coli O157 from Retail Foods in China
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Abstract:
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.
