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United States Department of Agriculture

Agricultural Research Service

Research Project: Molecular Biology of Human Pathogens Associated with Food

Location: Produce Safety and Microbiology Research

Title: Use of Photopolymerization for Genotyping Shiga Toxin-Producing Escherichia coli Recovered from Produce Production Regions in California

Authors
item Quiñones, Beatriz
item Swimley, Michelle
item Carychao, Diana
item Patel, Ronak
item Cooley, Michael
item Mandrell, Robert

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 28, 2011
Publication Date: N/A

Technical Abstract: Shiga toxin-producing Escherichia coli (STEC) is a leading cause of foodborne illness worldwide. To evaluate better methods to rapidly detect and genotype STEC strains, the present study employed the use of ampliPHOX, a novel colorimetric detection method based on photopolymerization, for pathogen identification with DNA microarrays. A low-density 30-mer DNA oligonucleotide microarray was designed to target O-antigen serotypes implicated in severe human disease as well as virulence determinants that code for adhesins, proteases, cytotoxins, and effectors and that are considered to be necessary for E. coli strains to be pathogenic. Results from the validation experiments demonstrated that the use of ampliPHOX allowed the accurate genotyping of the tested STEC strains, and positive hybridization signals were observed for only probes targeting virulence genes present in the reference strains. STEC isolates were recovered from enriched samples that were collected from wild animal feces, water, lettuce, and soil matrices. Genotyping results demonstrated that a larger group of the STEC isolates possessed genes encoding enterohemolysin (ehxA), serine protease (espP), subtilase cytotoxin (subA), STEC autoagglutinating adhesin (saa), and the O-antigen serotypes O26, O91, O103, O111, O113, O128, and O157. Thus, the use of DNA microarrays in combination with photopolymerization allowed the rapid genotyping and assessment of the potential virulence of STEC strains recovered from food production environments in California.

Last Modified: 9/2/2014
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