Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Technologies for Detecting and Determining the Bioavailability of Bacterial Toxins

Location: Foodborne Toxin Detection and Prevention

Title: Detection and isolation of non-O157 STECs

Authors
item Lin, Andrew -
item Clotilde, Laurie -
item Bernard Iv, Clay
item Nguyen, Lam -
item Kase, Julie -
item Son, Insook -
item Carter, John
item Lauzon, Carol -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 17, 2012
Publication Date: N/A

Technical Abstract: Escherichia coli containing one or more of the Shiga toxin genes are characterized as Shiga-toxin producing E. coli (STEC). E. coli serogroup O157 remains the most common STEC in the United States, but epidemiological studies suggest that over 60% of STEC infections are caused by non-O157 STECs, accounting for an estimated 113,000 illnesses annually in the U. S. STEC infections may be mild or asymptomatic, but some may lead to hemorrhagic colitis, hemolytic uremic syndrome and even death. Due to the increased food safety concern with these organisms, developing a reliable, sensitive, and rapid assay capable of detecting and isolating STEC in foods will directly benefit regulatory agencies by minimizing analysis time. STEC heart infusion washed blood agar with Mitomycin-C (SHIBAM) combines modifications to Beutin’s Washed Blood Agar (1) from Sugiyama et al., (2) (addition of Mitomycin C) and Kimura et al., (3) (optimal washed blood and base agar) to better isolate STECs. Most STECs appear hemolytic on SHIBAM plates and are easily distinguishable from background microbiota. Here, we have developed a Luminex based immunoassay capable of detecting E. coli O157, non-O157 STEC (O26, O45, O103, O111, O121, and O145) and/or their virulence factors (Shiga toxins 1 and/or 2) in food samples spiked at = 10 cfu of STEC. Using Magplex-C magnetic microspheres conjugated to O serogroup-specific antibodies is advantageous because they can bind to live cells and be separated by magnetic force to improve isolation of STECs. Combining the Luminex immunoassay and SHIBAM agar can make isolation of STECs less time consuming and less labor intensive.

Last Modified: 7/28/2014
Footer Content Back to Top of Page