Shiga Toxins Stay in the Forefront of E. coli Research

Do you remember when Lauren Rudolph, Michael Nole, Celina Shribbs, and Riley Detwiler made headlines? Sadly, these individuals are linked forever with some of the darkest days in U.S. foodborne illness history. They are the four children who died as a result of the E. coli O157:H7 contamination traced to hamburgers served at Jack in the Box restaurants back in 1993.

Twenty-five years after their tragic deaths at the tender ages of six years, two years, two years, and 17 months respectively, O157:H7 and other Shiga toxin-producing E. coli (STEC) are still a major threat to food safety and public health.

During 2017, of the 24,484 cases of U.S. foodborne illness identified by the CDC FoodNet, 2,050 cases were attributed to STEC (all serogroups were combined) as the cause, with an incidence of 4.2 cases per 100,000 population. Thus, STEC ranked fourth behind Campylobacter, Salmonella, Shigella, which placed first, second, and third, respectively in both number of cases and incidence rate.

As of May 16, 2018, 149 people infected with the outbreak strain of E. coli O157:H7 associated with romaine lettuce believed to originate in Yuma, Arizona have been reported from 29 states. Of those, 64 people have been hospitalized, including 17 who developed hemolytic uremic syndrome. One death has been reported.

These events are difficult reminders of the importance of the science and produce industries working together towards the continuous improvement of food safety programs, says Bonnie Fernandez-Fenaroli, executive director of the Center for Produce Safety (CPS), Woodland, California.

“The Center for Produce Safety was established in 2007 to identify produce food safety knowledge gaps, and where appropriate, fund research to fill those gaps,” Fernandez-Fenaroli relates. “While the CPS’ body of knowledge in many important areas, such as open water delivery systems and wash water management continues to grow, we must assure that the information we learn through our research is made available and useful for the produce industry.”

It’s no surprise that E. coli, most especially STEC, is the subject of constant food industry stakeholder scrutiny and research.

Risk Assessment and Consumer Outreach

Most notably, the University of Nebraska-Lincoln (UNL) has been spearheading a collaborative and wildly productive five-year project targeting risk assessment and consumer outreach for STEC and beef, courtesy of a $25 million grant funded by the USDA National Institute of Food and Agriculture (NIFA). As a NIFA Coordinated Agricultural Project (CAP) titled, “Shiga Toxigenic Escherichia coli in the Beef Chain: Assessing and Mitigating the Risk by Translational Science, Education and Outreach,” the project is known familiarly as STEC CAP, according to Rodney A. Moxley, DVM, PhD, a Charles Bessey Professor at the UNL School of Veterinary Medicine and Biomedical Sciences and STEC CAP project director.

“More than 50 scientists representing some 18 institutions are conducting integrated research, education, and extension projects on eight types of STEC,” Dr. Moxley says “Along with the best-known STEC, the notorious E. coli O157:H7, seven other non-O157 STEC strains that are not as well understood are being studied, partly because outbreaks due to these strains are rarely identified.”

Wide representation from the beef production and processing industry, beef industry technology providers, wholesale/retail/food service sector, academic and regulatory experts, and consumer advocacy organizations are involved as research and education contributors or technical advisors as members of the STEC CAP Stakeholder Advisory Board (SAB).

Dr. Moxley points out that more than 470 serotypes of STEC have been isolated from human patients.

“Scientists note that O157:H7 is something of an anomaly among STEC because it is relatively easy to culture and study,” he says. “In contrast, non-O157 STEC in general are harder to detect by culture and have a greater likelihood of being undetected. While large-scale E. coli outbreaks garner headlines, they represent only about 25 percent of infections. The rest are individual or small-scale outbreaks.”